. !. tn..€§.’.!..l g I“... .10 Si... .9 '51,! ‘t ., i. . l2»?! s. B... Mfiimu ,‘ a}; .s . a} I 9" . A! p iii-l . I}!!! :2)... 5.5.. . .5): 3.0.5.... I: I... but»! l".1i..n.h.hu MICHIGAN STATE UNNER I ll I: ll lf’rlltltliil f - l! l llllllll 3 1293 01037 9976 W This is to certify that the dissertation entitled METAL—METAL BONDED COMPLEXES IN EXTENDED MOLECULAR ARRAYS presented by Stuart L. Bartley has been accepted towards fulfillment of the requirements for Ph.D. degree in Chemistry flflflflw Major professor DMe August 269 1993 MSU u an Affirmative Action/Equal Opportunity Institution 0-12771 LIBRARY Michigan State Unlverstty PLACE IN RETURN BOX to mow-this chookoutflom your record. TO AVOID FINES Mum on or bdoro duo duo. DATE DUE DATE DUE DATE DUE MSU Is An Affirmative Action/Equal Opportunity Imtitmlon MMmS-pn METAL-METAL BONDED COMPLEXES IN EXTENDED MOLECULAR ARRAYS By Stuart L. Bartley A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Chemistry 1993 ABSTRACT METAL-METAL BONDED COMPLEXES IN EXTENDED MOLECULAR ARRAYS By Stuart L. Bartley Metal-metal bonded dinuclear complexes that are redox active and coordinatively unsaturated are targeted as building blocks in the synthesis of new materials that may exhibit interesting optical, magnetic, or conductive properties. The reactions of dimetal donor compounds (e.g. M2Cl4(PR3)4; M = Re, Mo) with polycyano organic acceptor compounds lead to the formation of covalently linked complexes. The tetranuclear compound [RezCl4(dppm)2]2(tt-TCNQ) (dppm = bis(diphenylphosphino)- methane, TCNQ = 7,7,8,8-tetracyanoquinodimethane) was characterized and is the first structurally characterized example of a complex containing a bridging TCNQ unit. Similar results were obtained using a variety of substituted dicyanoquinodiimines (DCNQI's). An alternative route to the direct ligation of redox active ligands to a metal center was accomplished using the tetrathiafulvalenyl-orth0-bisphosphine compound, thP-TTF-Pth. The reactions of chemically or electrochemically reduced forms of the polycyano acceptors with solvated metal-metal bonded complexes (eg. [Rh2(NCCH3)1()l(BF4‘)4) also lead to covalently linked complexes. Another approach to the synthesis of polymeric materials incorporating metal-metal bonds is the reaction of solvated dimetal cations with homoleptic dinuclear metal-cyanide anions. Several metal-cyanide compounds, including [Bun4N]4[M02(CN)8], were synthesized and spectroscopically and structurally characterized. In general, the chemistry of cyanide with dinuclear compounds has not been well examined, therefore, the chemistry of cyanide with several metal-metal bonded complexes was studied. To my wife Robin and my children Rebecca and Benjamin. iv ACKNOWLEDGEMENTS I would like to first thank Professor Kim R. Dunbar for her guidance and support during these past several years. It is primarily because of her enthusiasm and outstanding ability to teach that I was able to accomplish my goals. I also want to thank all of the past and present Dunbar group students, especially Steven Haefner, Laura Pence, and Sue- Jane Chen, for their excellent help and training when I first began in the lab. It was a pleasure to be able to spend three years in the same lab with Jui-Sui "Alice" Sun as she always had the answers for all of the tough questions. Also, thanks to John Matonic, Anne Quillevere, Gary Finniss, Xiang "Sean" Ouyang, Kemal Catalan, Calvin Ulzemeier, Vijay Saharan and Susan Baker for their help and friendship. Many thanks go to Michigan State University, the Department of Chemistry and the Center for Fundamental Materials Research, and the Council for Graduate Students for financial support. I would also like to thank Dr. Donald Ward for his help with many crystallographic problems and Professors Thomas J. Pinnavaia, James E. Jackson and Eugene LeGoff for being on my Dissertation committee. I want to thank my parents for their support. for having confidence in me and for giving me the freedom to do as I choose. I want to thank my mother- and father-in-law for easing the pressures of graduate school by giving me those needed weekend getaways to Grand Rapids and for helping to care for my children when I needed time for my studies. Finally, a special thanks to my wife Robin for being there for me every step of the way regardless of the circumstances and for making this experience a pleasurable one. vi TABLE OF CONTENTS page LIST OF TABLES .......................................................................... xvii LIST OF FIGURES ........................................................................... xx LIST OF SYMBOLS AND ABBREVIATIONS ................................. xxiv LIST OF COMPOUNDS ............................................................... xxviii CHAPTER I INTRODUCTION ............................................................................... l A. The Synthesis of Molecular Metals and Magnets from Charge-Transfer Reactions. ......................................................... 2 B. Complexes That Contain Covalently linked Donors or Acceptors. ................................................................................. 6 C. The Design of Magnetic Materials ........................................... 8 D. Inorganic-Organic Hybrid Polymers. ...................................... 9 E. Metal-Metal Bonds in Extended Arrays. ................................ 10 CHAPTER II REACTIVITY STUDIES OF Re2C14(dppm)2 WITH TCNE, TCNQ, AND TNAP ...................................................................................... l9 1. Introduction .................................................................................. 20 2. Experimental ................................................................................. 21 A. Synthesis ............................................................................. 21 (1) Preparation of R62C14(dpprmz ..................................... 21 vii (2) 1:1 Reactions of Re2C14(dppm)2 with TCNQ ................. 23 (i) Preparation of (1)-A .......................................... 23 (ii) Preparation of (1)-B ......................................... 23 (iii) Preparation of (1)-C ........................................ 24 (iv) Preparation of (1)-D ........................................ 24 (3) Preparation of [Re2C14(dppm)2]2(u-TCNQ) (2) ............ 24 (i) Bulk Reaction .................................................... 24 (ii) Slow Diffusion Reaction .................................... 25 (4) 1:1 Reactions of Re2C14(dppm)2 with TCNE ................. 25 (i) Preparation of (3)-A .......................................... 25 (ii) Preparation of (3)-B ......................................... 26 (iii) Refluxing Reaction in Toluene ........................... 26 (5) Reactions of RezCl4(dppm)2 with TNAP ...................... 27 (i) Preparation of [Re2C14(dppm)2](TNAP) (4) ......... 27 (ii) Preparation of [Re2C14(dppm)2]2(u-TNAP) (5) ............................... 27 B. X-Ray Crystallography ......................................................... 28 (1) [RezCl4(dppm)2]2(TCNQ)-8THF, (2)-8THF ................. 30 (i) Data Collection and Reduction ............................. 30 (ii) Structure Solution and Refinement ...................... 30 3. Results and Discussion .................................................................... 31 A. Reactions of Re2C14(dppm)2 with TCNQ ................................ 31 (1) Preparation ................................................................ 31 (2) Spectroscopic PI‘OPEFIILS 32 viii (3) X-ray Crystal Structure of [Re2C14(dppm)2]2(u-TCNQ)-8THF (2)-8THF .................... 42 (4) Magnetic and Electrical Properties ............................... 53 B. Reactions of Re2C14(dppm)2 with TCNE ............................... 56 (1) Preparation and Spectroscopic Properties ..................... 56 CHAPTER III THE USE OF N,N'-DICYANOQUINONEDIIMINES AS LINKING UNITS FOR THE DINUCLEAR COMPOUND RezCl4(dppm)2 ............. 74 1. Introduction .................................................................................. 75 2. Experimental ................................................................................ 75 A. Synthesis ............................................................................ 75 (1) Preparation of DCNPQI .............................................. 77 (2) Reaction of Re2C14(dppm)2 with DM-CNQMI ............... 78 (3) Reactions of Re2C14(dppm)2 with DCNQI ..................... 78 (i) Preparation of [Re2C14(dppm)2]2(tt-DCNQI) ........ 78 (ii) 1:4 Re2C14(dppm)2:DCNQI Stoichiometric Reaction. ............................................................... 79 (4) Reactions of RezCl4(dppm)2 with DM-DCNQI .............. 79 (i) 1:1 Reactions ..................................................... 79 (a) Preparation of [Re2C14(dppm)2](DM-DCNQI) (6)-A .............. 79 (b) Preparation of [Re2C14(dppm)2](DM-DCNQI) (6)-B .............. 80 (c) Reaction of 1:1 Re2C14(dppm)2 and DM-DCNQI in Toluene .................................. 80 (ii) Preparation of [Re2C14(dppm)z]2(u-DM-DCNQI) (7) ...................... 81 (a) Slow Diffusion Reaction ............................ 81 (b) Bulk Reaction .......................................... 81 (5) Reactions of Re2C14(dppm)2 with DCNNQI .................. 82 (i) 2:1 Re2C14(dppm)2:DCNNQI Reaction ................. 82 (ii) 1:1 Reaction ..................................................... 82 (6) Reactions of Re2C14(dppm)2 with DCNAQI .................. 83 (i) 1:2 RezCl4(dppm)2:DCNAQI Reaction ................. 83 (ii) 2:1 RezCl4(dppm)2:DCNAQI Reaction ................ 83 (7) 2:1 Reaction of RezCl4(dppm)2 with DC-DCNAQI ........ 84 (8) 2:1 Reaction of Re2C14(dppm)2 with DCNPQI .............. 84 (9) Reaction of [Re2C14(dppm)2]2(DM-DCNQI) (7) with DM-CNQMI. .................................................................. 85 B. X-ray Crystallography ......................................................... 85 (1) [RezCl4(dppm)2]2(DM-DCNQI)-4THF, (7)-4THF ......... 85 (i) Data Collection and Reduction ............................. 86 (ii) Structure Solution and Refinement ...................... 86 3. Results ......................................................................................... 87 A. Reactions of Re2C14(dppm)2 with DM-DCNQI ........................ 88 (1) Preparation and spectroscopic properties ...................... 88 (2) X-ray crystal structure of [Re2C14(dppm)2]3(DM-DCNQI)-4THF. (7)-4THF .............. 89 (3) Magnetic properties .................................................... 92 B. Reactions of RezCl4(dppm)2 with other DCNQIs ..................... 92 4. Conclusions ................................................................................... 99 CHAPTER IV REACTIONS OF M2Cl4(PR3)4, M2Cl4(P~P)2 (M = M0, Re; R = Et, Pr"; P~P = dppm. dmpm. dppe). AND [M2(NCCH3)1o][BF4]4 (M: Mo, Rh) WITH POLYCYANO ACCEP’I‘ORS ............................. 102 1. Introduction ................................................................................ 103 2. Experimental ............................................................................... 103 A. Synthesis ........................................................................... 103 (1) Reactions of Re2C14(PEt3)4 with TCNQF4 .................. 103 (2) Reaction of RezCl4(PEt3)4 with TCNQ ....................... 104 (3) Reaction of RezCl4(PEt3)4 with DM-DCNQI .............. 104 (4) Reactions of M02Cl4(dppe)2 with TCNQ .................... 104 (i) 1:2 M02C14(dppe)2:TCNQ Reaction ................... 104 (ii) 2:1 M02C14(dppe)2:TCNQ Reaction .................. 105 (iii) 4:1 [M02C14(dppe)2:TCNQ] Reaction ............... 105 (5) Reaction of M02C14(dppe)2 with TCNE ...................... 106 (6) Reaction of MozCl4(dppe)2 with TCNQF4 .................. 106 (7) Reaction of M02C14(dppe)2 with DM-DCMQI ............. 106 (8) Reaction of M02C14(dppm)2 with TCNQ .................... 107 (9) Reaction of M02C14(dppm)3 with TCNE ..................... 107 (10) Reaction of M02C14(PEt3)4 with TCNQ .................... 107 (l 1) Reaction of MO?,C14(PEIR)4 With TCNQF4 ................ 108 (12) Reaction of l\~"lozCl4(dmpm)2 with TCNQ .................. 108 xi (13) Reaction of M02C14(dmpm)2 with TCNE .................. 108 (14) Reaction of Re2C14(dppm)2 with TCNQF4 ................ 108 (15) Reaction of Re2C14(PPr"3)4 with DM-DCNQI ........... 109 (16) Reaction of [Rh2(NCCH3)10][BF4]4 with [Bun4N]TCNQ .............................................................. 109 (17) Reaction of [Rh2(NCCH3)10][BF4]4 with LiTCNQ ..... 109 (18) Reaction of [Rh2(NCCH3)1o][BF4]4 with LiTCNQ in H20 .......................................................................... 110 (19) Electrochemical preparation of "Rh(TCNQ)2" ........... 110 (20) Reaction of [Rh2(NCCH3)10][BF4]4 with Li[DM-DCNQI] ............................................................. 1 10 (21) Electrochemical Preparation of " [Rh(DM-DCNQI)2]" ..................................................... l 12 (22) Reaction of [M02(NCCH3)10][BF4]4 with [Bun4N][TCNQ] ............................................................ 112 3. Results and Discussion .................................................................. 112 A. Reactions of Dinuclear Complexes with Polycyano CHAPTER V Acceptors .............................................................................. 112 B. Reactions of Solvated Metal Cations with Reduced Forms of Polycyano Acceptors ............................................................... 118 4. Conclusions ................................................................................. 123 METAL—METAL BONDED COMPOUNDS WITH CYANIDE LIGANDS. ..................................................................................... 127 1. Introduction ................................................................................ 128 . Experimental ............................................................................... 128 A. Synthesis ........................................................................... 128 xii (1) Starting Materials ..................................................... 128 (2) Synthesis of [Bun4N]4[M02(CN)3] (8) ......................... 129 (3) Synthesis of [Bun4N]3[M02(02CCH3)(CN)6] (9) .......... 129 (4) Synthesis of [Et4N]4[M02(CN)3] (10) ......................... 130 (i) Method i ......................................................... 130 (ii) Method ii ....................................................... 130 (iii) Method iii ..................................................... 130 (5) Synthesis of [Bun4N]2[Re2(CN)6(dppm)2] (11) ............ 131 (6) Preparation of "M02(CN)4(NCCH3)x" ........................ 131 (7) Reaction of [Et4N]4[M02(CN)3] with [Rh2(NCCH3)101[BF4]4 ................................................... 132 (8) Reaction of [Et4N]4[M02(CN)g] with [R62(NCCH3)10][BF414 ................................................... 132 (9) Reaction of [Et4N]4[M02(CN)3] with [FCCNCCH3)6][BF412 ...................................................... 132 (10) Reaction of [Bun4N]3[M02(02CCH3)(CN)6] with [Rh2(NCCH3)101[BF4]4 ................................................... 133 (B). X-ray Crystallography ..................................................... 133 (1) [BU"4N]4[M02(CN)8]-8CHC13 (8)-8CHC13 .................. 133 (i) Data Collection and Reduction ........................... 133 (ii) Structure Solution and Refinement .................... 137 (2) [Bu’14N]3[M02(O;>CCH3)(CN)6] (9) ............................ 137 (i) Data Collection and Reduction ........................... 137 (ii) Structure Solution and Refinement .................... 138 xiii (3) [Bu"4N]2[Rez(CN)6(dppm)2l~8CH2C12 (11)-8CH2C12 ............................................................... 139 (i) Data Collection and Reduction ........................... 139 (ii) Structure Solution and Refinement .................... 139 3. Results and Discussion .................................................................. 140 A. Preparation of Cyanide Compounds from Carboxylate and Chloride Compounds. ............................................................. 140 (1) Preparation of Dimolybdenum-cyanide Complexes. ..... 140 (2) Preparation of [Bun4N]2[Re2(CN)6(dppm)2] (11) ........ 141 B. Spectroscopy ...................................................................... 142 C. Molecular Structures .......................................................... 144 (1) Crystal structure of [Bun4N]4[M02(CN)3].8CHCl3 (8)-8CHC13. ...................... 144 (2) Crystal structure of [Bun4N]3[M02(02CCH3)(CN)6] (9). ................................ 144 (3) Crystal structure of [BU"4N]2[R62(CN)6(dPPm)2]-8CH2C12 (1 1)-8CH2C12 ....... 149 D. Reactivity of M02(CN)84' towards solvated metal cations ....... 156 CHAPTER VI REACTIONS OF METAL-METAL BONDED COMPLEXES WITH PHOSPHINE-FUNCTIONALIZED TETRATHIAFULVALENE DONORS ........................................................................................ 165 1. Introduction ................................................................................ 166 2. Experimental ............................................................................... 166 A. Synthesis ........................................................................... 166 (1) Preparation of [Rh{Me3(PPh3)3TTF}]3[BF4] (12) ....... 167 xiv (2) Preparation of ReClz[Me2(PPh2)2'ITF]2 (l3) ............. 167 (3) Reactions of M02(02CCR3)4 (R = H, F) with Mez(PPh2)2TTF ............................................................ 168 (4) Reaction of [Rh2(NCCH3)1o](BF4)4 with Me3(PPh2)'l'I‘F ............................................................. 168 (5) Reaction of [Bu4nN]2Re2C13 with Me3(PPh2)TI‘F ....... 169 (6) Reaction of [Rh2(NCCH3)1o][BF4]4 with (PPh2)4'ITF .................................................................. 169 (7) Reaction of Re2C16(PBu3")2 with (PPh2)4'ITF ............ 170 B. X-ray Crystallography ........................................................ 170 (i) Data Collection and Reduction ........................... 171 (ii) Structure Solution and Refinement .................... 171 3. Results and Discussion .................................................................. 172 A. Synthesis and Spectroscopy. ................................................ 172 (1) Reactions of Me2(PPh2)2TTF .................................... 172 (2) Reactions of Me3(PPh2)TTF ...................................... 178 (3) Reactions of (PPh2)4'I‘TF .......................................... 178 B. X-ray Crystal Structure ...................................................... 179 CHAPTER VII REACTIONS OF THE ELECTRON-RICH TRIPLY BONDED COMPOUND Re2C14(dppm)2 WITH DIOXYGEN. ............................ 182 1. Introduction ................................................................................ 183 XV 2. Experimental Section ................................................................... 183 A. Synthesis ........................................................................... 183 (1) Synthesis of Rez(ll-O)(ll-C1)OC13(dppm)2-(l4) ........... 184 (i) Method A ........................................................ 184 (ii) Method B ....................................................... 184 (2) Synthesis of Rez(u-O)02Cl4(dppm)2 (15) ................... 185 (i) Method A ........................................................ 185 (ii) Method B ....................................................... 185 (iii) Rigorous Exclusion of H20 ............................. 186 B. X-ray Crystallographic Procedures ...................................... 186 (1) Rez(11-0)(u-Cl)0C13(dppm)2°(CH3)2CO (l4)-(CH3)2CO. ............................................................ 187 (2) Rez(u-0)O2Cl4(dppm)2-2(CH3)2C0 (15)-2(CH3)2CO ........................................................... 189 3. Results and Discussion .................................................................. 191 A. Synthesis ........................................................................... 191 B. Spectroscopy ...................................................................... 194 CHAPTER VIII CONCLUSIONS .............................................................................. 207 APPENDIX .................................................................................. 211 xvi 10. ll. LISTS OF TABLES page Summary of crystallographic data for [Re2C14(dppm)2]2(tt-TCNQ)-8THF, (2)-8THF. ........................... 29 Comparison of the CEN and C=C stretching frequencies of various TCNQ containing products ............................................. 34 Comparison of the electronic spectral data of various TCNQ and TCNE complexes ................................................................ 38 Selected bond distances(A), bond angles(°) and torsion angles(°) for [Re2C14(dppm)2]2(tt-TCNQ)~8THF, (2)-8THF. ........ 46 Comparison of selected bond distances and angles of dirhenium complexes exhibiting an unsymmetrical M2L9 geometry. ................................................................................ 49 Comparison of bond distances (A) and angle (°) of several TCNQ containing products. ....................................................... 52 Comparison of v(CEN) stretching frequencies for various TCNE containing complexes ...................................................... 61 Comparison of the infrared spectral features of the TCNQ and TNAP products. ................................................................. 67 Summary of crystallographic data for [Re2C14(dppm)2]2(u-DMDCNQI)-4THF (7)-4THF. ..................... 86 Selected bond distances(A), bond angles(°) and torsion angles(°) for [RezCl4(dppm)2]2(u-DM-DCNQI)~4THF. (7 )-4THF ................................................................................. 97 Tabulation of V(CEN) stretching frequencies for the products from reactions of Re2C14(dppm)2 with DCNQIs. ....................... 100 xvii 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. Comparison of the v(CEN) stretching frequencies for products from reactions of dinuclear donor complexes with TCNQ. .................................................................................. 114 Comparison of the v(CEN) stretching frequencies for products from reactions of dinuclear donor complexes with TCNE. .................................................................................. 115 Comparison of the v(CEN) stretching frequencies for products from reactions of dinuclear donor complexes with TCNQF4 ................................................................................ 116 Comparison of the v(CEN) stretching frequencies for products from reactions of dinuclear donor complexes with DM-DCNQI ........................................................................... 117 Summary of crystallographic data for [Bu4nN]4[Moz(CN)8]-8CHC13 (8)-8CHC13. ............................... 134 Summary of crystallographic data for [Bu4nN]3[Moz(02CCH3)(CN)6] (9). ......................................... 135 Summary of crystallographic data for [BU4nN]2[Re2(CN)6(dppm)2]-8CH2C12 (11)-8CH2C12. ............... 136 Selected Bond Distances (A) and Bond Angles (°) for [Bun4N]4[Moz(CN)g]~8CHC13, (8)-8CHC13. .............................. 146 Comparison of the Mo-Mo bond distances of selected quadruply bonded dimolybdenum complexes ............................. 147 Selected Bond Distances (A) and Bond Angles (°) for [Bun4N]3[M02(02CCH3)(CN)6] (9). ......................................... 150 Selected Bond Distances (A) and Bond Angles (°) for [Bun4N]2[Re2(CN)(,(dppm)2]'8CH2C12, (11)o8CH2C12. .............. 154 Comparison of V(C"=‘N) bands for mixed metal cyanide materials prepared in this study ................................................ 157 Summary of crystallographic data for Re2(H-O)(11-Cl)(O)Cl3(dppm)2'(CH3)QO. (l4)-(CH3)QO. ........... 190 xviii 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. Summary of crystallographic data for Re2(u-O)(O)2Cl3(dppm)2-2(CH3)2O, (15)-2(CH3)20. ............... 192 Selected Bond Distances (A) and Bond Angles (°) for Reg(it-O)(11‘CI)OC13(dppm)2-(CH3)20, (l4)-(CH3)2O ............... 200 Selected Bond Distances (A) and Bond Angles (°) for Re2(tt-O)02C14(u-dppm)2-2(CH3)CO, (15)-2(CH3)CO. ............. 204 Atomic positional parameters and equivalent isotropic displacement parameters (A2) and their estimated standard deviations for [RezCl4(dppm)2]2(u—TCNQ)-8THF, (2)-8THF ...... 21] Atomic positional parameters and equivalent isotropic displacement parameters (A2) and their estimated standard deviations for [RBZCl4(dPPm)2b(u-DMDG\JQI)-4TI-1F (7)-4THF. ......... 215 Atomic positional parameters and equivalent isotropic displacement parameters (A2) and their estimated standard deviations for [Bu4nN]4[M02(CN)3].8CHCl3 (8)-8CHC13 ............ 218 Atomic positional parameters and equivalent isotropic displacement parameters (A2) and their estimated standard deviations for [BU4nN]3[M02(02CCH3)(CN)6] (9). .................... 221 Atomic positional parameters and equivalent isotropic displacement parameters (A2) and their estimated standard deviations for [BU4”N}2[Re2(G\1)6(dppm)2}8CHzC12(11)-8CHzC12. 224 Atomic positional parameters and equivalent isotropic displacement parameters (A2) and their estimated standard deviations for [Rh{Me2(Ph2P)2'ITF}2][BF4] (12) ...................... 227 Atomic positional parameters and equivalent isotropic displacement parameters (A2) and their estimated standard deviations for Re2(1l'0)(tl-Cl)OCl3(dppm)2-(CH3)2CO (14)-(CH3)2CO. ..................................................................... 228 Atomic positional parameters and equivalent isotropic displacement parameters (A2) and their estimated standard deviations for ReQQi-ODQQAdppmn-XCI—hhm (15).2(CH3)2CI). ....................................................................... 230 xix 5‘3”!" 10. ll. l2. 13. LIST OF FIGURES page Side view of the stack in (TMTSF)2(CIO4) .................................... 3 Packing diagram of [(C5Me5)2Mn][TCNQ] .................................... 5 Selected precursors used for charge-transfer chemistry. ............... 22 Pathway of the 1:1 reaction between Re2C14(dppm)2 and TCNQ .................................................................................... 33 Infrared spectral monitoring of the conversion of (1)-A to (1)-B in CH2C12. ...................................................................... 36 Infrared spectral monitoring of the decomposition of a CH2C12 solution containing [RezG4(dppm)p_]2(u—TCI\JQ).(2) ................ 39 Electronic absorption spectrum of [Re2C14(dppm)2]2(p.-TCNQ) (2) in CHzClz. ................................ 41 ORTEP representation of [Re2C14(dppm)2]2(tt-TCNQ)8THF, (2)-8THF ............................ 43 Pluto representation without dppm ligands of [Re2C14(dppm)2]2(tt-TCNQ)8THF, (2)-8THF ............................ 45 Plot of ueff (B.M.) vs. temperature (K) of [RezCl4(dppm)2]2(tt-TCNQ) (2). ............................................... 54 Plot of lieff (B.M.) vs. temperature (K) of [Re2C14(dppm)2](TCNQ) (1)-A. ................................................ 55 Single crystal EPR spectrum of [Re2C14(dppm)2]2(u-TCNQ) (2) at -160°C .................................. 57 Packing diagram of [Re2C14(dppm1212(1l-TCNQ)-8THF. (2)8THF. View down C axis .................................................... 58 XX 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. Variable temperature 31P {1H} NMR (CDC13) spectra of [Re2C14(dppm)2](TCNE) (3)-A .................................................. 63 Cyclic voltammogram of [Re2C14(dppm)2](TCNE) (3)-A in 0.1 M TBABF4/CH2C12.versus Ag/AgCl at a Pt disk electrode .................................................................................. 64 Synthetic route to DCNQI molecules and their cyclic voltammetric properties. ........................................................... 76 Electronic absorption spectrum of [Re2C14(dppm)2]2(u-DM-DCNQI) (7) in CHzClz ......................... 90 ORTEP representation of [Re2C14(dppm)2]2(u-DM-DCNQI)-4THF, (7)-4THF. ................... 91 Pluto view without dppm ligands of [Re2C14(dppm)2]2(u-DM-DCNQI)-4THF, (7)t4THF. ................... 93 Stick modle packing diagram of [Re2C14(dppm)2]2(u-DM-DCNQI)-4THF, (7)~4THF viewed along the c axis ......................................................................... 94 Plot of [Jeff (B.M.) vs. temperature (K) of [Re2C14(dppm)2]2(tt-DM-DCNQI) (7). ....................................... 95 Solid state EPR spectrum of [Re2C14(dppm)2]2(tt-DM-DCNQI) (7) at -l60°C .......................... 96 Schematic drawing of the electrolysis cell used in the electrochemical synthesis of "Rh(TCNQ)2" and "Rh(DM-DCNQI)2" ................................................................ 1 1 1 Plot of ueff and l/x vs. temperature (K) of the product from the reaction of M02C14(dppe)2 with TCNQF4 ............................ 119 Proposed polymeric structure of "Rh(DM-DCNQI)2" ................ 124 ORTEP depiction of the molecular anion [M02(CN)8]4' with atoms represented by their 50% probability ellipsoids. ............... 145 xxi 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. Molecular structure of [M02(02CCH3)(CN)6]3' with the atom labeling scheme. With the exception of the H atoms, the atoms are represented by their 50% probability ellipsoids. .............................................................................. 148 ORTEP plot of a molecule of [Re2(CN)6(dppm)2]2' with non-hydrogen atoms represented by their 50% probability ellipsoids. .............................................................................. 152 View looking down on the equatorial plane of the anion [Re2(CN)6(dppm)2]2' emphasizing the unsymmetrical arrangement of the bridging CN group. .................................... 153 Thermogravimetric analysis of "M02(CN)4(NCCH3)X" ............... 159 Thermogravimetric analysis of "Rh2M02(CN)g(NCCH3)x". ........ 160 Thermogravimetric analysis of "Re2M02(CN)3(NCCH3)x". ........ 161 Thermogravimetric analysis of "Fe2M02(CN)3(NCCH3)x" .......... 162 Pluto representation of [Rh{Me2(Ph2P)2TTF}2][BF4] (12) ......... 173 Stick packing diagram of [Rh{ Me2(Ph2P)2'ITF}2][BF4] (12). ..................................................................................... 174 Cyclic voltammogram of [Rh{Me2(Ph2P)2T1‘F}2][BF4] (12) in 0.1 M TBABF4/CH2C12 vs Ag/AgCl at a Pt disk electrode ................................................................................ 176 Cyclic voltammogram of Remit-O)(u-C1)OC13(dppm)2 (14) in 0.1 M TBABF4/CH2C12 vs Ag/AgCl at a Pt disk electrode ................................................................................ 195 Cyclic voltammogram of Re2(p-O)02Cl4(dppm)2 (15) in 0.1 M TBABF4/CH2C12 vs Ag/AgCl at a Pt disk electrode ................ 198 ORTEP representation of Re2(ll'0)(1J-Cl)OCl3(dppm)2t(CH3)2CO (14)-(CH3)2CO with 35% probability ellipsoids. Phenyl ring atoms are shown as 0.1 A radius spheres .................................................. 199 xxii 40. ORTEP representation of Re2(|.l-O)02Cl4(dppm)2-2(CH3)2CO (15)-2(CH3)2CO with 40% probability ellipsoids. Phenyl ring atoms are shown as 0.1 A radius spheres. .............................................................. 203 xxiii LIST OF SYMBOLS AND ABBREVIATIONS Ag/AgCl B.M. br Bu" ca. cm cm-l CV °C DC—DCNAQI DCNAQI DCNNQI DCNPQI DCNQI DM-CNQMI DM-DCNQI Angstrom silver-silver chloride reference Bohr magneton broad n-butyl circa, about centimeter wavenumber cyclic voltamogram degee centigrade 1,5-dichloro-N,N'-dicyano-9,10- anthraquinonediirnine N,N'-dicyano-9, IO-anthraquinonediimine N,N'-dicyano- l ,4—naphthaquinonediimine N,N'-dicyano-6,13- pentacenequinonediimine N,N'-dicyano-1,4-benzoquinonediimine 2.6-dimethyl-N—cyano- 1 .4-benzoquinone-4- imine 2,5-dimethyl-N,N'-dicyano-1,4- benzoquinonediimine xxiv ZBPI‘WEED‘QW 3 (D doublet parts per million (ppm) bis(dimethylphosphino)methane bis(diphenylphosphino)methane bis(diphenylphosphino)ethane molar extinction coefficient anodic peak potential cathodic peak potential electromagnetic unit electron paramagnetic resonance estimated standard deviation ethyl Fast Atom Bombardment EPR g-value, gram Gauss hour Hertz infrared Kelvin liter wavelength medium moles per liter methyl XXV mg min. mL mmol mult 0X PPm Pr" red l’.t. sh SQUID TCNE milligram minute milliliter millimeter millimole multiplet bridging ligand microliter nanometer frequency nuclear magnetic resonance ohm oxidation parts per million n-propyl resistivity reduction room temperature singlet (NMR), strong (IR) shoulder Superconducting Quantum Interference Device temperature tetracyanoethylene xxvi TCNQ TCNQF4 TGA TNAP TBABF4 7,7,8,8-tetracyanoquinodimethane 7,7,8,8-tetracyano-2,3,5,6- tetrafluoroquinodimethane thermogravimetric analysis 11,11,12,12- tetracyanonapthaquinodimethane tetrathiafulvalene triplet tetra-n-butylammonium tetrafluoroborate teterahydrofuran tetramethylsilane ultraviolet Volt versus, very strong weak halide ligand xxvii LIST OF COMPOUNDS (1) ---------- [R62C14(dppm)21 (T CNQ) (2) ---------- [Re2C14(dppm)2]2(u-TCN Q) (3) ---------- [R62C14(dppm)21(TCNE) (4) ---------- [Re2C14(dppm)21 (TNAP) (5) ---------- [Re2C14(dppm)212(u-TNAP) (6) ---------- [RezC14(dppm)21(DM-DCNQI) (7 ) ---------- [Re2C14(dppm)2]2(u-DM-DCNQI) (8) ---------- [Bun4N]4[M02(CN)8] (9) ---------- [Bu"4N13[M02(02CCH3)(CN)61 (10) --------- [Et4N]4[M02(CN)8] (11) --------- [Bun4N121Rez(CN)6(dppm)2] (12) --------- [Rh{Mez(PPh2)21TF}2][BF41 (13) --------- ReC12[Me2(PPh2)2'ITF]2 (l4) --------- R62(u-0)(u-C1)OC13(dppm)2 <15) --------- Rez(u-O)02Cl4(dppm)2 xxviii CHAPTER I INTRODUCTION .1. 1h (large- 1‘: I . ‘Wf 4‘1‘0I1 \‘undhuyu \"AJ"AVF ‘b¥t¥‘» ‘1 A iu-U‘I‘? "H'bt‘e. 1 NH». . :- 1'0, F'\\.“ _\ i x, t :Hfig‘. 'ltuLl 2'. i .I‘R-‘afi’ \, ““5 I\‘ t Y A" 1' "“Ali 0 ,.‘ t 11"“ pl “.5“ u .1.“- “Ly :1, “VII \P'v "’7‘?! .nl.“‘~ ‘:-1 . ‘yk ‘I I” l l Izqt ‘ ‘ t" :41 ““¥(‘ 1‘», <1. 'I. .51,‘ i" ‘s, .. ‘ 4‘s 1 Q I. ~ 0 ‘ .uo V“ b .u' . ‘. .\ \1 'k '- i... v ”V ‘ H 2 A. The Synthesis of Molecular Metals and Magnets from Charge-Transfer Reactions. There is considerable interest in the design and synthesis of conducting organic charge-transfer salts, organic metals, and organic superconductors.1 Low-dimensional molecular solids comprised of donor- acceptor (D-A) stacks exhibit a variety of properties depending on the precursors and the stacking arrangement. Most charge-transfer solids either possess segregated stacking arrangements in which donors and acceptors are aligned in separate stacks, for example (TTF)(TCNQ), and usually exhibit electrical conductivity, or mixed stack arrangements in which the stacks contain alternating donors and acceptors and usually exhibit interesting optical as well as magnetic properties.2 The segregated structural motif allows for electrical conductivity provided at least one component is in a non-integral oxidation state (i.e.. "mixed valence," "partial oxidation," "incomplete charge transfer"). It has been shown that charge-transfer complexes, in which the difference between redox potentials between the donor and acceptor are small, result in products that exhibit the highest electrical conductivities. Such is the case for (TTF)(TCNQ) with well matched oxidation and reduction potentials that result in a material comprised of partially oxidized 'ITF and partially reduced TCNQ.2 Infrared spectroscopy is a useful tool for ascertaining the amount of charge transfer in these complexes.3 In the segregated stack structures, conduction bands form as the result of intermolecular Tc-overlap, thereby providing a pathway for charge mobility. In some cases superconductivity is even observed as in (TMTSF)2CIO4 (TMTSF = tetramethyltetraselenafulvalene) whose structure (Figure 1) contains partially oxidized TMTSF molecules in one-dimensional stacks.2 Due to Figure 1. Side view of the stack in (TMTSF)2(ClO4) v'm -' Lieli El . . 4W” _ “with - . Hon-t ~t \KIIM“ D ~30”: .,, it: C 1 ~‘ Js‘. “’t‘I‘h.‘ n-q.‘ 4 their similarity to 'I'I‘F, M(bdt)2 (bdt = bis-dithiolene) and M(dmit)2 (dmit = 1,3-dithiol-2-thione-4,5-dithiolate) units have been used to form conductive complexes with both inorganic and organic ions.4 In several examples, TTF itself was determined to bind directly to metal complexes through its S atom.4(b) The complex [Rh2(02CCI-I3)4('ITF)2] was structurally characterized and contains 'I'I‘F molecules bonded through its S atom to the Rh axial positions in which the doped version [Rh2(02CCH3)4(TTF)2]-I3 showed electrical conductivity.5 A large body of research in the field of ferromagnetic molecular charge-transfer complexes has been carried out by Miller et al. at Dupont. A variety of substituted (C5R5)2Fe donors have been reported to form magnetically interesting solids when combined with acceptors such as TCNE, TCNQ, Bis(dithiolato)-metalates, C4(CN)6 .6 The charge-transfer solid [(C5Me5)2Fe][TCNE] forms a mixed stack arrangement and exhibits ferromagnetism below 4.8 K.6 The manganocene derivative [(CSNe5)2Mn][TCNQ], shown in Figure 2, exhibits ferromagnetism with a critical temperature (Tc) of 6.2 K which was considered to be a breakthrough at its time.7 Later, the charge transfer salt [(CsMe5)2Mn][TCNE] was discovered to have a Tc of 8.8 K.8 The C01l'lplexes [(C6R6)2Cr][TCNE]9 and [(C5R5)2Cr][TCNE]10 are also fen‘Omagnetic, while [(C6R6)2Cr][TCNQ] complexes are diamagnetic.54 The iron and ruthenium derivatives of [(C6Me6)2M][TCNQ]x exhibited diaIl‘iagnetic behavior and were poor conductors when x = 2, but were paramagnetic and electrically conductive when x = 4.11 Materials Cornprised of [(C5Me5)2Fe]+ with molecules other than cyano-containing Organic moieties. such as [Fe(C5Me5)2][Ni(bds)2] (bds = bis(di- c . . . . . . halcogolene», have been found to exhibit ferromagnetic behavror.12 12 s -- _ WWW ,. a “éfin Figure 2. Packing diagram of [(C5Me5)2Mn][TCNQ] b1 ‘3 'A ll 1 4...... '3 1 Ekahkbu . l . l"‘fi\1 .‘ Il-‘ ‘:-*u‘e1 P ‘K -, ctr, k 0 l ‘ h w .1 “1‘ tug hp:- \ 41. '2' \ ‘kr‘, H‘;\ ‘1+ ‘1 ‘- ‘ Qt . ‘\ 1‘ a: h I s ‘. '5 1 . p. n. \I .15. u" ' .N t ,.. . I... I ‘h , v ‘1 ‘F‘h “'~ .. \“ ‘. .‘ W “e ’v to .'. 'I 6 While several other theories have been proposed, Miller cites the well- known McConnell model to explain the ferromagnetism in these mixed stacked matallocene-donor/it-acceptor complexes.6(a),13 B. Complexes That Contain Covalently linked Donors or Acceptors. Acceptor molecules such as TCNQ and TCNE have recently been shown to undergo charge transfer reactions with electron-rich organometallic species (C5R5)(CO)2Mn(THF) R = H, CH3 resulting in o-coordinated complexes where one or more N atoms are coordinated to the metal atom.14~15 Similarly, (CO)5 ReFBF3 reacts with TCNE and TCNQ to form o-coordinated di-nuclear and trinuclear nitrile adducts.16 The complexes [Ru(PPh3)2(TCNQ)] and [Cu(pdto)(TCNQ)]2 (pdto = 1,8- di-z-pyridyl-3,6 -dithiaoctane) both contain a o—n 1—coordination modes for TCNQ and have been structurally characterized.17 In other reactions, the electron-rich and coordinatively unsaturated diphosphazene-bridged dimthenium complex Ruz(ll-CO)(CO)4(11'L)2 [L = (RO)2PN(Et)P(OR)2] reacts with TCNQ or TCNE to yield products that contain both inner and Outer sphere TCNQ and TCNE; [Ru2(CO)5(lJ-L)2(n1-TCNX)](TCNX) (X = E, Q).13 In addition to the aforementioned examples, several metal Salts of TCNQ exhibit weakly coordinated TCNQ units.19 There have been a few examples where TCNQ was found to dimerize through o-bonding (ca. 1.64 3020 A serendipitous result in high Tc ferromagnetic materials resulted from the reaction of V(C6H6)2 and TCNE that produced an insoluble arrnorphous solid formulated as V(TCNE)2~1/2(CH2C12). This material is thollght to contain o-coordinated TCNE based on infrared spectroscopy, and was found to be ferromagnetic at room temperature.21 There are ”U.“ . uiull ' lCXEI t ‘""O’ H‘ sun I ' T :1 1C.) 'I'ttl ~y‘. ..1uLt‘u 7 many examples of complexes that contain o-coordinated TCNE13~16r15~14r22 several of which have been characterized by X-ray crystallography.23 The majority of products that contain bound molecules of TCNE exhibit either a o-nl or o—u—nz coordination mode. The first structurally characterized linear chain complex based on TCNE, [MnTPP][TCNE] (TPP = meso-tetra-phenylporphinato), was reported by Miller et al., although it was first synthesized by Basolo and co-workers in 19782300924 The compound was determined to be ferromagnetic with a Tc of 18 K.23(e) Other examples of linear-chain materials [M (hfacac)2][TCNE] (M = Co, Cu; hfacac = hexafluoroacetylacetonate) were reported by Wayland at about the same time.23(c) Recently, a two- dimensional structure consisting of o—u—n‘l-TCNE units linking Rh2(02CCF3)4, through the axial Rh sites, to form a layered material was discovered by researchers in Cotton's laboratories.23(f) The quadruply bonded dimolybdenum complex M02(L)2 (L = dibenzotetraaza-[l4]- annulene) forms a 1:1 charge transfer product with TCNE which reacts with dioxygen or water to form an molybdenum-0x0 product and C3(C3N)5.25 Another class of cyano-containing organic acceptors that has demonstrated an ability to coordinate to metal centers are the N,N'- dicyanoquinonediimines (DCNQIs). Aumtiller and Hiinig reported that a Variety of substituted DCNle could be readily synthesized from quinones; theSe exhibit accessible redox processes which make them good candidates for charge-transfer chemistry.26 A variety of donor-acceptor complexes incOrporating these molecules. including (TTF)(DCNQI), have been Stu died and found to exhibit electrical conductivity/.37 Single crystal X-ray StF11 Ctures of several complexes of the form M(DCNQ1)3 1 M = Cu. Ag. Tl. 11‘; 11: I A...) AED“. I 35 \ v; .“ M L1 1 . a. V .H‘J dug». J‘fwu.‘ B' “4.1 .‘P_. ‘7 s1'_.\.\. .7Pfia "y" n - b.’~‘-l 8 Li) are known and reveal layered two-dimensional sheets.28 In one reported example, DM-DCNQI was used to covalently link Ru2(02CR)4 (R = H, Et, "Pr, Ph) units to form linear chain materials.29 C. The Design of Magnetic Materials. In addition to the above examples of ferromagnetic materials which rely on charge transfer to form, researchers have been making important strides in assembling other types of covalent networks of one-, two- and three- dimensional magnetic materials with unpaired spins built in. For example, Gatteschi et al. have synthesized one dimensional magnetic chains consisting of metal hexaflouroacetylacetonates M(hfac)2 linked by nitronyl nitroxides (NITR) where M = Cu, Ni, Co, and Mn.30 When M = Mn and R = iPr, a ferrimagnetic complex with Tc = 7.6 K is formed as the result of alternating spins of 5/2 and 1/2.30 Kahn employed a similar approach in which ferrimagnetically coupled bimetallic chains, consisting of alternating Mn(S = 5/2) and Cu(S = 1/2) metals, are linked by oxamato bridges.31 In the crystal structure of MnCu(pbaOH)(H20)2 (pbaOH = 2-hydroxy-l,3- Propanediylbisoxamato), the ferrimagnetic chains are aligned such that the Shortest interchain separations are Mn---Cu creating a two dimensional ferromagnetic material with a Tc of 30 K. Recently, Kahn er al. reported a thl‘ee-dimensional compound that is magnetic below 22.5 K with the formula (rad)2Mn2[Cu(opda)]3(DMSO)2~2H20 (rad = 2-(4-N-methyl- pyridinium)-4,4,5,5-tetramethylimidazoline-l-oxyl-3-oxide: opda = ortho- phenylenebisoxamato) in which Mn(ll)6Cu(II)6 hexagons are fully lnterlocked.32 D. In YHI'N “.5 luvx rk. I ".“i‘ M.) Pki‘llls C ‘ C a‘ VI B\ '1‘» ' >‘ .i' {’3' . ‘U\‘ a; ‘- util‘i‘H \U'Ml‘ " lb ' ‘ Q's ‘ \ 0‘ kg u . .“9 t h‘ J. \‘ A u.‘\‘ .- '.’\‘ ~ . __. ‘ I 54“ V \ ‘t. ‘5 '3." 1 ., u.” . ‘. ,‘t .‘wv lilt- . cx‘ - 9 D. Inorganic-Organic Hybrid Polymers. Diisocyanides have been very successful at assembling metal units into polymeric arrays. These ligands have been found to react with [Rh(CO)2Cl]2 and [IrCl(cod)]2 to form insoluble two-dimensional network polymers that are formulated as [M(bridge)2Cl]n in which the non- chelating bidentate ligands act as rigid bridges between metal atoms.33 The two—dimensional sheets are stacked in an eclipsed fashion with columnar metal chains in which Rh-Rh distances in [Rh(Ba)2Cl]n (3.21 A), [Rh(Bb)Cl]n (3.36 A), and [Rh(Bc)Cl]2 (3.54 A) were determined from CN ‘NC CNnNC CN HNC powder X—ray diffraction methods.33 The mixed metal cobalt(II)— rhodium(1) organometallic polymer forms when 4, 4'-diisocyanobiphenyl is used as the connecting rods.34 Electrical conductivity occurs within and between the sheets and is dependent on the M-M interlayer diStances.33(C)~35 Interlayer spacing of these polymers are in the same r aIlge (3 - 4 A) as those found in the planar charge-transfer salts.35 The aCetonitrile complex Pd(NCCH3)2(BF4)2 reacts with diisocyanides to form polymers formulated as [Pd(B)2]n similar to those containing rhodium.36 By taking advantage of the formation of M-CN-M and IVI--NC-R-CN-M linkages. Robson er al. have synthesized extended 3-D fraIiieworks that contain large channels and cavities.37 In fact, chains, Sheets. and three dimensional structures have been observed for a variety Of metal-cyanide complexes. including the Prussian blues.38 An important . _ v hx—"rc .1 R - Y“:.r\ I n‘NIJH'I NCKMuI‘sI ,. 'h""” “Push E. .\l ‘h; "1“ “N \u. “Irv,“ ‘ 1"U\J 11 g 5 .I JI'HJ' l hlgr5‘ '-\vvd.‘L. I“ Q 1' § I.- ~ “k ‘ \ v ‘ 0 «w s_l A s‘. o. 1‘“ Vu‘ I.‘ .7 ,7 b. l " P Jr I". '2'!- ”K 10 potential direction for these is the tailoring of structures for catalytic applications. E. Metal-Metal Bonds in Extended Arrays. Macromolecular chemistry based on M-M multiple bonds has been the subject of recent work by Chisholm et al., particularly with regards to linking quadruply bonded molybdenum and tungsten dinuclear species in either perpendicular or parallel arrangements.39v4O In the quest for such robust, covalently linked, one dimensional polymers, tetranuclear complexes were synthesized by the exchange of carboxylate groups on M2(02CR)4 with dicarboxylates.39 The choice of the R' substituent 2M2(02CR)4+ HOzCR'COzH —> [M2(OzCR)3]2(tt-02CR'C02) determines whether the M2 units align in a parallel or perpendicular arrangement.39 The parallel systems exhibit interactions wherein an oxygen atom from one carboxylate ligand forms an axial interaction to the metal atom of a neighboring M2(02CR)4 unit in the solid state producing one dimensional arrays (which is a common occurrence for [M2(02CR)4]n Complexes).39~41 Liquid crystalline phases containing Mo-Mo quadruple b(Duds were synthesized by placing long alkyl R substituents in M02(02CR)4.41 The complex M02(B-diketonate)4, recently synthesized by the Chisholm group, consists of infinite stacks of M02 units. but instead of Weak intermolecular M02~~O bonds. the origin of the stacking is due entirely to ligand-ligand interactions.42 A variety of bidentate ligands have been successfully incorporated into polymeric frameworks that contain metal—metal bonded units. PYI‘azine has been used to form 1:1 polymeric complexes with M:(OzCR)4 31”“ llig‘i ‘maly‘ l Hulk“ its» . '9». LL. )1 L. . in“; _‘ “""\1 .“Wn ' "1“.” 3 ~b.t\ \ '1'. ‘ 1'1 ‘IIHI 11 (M = Cr, Cu) via axial coordination.43 Tetramethylethylenediamine (tmed) and 1,2-bis(dimethylphosphino)ethane (dmpe) both form 1:1 polymeric adducts with M02(02CCH3)4 as the result of axial adduct formation.44 Several diruthenium compounds of the type Ru2(02CR)4Cl exhibit infinite chain structure as the result of intermolecular interactions among the axial chloride ions.45~46 The polymeric complex [Ru2(OzCC2H5)4(phz)][BF4], were phenazine is the linking unit, displays antiferromagnetic interactions between Ruz units.47 It has been shown that antiferromagnetic electronic interactions between RuznvIII (S = 3/2) occur when there is a linear Cl' bridge.46 In another example, the rhodium carboxylate compound Rh2(02CC2H5)4 is linked into one-dimensional chains by the bidentate bases phenazine or 2,3,5,6-tetramethyl-p- phenylenediamine.43 Likewise, it is postulated that the 1:1 reaction between Rh2(02CCH3)4 and adenine bases result in similar polymeric products.49 The tetranuclear compound [{Ru2(chp)4}2(PYZ)](BF4)2 (Chp = u-6-chloro-2-hydroxypyridinato) was prepared from Ru2(chp)4Cl and pyrazine.50 In general the use of pyrazine has resulted in a variety of Coordination polymers including polymers that contain porphyrin Complexes of Fe(II), Ru(II) and Os(II).51 Interestingly, the solvated Complex [Cu(NCCH3)4]+ reacts with pyrazine and tetramethylpyrazine fol‘rning infinite sheet and chain polymers.52 Using organic polymerization methodologies. oligomeric urethanes with Mo-Mo or Fe-Fe bonds along the back-bone have been synthesized.53 The reaction of the organometallic ”diol" (R5-C5H4C(O)CH20H)2- IV102(CO)6 with an appropriate diisocyanate resulted in polymers that are photochemically reactive and undergo metal-metal bond photolysis.53 PO1,,V,mers of this type may find utility in degradable plastics.53 I ‘ I “an t; -t .Luuyu arm ( Mat-4... T‘ - h; .1. lil\ iii I . "Mum-- \llSIlL\ H‘L 1‘ Neil C ‘-» 13:21 . “7‘“ 'u- |~~5“‘\'l 1“ '5 . ‘, ..F \‘ I1 .. | d ‘o w..'. . inf.) -u 2."."_ 12 This dissertation describes the work relating to the use of multiply bonded dimetal compounds in the preparation of extended molecular arrays. Several approaches in developing this chemistry were undertaken. The first, detailed in Chapters 11, III, and IV, involves the charge transfer chemistry of a variety of dirhenium and dimolybdenum donor (electron rich) complexes with polycyano-containg organic acceptors (electron poor). In each case, covalently bonded species were formed as judged by X-ray crystallography and infrared spectroscopy. Both the oligomeric (Mz-L-Mz) and possibly polymeric ([Mz-L]n) phases are formed in these reactions; these are among the first examples of covalently linked donor- acceptor complexes that incorporate dimetal units. Chapter V reports on the synthesis of the first homoleptic multiply bonded dimetal-cyanide product, [Et4N]4[Moz(CN)3]. The synthesis and structure of this and other interesting dimetal-cyanide complexes, including [BundN]2[Re2(CN)6(dppm)2], that contains a rare side-on u-o-ir-binding mode for a cyanide ligand, are reported. Preliminary results from reactions of [Et4N]4[Moz(CN)8] with solvated dimetal cations in attempts to SYtlthesize polymeric mixed metal cyanide materials are also included. Chapter VI details a different approach to bind redox active organic ligands wherein phosphine-containing 'ITF ligands are reacted with dimetal Compounds to give stacked and/or polymeric materials. Finally, Chapter VII deals with the novel rhenium-oxo species that form from molecular Oz I‘eactions of Re2C14(dppm)2- Rtitl .“ 1#\ Al A A - 13 R eferences 1 - (a) Jerome, D. Science 1991, 252, 1509. (b) Torrance, J. B. Acc. Chem. Res. 1979, 12, 79. (c) Bryce, M. R. Chem. Soc. Rev. 1991, 20, 355. 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I‘l. . x; ‘h o:“\"t.‘ i 17.» 'M‘l !. . 1....'- ‘ 3. ‘ Ml s‘ F,» H1141 ‘ .“r. 4\~‘ uh 20 1- Introduction The search for new materials that exhibit electrical or magnetic prOperties is a major challenge to researchers in materials chemistry. New materials that are easily prepared in a pure form and can be successfully utilized into new and developing technologies are sought. Recently, there has been a great deal of interest regarding the syntheses of molecular-based materials using low temperature solution techniques. The molecular-based complex TCNQ-TTF (TCNQ = 7,7,8,8-tetracyanoquinodimethane; 'TI‘F = tetrathiafulvalene), which was the first molecular crystal to exhibit metallic behavior, and the selenium-based Bechgaard salts (TMTSF)2X ('I'MTSF = tetramethyltetraselenafulvalene) were among the first organic superconductors.1 There has also been considerable emphasis on the design of molecular-based ferromagnetic materials.2 Miller and others have synthesized a variety of donor-acceptor complexes with magnetically and electrically interesting properties from reactions of Cp2*M (M = Fe, Mn) with polycyano acceptor species such as TCNQ and TCNE (tetracyanoethylene).3 In more recent work, Manriques and Miller et al. discovered that the reaction between V(C6H6)2 and TCNE forms a room temperature ferromagnetic material formulated as V(TCNE)2-l/2(CH2C12) and is believed to contain o-bound TCNE.4 We have been exploring this metal donor organic acceptor approach with precursors of the type M2X4(PR3)4 and M2X4(P~P)2 (X = Cl, Br; M = M0, Re, W; R = Me, Et, I3r"; P~P = dppm, dppe) which, in addition to being coordinatively unsaturated, exhibit accessible and reversible oxidation processes.5 In particular. the dirhenium complex Re2C14(dppm)2, which possesses an electron-rich Re-Re triple bond. displays two reversible oxidations at E l/zmx) = 0.35 V and El/gmx) = 0.87 V vs Ag/AgCl. thus it is well suited 21 fOY charge-transfer chemistry with TCNQ whose first reduction potential occurs at Bugged) = 0.28 V (Figure 3)_5(a),6 Due to the presence of a Tit—component in the metal-metal bonding, the incorporation of the Rez unit in a polymeric arrangement may allow for a conduction pathway. Thus, we set out to study the charge-transfer chemistry of the donor complex Re2C14(dppm)2 with organic n-acceptor molecules with well-matched redox couples. This chapter reports the chemistry of Re2C14(dppm)2 with TCNQ, 'I‘CNE, and TNAP (11,11,12,l2-tetracyanonapthaquinodimethane) along with the spectroscopic and physical measurements of the resulting products. 2. Experimental A. Synthesis TCNQ and TCNE were purchased from Aldrich Chemicals and were sublimed prior to use. TNAP was purchased from TCI American and used as received. (1) Preparation of RezCl4(dppm)2 The compound Re2C14(dppm)2 was prepared in an analogous procedure to that reported in the literature.7 In a typical reaction 25 mL Of reagent grade methanol was added to a flask containing Re2C16(PBu"3)23 (0.750 g, 0.758 mmol) and dppm (1.55 g, 4.03 mmol). The mixture was refluxed for 3 h during which time a purple solid formed. The warm mixture was allowed to stand undisturbed for several rTlinutes to allow the solid to settle out of solution. The supernatant was Carefully decanted prior to filtering and the solid was washed with fresh r‘I‘lethanol (2 x 10 mL) and then finally washed with copious amounts of diethyl ether. After vacuum drying, the yield was 0.88 g (90%). To rule Out the presence of the oxidized species Re3C15(dppm)3 or other impurities. 22 /\ pn,p man, I Rgc 11’“ E O 35 V 9 1/2(ox) = . 01’ I Cl/ thPV 9th Re2C14(dppm)2 NC CN >=( r......=o.s4v NC ON TCNE NC on )=C>=( 131,208,, = 0.28 v NC on _ CN NC 99 E1/2(red) = 031 V TNAP Figure 3. Selected precursors used for charge-transfer chemistry. 23 the cyclic voltammogram of each new batch was checked against the corresponding data for an authentic sample of the compound. (2) 1:1 Reactions of RezCl4(dppm)2 with TCNQ (1) Preparation of (1)-A Separate solutions of Re2C14(dppm)2 (0.108 g, 0.084 mmol) in 10 mL of CH2C12 and TCNQ (0.0171 g, 0.084 mmol) in 10 mL of CH2C12 were cooled to -78°C using a dry ice/acetone bath. The Re2C14(dppm)2 solution was added to the TCNQ solution which caused an immediate color change to blue. The reaction mixture was allowed to stand for 2 h at -78°C without a noticeable change in color. The reaction volume was reduced to ca. 15 mL by vacuum after which time 20 mL of hexanes was added to effect precipitation of a blue solid. The volume was reduced by vacuum to ca. 10 mL and an additional 20 mL of hexanes was added. The solid was collected by filtration, washed with hexanes (2 x 10 mL), and vacuum dried; yield 0.115 g (92%). IR (CsI, Nujol, cm'l): v(CEN) 2195 (s), 2115 (m), v(C=C) 1582 (m). 1H NMR (CDC13) 8 = 8.12 (s,1H), 8 = 6.9 - 7.7 (m,20H), 8 = 5.51 (m,2H) ppm. 31P{1H} NMR (CDC13) not observed. (ii) Preparation of (1)-B Dichloromethane (10 mL) was added to a flask containing Re2C14(dppm)2 (0.054 g, 0.042 mmol) and TCNQ (0.009 g, 0.044 mmol) to give a dark blue solution. The reaction mixture was stirred at room temperature for 24 h during which time the color changed to dark green. The volume was reduced to ca. 4 mL by vacuum, and diethyl ether (6 mL) was added which effected the precipitation of a green solid. The solid was collected by filtration. washed with diethyl ether (5 mL) and vacuum dried. Jul-r 7 24 IR (CsI, Nujol, cm'l): v(CEN) 2183 (s), 2114 (s,br), 2085 (sh), v(C=C) 1571 (8). (iii) Preparation of (1)-C A solution consisting of RezCl4(dppm)2 (0.100 g, 0.078 mmol) in 10 mL of CH2C12 was added to a solution consisting of TCNQ (0.0206 g, 0.078 mmol) in 10 mL of CH2C12. A blue solution immediately formed. The Schlenk flask was equipped with a septum and a long syringe needle which was situated just above the reaction solution. A slow purge of nitrogen was maintained until all of the methylene chloride had evaporated (ca. 24 h). A black metallic film, that shatters easily deposited on the bottom of the flask. IR (CsI, Nujol, cm'l): v(CEN) 2185 (s), 2115 (s,br), v(C=C) 1567 (s). (iv) Preparation of (1)-D A solution containing TCNQ (0.0320 g, 0.156 mmol) in toluene (20 mL) was added to a refluxing solution consisting of Re2C14(dppm)2 (0.200 g, 0.156 mmol) in toluene (40 mL) over a period of 5 minutes. The reaction mixture was refluxed with stirring for 15 minutes during which time a green precipitate formed. The hot reaction mixture was filtered and the collected solid was washed with copious amounts of toluene and dried in vacuo; yield 0.110 g (47%). IR (CsI, Nujol, cm'l): v(CEN) 2185 (s), 2085 (s,br), v(C=C) 1570 (s). (3) Preparation of [Re2C|4(dppm)2]2(u-TCNQ) (2) (i) Bulk Reaction A solution containing TCNQ (0.0120 g, 0.059 mmol) in THF (15 mL) was added to a solution containing Re2C14(dppm)2 (0.150 g, 0.117 mmol) in THF (15 mL). The mixture was stirred for several minutes and allowed to stand overnight at room temperature to yield a crOp 25 of black microcrystals. The product was collected by filtration, washed with THF (3 x 5 mL), and vacuum dried; yield 0.140 g (86%). Anal. Calcd for C120H103N4C1302P3Re4: C, 49.45; H, 3.74; Cl, 9.73. Found: C, 49.38; H, 3.48; CI, 9.62. IR (CsI, Nujol, cm'l): v(CEN) 2187 (m), 2109 (s,br), v(C=C) 1573 (m), 1586 (w,sh). 1H NMR (CDC13) 8 = 7.1 — 7.8 (m), 8 = 3.73 (t), and 5 = 1.83 (p) ppm; the latter two resonances are attributed to lattice THF molecules. 31P{1H} NMR (CDC13) 8 = -14 ppm. Electronic spectroscopy (CHzClz): lmaxnm (8, M'lcm'l), 1080 (2.56 x 104), 1980 (2.20 x 104). (ii) Slow Diffusion Reaction Separate stock solutions of Re2C14(dppm)2 (0.150 g, 0.117 mmol, 15 mL of THF) and TCNQ (0.0120 g, 0.059 mmol, 15 mL of THF) were prepared; 2 mL of the Re2C14(dppm)2 solution was syringed into an 8 mm O.D. Pyrex tube9 and carefully layered with 2 mL of THF followed by 2 mL of the TCNQ solution. The tube was flame sealed under a slight vacuum and allowed to stand undisturbed. A total of seven tubes were prepared in this way. After ten days the black crystals that had formed at the interface of the layers in each tube were harvested and washed with THF; yield 10mg (6 %). IR (CsI, Nujol, cm-l): v(CEN) 2186 (m), 2104 (s,br), v(C=C) 1572 (m), 1586 (w,sh). (4) 1:1 Reactions of Re2C14(dppm)2 with TCNE (1) Preparation of (3)-A Two separate Schlenk tubes, one containing 0.111 g (0.087 mmol) of Re2C14(dppm)2 and the other containing 0.011 g (0.087 mmol) of TCNE, each dissolved in 10 mL of CH2C12, were cooled to -78'°C using a dry ice/acetone bath. The Re3C14(dppm)3 solution was transferred to the TCNE solution by cannula. and the temperature was maintained at -78OC. '50,.) '“b—‘i l I l"‘;\ .. " L. w 'r t" 1 a-“ ~ l D. ‘ ‘ ‘l“‘| Wg.’ IE‘K‘ 26 A dark blue-green solution resulted upon contact, and 5 mL of hexanes was added followed by reduction of the solution volume. This process was repeated three times and a blue-green solid was obtained. After a final addition of hexanes (15 mL) and further pumping under vacuum, the blue- green solid was collected by filtration, washed with hexanes, and dried in vacuo; yield 0.090 g (73%). IR (CsI, Nujol, cm'l): v(CEN) 2197 (s), 2121 (m). Electronic spectroscopy (CH2C12): hmaxnm (e, M'lcm'l), 750 (16,000). (ii) Preparation of (3)-B In a typical reaction, a solution consisting of TCNE (0.0198 g, 0.155 mmol) in CH2C12 (10 mL) was added to a solution consisting of Re2C14(dppm)2 (0.200 g, 0.155 mmol) in CHzClz (10 mL) to give a dark purple solution. The reaction solution was reduced to ca. 5 mL and treated with 20 mL of diethyl ether. The resulting dark purple solid was collected by filtration, washed with diethyl ether and vacuum dried; yield 0.173 g (79%). IR (CsI, Nujol, cm‘l): v(CEN) 2200 (s), 2128 (m). (iii) Refluxing Reaction in Toluene To a 100 mL Schlenk flask equipped with a condenser and stir bar was added 0.100 g (0.078 mmol) of Re2C14(dppm)2, 0.010 g (0.078 mmol) of TCNE, and 20 mL of toluene. The reaction mixture was stirred with refluxing for 4 h during which time the color of the reaction solution became dark green with a black precipitate. The hot reaction mixture was filtered, the product was washed with toluene (2 x 5 mL), and finally dried in vacuo; yield 0.041 g. The product was dissolved in 20 mL of CH2C12, filtered. and reduced in volume to ca. 10 mL by vacuum. The addition of 10 mL of hexanes and further pumping to remove the CHzClz gave a black precipitate. The product was collected by filtration. washed with hexanes 27 (2 x 5 mL) and vacuum dried; yield 0.038 g (34%). IR (CsI, Nujol, cm'l): v(CEN) 2211 (s), 2145 (m). (5) Reactions of Re2C14(dppm)2 with TNAP (1) Preparation of [RezCl4(dppm)2](TNAP) (4) Methylene chloride (10 mL) was slowly added to a Schlenk tube submerged in a dry ice/acetone bath (-78°C) that contained 0.061 g (0.048 mmol) of Re2C14(dppm)2 and 0.012 g (0.048 mmol) of TNAP. No immediate reaction was observed as judged by the persistent purple solution color of the Re2C14(dppm)2 compound. The Schlenk tube was removed from the bath for 5 minutes during which time the reaction solution became dark yellow-green. The Schlenk tube was then returned to the bath, and a small aliquot was removed for an electronic absorption spectrum (CH2C12): hmax nm (e, M'lcm'l), 1005 (12800), 478 (7600), 374 (5800). Spectra obtained over the period of 11 h at room temperature differed only in that the absorption centered at hmax = 1005 nm decreased in intensity. A infrared spectrum of the reaction solution in a CaF2 cell exhibited v(CEN) bands at 2195 (s) and 2126 (s) cm'l. A spectrum of the same solution after 11 h gave a spectrum with v(C:—:N) bands at 2186 (s), 2124 (s), and 2086 (s,br) cm'l. The reaction solution maintained at -78°C was layered with 20 mL of hexanes which resulted in the precipitation of a solid that was collected by filtration, washed with hexanes (2 x 10 mL) and dried in vacuo; yield 0.058 g (80%). IR (Csl, Nujol, cm'1)v(CEN) 2180(8), 2081 (s,vbr). (ii) Preparation of [RezCl4(dppm)2]2(u-TNAP) (5) A quantity of CH2C12 (10 mL) was slowly added to a Schlenk tube containing 0.104 g (0.081 mmol) of Re2C14(dppm)2 and 0.010 g (0.041 mmol) of TNAP that was submerged in a dry ice/acetone 28 bath (-78’C). No reaction was observed at this temperature as judged by the lack if color change. The Schlenk tube was removed from the bath for 5 minutes during which time the reaction solution became dark blue-green. The Schlenk tube was returned to the bath and a small aliquot was removed for an electronic absorption spectrum (CH2C12): Amaxnm (e, M‘lcm'l), 1072 (17600). The solution color immediately turned red-brown upon warming to room temperature. Spectra obtained over the period of 1 h at room temperature differed only in the intensity of the absorption at hmax = 1072 nm which decreased. A solution infrared spectrum revealed v(CEN) bands at 2186 (s) and 2101 (s,br) cm-l. The reaction solution maintained at -78°C was layered with 20 mL of hexanes resulting in the precipitation of a microcrystalline solid which was collected by filtration, washed with hexanes (2 x 10 mL), and dried in vacuo; yield 0.097 g (85%). IR (CsI, Nujol, cm'1)v(CEN) 2181 (m), 2101 (s,br). B. X-Ray Crystallography The structure of [Re2C14(dppm)2]2(u-TCNQ)r8THF, (2)-8THF, was determined by application of general procedures that have been fully described elsewhere.10 Crystallographic data were collected on a Rigaku AFC6S diffractometer equipped with monochromated MoKOL (lat = 0.71069 A) radiation. All data were corrected for Lorentz and polarization effects. Calculations were performed on a VAXSTATION 4000 computer by using the Texsan crystallographic software package of Molecular Structure Corporation.ll Crystallographic data for (2) are given in Table 1. 11111 ‘C I‘lmt k Ill... .‘ .\f'}‘l |‘JA|IAI I 1,4 aux- H 3 ! .‘ Ih\: \ . V I‘D-w I.W§ 5 29 Table 1. Summary of crystallographic data for [R62Cl4(dppm)212(u-TCNQ)-8THF, (2)-8THF. formula Re4P8N408C 144C18H156 formula weight 3347.08 space group P-l (#2) a, A 14.258(4) b, A 23.238(8) c, A 12.146(4) 01, deg 9795(3) 13, deg 104.31(2) 7, deg 72.64(2) V, A3 3713(2) Z 1 dcalc, g/cm3 1.497 p. (Mo K01), cm'1 35.76 temperature, °C -110 trans. factors, max., min. 0.61 - 1.00 Ra 0.043 wa 0.066 quality-of-fit indicator 2.39 aR=Z llFol' till/ZIFQI bRw = 12"“ F0 1 ' tFc bz/ZW lFO 12]1/2; w = 1/02( lFo l) cquality-of-fit = 12‘“ 11:0 l ' ch '12/ (Nobs'Nparameters)i 1/2 a ‘M ‘» 47,-}. 5b.... v D“- “I'd: ~‘y 1-_ y u‘ N ‘5 t. ‘ "F. 30 (1) [RezCl4(dppm)2]2(u-TCNQ)-8THF, (2)-8THF (i) Data Collection and Reduction Crystals of (2)-8THF were grown by slow diffusion of a THF solution containing TCNQ into a THF solution containing two equivalents of Re2C14(dppm)2. A black crystal with dimensions 0.40 x 0.36 x 0.20 mm3 was mounted on the tip of a glass fiber with silicone grease. Cell constants and an orientation matrix for data collection obtained from a least squares refinement using the setting angles of 23 carefully centered reflections in the range 35 S 20 3 40° corresponded to a triclinic cell. A total of 13158 unique data were collected at ~110 i 1°C using the (1)-scan technique to a maximum 20 value of 50°. The intensities of three representative reflections measured after every 150 reflections decreased by 7.3%, thus a linear correction factor was applied to the data to account for this decay. An empirical absorption correction, based on azimuthal scans of three reflections, was applied which resulted in transmission factors ranging from 0.61 to 1.00. (ii) Structure Solution and Refinement Based on a statistical analysis of intensity distribution and the successful solution and refinement of the structure, the space group was determined to be P-l (#2). The structure was solved by the SHELXS12 and DIRDIF25 structure programs and refined by full matrix least-squares refinement. All non—hydrogen atoms, except C(51) and the interstitial THF atoms, were refined with anisotropic thermal parameters. Hydrogen atoms were placed in calculated positions for the final stages of refinement. The final cycle of full matrix least-squares refinement included 9435 observations with F02 > 30(F02) and 685 variable parameters for residuals ofR = 0.043 and Rw = 0.066 and a quality-of—fit index of 2.39. 31 3. Results and Discussion The dirhenium donor complex Re2Cl4(dppm)2 reacts spontaneously with the polycyano organic acceptor compounds TCNQ, TCNE, and TNAP to form charge-transfer products. In reactions with TCNQ, the exact nature of the reaction products is highly dependent on the reaction conditions and stoichiometry. Different products from 1:1 Stoichiometric reactions, [Re2C14(dppm)2](TCNQ) (1)-A, (1)-B, (1)-C, and (1)-D, are isolated depending on reaction temperature and solvent. The molecular complex [Re2Cl4(dppm)2]2(u—TCNQ) (2) is produced as a crystalline solid from a careful layering of separate THF solutions of the two reactants. The structure of (2), determined by single crystal X-ray diffraction methods, reveals the presence of a novel bridging bidentate mode for TCNQ. Crystallographic data are summarized in Table 1. An ORTEP representation and packing diagrams are depicted in Figures 4, 5, and 6. A full table of positional and thermal parameters for compound (2) is located in the Appendix. Reactions of Re2C14(dppm)2 with TCNE produces [Re2C14(dppm)2](TCNE) (3)-A, at low temperatures, and (3)-B, at room temperature. Both contain o-coordinated TCNE as evidenced by NMR and infrared spectral results. These reactions were determined not to be dependent of stoichiometry. The reactions of Re2C14(dppm)2 with TNAP are similar to those with TCNQ in that the products formulated as [RezCl4(dppm)2l(TNAP) (4) and [R62C14(dppm)212(u-TNAP) (5) are produced from using 1:1 and 2:1 reaction stoichiometries. A. Reactions of Re2C14(dppm)2 with TCNQ (1) Preparation The reaction of equimolar quantities of Re2C14(dppm)2 with TCNQ in CHzClz at -78°C produces instantaneously a dark blue solution followed 32 by a color change to green upon warming to room temperature (see Figure 4). The blue solution is stable indefinitely at -78°C and a blue solid, [Re2C14(dppm)2](TCNQ) (1)-A, can be isolated by precipitation with diethyl ether. After decomposition of the blue product to the green species, one can isolate a green solid, (1)-B, by addition of diethyl ether. If benzene is used in place of CH2C12, a blue solution persists for several days at room temperature. Attempts to grow crystals suitable for a single crystal X-ray study of either of these products were unsuccessful. However, diethyl ether layerings of the 1:1 blue solution at -78°C produces yellow-green microcrystals that turn blue upon exposure to air and with warming above -78°C. Unfortunately, repeated attempts to mount the crystals without decomposition met with failure. When equimolar CHzClz solutions of Re2C14(dppm)2 and TCNQ are mixed and then evaporated to dryness, black films of (1)-C deposit on the walls of the reaction vessels. The reaction of equimolar quantities of Re2Cl4(dppm)2 with TCNQ in refluxing toluene produces (1)-D as a green solid . Using THF as the reaction solvent, the addition of one equivalent of TCNQ to two equivalents of Re2C14(dppm)2 produces the complex [Re2C14(dppm)2]2(p.-TCNQ) (2) which precipitates as black crystals. (2) Spectroscopic Properties The infrared spectral features of the aforementioned TCNQ complexes are quite unusual in comparison to other charge-transfer products of TCNQ. Selected infrared frequency values of these products are compared with TCNQ0 and TCNQ‘ in Table 2. It is clear that the prepared products are not outer-sphere charge-transfer products with TCNQ, but rather complexes containing o-coordinated TCNQ. 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It has previously been demonstrated that the degree of charge transfer in various TCNQ complexes can be estimated from the nitrile stretching frequencies.13 Comparison of the CEN and C=C stretching frequencies of (2) with TCNQ0 and TCNQ“ suggests the assignment of -1 to the bridging TCNQ in (2), which requires each dirhenium moiety to have a partial formal charge of 0.5+. The strong v(C-EN) band at 2104 cm'1 attributed to the bound nitrile in (2) is shifted to lower frequency as the result of significant din-1t* back- bonding. As the C.=_N bond stretches, the 111* orbitals are lowered, and as the CEN lengthens, the M-N distance decreases, thus increasing the overlap of the dlt-II:* orbitals.14 It has been shown that metal ions with strong back-bonding interactions (a net metal-to-ligand charge transfer) exhibit an intensity enhancement of the of the C-='N stretch.14 The infrared spectra of the 1:1 products (1)-A, (1)-B, (1)-C, (1)-D are also indicative of o-coordinated TCNQ' moieties. The major difference among these spectra is that (1)-D exhibits a strong and broad v(C'='N) band at 2085 cm;1 which is in the range for complexes that possess bridging TCNQ ligands, whereas (1)-A, (1)-B, and (1)-C exhibit nitrile stretching patterns indicative of a o—nl coordination mode. One is able to monitor the changes during the conversion of (1)-A to (1)-B using infrared spectroscopy. The initial spectrum of the blue mixture (Figure 5), that results from the mixing of separate equimolar CH2C12 solutions 4h W i i n’ 2300 2200 2100 2000 - 1 Wavenumber, cm Figure 5. Infrared spectral monitoring of the conversion of (1)-A to (1)-B in CHzClz. 37 containing Re2C14(dppm)2 and TCNQ exhibits similar v(CEN) bands to that of the Nujol mull infrared spectrum of (1)-A. No apparent spectral changes occur within 1 h, although a color change to green was observed. After 1 h the spectrum exhibits an increase in intensity of the lower energy band with the onset of a shoulder occurring on each band. As the reaction progresses, the shoulders become more intense; after 4 h the solution is completely green, and after 18 h the spectrum resembles that of (1)-B. The initial infrared spectrum of the blue-gray solution (Figure 6) that results from the mixing of the two reactants in CH2C12 using a 2:1 Re2Cl4(dppm)2:TCNQ stoichiometry exhibits v(CEN) bands at 2198 (m) and 2117 (s) cm'l. If monitored over a two day period, a peak at 2187 cm"1 develops while the band at 2198 cm'1 disappears. The location of the stretch at 2117 cm'1 remains constant but broadens over this time period. If the same experiment is performed using THF as the reaction solvent, nearly identical spectra are obtained (as compared to the reaction performed in CH2C12) during the early stages of the reaction. However, as the reaction progresses, a v(CEN) band at 2185 cm'1 appears with concomitant precipitation of a solid that results in poor spectral resolution. When the reaction between Re2C14(dppm)2 and TCNQ is performed in the presence of a large excess of TCNQ (at least 5 equivalents) in CHzClz, the solution infrared spectrum exhibits a v(CEN) band at 2222 (m) cm-1 indicative of free TCNQO in addition to v(CEN) bands 2195 (s) and 2120 (s) cm;1 that are also observed in the spectra of (1)-A. In addition to the infrared spectra. the electronic absorption spectra (UV-visible, near and mid IR) are also helpful in distinguishing between the various phases of the reactions between Re2C14(dppm)2 and TCNQ. Table 3 lists the 7mm values from spectra of various phases along with 38 Table 3 Comparison of the electronic spectral data of various TCNQ and TCNE complexes. Complex Solvent hmax nm e, M‘lcm'1 "[Re2C14(dppm)2](TCNQ)" (l)--Aa CH2C12 325 22200 380 18500 900 59100 1900 16600 "[Re2C14(dppm)2](TCNQ)" (1)-Aa THF 320 16300 370 15600 890 45400 1900 12900 [Re2C14(dppm)2]2(TCNQ) (2)b CHzClz 1080 25600 1980 22000 [Re2C14(dppm)2]2(TCNQ) (2)a CH2C12 1080 36700 1950 27900 [Re2C14(dppm)2]2(TCNQ) (2)9 CH2C12 430 15300 1075 25600 1975 25800 "[Re2C14(dppm)2](TCNQ)" (1)-D CH2C12 425 11200 950 8000 1950 (br) 10200 [Re2C14(dppm)2](TCNQ)za CHZCIZ 400 38800 900 18000 1850 4400 "[Re2C14(dppm)2]4(TCNQ)"a CHzClz 1090 50500 1975 41200 [Cp"‘(CO)2Mn]TCNQd toluene 1050 e [Cp"‘(CO)2Mn]4TCNQd toluene 141 84 50200 [Cp"‘(CO)2Mn]2TCNEd CH3CN 720 14100 1 145 25100 [Cp*(CO)2Mn]TCNEd toluene 789 17000 aSeparate solutions of the Rc2C14(dppm)2 and TCNQ compounds were mixed prior to the experiment. bSolid product of (2) dissolved in CHzClz CSolid product of (2) from the acetone reaction dissolved in CH2C12 dReferences 22 and 24 6not rcponed 39 1.5 min. - (.5... l l I I I 2300 2200 2100 2000 Ji- Wavenumber. cm' 1 Figure 6. Infrared spectral monitoring of the decomposition of a CH2C12 solution containing [Re2C14(dppm)2]2(u-TCNQ).(2). 40 those reported for other TCNQ-containing compounds. The spectrum of the 1:1 reaction solution between Re2C14(dppm)2 and TCNQ, (1)-A, in CH2C12 exhibits an intense absorption at a Amax = 900 nm (e = 5.91 x 104 M'lcm'l) and a less intense broad absorption at hmax = 1900 nm (e = 1.66 x 104 M'lcm'l). This spectrum also exhibits higher energy absorptions at hmax = 325 (e = 2.22 x 104 M'lcm'l) and 380 (8 = 1.85 x 104 M'lcm'l) nm. The same behavior is also observed when THF is used as the reaction solvent (see Table 3). When more than one equivalent of TCNQ is added to Re2C14(dppm)2, a strong absorption appears at hmax = 400 nm, indicative of free TCNQ. The spectrum of (2) performed in CH2C12 (Figure 7) contains intense absorptions at hmax = 1080 (e = 2.56 x104 M‘lcm‘l) and 1980 (8 = 2.20 x 104 M'lcm71) nm. A similar spectrum is obtained for the solution that results from mixing separate methylene chloride solutions of Re2C14(dppm)2 and TCNQ (2:1 stoichiometry). In another example, the dark green solid obtained by a 2:1 reaction between Re2C14(dppm)2 and TCNQ in acetone dissolved in CHzClz, results in a similar spectrum to that of (2); in this spectrum, however, the absorption near 430 nm is stronger than the same feature observed in other spectra recorded for (2). All spectra of the 2:1 [Re2C14(dppm)2:TCNQ] products exhibit the absorption near 430 nm, but intensities differ from one sample to another signalling various quantities of free TCNQ. This point is better illustrated from studying the effect of prolonged reaction times on the course of the reaction. The initial UV- visible spectrum of a 2:1 mixture of Re2C14(dppm)2 and TCNQ in CH2C12, exhibits a strong absorption at 1050 nm. As the blue-gray solution changes to blue-green and finally to yellow-green (ca. 14 h). the intensity of the absorption decreases by about 40%. At the same time. a peak near 430 nm 41 .NGNIU 5 AS AOZUH-1ENAE&3£USE «o 8.500% 5:903.“ 2:88.05 .5 FEEL 9:5 Eozmd>§> 00mm 000w 000w 000_. 00”; 00N— 000 _. 00m 000 00v 00m 1 1 4 4 d d d 1 1 l NOlldHOSBV Tee :2 88m «a sec :2 88m in E: on? u 08:: E: one. u x922 ‘ stir 42 grows in. This effect of solution aging may explain why some of the previous spectra of the 2:1 products exhibit this peak at various intensity levels. In the spectrum of (1)-A in CHzClz, the absorption at hmax = 900 nm, over a period of 7 h, decreases to about one-half its 01igina1 intensity, during which time the color changes from blue (1)-A to green (1)-B. (3) X-ray Crystal Structure of [RezCl4(dppm)2]2(u- TCNQ)'8THF, (2)-8THF A single crystal X-ray study of (2)-8THF confirms its 2:1 formulation, and reveals the presence of a novel bridging bidentate mode for TCNQ. The molecular structure of (2)-8THF, depicted in Figure 8, consists of two Rez units that are covalently linked through the trans cyanide groups of a bridging TCNQ molecule. The molecule is centrosymmetlic, with the midpoint of the TCNQ moiety being situated on an inversion center. During the refinement procedure it became necessary to fix the position of C(51). When allowed to refine unconstrained, the N(1)-C(51) distance became an unreasonably short 0.92 A, which is considerably less than the distance of 1.03 A that first appeared in the difference map. Furthermore, the C(51)-C(52) distance lengthens to an unreasonably long 1.52 A when unconstrained. Models that included fixing N(l), C(51), or Unconstrained Re(2) M— N( 1) 119—25— 0(51) fl C(52) Atom C(51) fixed Re(2)—3'—13—A— N(1) i933— C(51) 439: C(52) 43 mIHwANV HE’SAOZUHENRenegade—0N3: mo 8.3853202 mumO .w 3:»?— IT}- "1 {—1. W1 44 both were examined. When only N(l) was fixed, the N(1)-C(51) distance became 0.90 A, and when C(51) was fixed, the N(1)-C(51) distance refined to 1.03 A. The later refinement was chosen because it was the most chemically reasonable model. In addition to the above refinements, switching the identities of the N and C atoms which would make the group an isonitrile or replacing either the N or C atom with 0 all led to poorer refinements. We believe that the artificially short C-N distance that refines without constraint results from librational disorder of the CN groups that distorts the thermal ellipsoid and thus prevents an accurate assingment of the atoms location for bond distance calculations. It should be noted that the unligated C(53)-N(2) moiety refines to a more realistic value of l.12(2) A. The coordination geometries of the two Re atoms within each M2L9 dimer unit are different (see Figure 9). The nitrile-substituted metal center, Re(2), adopts an octahedral arrangement consisting of an axial chloride, Cl(2), as well as an equatorial chloride, Cl(l), and an equatorial nitrogen ligand, N(l). The geometry around Re(l) is trigonal bipyramidal which is similar to the geometries of the Re atoms in the parent complex Re2Cl4(dppm)2. Distances and angles within the dirhenium unit are within the usual ranges for derivatives of Re2C14(dppm)2.15 A list of selected bond distances and angles are given in Table 4. Of special note is the Re-Re separation of 2.2747(8) A, which is longer than the distance of 2.234(3) A found in the parent triply-bonded complex. In the absence of other considerations, one would predict a shorter metal—metal bond resulting from depopulation of an antibonding orbital upon oxidation (i.e. 621C4525*2 —> 02n4525*1)16, but in the present system the application of an Mng bonding scheme is an oversimplification. The combined affect of 45 5:.on .HES.8283:99.85:an ac seem: 8% 9653 8955888 9:5 .a 8:5... o «.0 o o o .80 o o 0 c3 0 O O o O .2 o .800 o o o O 0 $0 m3 0 o 0 So :0 0 no: So Po: «.0 tt..l:rill1l]]]l Table 4. 46 Selected bond distances(A), bond angles(°) and torsion angles(°) for [Re2C14(dppm)2]2(tt-TCNQ)-8THF, (2)-8THF. distances atom 1 atom 2 distance atom 1 atom 2 distance Re(l) Re(2) 2.2747(8) P(2) C(49) 1.83(l) Re(l) Cl(3) 2.348(3) P(3) C(25) 1.80(1) Re(l) Cl(4) 2.356(3) P(3) C(31) 1.8l(l) Re(l) P(2) 2.426(3) P(3) C(50) 1.80(l) Re(l) P(3) 2.432(3) P(4) C(37) 1.8l(1) Re(2) Cl(l) 2.387(3) P(4) C(43) l.84(1) Re(2) Cl(2) 2.589(3) P(4) C(50) 1.82( 1) Re(2) P(l) 2.496(3) N(l) C(51) 1.026(8) Re(2) P(4) 2.493(3) N (2) C(53) 1 . 12(2) Re(2) N( 1) 2.133(8) C(51) C(52) 1.40(l) P(l) C(l) 1.82(1) C(52) C(53) 1.43(2) P(l) C(7) 1.83(1) C(52) C(54) 1.42(2) P(l) C(49) l.83(1) C(54) C(55) 1.37(2) P(2) C(13) l.84(1) C(54) C(56) 1.43(2) P(2) C(19) 1.82(1) C(55) C(56)* 1.37(2) torsion angles atom 1 atom 2 atom 3 atom 4 torsion angle Cl(l) Re(2) Re( 1) Cl(3) 167.8(1) Cl(l) Re(2) Re(l) Cl(4) 10.0(1) Cl(3) Re(l) Re(2) N(l) 14.8(2) P( 1) Re(2) Re(l) P(2) 15.72(9) P(3) Re( 1) Re(2) P(4) 14.08(9) C(5 3) C(52) C(54) C(55) 5(2) 47 :52 .230 600 $50 398 9: Sam :50 :55 .600 $00 $50 €39 00 Sum 9:0 So: 650 9.00 G00 Emma :52 Cam Sam :5: 650 9.50 350 €33 9% Cam Sex ENE $00 9.00 £50 653 9: Sam 38 CE 350 850 $2 6852 30 Sam Eam So: 9.50 350 $50 $403 9:0 Sam :3 SE 9.50 $30 :50 SEAS Ca 9ch 8: :5: 850 800 :50 95.4w 3: 38¢ 950 63: 300 :30 :52 89% Ca 9ch 9.5.0 825 82 Cum 9.5 598 3: Sam 6.0 $93 82 Sam 3.. 95.4w 3: Sam 5.0 €5.52 9% Sam Ea 84.9; 950 Sam 60 Se; :52 Sex 50 6532 :50 :2 Sam 68.2 3.. $3. $0 €33 5a :52 Sam 95.2 9: Sam 60 58.3 a: Sex Cam €32 82 Sam 50 €33: 95.0 38 Cum €95 9% Sam 50 Emcee 60 Cum Sam 0.; m 82¢ a :53 2 :88 2mg m :88 m :83 — E08 moans .6265 .4 2...; 48 structural changes and nt-delocalization on the extent of Re-Re bonding must be taken into consideration. It is reasonable to argue, however, that a strong axial chloride interaction serves to weaken the o-component of the metal-metal bond thus resulting in an overall lengthening of the Re-Re distance. Although other M2L9 complexes, such as Re2C14(dppm)2(CO)17, have been noted before, these possess A-frame structures, whereas the structural type found in (2), in which the geometry is trigonal bipyramidal around one of the Re atoms and octahedral around the other Re atom, has been noted only in a few instances, namely in the nitrile complexes [Re2C13(dppm)2(NCR)2]X (X = Cl', PF6') (R = Me, Et, Ph, 4-PhC6H4, 1,2-C6H4CN) reported by Walton et al.18 These complexes contain equatorially bound nitriles and chlorides, and one axially coordinated chloride ligand. Comparisons of the Re-Re, Re-N, and Re-Cl axial distances, and P-Re-Re-P torsion angles for this structural type appear in Table 5. The values observed for (2) are quite similar to those of the [Re2C13(dppm)2(NCR)2]+ complexes. The most notable difference appears in the torsion angles, e.g., the P-Re-Re-P twist angle (14.90) is considerably smaller than the corresponding values in the [Re2C13(dppm)2(NCR)2]+ complexes. This difference can be understood in terms of metal-metal bonding. The [Re2C13(dppm)2(NCR)2]+ species are reported to be diamagnetic while for (2) there is partial oxidation of the Re2 core that results in the distruction of some of the 6* bonding. This introduces some 5 bonding into the molecule which favors a more eclipsed conformation (a smaller P-Re-Re-P torsion angle). With a smaller P-Re-Re-P torsion angle and a longer Re-Cl axial distance. a shorter Re-Re distance in (2) than in 49 3m 602.3 333 25553203 3m @083 68a €83 0&_~3200Eo0-~.326332035 0.8 $33 823 3:83 0EEEG02§E§E0§_ 08 633 $083 €23 $5name00ziaasn0§_ q: 633 $032 €33 5 620b3§5§§0~§ Cgemamsmd $356.; 2022 Qvomam 53:50 .EBEoow 332 .aoEoEEQg ca 95535 moonEoo 83558 .8 3&5 05 $0536 0:3 02028 no 533800 m 035. - Again} ' 50 the [RezCl3(dppm)2(NCR)2]+ complexes might be expected, however, the converse is true. It is interesting to note that in the structure of the mixed- valence RezILm complex Re2C15(dppm)2, which also possesses the M2L9 structural arrangement, the Re-Re separation is 2.263(1) and the P-Re-Re-P torsion angle is 3.99°.19 The torsion angle is smaller, as expected, but the Re-Re distance is similar to other ReznoII complexes listed in Table 5. This example undrscores the danger in equating the Re-Re separation with bond order or oxidation state. Other structural features of (2) can be explored by the fact that the two rhenium atoms are electronically different which leads to different Re-Cl and Re-P distances. The Re(1)-Cl distances are about 0.04 A shorter than the Re(2)-Clequamrial distance, and the Re(l)-P distances are about 0.07 A shorter than the Re(2)-P distances. This same trend is also observed in the structure of Re2C15(dppm)2.19 Once again, these structural differences are attributed to the different coordination environments around each rhenium atom, and assignments of formal charges on either rhenium atom cannot be rationally deduced from these data. Among the vast amount of literature pertaining to the chemistry of TCNQ, there are only several reports of covalently bonded TCNQ complexes and only a few reported X-ray crystallographic structures. The crystal structures of the simple salts of the alkali metals of TCNQ display metal cations which are either octahedrally (M+ = Na, Rb) or cubically (M+ = K, Cs) surrounded by nitrogen atoms of TCNQ}20 The metal- nitrogen distances in these structures are not very different from the sum of the van der Waals radii. In the crystal structure of AgTCNQ, however, the Ag atoms are coordinated to four nitriles in a distorted tetrahedral an‘rangement. with an average Ag-N distance of 3.322 A. which is clearly 51 indicative of a bonding interaction and establishes precedence for a o-tt4-TCNQ coordination mode.21 The existence of both o-TCNQ and o-u4-TCNQ binding modes for complexes of the unstable [CpMn(CO)2] fragment have been discussed in the literature, but these have not been varified by crystallography.22’23»24 In addition, the complex {[Re(CO)5]3(TCNQ)}(BF4)3 is reported to exhibit an o-tt3-TCNQ ligand.26 The only known example, other than (2), of a TCNQ complex that involves a metal-metal bonded dinuclear species is {Ru2(CO)5[M-(iPrO)2PN(Et)P(OiPr)2]2(o-TCNQ)}, although this complex was not structurally characterized.26 The crystal structures of [Rb+l 8-crown-6TCNQ'12 and [Ru(PPh3)2(TCNQ)]2 reveal a less common type of TCN Q coordination in which a dimeric "(TCNQ)2" unit bridges two metal centers with each metal being coordinated to two N atoms, one on each TCNQ molecule”.28 In the structure of the complex [Cu(pdto)(TCNQ)]2 (pdto = 1,8-di-2-pyridyl- 3,6-dithiaoctane) the Cu atoms are coordinated to only one N atom on TCNQ and dimerization occurs via 1t-n: interactions between adjacent TCNQ units.29 The complexes [Ni(bdpa)]2[TCNQ][X]2 (X = C104, BPh4) and [Ni(bdpa)][TCNQ][ClO4] [bdpa = bis(3-dimethylarsinopropyl)phenyl- arsene] were not structurally characterized, but were spectroscopically determined to contain a cis-o—ttZ-TCNQ moiety rather than the trans arrangement depicted in the structure of (2).30 The bond distances and angles within the TCNQ unit in (2) are considerably different from those found in TCNQ” as shown in Table 6. In comparing the bond distances in (2) and other TCNQ” containing species to those in TCNQ”. bonds a and c are lengthened while bonds b and d are 52 Table 6. Comparison of bond distances (A) and angle (°) of several TCNQ containing products. a. reference 48 b. [R62C14(dppm)2]2(u-TCNQ) c. reference 49 d. reference 50 N N \. a VI / \d C IV ' \ m / C — C n C — v / \ / "’ \ / _° °\ N N Bmd/ file TCNQEl (2)- SITE N-M:PZ'I‘--'l‘(l\IQc [Fe(CsEt5)2I[U\le a 1.346 1.37 1.349 1.370 b 1.446, 1.450 1.37, 1.43 1.446 1.418, 1.413 c 1.374 1.42 1.379 1.423 d 1.441, 1.440 1.43, 1.40 1.422 1.413, 1.419 a 1.141, 1.139 1.03, 1.12 1.151 1.148, 1.413 I 1207,1210 120, 121 119.9 121.1, 121.5 ll 118.3 119 120.1 117.4 Ill 1207,1210 119, 122 119.9 121.2, 121.4 IV 121.8, 122.0 125, 119 122.6 1215, 121.6 V 1161 116 114.9 116.9 VI 179.6, 179.4 173.0, 177 177.7 179.5, 179.0 53 shortened. These changes in bond lengths are expected and can be explained by a contribution from the structure (11) for TCNQ’. As reported in work by Hoekstra et al., the charges in the reduced forms of N N N ' \\‘ ’0 9‘ ’l c 16 c c —C— -—> W 0 0:? c\\\ II? C‘“ N I N N 11 N TCNQ reside predominately on the N atoms which explains the nucleophilic tendency of TCNQ'.20(b) (4) Magnetic and Electrical Properties The compounds [Re2Cl4(dppm)2](TCNQ) (1) and [Re2C14(dppm)2]2(tt-TCNQ) (2) are paramagnetic as indicated by magnetic susceptibility and EPR spectroscopy. Both (1) and (2) exhibit temperature dependent susceptibilities as a consequence of antiferromagnetic coupling. The neff vs. temperature plots of (1)-A and (2) are displayed in Figures 10 and 11; the products exhibit room temperature values of 3.1 and 1.9 B.M., respectively, which roughly represent 2 and 1 unpaired electrons. In (1)-A, one would expect 2 unpaired electrons if complete electron transfer had occurred to form [Re2C14(dppm)2]+(TCNQ)‘. In the case of (2), the product [Reg]"'0~5(}.t-TCNQ")[Re2]+0-5 contains strongly coupled dirhenium units which causes a net ueff value to be ca. 1 electron. The EPR spectra of the 1:1 products [Re2C14(dppm)2](TCNQ) (1) all exhibit sharp signals centered near g = 2.003 indicating the presence of free TCNQ‘. This is in accord with the presence of the absorption, attributed to free TCNQ', in the UV-visible spectra near 400 nm for these 54 1.6- Ileff 1 J and“ I ‘ T , . o 100 200 300 400 Temperature, K Figure 10. Plot of heff (B.M.) vs. temperature (K) of [R62C14(dppm)2]2(u-TCNQ) (2). 55 “eff 400 Figure 1]. Plot of [Jeff (B.M.) vs. temperature (K) of [R62C14(dppm)2](TCNQ) (1)-A. 56 complexes. Only in the spectrum of (1)-D is a weak and broad metal-based signal noticeable. On the other hand, the EPR spectrum of [RezCl4(dppm)2]2(p.—TCNQ) (2) on a crystalline sample exhibits only a broad signal centered at g = 2.004 (Figure 12). The EPR spectra of bulk precipitate samples of (2) exhibit the characteristic sharp signal near the free electron value due to varying amounts of TCNQ' in the sample. The electrical conductivities of several samples measured on pressed pellets by the four probe technique}1 are indicative of semiconductor behavior. The plots of lnR vs. UT of (1)-A, and (2) are linear from which band gaps of 0.50 and 0.43 eV and room temperature conductivities of 1 x 10'6 and 1 x 10'5 Q'lcm'1 are determined respectively. These values are 1/100 to 1/1000 of the expected conductivities for single crystals, unfortunately, rubust crystals suitable for measurements were not obtained. Single crystals used for the X-ray study lose THF solvent of crystallization quite readily turning to powder within minutes of being removed from the mother liquid. The conductivity pathway is not likely to be through direct TCNQ-TCNQ interactions as dictated by the large separation between TCNQ moieties observed in packing diagram for (2) (Figure 13). However, close contacts between Rez units and the presence of solvent molecules may be responsible for the observed conductivities. B. Reactions of RezCl4(dppm)2 with TCNE (1) Preparation and Spectroscopic Properties When solutions of Re2C14(dppm)2 are treated with TCNE, immediate reactions occur to produce [Re2C14(dppm)2](TCNE) (3) as judged by the formation of highly colored reaction solutions. When the reactions are performed at -78°C. blue-green solutions form and a blue- green solid. (3)-A. which is stable at room temperature. is obtained by 57 T .L 500 G MW‘WW Figure 12. Single crystal EPR spectrum of [Re2C14(dppm)2]2(tt-TCNQ) (2) at -160°C. 58 Figure 13. Packing diagram of [Re2C14(dppm)2]2(u-TCNQ)-8THF, (2)-8THF. View down C axis. 59 precipitation using hexanes. When the reactions are performed at room temperature, dark purple solutions persist in which a purple solid, (3)-B, is isolated using hexanes or diethyl ether as the precipitating solvent. Infrared spectral data reveal that the blue-green and purple products, (3)-A and (3)-B, contain o-coordinated TCNE. The v(CEN) bands occur at 2197 and 2121 cm'1 for (3)-A and 2200 and 2128 cm-1 for (3)-B as compared to TCNEO, whose C.=.N stretches are located at 2256 and 2221 cm-1. These solids are soluble in most common solvents (e.g. CH3CN, THF, CHzClz, acetone, toluene, benzene, and alcohols). Slow evaporation or slow diffusion of hexanes or diethyl ether into solutions of the products have not yet produced crystalline materials, thereby precluding X-ray structural determinations. There are numerous examples of TCNE complexes in the literature with the most frequently encountered coordination mode for TCNE being the 1t-type as in the metallocene-TCNE complexes [i.e. M(C5R5)2TCNE; M = Fe, Cr, Co; R = H, Me, Et] that exhibit interesting magnetic properties at low temperatures.3 In addition to the n-TCNE complexes, several o-coordinated TCNE complexes have recently been reported, the most intriguing example being the room temperature ferromagnet V(TCNE)2-1/2(CH2C12) characterized mainly by infrared spectroscopy.4 Among the examples whose X-ray crystallographic structures have been determined, the complexes V(C5 H 5 )2 B r ( TC N E ) , 3 2 Os(SzPR2)2(PPh3)(TCNE),33 and Mn(CO)2(C5H5)(TCNE)34 all contain TCNE which is bonded to a metal center through only one N atom on TCNE. In the structure of the complex [Ir(CO)(PPh3)2]3[TCNE], the TCNE bridges the two Ir centers in a trans -M2-N-o-bound arrangement as does TCNQ in the structure of (2)35 The structures of the complexes 60 [MnTPP-TCNE]X (TPP = meso-tetraphenylporphinato)36 and [Cu(hfacac)2oTCNE]x (hfacac = hexafluoroacety1acetonates)37 contain trans -N-o-bound TCNE and are polymeric. The values of the v(C.=_N) stretching frequencies of these and other TCNE containing complexes are listed along with the values obtained for [Re2C14(dppm)2](TCNE) (3)-A and [Re2Cl4(dppm)2](TCNE) (3)-B in Table 7. The values of v(CEN) for the [Re2C14(dppm)2](TCNE) products are quite comparable to those found for the crystallographically determined complex Mo(CO)2(C5H5)(TCNE) supporting the assignment of a o-N-bound T CNE‘ moiety in the [Re2C14(dppm)2](TCNE) products. The electronic absorption spectrum for (3)-A exhibits a strong absorption at kmax = 750 nm. This transition is assigned to a M—>TCN E charge-transfer band and is observed in several M-o-N-bound complexes.24~33 Complexes that do not contain o-coordinated TCNE, but rather n-bonded TCNE as in the complex [Fe(CsMe5)2]TCNE, exhibit electronic absorptions near 400 nm assignable to 1c—1c* transitions.3~22,38 As indicated by magnetic measurements, (3)-A is diamagnetic due to the significant dtt-pn interaction. This is not unusual, as diamagnetism is likewise observed in Os(S2PR2)2(PPh3)TCNE and V(C5H5)2Br(TCNE).32~33 The 1H NMR(CDC13) spectrum of (3)-A consists of several complex multiplets between 5 = 7.1 to 6 = 7.8 ppm attributed to the phenyl protons on dppm. A set of resonances centered at 5 = 5.68 and 5 = 5.61 ppm in an ABX4 pattern are the result of inequivalent methylene protons on the two dppm ligands. unlike the pentet which occurs at 8 = 5.21 ppm in an AA'X4 pattern for the parent compound Re2C14(dppm)2.39 The 31P{ 1H} NMR spectrum reveals two types of phosphorous nuclei in an AA'BB' pattern 61 08:9000300080550: n 0802 Einmoqic0nm§0r305 n mm... 00580000 3:830:05 * 000.5000 8: 0.03 00230:: 0>cs0m .0 0:083:00 So :0 EU 40.32 .0 R comma .020 .080 o 3.0 ._...Ez0.038§0=0_ 0m 3 030 .05 020 .95 as -_ Sue 202050045. mm E 300 .05 0:0 .0 3:0 ...Ez0.:2%i$600£ 43.0 9.0 mg .3 nos .330 as -0 o 020530020005 4 3 $8 .90 gm -N o AN_0£0§.20200> 083 05 as as .3 SR -0 o 0-5 Angieaaegsa 0:25 as 20 mg .3 8mm -_ o .10 6200350032085 3m 3 3:0 .3 $8 -_ a .mz0tfiozm0xa mm 3 $8 .3 0:0 -0 a Lmz0t§32000§ a 05 as .3 080 o 0204 00:80.00”— AZmUv> 0320 53052000 003800 00083800 $058.50 mZUH 0:22; 8.“ 0065:0000 $330.5... AZmUV> .00 5050800 .5 030,—. 62 with resonances at 5 = —14.6 and 8 = —19.9 ppm. These NMR spectral features are in accord with either an A-frame type (I) or non-A-frame type (II) seen for other complexes of the types Re2C14(dppm)2L, and [Re2C13(dppm)2L2]+.17913.39’40 The low temperature 31P{1H} NMR pAP NC CN Cl l Cl Cl c>—=< \ / \ / (RB—R6 AP "ll/C CN cu | |\ I' “I" N / PVP \\\c cu lRe—Re—Cl )—< l ’l _ CI Cl NC CN PVP I II spectrum of (3)-A in CDCl3 at -50°C, shown in Figure 14, exhibits a single broad resonance at 8 = -21.4 ppm which is consistent with the transformation to a more symmetrical molecule with equivalent phosphorous nuclei. A cyclic voltammogram of (3)-A (vs. Ag/Ag+ in 0.1M TBABF4/CH2C12) exhibits a reversible reduction at E1/2 = -O.lO V which is more negative than the reduction potential for free TCNE (see Figure 15). This is consistent with metal-to-ligand electron transfer increasing the electron density on TCNE and making it more difficult to reduce.24~41 A reversible metal-based oxidation at 131/2 = 0.72 V is at more positive potential than the first oxidation for Re2C14(dppm)3. This is also a consequence of metal-to-ligand charge transfer. 63 20°C 'VYY‘YVVVY‘V‘VI'Y"TY'V'TTVYYY'VYYIYYYII'YVVYY‘VVYTTYTTYfl—VYYYY‘I vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv W '5 '3 ‘10 ‘12 '14 - l5 18 O _ '24 -25 “:8 00m Figure 14. Variable temperature 31P {1H} NMR (CDCl3) spectra of [Re2Cl4(dppm)2](TCNE) (3)-A- 64 1 0.8 0.6 0.4 0.2 0 -O.2 -0.4 Volts Figure 15. Cyclic voltammogram of [Re2Cl4(dppm)2](TCNE) (3)-A in 0.1 M TBABF4/CH2C12.versus Ag/AgCl at a Pt disk electrode. 65 When a blue-green solution of (3)-A in CHzClz is allowed to stand at room temperature over the period of ca. 20 h, the solution color eventually turns dark purple. UV-visible spectra during this period exhibit a feature at lmax = 750 nm that decreases in intensity, and a peak that grows in near Xmax = 500 nm. The final spectrum exhibits absorptions at lmax = 518 and 668 nm. Reactions performed with as many as 6 equivalents of TCNE yield virtually identical results. When THF is used in place of CH2C12, these changes occur more slowly. With THF noticeable changes in the UV- visible spectrum are observed only after 48 h. The spectra of the 1:1 THF reaction solutions exhibit absorptions at kmax = 488 nm with a shoulder at lmax = 677 nm in addition to an intense absorption at kmax = 750 nm. Over a period of 3 weeks the absorption at lmax = 750 nm slowly diminishes while that at kmax = 488 nm gradually becomes more intense. The absorption at lmax = 677 nm, which initially becomes stronger, slowly decreases in intensity over time. The reaction between Re2C14(dppm)2 and 0.5 equivalents of TCNE in THF immediately produces a dark blue solution with an electronic absorption at kmax = 748 nm, but within two days, the color changes to a dark olive-green and the corresponding UV- visible spectrum contains weak absorptions at kmax = 450 and 650 nm. The infrared spectra of THF solutions containing 1:5, 2:5, 1:1, and 2:1 ratios of Re2C14(dppm)2:TCNE all contain v(CEN) bands at 2197 (s) and 2123 (m) cm'1 indicating that no dependence on stoichiometry. Only in the spectrum of the 1:5 solution do other peaks, attributed to free T C N E 0, appear in the v (C E N) region. 66 C. Reactions of Re2C14(dppm)2 with TNAP (1) Preparation and Spectroscopic Properties The reactions between Re2C14(dppm)2 and TNAP yield products that exhibit spectroscopic features similar to those observed for the products from the reactions between Re2C14(dppm)2 and TCNQ. The 1:1 reaction between Re2C14(dppm)2 and TNAP in CH2C12 produces an instantaneous color change to yellow-green from which [Re2C14(dppm)2](TNAP) (4)-A is precipitated as an olive-green solid by the addition of hexanes. The solution infrared spectrum of (4)-A exhibits v(CEN) bands at 2195 and 2126 cm'1 which are similar to those observed for (3)-A (see Table 8). Although, judging by color, the solution appears to be stable at room temperature, the solution infrared spectrum undergoes changes. After 11 h, new v(C:—:N) bands appear at 2183, 2114, and 2085 cm'l; these are at similar frequencies to the v(CEN) bands observed in the spectra of solutions of (3)-A. The electronic absorption spectrum of (4)-A in CHzClz exhibits absorptions at Amax = 374, 478, and 1005 nm, with the intensity of the absorption at 1005 nm decreasing after 1 day at room temperature. The 2:1 reaction between RezCl4(dppm)2 and TNAP in CHzClz produces an instantaneous blue-green solution which is stable only at low temperatures. The addition of hexanes to this solution, while kept at -78°C, affords a product formulated as [Re2C14(dppm)2]2(u-TNAP) (5)-A as a black crystalline solid. When solutions of (5)-A are warmed to room temperature, the color quickly turns to red-brown, (5)-B, preventing solution studies of (5)-A. The solution infrared spectrum of (5)-B exhibits v(CEN) bands at 2186 and 2101 cm-1 which are similar to those observed for (2) (see Table 8). The electronic absorption spectrum of (5)-B in 67 Table 8. Comparison of the infrared spectral features of the TCNQ and TNAP products. Complex Acceptor v(CEN) bands cm-1 (3)-A TCNQ 2195 (s), 2115 (m) (4)-A TNAP 2195 (s), 2126 (m) (3)-B TCNQ 2183 (S), 2114 (s,br) 2085 (sh) (4)-B TNAP 2186 (S), 2124 (s,br) 2089 (Sb) (2) TCNQ 2187 (m), 2109 (s,br) (5)-B TNAP 2186 (m), 2101 (s,br) 68 CH2C12 exhibits one features at kmax = 1072 and 2050 nm which slowly decreases in intensity with time. 69 References 1. (a) Ferraro, J. R.; Williams, J. M. Introduction to Synthetic Electrical Conductors, Academic Press, Inc. 1987. (b) Williams, J. M.; Schultz, A. J.; Geiser, U.; Carlson, K. D.; Kini, A. M.; Wang, H. H.; Kwok, W.-K.; Whangbo, M.-H.; Schirber, J. E. Science 1991, 252, 1501. (c) Bryce, M. R. Chem. Soc. Rev. 1991, 20, 355. (d) Proceeding of the International Conference on Science and Technology of Synthetic Metals (ICSM88) Santa Fe, NM, USA (Synth. Met. 1988, B1-B656). 2. (a) Kollmar, C.; Kahn, O. Acc. Chem. Res. 1993, 26, 259. (b) White, R. M. Science, 1985, 229, 11. (c) Miller, J. S.; Epstein, A. J. Angew. Chem. 1993, 32, 000. ((1) Miller, J. S. Adv. Mater. 1992, 4, 298. (e) Kahn, 0. Comments Inorg. Chem. 1984, 3, 105. (f) Rey, P Acc. Chem. Res. 1989, 22, 392. (g) Caneschi, A.; Gatteschi, D.; Renard, J. P.; Rey, P.; Sessoli, R. Inorg. Chem. 1989, 28, 3314. (h) van Koningsbruggen, P. J.; Kahn, 0.; Nakatani, K.; Pei, Y.; Renard, J. P.; Drillon, M.; Legoll, P. Inorg. Chem. 1990, 29, 3325. 3. (a) Miller, J. S.; Epstein, A. J. Angew. Chem. 1993, 32, 000 (b) Miller, J. S.; Epstein, A. J.; Reiff, W. M. Chem. Rev. 1988, 88, 201. (c) Miller J. S.; Calabrese, J. C.; Rommelmann, H.; Chittipeddi, S. R.; Zhang, H. H.; Reiff, W. M.; Epstein, A. J. J. Am. Chem. Soc. 1987, 109, 769. ((1) Ward, M.S.; Johnson, D. C. Inorg. Chem. 1987,26, 4213. (e) Broderick, W. E.; Thompson, J. A.; Day, E. P.; Hoffman, B M. Science 1990, 249, 401. 4. Manriquez, J. M.; Yee, G. T.; McLean, R. 8.; Epstein, A. J.; Miller, J. S. Science 1991, 252, 1415. 5. (a) Zietlow, T. C.; Klendworth, D. D.; Nimry, T.; Salmon, D. J.; Walton, R. A. Inorg. Chem. 1981,20. 947. (b) Barder, T. J.; Cotton, F. A.; Lewis, D.; Schwotzer. W.; Tetrick, S. M.; Walton, R. A. J. Am. Chem. Soc. 1984, 106, 2882. 6. Scan rate 200 mV/sec, 0.1 M TBAI—l, in CHzClz. The Cp2Fe”/Cp2Fe+ couple was refernced at +0.50 V. 7. Barder, T. J.; Cotton. F. A.; Dunbar. K. R.; Powell, G. L.; Schwotzer. \V.: Walton. R. A. Inorg. Chem. 1985. 24. 2550. 10. 11. l2. 13. 14. 15. 16. 70 San Filippo, J., Jr. Inorg. Chem. 1972, I I , 3140. Standard procedure for thin tube layering reactions: A 6 or 8 mm outer diameter pyrex tube is cut to a length of ca. 16 inches and sealed at one end. The tube is connected to an apparatus consisting of a ground glass stopcock and 14/20 size female joint using a 1/2 inch piece of Tygon tubing of appropriate diameter. The glass tube is heated with a flame while under vacuum and allowed to cool prior to use. After the addition of solutions and solvents, the tube is allowed to stand for ca. 10 min. prior to flame sealing to allow for evaporation of solvent away from the area to be sealed. Before sealing, with the stopcock closed, a slight vacuum is created in the gas manifold by closing the nitrogen inlet and pumping and filling several times on the hose leading to the apparatus with only the mercury bubbler open. This is repeated several times until the mercury is drawn up about 2 inches. The stopcock to the thin tube is gently opened and the tube is slowly and evenly sealed using a flame at least 3 inches above the solution level. The mercury level is monitered while sealing to ensure the vacuum is not lost. (a) Bino, A.; Cotton, F. A.; Fanwick, P. E. Inorg. Chem. 1979, 18, 3558. (b) Cotton, F. A.; Frenz, B. A.; Deganello, G.; Shaver, A. J. Organomet. Chem. 1973, 50, 227. TEXSAN-TEXRAY Structure Analysis Package, Molecular Structure Corporation 1985. Sheldrick, G. M. In: Crystallographic Computing 3 . Eds.; G.M. Sheldrick, C. Kruger, and R Goddard. Oxford U.K., 1985; pp. 175 - 189. Robles-Martinez, J. G.; Salmeron-Valverde, A.; Alonso. E.; Soriano, C. Inorg. Chem. Acta 1991, 179. 149. Taube, H.; Johnson, A. J. Indian Chem. Soc. 1989, 66, 503 (a) Fanwick, P. E.; Price, A. C.; Walton, R. A. Inorg. Chem. 1988, 27, 2601. (b) Price, A. C.; Walton, R. A. Polyhedron 1987, 6, 729. For a study on the effect of bond length on bond order of Mng complexes see: Cotton. F. A.; Dunbar. K. R.: Falvello. L. R.; Tomas. M.; Walton. R. A. J. Am. Chem. Soc. 1983. 105. 4950. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 71 Cotton, F. A.; Dunbar, K. R.; Price, A. C.; Schwotzer, W.; Walton, R. A. J. Am. Chem. Soc. 1986, 108, 4843. (a) Barder, T. J.; Cotton, F. A.; Falvello, L. R.; Walton, R. A. Inorg. Chem. 1985, 24, 1258. (b) Derringer, D. R.; Shih, K.-Y.; Fanwick, P. E.; Walton, R. A. Polyhedron, 1991, 10, 79. (c) Fanwick, P. E.; Qi, J.-S.; Shih, K.-Y.; Walton, R. A. Inorg. Chem. Acta, 1990, I72, 65. Cotton, F. A.; Shive, L. W.; Stults, B. R. Inorg. Chem. 1976, 15, 2239. (a) Fritchie, C. J.; Arthur, P. Acta Cryst. 1966, 21, 139. (b) Hoekstra, A.; Spoelder, T.; Vos, A. Acta Cryst. 1972, 828, 14. (c) Konno, M.; Saito, Y.; Acta Cryst. 1974, B30, 1294. Shields, L. J. Chem. Soc., Faraday Trans. 2 1985, 81 , 1. Gross, R.; Kaim, W. Angew. Chem. Int. Ed. 1987, 26, 251. Olbrich-Deussner, B.; Gross, R.; Kaim, W. J. Organomet. Chem. 1989, 366, 155. (a) Gross-Lannert, R.; Kaim, W.; Olbrich-Deussner, B. Inorg. Chem. 1990, 29, 5046. (b) Cotton, F. A.; Daniels, L. M.; Dunbar, K. R.; Falvello, L. R.; Tetrick, S. M.; Walton, R. A. J. Am. Chem. Soc.1985,107,3524. DIRDIF: Direct Methods for Difference Structure, An Automatic Procedure for Phase Extension; Refinement of Difference Structure Factors. Beurskens, R. T. Technical Report, 1984. Bell, S. E.; Field, J. S.; Haines, R. 1.; Moscherosch. M.; Matheis, W. Kaim, W. Inorg. Chem. 1992, 31, 3269. Grossel, M. G; Evans, F. A.; Hriljac, J. A.; Morton, J. R.; LePage, Y.; Preston, K. F.; Sutcliffe, L. H.; Williams. A. J. J. Chem. Soc., Chem. Commun. 1990, 439. Ballester, L.; Barral, M. C.; Gutierrez. A.; Jiménez-Aparicio, R.; Martinez-Mayo, J. M.; Perpifian, M. F.: Monge. M. A.; Ruiz-Valero, C. J. Chem. Soc., Chem. Commun. 1991, 1396. Humphrey, D. G.; Fallon. G. D.: Murray, K. S. J. Chem. Soc. Chem. Commun. 1988. 1356. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 72 Booth, B. L.; McAuliffe, C. A.; Stanley, G. L. J. Chem. Soc., Dalton 1982, 535. van der Pauw, L. J. Philips Research Reports 1958, 13, l. Rettig, M. F.; Wing, R. M. Inorg. Chem. 1969, 8, 2685. McQueen, A. E. D.; Blake, A. J .; Stephenson, R. A.; Schroder, M.; Yellowlees, L. J. J. Chem. Soc., Chem. Commun. 1988, 1533. Braunworth, H.; Huttner, G.; Zsolnai, L. J. Organomet. Chem. 1989, 372, C23. Yee, G. T.; Calabrese, J. C.; Vazquez, C.; Miller, J. S. Inorg. Chem. 1993, 32, 377. Miller, J. 8.; Calabrese, J. C.; McLean, R. S.; Epstein, A. J. Adv. Mater. 1992, 4, 498. Bunn, A. G.; Carroll, P. J.; Wayland, B. B. Inorg. Chem. 1992, 31, 1297. Dixon, D. A.; Miller, J. S. J. Am. Chem. Soc. 1987, 109, 3656. Barder, T. J.; Cotton, F. A.; Lewis, D.; Schwotzer, W.; Tetrick, S. M.; Walton, R. A. J. Am. Chem. Soc. 1984, 106, 2882. Fanwick, P. E.; Qi, J.-S.; Walton, R. A. Inorg. Chem. 1990, 29, 3787. Olbrich-Duessner, B.; Kaim, W.; Gross-Lannert, R. Inorg. Chem. 1989, 28, 3113. TCNQ was purchased from Aldrich Chemical Co. and sublimed before using. The infrared spectra was done as a Nujol mull and obtained on our equipment. Acker, D. S.: Harder, R. J.; Hertler, W. R.; Mahler, W.; Melby, L. R.; Benson. R. E.: Mochel, W. E. J. Am. Chem. Soc. 1960, 82, 6408. Melby, L. R.: Harder, R. J.; Hertler. W. R.; Mahler. W.; Benson, R. E.; Mochel. \V. E. J. Am. Chem. Soc. 1962. 84. 3374. 45. 46. 47. 48. 49. 50. 73 Miller, J. S.; Reiff, W. M.; Zhang, J. H.; Preston, L. D.; Reis, A. H. Jr.; Gebert, E.; Extine, M.; Troup, J.; Dixon, D. A.; Epstein, A. J.; Ward, M. D. J. Phys. Chem. 1987, 91, 4344. Broderick, W. E.; Hoffman, B. M. J. Am. Chem. Soc. 1991, 113, 6334. Sacher, W.; Nagel, U.; Beck, W. Chem. Ber. 1987, 120, 895. Long, R. E.; Sparks, R. A.; Trueblood, K. N. Acta Cryst. 1965, I8, 932. Kobayashi, H. Bull. Chem. Soc. Japan 1973, 46, 2945. Chi, K.-M.; Calabrese, J. C.; Reiff, W. M.; Miller. J. S. Organomet. 1991, 10, 688. CHAPTER III THE USE OF N,N'-DICYANOQUINONEDIIMINES AS LINKING UNITS FOR THE DINUCLEAR COMPOUND RezCl4(dppm)2 . 74 75 l - Introduction The search for new molecules capable of linking dinuclear metal complexes like led us to the study of the recently discovered cyano- containing N,N'-dicyanoquinonediimines (DCNQIs). Aumiiler and Hiinig reported that a variety of substituted DCNQIs could be readily synthesized from quinones (see Figure 16).1 Many of these compounds exhibit accessible redox processes which make them good candidates for charge- transfer chemistry with Re2C14(dppm)2.2,6 In particular, the electrochemical properties of 2,5-dimethyl-N,N'-dicyanoquinonediimine (BM-DCNQI) are very similar to TCNQ. The DCNQIs have the ability to form complexes which exhibit high single crystal conductivities.3~4 X-ray S tructures of a number of M(DCNQI)2 complexes have been determined; the cations are typically covalently linked to form layered two-dimensional S lieets.3»5 Such structures have not been found for complexes of TCNQ, thus we sought to compare the chemistry of the DCNQIs with RezCl4(dppm)2 to the results for TCNQ reported in Chapter II. 2 .. Experimental A. Synthesis The compounds 2,6-dimethyl-N-cyano-1,4-benzoquinone-4-imine C DM-CNQMI), N,N'-dicyano-l,4-benzoquinonediimine (DCNQI), 2,5- Climethyl-N,N'-dicyano-l,4-benzoquinonediimine (DM-DCNQI), N,N'- Clicyano-1,4-naphthaquinonediimine (DCNNQI), N.N'—dicyano-9,10- anthraquinonediimine (DCNAQI), and 1,5-dichloro-N,N'-dicyano-9,10- anthraquinonediimine (DC-DCNAQI) were synthesized according to literature procedures.1 All of these compounds were characterized by cyclic voltammetry and IR. UV-visible. 1H NMR. 13C NMR. and GC-mass spectroscopies. 76 51mm (V0118) vs. A AgCl in CH3CN o R R = H: +0.25. -0.32 R DCNQI 0 R = CH3: +0.21. -0.38 DM-DCNQI N 0 so 0 +0.19. -0.35 DCNNQI 0 CN 1 2 ——>- —> a 0 cos 12:11: -O.11.-0.46 DCNAQI R = Cl; -0.20, 0.43 9 R DC-DCNAQI -().23, —().97 N Fl 0 N R N N C DM—CNQMI 055.5% .00. . 3 1 z TiCl.» 2 = Me3SiNCNSiMe3 3 H ,c N :I R I N NC ’ I N I I N. ,c R N I I ,N No ,c N I I ,N NC ,c N :I C 0 Figure 16. Synthetic route to DCNQI molecules and their cyclic voltammetric properties. 77 (1) Preparation of DCNPQI The compound N,N'-dicyano-6,l3-pentacenequinonediimine, although not reported in the literature, was synthesized using a similar method described by Aumiiller.1 A quantity of pentacenequinone (O .616 g, 2.00 mmol) was added to a 100 mL Schlenk flask followed by addition of 25 mL of CH2C12. To this solution was added 5.68 mL (25 mmol) of bis(trimethylsilyl)carbodiimide (Me3SiN=C=NSiMe3) followed by 1.1 mL (10 mmol) of titanium tetrachloride forming a dark red-brown solution. The reaction was stirred at room temperature for 72 h after which time the reaction mixture was poured into a large beaker Containing 500 mL of petroleum ether (boiling range: 35-60°C) to give a precipitate which was collected by gravity filtration. The solid was dissolved in ca. 1 L of hot benzene and filtered. The yellow filtrate was reduced in volume to ca. 50 mL using a rotary evaporator and an orange S clid was precipitated by adding 500 mL of petroleum ether. The solid Was collected by filtration and vacuum dried. A GC chromatogram of the product indicated that 3 separate components were present, thus, the :3 Ioduct was further purified by eluting a CH2C12 (400 mL) solution of the product through a silica gel (65-200 mesh) column (12 inches long by 1 inch diameter) and the product was further eluted with CHzClz (ca. 1 L) ll mtil colorless eluents were obtained. The remaining two bands, a dark brown-orange band near the top of the column and a red-pink band around the middle of the column, were not collected. The yellow CHzClz eluent was concentrated to 50 mL using the rotary evaporator from which a bright orange solid was precipitated by adding 200 mL of petroleum ether. The solid was collected by filtration and vacuum dried: yield 0.350 g (49%). IR (Csl. Nujol. cm‘l): v(CEN) 2149 (m). 2162 (sh). 2177 (sh). 78 v(C=C) 1597 (s), v(C=N) 1539 (8). mass spectrum (70eV): m/z = 356 ( 1 00%, M+), 330 (12%, M+-CN), 329 (17%, M+-HCN), 315 (7%, M+-H-NCN), 302 (14%, M+-2HCN). A cyclic voltammogram of the compound in a 0.1 M TBABF4/CH3CN solution did not reveal any electrochemical processes between +2.0 and -2.0 V. (2) Reaction of Re2C14(dppm)2 with DM-CNQMI A solution consisting of 0.0132 g (0.082 mmol) of DM-CNQMI dissolved in 5 mL of THF was added to a stirring solution containing 0. 105 g (0.082 mmol) of Re2C14(dppm)2 dissolved in 10 mL of THF which resulted in the immediate production of a dark green solution. A UV-visible spectrum of the reaction solution showed an absorption at lmax = 812 nm and a solution infrared spectrum (Can cells, THF reference) revealed a v(CEN) band at 2195 (vs) cm-l. The reaction was stirred for 4 h at room temperature with no further change in color. The reaction solution was reduced in volume by vacuum and a green solid was precipitated by the addition of hexanes (20 mL). The solid was collected by filtration, washed with copious amounts of hexanes, and vacuum dried; Yield 0.061 g (51%). IR (CsI, Nujol, cm‘l): v(CEN) 2096 (vs), v(C=O) l 645 (w), v(C=C) 1610 (w), v(C=N) 1576 (m). (3) Reactions of Re2C14(dppm)2 with DCNQI (i) Preparation of [RezCl4(dppm)2]z(u-DCNQI) A THF (12 mL) solution containing 0.0061 g (0.039 mmol) of DCNQI was added to a THF (8 mL) solution containing 0.100 g (0-078 mmol) of Re2C14(dppm)2 to give a green precipitate within S rTlinutes. The solid was collected by filtration, washed with THF, and V acuum dried; yield 0.073 g (59%). IR (Csl. Nujol. cm‘l): 79 v (CEN) 2090 (vs), v(C=N) 1505 (vw), v(C=C) not observed. UV-visible(CH2C12) lmax = 1003 and 691 nm. (ii) 1:4 Re2C14(dppm)2:DCNQI Stoichiometric Reaction Methylene chloride (20 mL) was added to a Schlenk flask that c ontained 0.050 g (0.039 mmol) of Re2C14(dppm)2 and 0.0244 g (0.156 mmol) of DCNQI resulting in the immediate formation of a dark green solution. The reaction mixture was placed in the refrigerator (5°C) for 2 weeks during which time a dark green solid slowly precipitated. The solid was collected by filtration, washed with CH2C12, and vacuum dried; yield 0.072 g (96%). IR (CsI, Nujol, cm'l): v(CEN) 2090 (vs,br), 2240 (w). The same product was obtained in slightly lower yields (0.049 g) when the reaction was performed in toluene. (4) Reactions of Re2C14(dppm)2 with DM-DCNQI (i) 1:1 Reactions (a) Preparation of [Re2C14(dppm)2](DM-DCNQ1) (6)-A Methylene chloride solutions (5 mL each) of Re2C14(dppm)2 (0.100 g, 0.078 mmol) and DM-DCNQI (0.0143 g, 0.078 mmol) were Cooled to -78°C using a dry ice/acetone bath. The Re2C14(dppm)2 solution was added to the DM-DCNQI solution through a cannula producing a dark blue solution with a v(CEN) band at 2053 cm’l. This infrared solution tllrned green within 5 minutes yielding a spectrum with a v(CsN) band at 2082 cm'l. A UV-visible spectrum of the reaction solution exhibited absorptions at lmax = 830 (e = 23100 M‘lcm'l) and 334 (e = 35100 M'lcm'l) nm. The solution volume was reduced to ca. 5 mL by vacuum while being maintained at low temperatures. and 30 mL of heXanes was added to precipitate a blue solid which was collected by 80 filtration, washed with hexanes (2 x 10 mL) and dried in vacuo; yield 0-096 g (84%). IR (CsI, Nujol, cm°1) v(CEN) 2070 (s,br). ([3) Preparation of [RezCl4(dppm)2](DM-DCNQI) (6)-B A solution containing 0.0144 g (0.078 mmol) of DM-DCNQI in 8 mL of THF was transferred to a 50 mL Schlenk flask containing 0.100 g (0.078 mmol) of Re2C14(dppm)2 in 10 mL of THF producing an immediate dark blue solution of (6)-A. After 5 minutes, a UV-visible spectrum of the reaction solution exhibited a strong absorption at lmax = 812 nm and a higher energy absorption at hmax = 342 nm. The reaction mixture was stirred for 24 h at room temperature during which time the color changed to dark green. The solution volume was reduced under vacuum followed by treatment of diethyl ether (ca. 20 mL) which caused the precipitation of an olive-green solid of (6)-B. The solid was collected by filtration, washed with diethyl ether, and vacuum dried; yield 0.077 g (67%). IR (CsI, Nujol, cm'l): v(CEN) 2091 (s,br), v(C=C) 1587 (vw), v(C=N) 1576 (vw). (c) Reaction of 1:1 RezCl4(dppm)2 and DM-DCNQI in Toluene A reaction mixture containing Re2C14(dppm)2 (0.100 g, 0-078 mmol), DM-DCNQI (0.0143 g, 0.078 mmol), and toluene (20 mL) was refluxed causing the immediate formation of a dark-blue solution. Wi thin 10 minutes, the solution turned dark green and a green solid precipitated. The mixture was refluxed for 45 minutes after which time a black solid was collected by filtration. The product was dissolved in CHzClz (ca. 10 mL) and the green solution was filtered leaving behind an insoluble black solid. The solid was washed with CH2C12 until colorless fil1:1-ates were achieved and then dried in vacuo; yield 0.053 g (46%). IR (Q81, Nujol. cm-l): v(CEN) 2054 (s.br). v(C2C) 1588 (vw). v(C=N) 1 S75 (vw). The green filtrate was reduced in volume and layered with 15 81 1111. of hexanes causing the eventual formation of an olive-green solid which was collected by filtration, washed with hexanes, and dried in vacuo; yield 0.016 g (14%). IR (CsI, Nujol, cm'l): v(C.=_N) 2075 (s), v(C=C) l 588 (vw), v(C=N) 1574 (vw). (ii) Preparation of [RezCl4(dppm)2]2(u-DM-DCNQI) (7) (a) Slow Diffusion Reaction A quantity of DM-DCNQI (0.0073 g, 0.039 mmol) was dissolved in 5 mL of THF and slowly added to a Schlenk tube containing 0.100 g (0.078 mmol) of Re2C14(dppm)2 dissolved in 5 mL of THF. The Schlenk tube was placed in the refrigerator for 2 days during which time a black crystalline solid formed. The solid was collected by filtration, washed with 'THF, and dried in vacuo; yield 0.076 g (71%). Anal. Calcd for C110H96N4C13P3Re4: C, 48.04; H, 3.52; N, 2.04. Found C, 47.98; H, 3.81; N, 2.01. 1H NMR (CDCl3, ppm) 5 = 7.0 — 7.9 (m), 5 = 3.73 (t), and 8 = 1.83 (p). A 31P{1H} NMR signal was not observed. IR (CsI, Nujol, cm'l): v(C.=_N) 2056 (s,br), v(C=C) 1586 (w), v(C=N) 1572 (w). Electronic spectroscopy (CHzClz): Kmax nm (e, M'lcm'l), 696 (4600), I 035 (27000), 1800 (36000). (1)) Bulk Reaction A solution containing 0.0073 g (0.039 mmol) of DM-DCNQI in 20 mL of benzene was slowly added to a stirring solution containing 0- 100 g (0.078 mmol) of Re2C14(dppm)2 in 10 mL of benzene to form an initial dark blue solution. After 10 minutes, a black solid precipitated which was collected by filtration, washed with benzene, and vacuum dried; yield 0.084 g (78%). IR (KBr pellet. cm'l): v(CEN) 2250 (w), 2218 (w), 2- 1 01 (vs), v(C=C) 1588 (w). v(C=N) 1574 (w). Electronic spectroscopy 82 (CH2C12): Amax = 702 and 1039 nm. Identical results were obtained when THF was used as the reaction solvent. (5) Reactions of Re2C14(dppm)2 with DCNNQI (i) 2:1 Re2C14(dppm)2:DCNNQI Reaction A solution containing 0.0074 g (0.036 mmol) of DCNNQI in 10 mL of THF was slowly added to a solution consisting of 0.093 g (0.072 mmol) of Re2C14(dppm)2 in 10 mL of THF resulting in the formation of a dark red-purple solution. A solution infrared spectrum (CaF2 cells, THF reference) revealed two v(CEN) bands at 2140 (m) and 2075 (s) cm'l, and an electronic absorption spectrum exhibited absorptions at lmax = 534 and 1026 nm. The reaction solution was stirred at ambient temperature for two days during which time the color changed to brown. Two 2 mL portions of the solution were layered with diethyl ether and hexanes in 8 mm outer diameter Pyrex tubes. Unfortunately no crystalline material was obtained. The remainder of the solution was reduced in volume and an olive-green solid was precipitated using diethyl ether, collected by filtration, washed with diethyl ether, and vacuum dried; yield 0.0374 g (37%). IR (CsI, Nujol, cm'l): v(CEN) 2100 (s), v(C=C) 1587 (w), v(C=N) 1574 (w). (ii) 1:] Reaction A solution containing 0.087 g (0.068mmol) of Re2C14(dppm)2 (1i ssolved in 10 mL of THF was added through a cannula to a THF (5 mL) SOlution containing 0.014 g (0.068 mmol) of DCNNQI producing a dark green solution. The reaction solution quickly turned dark brown. Infrared and electronic absorption spectra obtained within 5 minutes revealed V (Cr—2N) bands at 2130 (w) and 2080 (m) cm:1 (Can cells, THF reference) Clnd electronic transitions at hmux = 843 and 1026 nm. The reaction 83 solution was reduced in volume and layered with diethyl ether (20 mL) which effected the precipitaion of a brown solid. The solid was collected by filtration, washed with diethyl ether, and dried in vacuo; yield 0.072 g (71%). IR (CsI, Nujol, cm’l): v(CEN) 2095 (s), v(C=C) 1587 (w), v(C=N) 1574 (w). (6) Reactions of Re2C14(dppm)2 with DCNAQI (i) 1:2 RezCl4(dppm)2:DCNAQI Reaction Separate CH2C12 solutions of Re2C14(dppm)2 (0.100 g, 0.078 mmol, 10 mL of CH2C12) and DCNAQI (0.040 g, 0.156 mmol, 7.5 mL of CH2C12) were prepared and the DCNAQI solution was added to the Re2C14(dppm)2 solution in four equal portions (ca. 1.9 mL each). After each addition, a 1 mL aliquot was removed for infrared and UV-visible spectral measurements. The color of the reaction became dark green after the first addition and remained the same color throughout the reaction. The IR spectra of each aliquot exhibited strong v(CEN) bands at 2080 cm-1 and the final spectrum exhibited a shoulder near 2170 cm-1. The UV- visible spectrum of the initial solution exhibited a single strong absorption at hmax = 934 nm, but with further addition of the DCNAQI solution this absorption decreased in intensity as an absorption at Kmax = 333 nm appeared. The reaction solution was reduced in volume under vacuum and hexanes was added to precipitate an olive-green solid. The solid was Collected by filtration, washed with hexanes, and vacuum dried; yield 0-076g (50%). IR (CsI, Nujol, cm-l): v(CEN) 2068 (s,br), v(C=C) 1 585 (w) and 1573 (w), v(C=N) 1560 (w). (ii) 2:1 Re2C14(dppm)2:DCNAQI Reaction A toluene (10 mL) solution containing 0.0062 g (0.024 mmol) of DCNAQI was added to a toluene solution containing 0.062 g (0.048 mmol) 84 of RezCl4(dppm)2 resulting in a green solution. This solution was filtered through a Schlenk frit and the green filtrate was slowly reduced in volume to yield a black crystalline solid which was collected by filtration, washed with toluene, and vacuum dried; yield 0.028 g (40%). IR (CsI, Nujol, cm'l): v(CEN) 2058 (s). (7) 2:1 Reaction of Re2C14(dppm)2 with DC-DCNAQI A solution consisting of 0.0127 g (0.039 mmol) of DC-DCNAQI and 10 mL of THF was slowly added to a Schlenk tube containing 0.100 g (0.078 mmol) of Re2C14(dppm)2 dissolved in 10 mL of THF resulting in the spontaneous formation of a dark green solution. A solution IR spectrum (Can cells, THF reference) exhibited a v(CEN) band at 2075 cm'1 and an electronic transitions at kmax = 921 nm. The volume of the reaction solution was reduced to ca. 5 mL under vacuum and EtzO (15 mL) was added to precipitate an olive-green solid which was collected by filtration, washed with diethyl ether, and vacuum dried; yield 0.093 g (82%). IR (CsI, Nujol, cm’l): v(CzN) 2041 (s,br). (8) 2:1 Reaction of Re2C14(dppm)2 with DCNPQI A solution containing DCNPQI (0.0136 g, 0.038 mmol) dissolved in 10 mL of THF was slowly added to a THF (10 mL) solution containing Re2C14(dppm)2 (0.0983 g, 0.076 mmol) producing a dark green solution. A solution IR spectrum (Can cells, THF reference) obtained after 5 minutes exhibited a v(CEN) band at 2090 cm'l. The reaction solution was allowed to stand for 2 h at room temperature during which time an olive-green solid precipitated. The reaction mixture was left undisturbed for an additional 4 days to ensure that the reaction was complete. The solid was collected by filtration. washed with THF. and vacuum dried: yield 85 0.097 g (87%). IR (CsI, Nujol, cm'l): v(CEN) 2089 (vs). Electronic spectroscopy (CH2C12), Amax = 306 and 845 nm. (9) Reaction of [RezCl4(dppm)2]2(DM-DCNQI) (7) with DM- CNQMI A CH2C12 (5 mL) solution containing 0.0058 g (0.036 mmol) of DM-CNQMI was slowly added to a CH2C12 (5 mL) solution of (7) (0.053 g, 0.019 mol) at -78°C with no observed color change. A small portion (ca. 1 mL) of the reaction solution was removed and a solution infrared spectrum (CaF2 cells, THF reference) was obtained which exhibited a single v(CEN) band at 2085 cm'l. The reaction was warmed to room temperature, the volume was reduced to ca. 5 mL, and 20 mL of hexanes was added resulting in the precipitation of a brown solid. The solid was collected by filtration, washed with hexanes, and vacuum dried; yield 0.040 g (61%). B. X-ray Crystallography (1) [RezCl4(dppm)2]2(DM-DCNQI)-4THF, (7)-4THF The structure of [RezCl4(dppm)2]2(u-DM-DCNQI)-4THF (7)t4THF was determined by application of general procedures that have been fully described elsewhere.7 Crystallographic data were collected on a Rigaku AFC6S diffractometer equipped with monochromated MoKa (ha = 0.71069 A) radiation. The data were corrected for Lorentz and polarization effects. Calculations were performed on a VAXSTATION 4000 computer by using the Texsan crystallographic software package of Molecular Structure Corporation.8 Crystallographic data for (5) are given in Table 9. 86 Table 9. Summary of crystallographic data for [Re2Cl4(dppm)2]2(u-DMDCNQD-4THF (7)-4THF. formula formula weight space group a, A b, A c, A 01, deg 15. deg 11. deg v, A3 Z dcalc, g/cm3 11(Mo K01), cm-1 temperature, °C trans. factors, max., min. Ra wa quality-of-fit indicator Re4P8N4O4C126C18H128 3038.66 P-l (#2) l4.152(5) 22.927(8) 12.091(4) 9661(3) 104.17(3) 75.17(3) 3713(2) 1 1.374 36.08 -100 1.00 - 0.63 0.089 0.134 3.03 aR=2 ”Fol‘ [Fell/Erol. bRw = [2w( IF.) I - 11:, 112/2w 11:0 mm; w = 1/c2<11=o b Cquality-of-fit = [2W( 11:0 l ' ch bZ/(NobS‘NparametersnIf2 87 (i) Data Collection and Reduction Crystals of (7) were grown by slow diffusion of a THF solution containing DM-DCNQI into a THF solution containing two equivalents of Re2C14(dppm)2. A black crystal with dimensions 0.30 x 0.40 x 0.30 mm3 was mounted on the tip of a glass fiber with silicone grease. Cell constants and an orientation matrix for data collection obtained from a least squares refinement using 22 carefully centered reflections in the range 23 S 20 S 26° corresponded to a triclinic cell. A total of 12940 unique data were collected at -100 i 1°C using the (1)-20 scan technique to a maximum 20 value of 50°. The intensities of three representative reflections measured after every 150 reflections decreased by 9.0 % thus a linear correction factor was applied to the data to account for this decay. An empirical absorption correction, using the program DIFABS,9 was applied which resulted in transmission factors ranging from 1.00 to 0.63. (ii) Structure Solution and Refinement Based on a statistical analysis of intensity distribution, and the successful solution and refinement of the structure, the space group was determined to be P-l (#2). The structure was solved by MITHRII.10 and DIRDIFll structure programs and refined by full matrix least-squares refinement. The position of all non-hydrogen atoms, except C(49) and the interstitial THF atoms, were refined with either isotropic or anisotropic thermal parameters. Hydrogen atoms were placed in calculated positions for the final stages of refinement. The final cycle of full matrix least- squares refinement included 5175 observations with F02 > 30(F02) and 341 variable parameters for residuals of R = 0.089 and Rw = 0.134 and a quality-of—fit index of 3.03. 88 3. Results The dinuclear donor compound Re2C14(dppm)2 reacts with a variety of substituted DCNQIs to form covalently linked charge-transfer products as judged by infrared spectral data and X-ray crystallography. Single crystals of [Re2C14(dppm)2]2(tt-DM-DCNQI) (7) were synthesized from the layering of THF solutions of the starting materials and the X-ray crystal structure establishes the presence of a bridging DM-DCNQI. Crystallographic data are summarized in Table 9 and an ORTEP representation and packing diagrams are depicted in Figures 18, 19, and 20. A full table of positional and thermal parameters for complex (7 ) is located in the Appendix. A. Reactions of RezCl4(dppm)2 with DM-DCNQI (1) Preparation and spectroscopic properties The reaction of Re2Cl4(dppm)2 with DM-DCNQI in which a 1:1 molar ratio instantaneously produces a dark blue solution of (6)-A which is stable only at low temperatures (-78°C). The infrared spectrum of the solution exhibits a v(CEN) band at 2053 cm'1 and the electronic absorption spectrum shows a strong absorption at kmax = 830 nm. When the solution is allowed to stand at room temperature, the color turns dark green, and the absorption at 830 nm decreases in intensity during the conversion from (6)-A to (6)-B. The infrared spectrum of (6)-B exhibits a single strong v(CEN) band at 2091 cm'l. When 2 equivalents of Re2C14(dppm)2 are reacted with DM-DCNQI in either THF or benzene, microcrystalline samples of [Re2Cl4(dppm)2]2(tt-DMDCNQI) (7) precipitate from solution. Single crystals are grown using slow diffusion techniques. The infrared spectrum of (7) exhibits a strong v(CEN) band at 2056 cm‘1 and the electronic absorption spectrum exhibits strong absorptions at kmax = 1035 89 and 1800 nm, shown in Figure 17, indicative of a symmetrically bridged DM-DCNQI moiety. Methylene chloride solutions of (7) are not stable at room temperature as confirmed by the slow decay in intensity of the absorptions in the electronic absorption spectrum. A 1H NMR spectrum of (7) in CDC13 displays a complex set of multiplets between 5 = 7 and 8 ppm due to phenyl protons in addition to resonances at 8 = 3.73 (t) and 8 = 1.83 (p) ppm which are attributed to the THF molecules of crystallization. A cyclic voltammogram of (7) in a 0.1 M TBABF4/CH2C12 electrolyte solution does not exhibit any reversible oxidation or reduction processes between +1.5 and -1.5 V, although a weak quasi-reversible process appears at +0.5 V. The cyclic voltammogram of (7) is broad with numeraous superimposed features as compared to the blank scan of the electrolyte solution. Increasing the concentration of (7) only serves to broaden the cyclic voltammogram. An addition of 1 equivalent of Re2C14(dppm)2 to an electrolyte solution containing DM- DCNQI (0.1 M TBABF4/CH2C12) almost completely eliminates the reversible reduction process that occurs at -0.49 V for pure solutions of DM-DCNQI, while the first reduction at +0.13 V remains unchanged. The addition of a second equivalent of Re2C14(dppm)2 produces a cyclic voltammogram similar to that observed for (7) which has a quasi- reversible process ca. 0.5 V. Further addition of Re2C14(dppm)2 and subsequent scans produce featureless cyclic voltammograms. (2) X-ray crystal structure of [Re2C14(d ppm ) 2]2( D M - DCNQI)-4THF, (7)-4THF The molecular structure of (7), depicted in Figure 18, closely resembles the structure of [Re2C14(dppm)2]2(u-TCNQ) (2) since the DM- DCNQI moiety links together two Re2C14(dppm)2 molecules through the 90 CONN .2026 5 S 3200-291:Eeaaeeosa so 8.500% noun—.830 0:80.005 35 50204032, ooom oomv comp ooe— com F coop com 0 1 d d 4 4 # d 7:512 ooonm u 0 E: mmop u mex 7507—). ooomm u 0 E: comp u xmci .2 2:0; com NOLLdHOSSV 91 EELS miscozoaéaéa23.035302 to 835852 $0.00 .2 tan; ,1 ,1“ / . l ,‘ .0 92 o-coordination of its cyano groups. The molecule is centrosymmetric, with the midpoint of the DM-DCNQI moiety being situated on an inversion center. The coordination environment around Re(l) and Re(2) are octahedral and trigonal bipyramidal respectively. A list of selected bond distances and angles are given in Table 10. The Re-Re distance of 2.268(2) A is slightly shorter than the cooresponding distance found in the structure of (2) (2.275 A) which may reflect the lower reduction potential for DM- DCNQI vs. TCNQ. The Re(1)—Cl(2) distance of 261(1) A is longer than the other Re-Cl distances as a result of occupying an axial site (see Figure 19). The Re(1)—N(1) distance of l.86(3) A is considerably shorter than the Re—N distance found in the structure of (2) (2.133 A). Other distances and angles in the dirhenium unit are within the range for derivatives of Re2C14(dppm)2.12 The packing diagram (Figure 20) shows that the molecules stack along the a axis in which there is a distance of ca. 14 A between adjacent DM-DCNQI centers, although other closer contacts exist among atoms on the phenyl rings and solvent molecules. (3) Magnetic properties The complex [Re2C14(dppm)2]2(u-DM-DCNQI) (7) is paramagnetic as determined by magnetic susceptibility (Figure 21) and EPR (Figure 22) measurements. The plot of ueff vs. temperature (Figure 21) shows a decrease in [Jeff at lower temperatures which is consistent with antiferromagnetic coupling. The room temperature effective moment is 1.8 B.M. which is indicative of ca. 1 unpaired electron. This is similar to the value of 1.9 B.M. exhibited for [Re2C14(dppm)2]2(u-TCNQ) (2). B. Reactions of RezCl4(dppm)z with other DCNQIs The compounds DCNQI, DCNNQI, DCNAQI, DC-DCNAQI, and DCNPQI produce charge—transfer products when reacted with 93 mass 0515209291:.mfleaassomom. to scam: see .85; so; 9:5 .a. saw: 0 C «.00 0:0 . . . . . m0 . FOE wz C 0 So 0 C O O O 0 «mm C 20 «no. 0 N2 0 o e o mmo SO .038 0 05 mac—m Baas ”ESE 0520209291:$533536 0c semen 0.5.25 use: 88 .3 2:0: sit) 3.. 95 20 1.8; dial . 1.64 f 2: t4- 3 O :1. ‘ .EFP 1.2 - “Baum“. 1 L0 0.8 I V I Y I v I v 0 100 200 300 400 Temperature, K Figure 21. Plot of ueff (B.M.) vs. temperature (K) of [R62C14(dPPm)2]2(H-DM-DCNQI) (7 ). 96 Figure 22. Solid state EPR spectrum of [Re2C14(dppm)2]2(tt-DM- DCNQI) (7) at -160°C. 97 Table 10. Selected bond distances(A), bond angles(°) and torsion angles(°) for [Re2C14(dppm)2]2(u-DM-DCNQI)-4THF, (7)-4THF. distances atom 1 atom 2 distance atom 1 atom 2 distance Re(l) Re(2) 2.268(2) P(2) C(49) 1.88(1) Re(l) Cl( 1) 2.38( 1) P(3) C(25) 1.82(5) Re(l) Cl(2) 2.61(l) P(3) C(31) 1.91(5) Re(l) P(l) 2.49(1) P(3) C(50) 1.87(4) Re(l) P(4) 2.49(1) P(4) C(37) 1.82(4) Re(l) N(l) 1.86(3) P(4) C(43) 1.89(4) Re(2) Cl(3) 233(1) P(4) C(50) 1.84(4) Re(2) Cl(4) 2.35(1) N( 1) C(51) 1.11(5) Re(2) P(2) 2.42(1) N(2) C(51) 1.37(5) Re(2) P(3) 2.41(1) N (2) C(52) 1.50(5) P(l) C(l) 1.78(4) C(52) C(53) 1.44(6) P(l) C(7) 1.76(4) C(52) C(54) l.38(5) P( 1) C(49) 1.81(1) C(53) C(54)* 1.27 (5) P(2) C(13) 1.83(4) C(53) C(55) 1.62(7) P(2) C(19) l.92(4) torsion angles atom 1 atom 2 atom 3 atom 4 torsion angle Re(l) N(l) C(51) N(2) 152(3) Cl(l) Re(l) Re(2) Cl(3) l 1.6(4) Cl(l) Re(l) Re(2) Cl(4) 167.1(4) Cl(3) Re(2) Re(l) N(l) 163(1) Cl(4) Re(2) Re(l) N ( 1) 18(1) P(l) Re(l) Re(2) P(2) 15.2(3) P(3) Re(2) Re(l) P(4) 16.5(4) P(3) Re(2) Re(l) N(l) 105(1) N(2) C(52) C(53) C(55) 0(6) N(2) C(52) C(54) C(53)* 180(4) C(51) N(2) C(52) C(53) 177(4) 98 $08 Asa Qua Sea 9%: .230 2.30 A80 6:2 320 Qua 38 E 5 $.30 $30 $00 63: 50 Sea 38 3:: $80 $30 330 £wa :02 :5 sea 3:2 .330 830 A30 83 32 38 3a ea: :30 A80 300 632 3a :3 3a $22 :30 $00 $2 33 32 88 $0 $02 $20 300 Sz 30% 3a Boa $0 $02 $2 :30 82 $30 Ea Sea 8:0 $52 $00 $2 :30 ES: :02 Boa 30 580 :30 32 :3 $03 ea 33. 3.0 $0.42 Ea Qua Ea 34$ Ea sea 30 $0.8 5a Sea 30 Emma 30 Sea 30 33a Ea Qua $0 33 32 Boa Qua $0.5 5a Qua 3:0 3:? 3a Sea Qua $0.40 Ea Qua 56 34.3 3a Sea 38 $3: $0 Qua 50 6:: 3:0 88 Qua 64.8 5a 5oz an $08 30 Sum 38 0&5 m 880 N 880 a 820 0&5 m 880 m ES“ a :83 8&5 .3880 .3 ~33. 99 Re2C14(dppm)2. The infrared spectra of these products, listed in Table 11, exhibit strong v(CEN) bands between 2040 and 2100 cm'1 which are indicative of nitrile coordination. The reaction between the mono-cyano compound DM-CNQMI and Re2C14(dppm)2 produces a dark green solution that exhibits an absorption at kmax = 812 nm which is identical to the spectrum of (6)-A (in THF). This supports the assignment of this transition as being a metal-to-ligand rather than a metal-to-metal charge- transfer process since a bridging arrangement is not possible for complexes containing DM-CNQMI. Reactions between DCNQI and Re2C14(dppm)2 mimic those between Re2C14(dppm)2 and DM-DCNQI as judged by infrared and electronic absorption spectra. The products from the reactions between the larger acceptors DCCNQI, DCNAQI, DC-DCNAQI, DCNPQI and Re2C14(dppm)2 are obtained using similar methods as described for the reactions of the other acceptor compounds. These products produce infrared and electronic absorption spectra that are characteristic of nitrile coordinated products. 4. Conclusions The reactivity of DM-DCNQI towards Re2C14(dppm)2 closely resembles the reactivity of TCNQ towards Re2C14(dppm)2 as expected. Both TCNQ and DM-DCNQI form blue 1:1 complexes with Re2C14(dppm)2 at low temperatures while products (2) and (7) crystallize from THF solutions in the presence of two equivalents of RezCl4(dppm)2. The compound Re2C14(dppm)2 reacts with variety of DCNQIs and all form covalently linked complexes as judged by infrared and electronic absorption spectra. 100 Table 11. Tabulation of v(CEN) stretching frequencies for the products from reactions of Re2C14(dppm)2 with DCNQIs. Acceptor D:A v(CEN) band cm-1 DM-CNQMI 1:1 2096 (vs) DCNQI 2:1 2090 (vs) DCNQI 1:4 2090 (vs,br), 2240 (w) DM-DCNQI (7) 2:1 2056 (s,br) DM-DCNQI (6)-A 1:1 2091 (s,br) DM-DCNQI (6)-B 1:1 2070 (s,br) DCNNQI 2:1 2100 (s) DCNNQI 1:1 2095 (s) DCNAQI 1:2 2068 (s,br) DCNAQI 2:1 2058 (S) DC-DCNAQI 2:1 2041 (s,br) DCNPQI 2:1 2089 (vs) DM-CNQMI = 2,6-dimethyl-N-cyano-1,4-benzoquinone-4-imine DCNQI = N,N'-dicyano-1,4-benzoquinonediimine DM-DCNQI = 2,5-dimethyl-N,N'-dicyano-1,4-benzoquinonediimine DCNNQI = N ,N'-dicyano-l ,4-naphthaquinonediimine DCNAQI = N,N'-dicyano-9,lO-anthraquinonediimine DC-DCNAQI = 1,5-dichloro-N,N'-dicyano-9,lO-anthraquinonediimine 101 References 10. 11 12. Aumuller, A.; Hunig, S. Liebigs Ann. Chem. 1986, 142. Bartley, S. L.; Dunbar, K. R. Angew. Chem, Int. Ed. Engl.l99l, 30, 448. Aumiiller, A.; Hunig, 8.; Von Schiitz, J.-U.; Werner, H. P.; Wolf, H. C.; Klebe, G. Mol. Cryst. Liq. Cryst. Inc. Nonlin. Opt. 1988, 156, 215. (a) Enkelmann, V. Angew. Chem, Int. Ed. Engl. 1991, 30, 1121. (b) Aumuller, A.; Erk, P.; Hiinig, S.; Meixner, H.; von Schiitz, J .-U.; Werner, H.-P. Leibigs Ann. Chem. 1987, 997. (c) Aumuller, A.; Erk, P.; Hunig, S.; von Schu'tz, J.-U.; Werner, H.-P.; Wolf, H. C.; Klebe, G. Chem. Ber. 1991, 124, 1445. (a) Kato, R.; Kobayashi, H.; Kobayashi, A. J. Am. Chem. Soc. 1989, III, 5224. (b) Kato, R.; Kobayashi, H.; Kobayashi, A. Synth. Met. 1988, 27, B263. Aumuller, A.; Hiinig, S. Liebigs Ann. Chem. 1986, 165. (a) Bino, A.; Cotton, F. A.; Fanwick, P. E. Inorg. Chem. 1979, 18, 3558. (b) Cotton, F. A.; Frenz, B. A.; Deganello, G.; Shaver, A. J. Organomet. Chem. 1973, 50, 227. TEXSAN-TEXRAY Structure Analysis Package, Molecular Structure Corporation 1985. Walker, N; Stuart, D. Acta Crystallogn, Sect. A: Found Crystallogr. 1983, A39, 158 MITHRILL: Integrated Direct Methods ComputerProgram. Gilmore, C. J. Appl. Crystallogr. 1984, 17, 42. DIRDIF: Direct Methods for Difference Structure. An Automatic Procedure for Phase Extension; Refinement of Difference Structure Factors. Beurskens, R. T. Technical Report. 1984. (a) Fanwick. P. 13.; Price. A. C.; Walton. R. A. Inorg. Chem. 1988, 27, 2601. (b) Price. A. C.; Walton. R. A. Polyhedron 1987. 6. 729. CHAPTER IV REACTIONS OF M2Cl4(PR3)4, M2Cl4(P~P)2 (M = M0, Re; R = Et, Pr"; P~P = dppm, dmpm, dppe), AND [M2(NCCH3)10][BF4]4 (M: Mo, Rh) WITH POLYCYANO ACCEPTORS. 103 1. Introduction After our discovery of the novel covalently linked complexes that result from the reactions of Re2C14(dppm)2 with TCNQ, TCNE, DCNQI's, and TNAP (Chapters II and III), further studies of analogous reactions of dinuclear molybdenum and rhenium complexes were performed to probe the generality of the approach. There exists a wide selection of metal complexes with different M-M bond orders and different chemical, redox and structural properties. Also, the fully solvated dinuclear cations e.g. [Rh2(NCCH3)1o]4+ could be used in the preparation of inorganic-organic hybrid polymers when matched with appropriate bidentate precursors. 2. Experimental A. Synthesis The dinuclear metal complexes Re2C14(PEt3)4,1 Re2C14(PPr"3)4,1 MozCl4(PEt3)4,2 MozCl4(dppm)2,3 MozCl4(dmpm),4 M02C14(dppe)2,5 [Rh2(NCCH3)10][BF4]4.6 [M02(NCCH3)10][BF4]4.7 [Bun4NlTCNQ,8 LiTCNQ,9 TCNQF4,10 and DM-DCNQI11 were all prepared according to literature procedures. TCNQ and TCNE were purchased from Aldrich Chemicals and sublimed prior to use. Li[DM-DCNQI] was synthesized as black needle crystals from the reaction between Lil and DM-DCNQI in boiling acetonitrile. (1) Reactions of Re2C14(PEt3)4 with TCNQF4 In a typical reaction Re2C14(PEt3)4 (0.050 g, 0.051 mmol), TCNQF4 (0.05 g, 0.146 mmol), and CH2C12 (10 mL) were added to a reaction vessel and stirred for 5 h at room temperature. The initial green color of the reaction slowly changed to black with comcomitant deposition of a black precipitate. The solid was collected by filtration. washed with CHzClz and diethyl ether and vacuum dried; yield 0.04] g. IR (KBr pellet): V(_C_=_N) 104 2202 (s,sh), 2104 (vs,br). Additional solid was obtained treating the filtrate with diethyl ether. Both solids exhibited identical infrared spectra. Many reactions employing different ratios of starting material and a variety of solvent combinations yielded solids with very similar infrared spectra. (2) Reaction of RezCl4(PEt3)4 with TCNQ A solution of TCNQ (0.022g, 0.108 mmol) dissolved in 15 mL of THF was carefully layered on a CHzClz (4 mL) solution of Re2C14(PEt3)4 (0.050 g, 0.051 mmol) which produced a dark brown solid precipitate within 20 minutes. The reaction tube was allowed to stand undisturbed for 8 days to allow for complete diffusion of the layers; the resulting solid was collected by filtration, washed with CH2C12, and vacuum dried; yield 0.009 g. IR (CsI, Nujol, cm‘l): v(CEN) 2189 (s), 2091 (vs,br). (3) Reaction of RezCl4(PEt3)4 with DM-DCNQI A THF (5 mL) solution of DM-DCNQI (0.012 g, 0.063 mmol) was slowly added to 5 mL of a THF solution of Re2C14(PEt3)4 (0.055 g, 0.056 mmol) resulting in the immediate formation of an orange-brown solution. A dark green solid precipitated after 2 h and was harvested by filtration, washed with THF, and dried in vacuo; yield 0.033 g. IR (CsI, Nujol, cm'l): v(CEN) 2105 (vs,br). (4) Reactions of MozCl4(dppe)2 with TCNQ (i) 1:2 MozCl4(dppe)2:TCNQ Reaction Quantities of MozCl4(dppe)2 (0.100 g, 0.088 mmol), 0.036 g (0.176 mmol) of TCNQ, and 25 mL of CHzClz were combined in a Schlenk flask to give an initial green solution which turned blue within 10 minutes. A UV-visible spectrum showed an intense absorption at 105 kmax = 915 nm. The reaction mixture was stirred at room temperature for 7 days with no further change as indicated by UV-visible spectra. The reaction volume was reduced by vacuum and treated with 30 mL of diethyl ether resulting in a blue solid precipitate which was collected by filuation, washed with diethyl ether, and vacuum dried; yield 0.074 g. IR (CsI, Nujol, cm'l): v(CEN) 2180 (m), 2090 (5). (ii) 2:1 MozCl4(dppe)2:TCNQ Reaction A reaction mixture consisting of M02C14(dppe)2 (0.200 g, 0.176 mmol), TCNQ (0.018 g, 0.088 mmol), and toluene (30 mL) was refluxed for 10 minutes to give a dark green solution. The solution was refluxed for another 1 h during which time a black solid precipitated. The solid was collected by filtration, washed with toluene and diethyl ether, and dried in vacuo; yield 0.193 g. IR (CsI, Nujol, cm'l): v(CEN) 2186 (m), 2091 (s). (iii) 4:1 [MozCl4(dppe)2:TCNQ] Reaction Toluene (10 mL) was syringed into a flask containing 0.200 g (0.176 mmol) of M02C14(dppe)2 and 0.009 g (0.044 mmol) of TCNQ. Although no immediate reaction was observed, a blue solution containing a blue solid appeared within 24 h. The reaction mixture was stirred at room temperature for 4 days after which time the blue solid was collected by filtration, washed with fresh toluene, and vacuum dried; yield 0.0192 g. IR (CsI, Nujol, cm'l): 2189 (m), 2099 (s). Identical results were obtained when acetone was used as the reaction solvent. 106 (5) Reaction of MozCl4(dppe)2 with TCNE To a 100 ml. Schlenk flask was added 0.100 g (0.088 mmol) of MozCl4(dppe)2, 0.0227 g (0.177 mmol) of TCNE and 25 mL of CH2C12 resulting in an immediate dark blue solution to form. A UV-visible spectrum of the reaction solution exhibited a strong absorption at lmax = 654 nm. The mixture was stirred at room temperature for 6 days without any detectable changes. The solution was reduced in volume by vacuum followed by the addition of 30 mL of diethyl ether producing a blue solid precipitate. The solid was collected by filtration, washed with diethyl ether, and vacuum dried. IR (CsI, Nujol, cm'l): v(CEN) 2200 (m), 2120 (s). (6) Reaction of MozCl4(dppe)2 with TCNQF4 Methylene chloride (20 mL) was syringed into a reaction vessel containing M02C14(dppe)2 (0.100 g, 0.088 mmol) and TCNQF4 (0.060 g, 0.176 mmol) immediately forming a black solution, which produced a black film-like solid after 4 days. The mixture was filtered through a Schlenk frit and a black solid was isolated, washed with 15 mL of CH2C12, and dried in vacuo; yield 0.108 g. IR (CsI, Nujol, cm'l): 2199 (s), 2132 (vs,br). (7) Reaction of MozCl4(dppe)2 with DM-DCMQI Methylene chloride (10 mL) was added to a flask containing 0.210 g (0.186 mmol) of M02C14(dppe)2 and 0.0085 g (0.049 mmol) of DM- DCNQI which resulted in a purple solution within 30 minutes. The reaction mixture was stirred at room temperature for 24 h during which time a red solution and a brown-red precipitate ensued. The reaction mixture was allowed to stir for an additional 24 h at which time the brown- red solid was collected by filtration. washed with CHzClz and vacuum Mo IESL 107 dried; yield 0.050 g. IR (CsI, Nujol, cm'l): v(C.=.N) 2085 (s). The red filtrate was reduced in volume and layered with diethyl ether to give a brown-red solid which was collected by filtration, washed with diethyl ether, and dried in vacuo; yield 0.101 g. IR (CsI, Nujol, cm'l): v(C-='N) 2083 (m). (8) Reaction of M02C14(dppm)z with TCNQ To a 100 mL Schlenk flask was added 0.100 g (0.091 mmol) of M02C14(dppm)2, 0.0240 g (0.118 mmol) of TCNQ, and 10 mL of CH2C12 resulting in a dark green solution. After stirring for 35 minutes at ambient temperature, a UV—visible absorption spectrum was recorded; this revealed a strong feature at kmax = 900 nm. The reaction was stirred for 70 minutes before adding 10 mL of CH2C12 and 40 mL of diethyl ether. The resulting black solid precipitate was collected by filtration and dried in vacuo; yield 0.038 g IR (CsI, Nujol, cm'l): 2193 (m), 2115 (s), 1968 (w). (9) Reaction of MozCl4(dppm)2 with TCNE A mixture containing MozCl4(dppm)2 (0.100 g ,0.091 mmol), 0.0232 g (0.181 mmol) of TCNE, and 30 mL of toluene was refluxed for 3 days resulting in the deposition of a black solid. The solid was collected by filtration and washed with toluene. IR (CsI, Nujol, cm'l): v(CEN) 2215 (s), 2130 (w). (10) Reaction of MozCl4(PEt3)4 with TCNQ To a 50 mL Schlenk flask was added 0.036 g (0.045 mmol) of M02C14(PEt3)4, 0.012 g (0.059 mmol) of TCNQ, and 20 mL of CH2C12. The initial blue solution slowly turned green and eventually deposited a green solid after the addition of diethyl ether. The solid was collected by filtration and washed with diethyl ether. IR (CsI. Nujol. cm'l): 2188 (s), 2128 (s). 108 (11) Reaction of MozCl4(PEt3)4 with TCNQF4 A solution containing 0.021 g (0.061 mmol) of TCNQF4 and 5 mL of acetone was carefully layered over a solution containing 0.050 g (0.061 mmol) of MozCl4(PEt3)4 and 8 mL of CH2C12. After one day a brown precipitate had formed at the bottom of the Schlenk tube. The solid was collected by filtration, washed with copious amounts of CH2C12, and vacuum dried. yield 0.049 g. IR (CsI, Nujol, cm'l): v(CEN) 2198 (s), 2143 (s). (12) Reaction of M02C14(dmpm)2 with TCNQ A mixture consisting of 0.050 g (0.083 mmol) of M02C14(dmpm)2, 0.028 g (0.137 mmol) of TCNQ, and 15 mL of CH2C12 was stirred at room temperature for 5 h resulting in the formation of a grey precipitate. The solid was collected by filtration, washed with CH2C12 until colorless filtrates were obtained, and vacuum dried; yield 0.049 g. IR (KBr pellet): v(CEN) 2189 (s), 2116 (vs). (13) Reaction of M02C14(dmpm)2 with TCNE A solution comprised of 0.0216 g (0.169 mmol) of TCNE dissolved in 10 mL of CHzClz was slowly added to a CHzClz solution (20 mL) of M02C14(dmpm)2 (0.0794 g, 0.131 mmol) to give a purple solution. The solution was stirred at room temperature for several hours before being reduced in volume under vacuum. Hexanes (30 mL) was added and a vacuum applied to remove additional CH2C12 until the supernatant became colorless. The purple solid was collected by filtration, washed with hexanes, and vacuum dried. IR (CsI, Nujol, cm'l): 2200 (m). 2129 (m). (14) Reaction of RezCl4(dppm)2 with TCNQF4 A solution consisting of TCNQF4 (0.0131 g, 0.038 mmol) in 10 mL of acetone was added to a solution consisting of Re2C14(dppm‘)2 (0.050 g, 109 0.038 mmol) dissolved in 10 mL of acetone. The initial red solution turned to green over a period of 4 days while stirring at room temperature. Diethyl ether (20 mL) was added to precipitate a green solid which was collected by filtration, washed with diethyl ether, and vacuum dried; yield 0.021 g. IR (CsI, Nujol, cm-l): v(CEN) 2203 (m), 2145 (s). (15) Reaction of Re2C14(PPr"3)4 with DM-DCNQI A THF (5 mL) solution of DM-DCNQI (0.0042 g, 0.023 mmol) was slowly added to a THF (5 mL) solution of Re2C14(PPr"3)4 (0.053 g, 0.046 mmol) producing an orange-brown solution. The mixture was placed in the refrigerator (-5°C) for 5 days without any noticeable change in color. The volume was reduced under vacuum and 20 mL of hexanes was added to effect the precipitation of a brown solid. The product was harvested by filtration, washed with hexanes, and vacuum dried; yield 0.015 g. IR (CsI, Nujol, cm'l): v(CEN) 2116 (s). (16) Reaction of [Rh2(NCCH3)1o][BF4]4 with [Bun4N]TCNQ An acetonitrile (10 mL) solution of [Rh2(NCCH3)1o][BF4]4 (0.0262 g, 0.027 mmol) was added dropwise to 0.0486 g (0.108 mmol) of [Bun4N]TCNQ dissolved in 10 mL of acetonitrile. A dark red solid immediately precipitated. The mixture was stirred at room temperature for 30 minutes to ensure complete reaction. The product was harvested by filtration, washed with acetonitrile, and dried in vacuo; yield 0.029 g. IR (CsI, Nujol, cm‘l): v(CEN) 2336 (w), 2219 (w). 2193 (w), «2100 (very strong and broad stretch between 2050 and 2150 cm'l). (17) Reaction of [Rh2(NCCH3)10][BF4]4 with LiTCNQ A solution of [Rh2(NCCH3)1()][BF4]4 (0.0923 g, 0.096 mmol) dissolved in 10 mL of acetonitrile was slowly added to an acetonitrile (30 mL) solution containing LiTCNQ (0.0860 g, 0.408 mmol) causing the 1 10 inunediate formation of a dark red precipitate. After standing undisturbed for ca. 12 h, the solution was filtered and the solid was washed with c0pious amounts of acetonitrile, and dried in vacuo; yield 0.097 g. IR (CsI, Nujol, cm'l): 2334 (w), 2112 (w), 2190 (w), 2064 (vs,vbr). (18) Reaction of [Rh2(NCCH3)10][BF4]4 with LiTCNQ in H20 A solution consisting of 0.020 g (0.021 mmol) of [Rh2(NCCH3)1o][BF4]4 dissolved in 5 mL of H20 was slowly added to a stirring solution containing 0.020 g (0.095 mmol) of LiTCNQ H20 (3 mL). A dark purple solution and a black precipitate formed. The solid was collected by filtration, washed with H20 and diethyl ether, and vacuum dried; yield 0.020 g. IR (CsI, Nujol, cm'l): v(CEN) 2220 (m), 2195 (m), 2145 (s). (19) Electrochemical preparation of "Rh(TCNQ)2" In a four compartment electrochemical cell (see Figure 23) a solution consisting of 0.020 g (0.021 mmol) of [Rh2(NCCH3)1o][BF4]4, 0.020 g (0.098 mmol) of TCNQ, and 6 mL of acetonitrile was added to the working compartment. A 0.5 M TBABF4/acetonitrile solution was used to fill the remaining compartments. A potential of +0.1 V was applied to the cell for two days which caused the formation of a red gelatinous precipitate on the platinum gauze electrode. The product was collected by filtration, washed with acetonitrile, and vacuum dried; yield 0.013 g. IR (CsI, Nujol, cm'l): v(CEN) 2335 (m), 2219 (m,sh), 2190 (m,sh), 2141 (s,vbr). (20) Reaction of [Rh2(NCCH3)10][BF4]4 with Li[DM-DCNQI] To a Schlenk flask containing [Rh2(NCCH3)10][BF4]4 (0.050 g, 0.052 mmol) and Li[DM-DCNQI] (0.040 g, 0.217 mmol) was added 15 mL of acetonitrile resulting in a dark brown-red solution. The mixture was stirred with slight warming for 1 day. The solution was passed 111 ¢ Pt gauze Ag/AgCl electrode reference Pt wire i electrode ‘0 ’J s—r—z L-q—d - p----d l I I I I I ’ \ \ frit \ Figure 23. Schematic drawing of the electrolysis cell used in the electrochemical synthesis of "Rh(TCNQ)2" and "Rh(DM-DCNQI)2". 112 through a frit and treated with 20 mL of CH2C12 producing a finely divided solid. The solid was collected by filtration, washed with CH2C12, and dried in vacuo; yield 0.040 g black solid. The IR (CsI, Nujol) spectra of the solid exhibits a strong v(C.=_N) band at 2050 cm'l. (21) Electrochemical Preparation of "[Rh(DM-DCNQI)2]" An acetonitrile (5 mL) solution containing 0.020 g (0.021 mmol) of [Rh2(NCCH3)1o][BF4]4 and 0.015g (0.083 mmol) of DM-DCNQI was added to the working electrode compartment, which consisted of a Pt wire gauze electrode, of a 4 chamber electrochemical cell (see Figure 23). The other 3 chambers were filled with a 0.01 M TBABF4/acetonitrile electrolyte solution. A voltage of +0.05 V was applied to the cell for 24 h producing a red solid on the gauze electrode. The solid was removed from the electrode with CH3CN washings, collected by filtration, washed with additional acetonitrile, and vacuum dried; yield 0.013 g. IR (CsI, Nujol, cm'l): v(CEN) 2039 (s). (22) Reaction of [M02(NCCH3)10][BF4]4 with [Bun4N][TCNQ] An acetonitrile (10 mL) solution containing [Moz(NCCH3)1o][BF4]4 (0.0250 g, 0.028 mmol) was added to an acetonitrile (7 mL) solution containing [Bun4N][TCNQ] (0.050 g, 0.112 mmol) which resulted in the instantaneous formation of a dark green precipitate. The solid was collected by filtration, washed with acetonitrile, and vacuum dried; yield 0.022 g. IR (CsI, Nujol, cm'l): v(CEN) 2191 (s), 2108 (vs,br), 1986 (w). 3. Results and Discussion A. Reactions of Dinuclear Complexes with Polycyano Acceptors A variety of metal-metal bonded dimolybdenum and dirhenium donor complexes react with polycyano acceptors to form covalently bonded charge-transfer products. Most of these products are highly colored and 113 exhibit strong absorptions in their electronic spectra. Some products simply precipitate from the reaction solvent(s) used, while others require the addition of diethyl ether or hexanes. Slow diffusion reactions are not particularly useful, as the products form instantaneously resulting in finely divided solids at the interface of the layered solvents. In one example, the green filtrate from the reaction between MozCl4(dppm)2 and TCNQ (CH2C12/Et20 solvents) produced disk-shaped solids that appeared to be crystalline, but were apparently not, as the did not diffract X-rays. Infrared spectra of the products are listed in Tables 12 - 15. A common feature amoung these spectra is that compounds containing TCNQ, TCNE, or TCNQF4 all exhibit two strong absorptions; one freature is sharp and in the range 2215 to 2180 cm'l, but less intense than a second stretch which appears in the range 2145 to 2090 cm-1. From these results we observe an apparent lack of v(CEN) dependence on redox differences between the donor and acceptor molecules. For example, the TCNQ products of M02C14(dppe)2 and Re2C14(PEt3)4 (1:2 donorzacceptor) exhibit similar frequencies for v(CEN) stretches although the first oxidation potential for Re2C14(PEt3)4 occurs at a 0.95 V more negative potential than M02C14(dppe)2. One would expect that a lower oxidation potential would increase the amount of charge transferred to the acceptor resulting in lowering of the observed v(CEN) stretches as demonstrated previously for other charge-transfer products of TCNQ.”- These data suggest that the most likely mechanism leading to coordination is an inner sphere rather than outer sphere charge-transfer process. As expected, however, the dimetal systems with lower oxidation potentials react faster with the acceptor species than those with higher oxidation potentials. It may then be proposed that regardless of the initial driving force for redox 114 Table 12. Comparison of the v(CEN) stretching frequencies for products from reactions of dinuclear donor complexes with TCNQ“. Dinuclear complex E1/2(ox) D/A v(CEN) cm'1 Re2Cl4(dppm)23 0.35 1:1 2195 (s), 2115 (m) Re2Cl4(dppm)2b 0.35 1:1 2183 (s), 2114 (s,br), 2085 (sh) Re2C14(dppm)2 0.35 2:1 2187 (s), 2109 (s,br) M02C14(dPPe)2 0.62 1:2 2180 (m), 2090 (s) M02C14(dppe)2 0.62 2:1 2186 (m), 2091 (s) M02C14(dppe)2 0.62 4:1 2189 (m), 2099 (s) M02C14(dppm)2 0.66 1:1 2193 (m), 2115 (s), 1968 (w) M02C14(PEt3)4 0.61 1:1 2188 (s), 2128 (s) M02C14(dmpm)2 0.45 1:2 2189 (s), 2116 (vs) Re2Cl4(PEt3)4 -0.33 1:2 2189 (s), 2091 (vs,br) *TCNQO: v(CsN) = 2222 cm’l, 131/206(1) = 0.28 v a. Product (1)-A b. Product (1)-B 115 Table 13. Comparison of the v(&N) stretching frequencies for products from reactions of dinuclear donor complexes with TCNE“. Dinuclear complex E1/2(ox) D/A v(CEN) cm'1 Re2Cl4(dppm)2a 0.35 1:1 2197 (s), 2121 (m) Re2Cl4(dppm)2b 0.35 1:1 2200 (s), 2128 (m) Re2C14(PEt3)4 - 0.33 1:1 2207 (s), 2140 (m) M02C14(dppm)2 0.66 1:2 2215 (s), 2130 (w) M02C14(dppe)2 0.62 1:2 2200 (m), 2120 (s) M02C14(dmpm)2 0.45 1:1 2200 (m), 2129 (m) *TCNEO: v(CEN) = 2256, 2221 cm'l,E1/2(r¢d)= 0.34 v a. Product (3)-A b. Product (3)-B 116 Table 14 Comparison of the v(CEN) stretching frequencies for products from reactions of dinuclear donor complexes with TCNQF4*. Dinuclear complex El/2(ox) D/A v(C.=.N) cm'1 Re2C14(dppm)2 0.35 1:1 2203 (m), 2145 (s) M02C14(dppe)2 0.62 1:2 2199 (s), 2132 (vs,br) M02C14(PEt3)4 0.61 1:1 2198 (s), 2143 (s) R62C14(PEt3)4 -0.33 1:3 2202 (s,sh), 2104 (vs,br) Re2Cl4(PEt3)4 -0.33 1:1 2195 (m), 2100 (s) Re2Cl4(PEt3)4 -0.33 1:2 2190 (m), 2100 (s) *TCNQF40: V(CEN) = cm'l, El/2(red) = 0.40 V 117 Table 15. Comparison of the v(CEN) stretching frequencies for products from reactions of dinuclear donor complexes with DM- DCNQI*. Dinuclear complex E1/2(ox) D/A v(CEN) cm'l Re2C14(dppm)2 0.35 2:1 2070 (s,br) M02C14(dppe)2 0.62 4:1 2085 (s) Re2Cl4(PEt3)4 -0.33 1:1 2105 (vs) Re2C14(P-n-Pr3)4 2:1 2116 (s) *DM—DCNQIO: v(CsN) = 2197 cm'1,E1/2(rcd)= 0.21 v 1 18 chemistry to occur between the two compounds, the retro charge-transfer process, which occurs upon coordination, is similar for all products. In other words, a highly charged TCNQ unit is more nucleophilic than a less charged TCNQ, and essentially behaves as a better donor, and transfers more charge in the retro charge-transfer process. Thus, net charge transfer is similar in all cases where coordination results, assuming similar D:A ratios. All samples that were tested for magnetic properties were found to exhibit paramagnetic behavior. The majority of the samples exhibit temperature dependent paramagnetism (non-Curie-Weiss behavior). Exact values for ueff were not assigned because of ambiguities in the molecular formulae. The neff values at 300K for the products obtained from the reactions between Re2C14(PEt3)4 and TCNQF4, and M02C14(dppm)2 and TCNQ, for example, are ca. 7 B.M. based on the formation of 1:1 adducts. These unusually high values may be due to either impurities or ligand loss. The latter would result in lower formula weights, thus leading to a smaller calculated ueff per molecular unit. The black solid obtained from the reaction between M02C14(dppm)2 and TCNQF4 exhibits Curie-Weiss behavior (see Figure 24). The plot of neff vs. temperature displays a fairly constant value for [lgff consistent with a simple paramagnet S = 1/2 and displays a room temperature (300 K) value near that expected for one free electron. B. Reactions of Solvated Metal Cations with Reduced Forms of Polycyano Acceptors Another approach leading to the synthesis of complexes containing o-bonded TCNQ involved the use of solvated metal cations. The homoleptic complexes [M3(NCCH3)1()]4+ (M = Mo. Rh), in which the 119 800 1.9 6w. '1.8 a e * - g 2. a 400‘ ”1.7 m 3.5 *5 E 1 {Q 200. l/x —o— .13 Heft —’_ _ O l ' I ' I ‘ 15 0 100 200 300 400 Temperature, K Figure 24. Plot of lieff and llx vs. temperature (K) of the product from the reaction of M02C14(dppe)2 with TCNQF4. 120 dinuclear metal centers are ligated by acetonitrile units, are excellent synthons for the development of macromolecular arrays. The complex [Rh2(NCCH3)1o][BF4]4 when reacted with TCNQ“ yields a product with spectroscopic features clearly indicative of Rh-TCNQ coordination. The reactions of four equivalents of LiTCNQ or [Bun4N][TCNQ] in acetonitrile lead to the immediate formation of dark red solids. The electrochemical reduction of TCNQ in the presence of [Rh2(NCCH3)1o][BF4]4 in acetonitrile also produces dark red solids. The infrared spectra of these complexes exhibit v(CEN) bands at ~2335 (w), ~2220 (w), and ~2190 (w) cm'1 along with a strong stretch between ~2050-2150 cm'l. The stretch at 2335 cm'1 suggests that there may still remain coordinated acetonitrile in the product. The other stretches are consistent with coordinated TCNQ: Based on the reaction stoichiometry, and the loss of BF'4 ions, as indicated by infrared spectra, the product is loosely formulated as "[Rh2(TNCQ)4(NCCH3)x]". The solid is soluble in dimethyformamide and partially soluble in dimethyl sulfoxide. Slow diffusion of acetonitrile solutions of [Rh2(NCCH3)1o][BF4]4 and TCNQ' produce only amorphous solids. Controlled potential and controlled current experiments also failed to yield crystalline products. Magnetic measurements performed on the solid reveal non-Curie-Weiss behavior with an effective moment of 4.55 B.M. at 300K based on the formulation "Rh2(TCNQ)4". Slow addition of LiTCNQ or [Bun4N][TCNQ] to an acetonitrile solution of [Rh2(NCCH3)1()][BF4]4 produces dark red-orange reaction solutions. Precipitates form only when 4 or more equivalents of TCNQ' are added. The identical reaction done at -420C produces similar results. Adding 4 equivalents of TCNQ' to a [Rh3(NCCH3)1()][BF4]4 solution at low temperature does not allow for crystal growth. but rather gives finely 121 divided solids. Reactions using solvents other than acetonitrile produce similar results, for example the reaction between [Rh2(NCCH3)10][BF4]4 and LiTCNQ in water results in the precipitation of a black solid that exhibits a nearly identical infrared spectrum to the product obtained from acetonitrile. Electrochemical reactions between [Rh2(NCCH3)1o][BF4]4 and TCNQ, performed in nitromethane, yield similar solids to those obtained from acetoniu‘ile and water. It should be noted that no reaction between [Rh2(NCCH3)1o][BF4]4 and TCNOO was observed to occur in acetonitrile. The reaction between [Rh2(NCCH3)10][BF4]4 and Li[DM-DCNQI] in acetoniu'ile produces a solid that contains o—bonded DM-DCNQI- as judged by the single, intense absorption at v(CEN) = 2050 cm'1 in the infrared spectrum. Stretches attributed to acetonitrile are absent. Similar results are obtained from the electrochemical generation of DM-DCNQI- in the presence of [Rh2(NCCH3)1o][BF4]4. These solids also have limited solubilities (DMSO and DMF). Controlled potential and controlled current syntheses of "Rh2(DM-DCNQI)4" unfortunately did not produce single crystals adequate for X-ray crystallography. Reactions between [M02(NCCH3)10][BF4]4 and [Bun4N][TCNQ] lead to the formation of dark green solids whose infrared spectra reveal v(Cz-N) bands at 2191 (s) and 2108 (vs,br) cm'l demonstrative of coordinated TCNQ: There are no stretches present that can be attributed to acetonitrile or [BF4]-. An additional weak stretch at 1986 cm'1 is also observed which is likewise observed in the infrared spectra of other TCNQ complexes of dimolybdenum. The origin of this stretch is not fully understood but may be due to a 7t rather than a o coordination (or a combination of the two) by the CN group on TCNQ to the metal. 122 The reactions between [M2(NCCH3)10][BF4]4 (M = Mo, Rh) and L- (L=TCNQ, DM-DCNQI) result in the formation of insoluble solids which are believed to be covalently bonded complexes having the formulations of "M2(L)4". The structures of these products are unknown due to our lack of success in growing crystals suitable for an X-ray structure determination, but based on infrared spectral data, it may be predicted that a two- or three-dimensional polymeric structure could exist. For example, the product "Rh2(DM-DCNQI)4", which may be referred to in empirical form as "Rh(DM-DCNQI)2" exhibits only one v(CEN) band in its infrared spectra which suggests that all the CEN moieties are equivalent. The DM- DCNQI- moiety, therefore, must be acting as a symmetrical bridge linking the rhodium units. Assuming a square planar arrangement between the rhodium for the compound as depicted in Figure 25, a two-dimensional layer structure is proposed. This would not be unprecedented since the mononuclear complexes of the type M(DM-DCNQI)2 (MzAg, Li, Na, K, Cu, T1) have been crystallographically determined to exhibit this type of structure.13 These highly conducting materials were electrochemically synthesized as black needles using acetonitrile solutions of [C104]: [PF6]-, or [BF4]- salts of the cations under constant current conditions.13(a) The crystal structures of these complexes consist of two-dimensional sheets which are layered to form three-dimensional structures having average interplanar distances between the DCNQI units of ca. 3.2 A. In the proposed structure of "Rh(DM-DCNQI)2", direct Rh-Rh bonding would be limited to a minimum of ca. 3.2A if a similar structure would exist. A similar argument could be advanced for the product "Rh(TCNQ)2". The infrared spectrum of this product supports the presence of both bound and free CEN units on TCNQ. as previously demonstrated for other complexes 123 of TCNQ, implying a trans bridging TCNQ arrangement. A structure similar to that in Figure 25 may exist, but only 1/2 of the CEN groups would be ligated if one assumes a four-fold coordination environment about each Rh center. Again, the possibility of Rh-Rh bonding cannot be determined without futher information such as structural data or raman spectroscopy. Considering the fact that products with similar specu'oscopic properties are obtained by the reactions of [M02(NCCH3)10][BF4]4 and [Rh2(NCCH3)10][BF4]4 with TCNQ-, similar structures are predicted. Conclusions Reactivity of a specific acceptor species with a variety of dinuclear compounds of varying oxidation potentials aided in understanding the realative unimportance of outersphere charge-transfer proccesses in forming covalently bonded species. The infrared spectroscopic results of the products indicate that varying the redox potentials on similar dinuclear compounds of molybdenum and rhenium does not alter the ability to form covalently bonded complexes with polycyano organic acceptors. No relationships could be established between the oxidation potential of the metal complexes and the v(CEN) stretching frequencies in the infrared spectra of the products. A strong tendency was observed for polycyano acceptors to bind to unsaturated metal compounds which bodes well for the generality of this approach. In addition to the above charge-transfer reactions, reactions involving the fully solvated dinuclear compounds [Rh2(NCCH3)10][BF4]4 and [Moz(NCCH3)10][BF4]4 were studied with chemically or electrochemically reduced forms of TCNQ and DM—DCNQI resulting in the synthesis of covalently bonded polymeric materials. -ZI-2 124 ---|;2h-N:.—'-N N . III Q : N-i-N—Bh-NE-N be N. a: Q t n." N-EN- N. z-uz-é '- é up TI 2' I: z I -3- I 2 1| ,2 ---l'ih-Nl-N III. N i N ’" ... Q ' I); ,N ‘N-iN-EII‘I—Ni-N III l'l I d NiN- Bh-Na-N , N Ir 1|! Q ll .- I N' -2§- Figure 25. Proposed polymeric structure of "Rh(DM-DCNQI)3". 125 References 1. Brant, P.; Walton, R. A. Inorg. Chem. 1978, 17, 2674. 2. Glicksman, H. D.; Jamer, A. D.; Smith, T. J.; Walton, R. A. Inorg. Chem. 1976, 15, 2205. 3. Best, S. A.; Smith, T. J.; Walton, R. A. Inorg. Chem. 1978, I7, 99. 4. Cotton, F. A.; Falvello, L. R.; Harwood, W. S.; Powell, G. L.; Walton, R. A. Inorg. Chem. 1986, 25, 3949. 5. Agaskar, P. A.; Cotton, F. A. Inorg. Chem. 1984, 23, 3383. 6. (a) Dunbar, K. R. J. Am. Chem. Soc. 1988, 110, 8247. (b) Dunbar, K. R.; Pence. L. E. Inorg. Synth. 1991, 29, in press. 7. Cotton, F. A.; Wiesinger, K. J. Inorg. Chem, 1991, 30, 871. 8. Acker, D. S.; Harder, R. J.; Hertler, W. R.; Mahler, W.; Melby, L. R.; Benson, R. E.; Mochel, W. E. J. Am. Chem. Soc. 1960, 82, 6408. 9. Melby, L. R.; Harder, R. J.; Hertler, W. R.; Mahler, W.; Benson, R. E.; Mochel, W. E. J. Am. Chem. Soc. 1962, 84, 3374. 10. Wheland, R. C.; Martin, E. L. J. Org. Chem. 1975, 40, 3101. ll. Aumiiller, A.; Hunig, S. Liebigs Ann. Chem. 1986, 142. 12. Robles-Martinez, J. G.; Salmeron-Valverde. A.; Alonso. 13.; Soriano, C. Inorg. Chem. Acta 1991, 179, 149. 13. (a) Kato, R.; Kobayashi, H.; Kobayashi, A. Synth. Met. 1988, 27, B263. (b) Kato, R.; Kobayashi, H.; Kobayashi, A. J. Am. Chem. Soc. 1989, 111, 5224. (c) Enkelmann, V. Angew. Chem. Int. Ed. Engl.1991, 30, 1121. (d) Aumuller, A.; Erk, P.; Hunig, S.; Meixner. H.; von Schlitz, J.-U.; Werner. H.-P. Leihigs Ann. Chem. 1987, 997. (e) Aumiiller. A.; Erk, P.; Hunig, 8.; von Schiitz, J.-U.; Werner, H.-P.; Wolf, H. C.; Klebe. G. Chem. Ber. 1991. 124, 1445. (f) Kobayashi, A.; Mori. T.; Inokuchi. H.; Kato. R.; Kobayashi, H. Synth. Met. 1988,27. B275. (g) Kato. R.; Kobayashi, H.; Kobayashi, A.; Mori. T.; Inokuchi. H. Chem. Lett. 1987, 1579. (h) Aumiiller. A.; Erk. P.; Klebe. G.; Hiinig. 8.: von Schiitz. J.-U.: Werner. H.-P. Angew. Chem. Int. Ed. Eng]. 1986. 25. 740. 126 (i) Erk, P.; Gross, H.-J.; Hunig, S.; Langohr, U.; Meixner, H.; Werner, H.-P.; von Schiitz, J.-U.; Wolf, H. C. Angew. Chem. Int. Ed. Engl. 1989, 28, 1245. (i) Aumuller, A.; Erk, P.; Hunig, S.; von Schiitz, J.-U.; Werner, H.-P.; Wolf, H. C.; Klebe, G. Mol. Cryst. Liq. Cryst. Inc. Nonlin. Opt. 1988, 156, 215. (k) Hiinig, S.; Aumiiller, A.; Erk, P.; Meixner, H.; von Schiitz, J .-U.; Gross, H.-J.; Langohr, U.; Werner, H.-P.; Wolf, H. C.; Burschka, C.; Klebe, G.; Peters, K.; Schnering, H. G. Synth. Met. 1988, 27, B181. CHAPTER V METAL-METAL BONDED COMPOUNDS WITH CYANIDE LIGANDS. 128 1. Introduction Controlled self assembly reactions can lead to infinite frameworks in which the structure property relationships are easily tailored by altering the precursors. Extended 3-D frameworks with channels and cavities can be designed if rodlike units are used such as the approach being popularized by Mochl et al. in their "molecular lego" chemistry involving rigid staffane linking metal centers.l Recently, unique "scaffoldings" have been created by Robson et al. by utilizing M-CN-M likages.2 In fact, chains, sheets, and three dimensional structures exist for a variety of metal- cyanide complexes, the most notable being the Prussian blues.3 There is a wealth of cyanide chemistry of the transition metals,3 but little pertains to metal-metal bonded complexes.4 In the search for suitable linking units to span dimetal compounds, the simple CN‘ ligand was chosen because of its bifunctionality. If CN‘ ligands are placed on dimetal units, then under the right conditions, spontaneous self assembly could occur to produce polymeric materials. The non-aqueous chemistry of metal-metal bonded systems with cyanide ion was investigated. 2. Experimental A. Synthesis (1) Starting Materials The compounds M02(02CU13)4.5 M02(02(X3F3)4.6 [Rh2(NCUI3)10][BF4l4.7 [M02(NCCHs)1o][BF4]4,8 [R62(NCCH3)101[BF414,9 [Fe(NCCH3)6][BF41210 and Re2C14(dppm)411 were prepared according to literature methods. The cyanide salt [Et4N]CN was prepared by standard procedures.12 The reagent [Bun4N]CN was purchased from Aldrich Chemicals and used without further purification. For the cyanide chemistry. all glassware was flame dried under vacuum prior to use. 129 (2) Synthesis of [Bun4N]4[M02(CN)3] (8) A CHC13 (8 mL) solution containing [Bun4N]CN (0.534 g, 1.99 mmol) was added to Moz(02CCH3)4 (0.106 g, 0.248 mmol) dissolved in 4 mL of CHC13 to give a dark purple reaction solution which was stirred at room temperature for 5 days during which time the color changed to blue. Addition of hexanes (5 mL) followed by cooling to 0°C for 2 days led to the precipitation of a bright blue crystalline solid. After a second addition of hexanes (2 mL) and chilling at 0°C for 1 day, the product was collected by filtration, washed with hexanes (3 x 3 mL) and dried in vacuo; yield 0.133 g (40%). Anal. Calcd for C72H144N12M02: C, 63.13; H, 10.60; N, 12.27. Found: C, 61.63; H, 10.75; N, 11.54. The low values for the carbon and nitrogen analyses are attributed to residual CHC13 trapped in the crystalline form of the sample; this is supported by X-ray data that reveal the presence of 8 CHC13 molecules per [M02(CN)3]4' anion in the crystal form. IR (CsI , Nujol mull, cm'l): 2095 (s), 1153 (m), 1107 (w), 1060 (w), 1030 (w), 968 (w), 887 (m), 801 (w). (3) Synthesis of [Bun4N]3[M02(02CCH3)(CN)6] (9) In a typical reaction, a solution consisting of [Bun4N]CN (1.427 g, 5.31 mmol) in 10 mL of THF was slowly added to a sample of Moz(02CCH3)4 (0.379 g, 0.88 mmol) in 10 mL of THF to give a dark purple solution. The reaction was stirred at room temperature for 5 min during which time a red-purple solid precipitated. Additional product was harvested in the form of red-purple microcrystals that appeared after the reaction mixture was left undisturbed for 12 h; the crystals were collected by filtration, washed with THF (2 x 10 mL), and vacuum dried; yield 0.93 g (92%). Anal. Calcd for C56H111N903M02: C. 59.29: H. 9.86; N. 11.11. Found: C. 59.05: H. 9.63: N. 10.78. IR (CsI . Nujol mull. cm'l): 130 2105 (m), 2099 (m), 1604 (w), 1531 (w), 1154 (m), 1026 (w), 887 (m), 673 (m). UV—visible spectrum (CH2C12): kmaxnm (e, M'lcm'l), 557 (2.5 x 103), 276 (5.4 x 103). (4) Synthesis of [Et4N]4[M02(CN)3] (10) (i) Method i To a flask charged with Moz(02CCH3)4 (0.100 g, 0.234 mmol) and [Et4N]CN (0.488 g, 3.12 mmol) was added 10 mL of CH2C12 which resulted in the formation of a blue solution. The reaction mixture was stirred at room temperature for 3 h, during which time a bright blue precipitate formed. The solid was collected by filtration, washed with CH2C12 (3 x 5 mL) and dried in vacuo; yield 0.172 g (80%). The compound is soluble in EtOH, CH3CN, and H20, and was recrystallized from CH3CN to insure complete removal of [Et4N][02CCH3]. IR (CsI, Nujol mull, cm‘l): 2095 (s), 1490 (m), 1323 (w), 1176 (s), 1003 (m), 788 (m), 666 (w), 390 (w), 358 (w), 293 (w). UV-visible spectrum (CHzClz): hmax nm (e, M'lcm'l), 601 (3.0 x 103), 277 (4.9 x 103). (ii) Method ii A CH2C12 (10 mL) solution consisting of 0.200 g (0.31 mmol) of Moz(02CCF3)4 was added to a stirred CH2C12 (10 mL) solution consisting of 0.436 g (2.79 mmol) of [Et4N]CN causing a blue reaction mixture to form. The mixture was allowed to stand undisturbed for 2 h during which time a blue solid floated to the top of a dark green solution. The blue product was collected by filtration, washed with CH2C12 (3 x 3 mL) and EtzO (3 x 3 mL), and dried in vacuo; yield 0.232 g (81%). (iii) Method iii A flask containing [Bu’14N]3[l\~log(OzCCH3)(CN)(,] (2) (0.100 g, 0.088 mmol). [BuniNlCN (0.095 g. 0.35 mmol) and 10 mL of CHZCIQ was 131 treated with [Et4N]Cl (0.146 g, 0.88 mmol) in 5 mL of CH2C12. A reaction swiftly ensued with the deposition of a bright blue precipitate. The reaction mixture was stirred for 12 h at room temperature after which time the solid was collected by filtration and washed with CH2C12 (3 x 5 mL); Yield 0.071 g (88%). (5) Synthesis of [Bun4N]2[Re2(CN)6(dppm)2] (11) The salt [Bun4N]CN (0.133 g, 0.050 mmol) in 5 mL of CH2C12 was added to a solution of Re2C14(dppm)2 (0.100 g, 0.078 mmol) in 10 mL of CH2C12 leading to the formation of a green solution with the concomitant deposition of a bright green microcrystalline solid within 5 minutes. The solution was reduced in volume to 5 mL and the product was collected by filtration, washed with toluene (3 x 5 mL), and dried in vacuo; yield 0.093 g (67%). IR (CsI, Nujol mull, cm*1): 2091 (m,sh), 2078 (s), 1906 (s), 1588 (w), 1574 (w), 1433 (m,sh), 1277 (m), 1126 (w), 1094 (s), 1028 (m), 785 (s), 758 (w), 737 (m), 718 (m), 691 (s), 523 (s), 490 (s), 419 (s). The compound is soluble in acetonitrile and only sparingly soluble in CH2C12. The product was recrystallized from CH2C12 as the CH2C12 solvate [Bun4N]2[Re2(CN)6(dppm)2].8CH2C12. 1H NMR (PPm, CD3CN, 22°C, 300 MHz): 8 = 7.48 (mult, 16H, Ph); 5 = 6.96 (mult, 24H, Ph); 5 = 5.44 (s, 16H, CHzClz); 5 = 3.30 (pentet, 4H, -CH2-); Bu’14N: 5 = 3.05 (mult, 16H); 5 = 1.58 (mult, 16H); 5 = 1.33 (sextet, 16H), 5 = 0.95 (triplet, 24H). 31P{ 1H} NMR (CD3CN, 22 OC relative to 85% H3P04): 5 = -l 1.39 (5) ppm. UV-visible (CH3CN): Kmax nm (e, M-lcm'l), 969 (2.5 x 102), 694 (1.4 x 102). (6) Preparation of "M02(CN)4(NCCH3)X" A CH3CN (10 mL) solution containing [Bu’14N1CN (0.487 0 c9 1.81mmol) was added to a CH3CN (30 mL) solution containing 132 [M02(NCCH3)10][BF4]4 (0.400 g, 0.45 mmol) to give a green precipitate. The solid was collected by filtration, washed with CH3CN (2 x 10 mL), and dried in vacuo; yield 0.243 g. IR (CsI, Nujol, cm‘l): 2317 (m), 2288 (m), 2249 (w), 2188 (w), 2110 (s,br), 1067 (s), 1034 (w,sh), 511 (w), 484 (w,br). (7) Reaction of [Et4N]4[M02(CN)3] with [Rh2(NCCH3)1o][BF4]4 A CH3CN (5 mL) solution containing 0.050 g (0.054 mmol) of [Et4N]4[Moz(CN)3] was added to a CH3CN (5 mL) solution containing 0.052 g (0.054 mmol) of [Rh2(NCCH3)10][BF4]4 to give a black solid precipitate. The solid was collected by filtration, washed with CH3CN (2 x 10 mL), and dried in vacuo; yield 0.031 g. IR (CsI, Nujol, cm'l): 2334 (m), 2112 (s,br), 1647 (m), 1306 (w), 1175 (w), 914 (w), 968 (m), 787 (w), 461 (w,br). (8) Reaction of [Et4N]4[M02(CN)3] with [Re2(NCCH3)10][BF4]4 A CH3CN (5 mL) solution containing 0.050 g (0.054 mmol) of [Et4N]4[M02(CN)3] was added to a CH3CN (5 mL) solution containing 0.062 g (0.054 mmol) of [Re2(NCCH3)10][BF4]4 to give a green precipitate. The solid was collected by filtration, washed with CH3CN (2 x 10 mL), and dried in vacuo; yield 0.042 g of the final black solid. IR (CsI, Nujol, cm'l): 2209 (m), 2095 (s,br), 1651 (w), 1196 (m), 968 (m), 788 (w), 461 (w,br). (9) Reaction of [Et4N]4[M02(CN)3] with [Fe(NCCH3)6][BF4]2 Acetonitrile (15 mL) was added to a Schlenk tube containing 0.0968 g (0.105 mmol) of [Et4N]4[M02(CN)8] and 0.100 g (0.210 mmol) of [Fe(NCCH3)6][BF4]2 resulting in the immediate precipitation of a dark green solid. The solid was collected by filtration. washed with CH3CN 133 (2 x 10 mL), and dried in vacuo; yield 0.069 g. IR (CsI, Nujol, cm'l): 2311 (w), 2280 (w), 2211 (w), 2096 (s,br). (10) Reaction of [Bun4N]3[M02(02C C H 3)(CN)6] with [Rh2(NCCH3)10][BF4]4 A 10 mL solution containing 0.157 g (0.138 mmol) of [Bun4N]3[M02(02CCH3)(CN)6] was added to a 10 mL solution containing 0.100 g (0.103 mmol) of [Rh2(NCCH3)1o][BF4]4 to give a black precipitate. The solid was collected by filtration, washed with CH3CN (2 x 10 mL), and dried in vacuo; yield 0.093 g. IR (CsI, Nujol, cm'l): 2325 (w), 2286 (w), 2249 (w), 2110 (s,br), 2042 (s,br), 1521 (w), 1030 (m), 972 (w), 679 (s), 621 (w), 473 (w). (B). X-ray Crystallography Structures were determined by application of general procedures fully described elsewhere.13 Crystallographic data for [Bun4N]4[M02(CN)3]-8CHC13,(8)-8CHC13, [Bun4Nl3IM02(OCCH3)CN)8]. (9), and [Bun4N]2[Re2(CN)6(dppm)2]~8CH2C12, (11)-8CH2C12 were collected on a Rigaku AFC6S diffractometer with monochromated MoKoz (ha = 0.71069 A) radiation. All data were corrected for Lorentz and polarization effects. Calculations were performed on a VAXSTATION 4000 computer by using the Texsan crystallographic software package of Molecular Structure Corporation.l4 Crystallographic data for the three compounds are compiled in Tables 16. 17, and 18. (l) [Bun4N]4[M02(CN)3]°8CHC|3 (8)-8CHC13 (i) Data Collection and Reduction Suitable crystals of [Bu’14N]4[Moz(CN)g]~8CHC13 were grown by slow diffusion of hexanes into a CHC13 solution of the compound in a flame sealed 8 mm O.D. glass tube at 25CC. A blue crystal of approximate 134 Table 16. Summary of crystallographic data for [Bu4nN]4[M02(CN)3]-8CHCI3 (8)-8CHC13. formula formula weight space group a, A b, A c, A 0:, deg 13. deg 7. deg V, A3 Z dcalc, g/cm3 1; (Mo Kat), cm'1 temperature, °C trans. factors, max., min. Ra wa quality-of-fit indicator 3R=211F01-1Fc11/21F01. M02C80N12C124H152 2324.84 Pbca (#61) 20.526 (8) 28.122 (5) 19.855 (7) 90 90 90 11461 (4) 4 1.347 8.20 -100 1.00, 0.68 0.082 0.083 4.03 bRw = [2w( 1F01- IFc l)2/}:w 1F012]1/2; w = 1/02(1Fo I) Cquality-of-f'1t= [2w( 11301 - 1FC I)2/(N0b,-Npmmele,s)1 ”2 135 Table 17. Summary of crystallographic data for [3114an3IM02(02CCH3)(CN)61 (9). formula formula weight space group a, A b, A c, A 01, deg 13. deg 7. deg v, A3 Z dcalc, g/cm3 [1 (Mo Kat), cm-l temperature, °C trans. factors, max., min. Ra wa quality-of-fit indicator aR=z 11Fo1' 1Fc11/21Fo1. M02C56N902H1 11 1134.43 P21 (#4) 12.046 (3) 16.05 (1) 16.854 (3) 90 94.11 (2) 90 3250 (2) 2 1.159 4.16 -100 1.00, 0.20 0.067 0.067 2.89 bRw = [£w( IF0 I - 1Fc1)2/2w It:0 1211/2; w = 1/02(|1=o 1) Cquality-of-fit = 1£W( 1F0 1 ’ 1Fc 1)2/(I‘Job3‘1\lp11ramctcrs)1v2 136 Table 18. Summary of crystallographic data for [BU4"N]21R62(CN)6(dppm)2l°8CH2C12. (11)-8CH2C12 formula formula weight space group a, A b, A c, A 0t, deg 13. deg 7. deg v, A3 Z dcalc, g/cm3 [.1 (Mo Kat), cm-l temperature, °C trans. factors, max., min. Ra wa gality-of-fit indicator 2'IRZEIIFOI-1FC11/21F01. R62C116P4C96N8H132 2461.70 ’ P-l (#2) 13.835 (2) 18.172 (2) 12.261 (1) 106.788 (8) 107.850 (9) 93.894 (9) 2767.5 (6) 1 1.477 27.06 -100 1.00, 0.64 0.041 0.045 1.94 bRw = 12M 1F01- 1Fc|)2/£w 1FO 1211/2; w = 1/02( 11:0 |) Cquality-0H it = [Zw( lF0 I - IFC |,)2/(_Nobstmmem)I1/2 137 dimensions 0.40 x 0.50 x 0.40 mm3 was mounted on a glass fiber. Cell constants and an orientation matrix for data collection obtained from a least squares refinement using the setting angles of 25 carefully centered reflections in the range 15 S 20 S. 24° corresponded to an orthorhombic cell. A total of 10963 data were collected at -100 i 1°C using the (1)-scan technique to a maximum 20 value of 50°. The intensities of three representative reflections measured after every 150 reflections decreased by 6.1% thus a linear correction factor was applied to the data to account for this decay. A correction for secondary extinction was applied (coefficient = 0.19919E-07). (ii) Structure Solution and Refinement The systematic absences in the data led to the space group Pbca. The structure was solved by MI'I‘HRIL15 and DIRDIF 16 structure programs and refined by full matrix least-squares refinement. All non-hydrogen atoms were refined with anisotropic thermal parameters whereas hydrogen atoms were placed in calculated positions for the final stages of refinement. After isotropic convergence had been achieved, an empirical absorption correction was applied using the program DIFABS,17 which resulted in transmission factors ranging from 0.68 to 1.00. The final cycle of full matrix least-squares refinement included 4972 observed reflections with F02 > 36(F02) and 533 variable parameters to give R = 0.082 and Rw = 0.083 and a quality-of-fit index of 4.03. (2) [BU"4N13[M02(02CCH3)(CN)61 (9) (1) Data Collection and Reduction Large red-purple crystals of [Bu’14N]3[M02(02CCH3)(CN)6] were grown by slow diffusion of diethyl ether into a CH3C13 solution of the compound in a flame sealed 8 mm O.D. glass tube at room temperature. 138 A crystal of approximate dimensions 0.72 x 0.23 x 0.47 mm3 was mounted on the tip of a glass fiber and secured with silicone grease. Cell constants and an orientation matrix for data collection, obtained from a least squares refinement using the setting angles of 16 carefully centered reflections in the range 20 .<. 20 S. 27°, corresponded to a monoclinic cell. A total of 6240 reflections were measured at -100 i 1°C to a maximum 20 value of 50° using the (1)—20 scan technique. The crystal diffracted poorly due to a large mosaic spread and only 3108 unique reflections were of the intensity F02 > 36(F02). Three check reflections measured every 200 data points declined by 1.3 % which was accounted for by a linear correction factor. A correction for secondary extinction was also applied (coefficient = 0.1379lE-06). (ii) Structure Solution and Refinement The space group P21 was selected on the basis of systematic absences. The unique Mo atom was located by SHELX-S8618 and the remaining atoms were established by DIRDIFl6 structure programs and refined by full matrix least-squares refinement. After all non-hydrogen atoms had been refined isotropically, an empirical absorption correction was applied using the program DIFABS.17 Hydrogen atoms were included in the refinement in calculated positions. The final cycle of full matrix least- squares refinement was based on 3108 observed reflections with F02 > 30(F02) and 497 variables to give R = 0.067 and Rw = 0.067 and a quality-of-fit index of 2.89. Both enantiomorphs were refined and the difference in R values led to a 99% level of confidence by the Hamilton significance test. favoring the assingment of the original enantiomorph. 139 (3) [Bu"4Nl2[Re2(CN)6(dPPm)2l°8CH2C12 (11)°8CH2C12 (1) Data Collection and Reduction Suitable crystals of [Bun4N]2[Re2(CN)6(dppm)2]~8CH2C12 were obtained by slowly cooling a saturated CH2C12 solution of the compound. A crystal of approximate dimensions 0.52 x 0.26 x 0.16 mm3 was mounted on the end of a glass fiber with the aid of silicone grease. A least squares refinement using the setting angles of 19 carefully centered reflections in the range 20 S 20 S 30° gave cell constants that correspond to a triclinic crystal system. A total of 10184 data were collected at a temperature of -100 i 1°C using the (1)-20 scan technique in the range 7 S 20 S 50° and were corrected for secondary extinction (coefficient = 0.86499E-07). The intensities of three representative reflections which were measured after every 150 reflections decayed by only 0.25%. An absorption correction based on three ul-curves with a x value near 90° were used as the basis for an absorption correction and resulted in transmission factors ranging from 0.64 to 1.00. (ii) Structure Solution and Refinement The structure was solved by MITHRIL15 and DIRDIF16 structure programs and refined by full matrix least-squares refinement. All non- hydrogen atoms were refined with anisotropic thermal parameters with the exception of atoms in the CH2C12 interstitial solvent; hydrogen atoms were included in calculated positions. The final cycle of full matrix least-squares refinement was based on 7767 observed reflections with F02 > 30(F02) and 801 variable parameters to give R = 0.041 and Rw = 0.045 and a quality- of-fit index of 1.94. 140 3. Results and Discussion A. Preparation of Cyanide Compounds from Carboxylate and Chloride Compounds. (1) Preparation of Dimolybdenum-cyanide Complexes. In spite of the rich chemistry involving the cyanide ligand,3 the preparation of low valent cyanide complexes with metals that form strong M-M interactions has not been pursued to any great extent. With the exception of [Et4N]4[M02(CN)3], formulated on the basis of IR and elemental data,19 there are no reports of homoleptic dinuclear cyanide compounds in the literature to our knowledge. We wondered if the lack of activity in this area was due to the fact that metal-metal bond chemistry is typically performed in non-aqueous solvents whereas classical cyanide chemistry is carried out under aqueous conditions or in liquid ammonia. To test this assumption, we set out to synthesize cyanide and mixed ligand cyanide compounds beginning with dinuclear starting materials. Initially, reactions between dimolybdenum tetracarboxylates and Me3SiCN led to black solids and oils that exhibited v(CEN) bands ranging from 2140 to 1970 cm'l. Subsequently, reactions of M02(02CR)4 (R = CH3, or CF3) with [R4N]CN (R = Et, Bu") were found to proceed rapidly in organic media to give [Bun4N]4[M02(CN)g]-8CHC13 (8) and [Bun4N]3[M02(02CCH3)(CN)6] (9). Chemistry of M02(02CR)4 (R 2 CH3, or CF3) with eight equivalents of [Bu"4N]CN or [Et4N]CN in CH2C12 produces the blue octacyanide anion [M02(CN)8]4', with the highest yield obtained from [Et4N]CN and M02(02CCH3)4. Substitutions involving [Bu"4N]CN are less desirable. as these reactions invariably lead to intractable oily products contaminated with the purple intermediate [Bu’l4N]3[Moz(OzCCH3)(CN)6]. (9). The anion in (9). 141 [M02(02CCH3)(CN)6]3', was rationally prepared by reaction of six equivalents of [Bun4N]CN with Moz(02CCH3)4 in THF and subsequently converted to [M02(CN)3]4- by addition of [Bun4NJCN to a solution of the compound in CH2C12. The final product is difficult to isolate as the [Bun4N]+ salt, but it can be precipitated as [Et4N]4[M02(CN)3] when treated with [Et4N]Cl. Attempts to prepare the mono- or bis-substituted anions [M02(02CCH3)3(CN)2]- and [M02(02CCH3)2(CN)4]2' by an analogous procedure produced only mixtures of [Bun4N]3[M02(02CCH3)(CN)6] and Moz(02CCH3)4 as judged by NMR spectroscopic monitoring of reactions performed in deuterated solvents. Attempts at synthesizing M02(CN)4(PR3)4 compounds using similar synthetic proceedures as in the syntheses of M02C14(PR3)4 compounds have so far led to only to samples of [M02(CN)8]“".20 (2) Preparation of [Bun4N]2[Re2(CN)6(dppm)2] (11). As part of the generality of our approach, we sought to demonstrate that Cl‘ ligands of multiply-bonded compounds also readily exchange with CN‘ in non-aqueous solvents. The reaction of purple Re2C14(dppm)2 with excess CN' in toluene or CH2C12 proceeds at ambient temperatures with precipitation of green [Bun4N]2[Re2(CN)6(dppm)2] (11), the first example of a M-M bonded anion of the type [M2L10]2'. No evidence for the formation of partially substituted compounds or the simple adduct [Re2C14(CN)2(dppm)2]2' was observed. [Re2(CN)6(dppm)2]2' is quite stable in air, and. indeed, is inert to CO under prolonged reflux conditions in CH2C12, further underscoring the stability of this dinuclear unit supported by six cyanide ligands. 142 B. Spectroscopy The electronic spectra of [M02(CN)3]4' and [M02(02CCH3)(CN)6]3‘ exhibit transitions in the visible region characteristic of 5->5* transitions at Amax values of 601 and 557 nm respectively. The value for the octacyanide complex is considerably lower in energy than the corresponding transitions in homoleptic quadruply bonded M024+ compounds with halide ligands, e.g. [M02C13]4' exhibits a 5-5* transition at 530 nm.21 Clearly the energy separation of the 5 and 5* molecular orbitals is considerably smaller in the presence of cyanide ligands acting as strong donors. The infrared spectrum of [Bun4N]4[M02(CN)3] reveals two v(CEN) stretches at 2095 cm'1 and 2103 cm'1 in the solid state and one stretch at 2096 cm"1 in CH2C12 solution. Two bands, a2u + eu, are expected in the absence of solid-state splitting effects for a molecule of D411 symmetry, and the Ieu/Ia2u is approximately 8.4 based on (1/2)tan2(0), where 0 is the C-Mo-Mo angle (103.7 ave.).22 The high energies of the cyanide stretches indicate that the cyanide groups are acting as strong donors and not as n-acceptors. The anion [M02(02CCH3)(CN)6]3' exhibits v(CEN) stretches at 2099 and 2105 cm"1 for two distinct types of CEN in a sz symmetry environment. As in [M02(CN)8]4', these stretching frequencies are higher than free CN‘ for which v(CEN) occurs at 2050 cm'1 in [Bun4N]CN. The 1H NMR spectrum of [Bun4N]4[Moz(CN)g] in CD2C12 displays only resonances at 5 = 0.98, 1.49, 1.72, 3.42 ppm (3:2:2:2 integration) for the butyl substituents of the [Bun4N]+ groups. When M02(02CCF3)4 is used in synthesis of [Et4N]4[M02(CN)8], 19F NMR is useful in determining the complete loss of the 02C C F 3‘ groups. For [Bu’74N]3[Moz(OzCCH3)(CN)6], the 1H NMR spectrum in CDC13 exhibits a singlet at 5 = 2.60 ppm for the methyl group of (H—OQCCHR) in addition to 143 the [Bun4N]+ resonances at 5 = 0.92, 1.47, 1.68, 3.36 ppm (3:2:2:2 integration). [Bun4N]2[R62(CN)6(dppm)2], (11), displays v(CEN) stretches indicative of terminal (2097 and 2081 cm'l) and bridging cyanide ligands (1935 cm'l). The compound exhibits very low solubility in nearly all solvents except acetonitrile, in which it is sufficiently soluble to allow for solution measurements. A 31P{ 1H} spectrum of (11) recorded in CD3CN at 22 °C relative to 85% H3P04 contained a singlet at -11.39 ppm which is in the range of chemical shifts observed for Re24+ complexes containing trans dppm ligands.24 1H NMR spectral properties of the anion are typical for symmetrical bis-dppm complexes of Re(II); (1H NMR, CD3CN, 22 0C, 300 MHz): 5 7.48 (mult, 16H, Ph); 6.96 (mult, 24H, Ph); 5.44 (s, 16H, CH2C12); 3.30 (pentet, 4H, -CH2-). The pentet for the methylene bridgehead group arises from four equivalent methylene protons undergoing virtual coupling with four equivalent P nuclei (J(p-H) = 3.9 Hz). Electronic d-d transitions for [Re2(CN)6(dppm)2]2' occur at 969 and 694 with 8 values in the 1-2 x 102 range. Since no other unambiguous examples of an Re24+ unit in an edge-sharing bioctahedral (ESBO) geometry exist, these transitions cannot be assigned on the basis of analogous systems. Electrochemical studies of (11) in CH3CN revealed that the anion does not undergo any redox processes in the range +1.8 to -1.8 V vs Ag/AgCl. In contrast, Re24+ complexes of the M2L8 type (621t4525*2) exhibit two reversible or quasi-reversible oxidations corresponding to loss of the 5* electrons.23~24 The situation is quite different in the present case, however. as the orbital overlap scheme of an ESBO compound places the last two electrons in a It* level 144 (02n2(55*)41t*2). There is, therefore, no justification for correlating the redox properties of the two different geometries. C. Molecular Structures (1) Crystal structure of [Bun4N]4[l\/102(CN)3]-8CHG3,(8)-8CH(J3. The structure of [Bun4N]4[M02(CN)3]-8CHC13 constitutes the first crystallographically determined dinuclear homoleptic cyanide complex. An ORTEP diagram of the molecular anion is depicted in Figure 26. A list of selected bond distances and angles for the compound is given in Table 19. This anion constitutes an important example of an unsupported metal- metal quadruple bond in the presence of n-acceptor ligands. For comparative purposes, the Mo-Mo distances of unsupported homoleptic dimolybdenum compounds are listed in Table 20 along with those of compounds (8) and (9). Among the unbridged compounds, [M02(CN)3]4', (8), possesses the shortest M-M interaction, a rather surprising finding, as n-acceptor CN‘ ligands would be expected to produce the opposite effect. As the infrared data in the v(CEN) indicated, the ligands in compound (8) appear to be serving purely as donors for the M024+ core, thereby increasing the electron density at the metal centers and therefore M-M overlap. Other important metric parameters are Mo-Cav = 2.21 A, C-Nav = 1.14 A, 0 £4 Figure 27. Molecular structure of [Moz(02CCH3)(CN)6]3' with the atom labeling scheme. With the exception of the H atoms, the atoms are represented by their 50% probability ellipsoids. 149 ~0.08A than that in [M02(CN)3]4', but slightly longer than the corresponding distance in M02(02CCH3)4. The CEN bond distances in (9), none of which are related by crystallographic symmetry, vary from 1.09 A to 1.19 A. These differences are ascribed to packing influences of the anion with the tetrabutylammonium cations, as evidenced by close contacts (2.4 - 2.8 A) between two [Bun4N]+ cations and the N atoms of several cyanide ligands. Important bond distances and angles for (9) are provided in Table 21. (3) Crystal structure of [Bun4N]2[Re2(CN)6(dppm)2]°8CH2C12, (ll)-8CH2C12 The single crystal X—ray structure of [Bun4N]2[Re2(CN)6(dppm)2]-8CH2C12 is quite unusual for several reasons. Firstly, it is the only example of an edge-sharing compound that clearly falls into the category of a RCZIIJI rather than a RezmsIII species, secondly the anion [Re2(CN)6(dppm)2]2' is the first [M2L10]2' species to be reported, and thirdly it contains a very rare mode of coordination for the cyanide ligand. The full ORTEP is depicted in Figure 28, and a skeletal viewpoint of the equatorial plane is provided in Figure 29. Selected bond distances and angles are provided in Table 22. The drawing in Figure 29 clearly shows that the four terminal cyanide and two bridging cyanide ligands are arranged in a pseudo-edge sharing bioctahedral arrangement. The bridging cyanide ions are bound to the Re-Re unit in an 112 fashion consisting of a (5 bond between C(1) and Re(l) and a n-interaction between the C(1)EN(l)moiety and Re(1)*. This type of situation has been crystallographically documented in only one previous instance. namely in the dimolybdenum complex [BuniN][Cp2M02(CO)4(CN)].4(a) This asymmetrical bridging CN mode has been documented in the complexes 150 5 a: @0 60 S 2.5 220 2002 S a: 220 222 6 :0 50 622 S 2.2 60 62 S 03 $0 €02 S 8.2 $0 232 2: SN 60 S22 5 :2 50 62 5 25 60 302 5 2.2 60 282 5 85 $0 322 0 2.2 80 82 20 05 S0 €02 E 8.2 E0 50 8 m5 :5 €02 6 an; E0 80 S :8 522 :22 0053.8 N 805 _ :85 005206 N :55 2 :55 20053.6 2220023008022.22:3: c2 C 820.2. 28m 23 £0 285220 252 020222 5 22:. 151 28 tom 280 28022 820 20 82 280 E0 200 E :02 30 2022 200 20 :2 280 E0 200 22 m2: 280 2002 2:02 5 022 280 $5 2220 G2 21.82 200 @2022 2:022 20 $2 222 220 2022 22 3.2: $0 2002 802 222 02.2 282 230 $202 $2 2.20 280 2802 2:02 28 32 $22 $20 3202 AC m.mm2 200 222022 280 5 2.: 52 50 322 22 new 200 302 2:0 23 2.2 282 280 22202 At 0.2% 280 2:02 EU 23 $2 22272 2220 222022 62 22.92 280 2:02 2:0 220 a: 60 60 502 E a.; 280 502 2 :0 20 2: E0 200 S22 22 4.202 200 802 30 2C fimi 620 28022 230 62 @202 280 2:022 2802 $2 wdm 320 82022 $20 AS 302 280 22202 2822 AC max 280 82022 $20 23 082 2220 2:022 2822 28 3.2 220 €22 200 20 05 200 E22 2002 0&5 m 805 m 805 2 805 0&5 m 605 m 805 2 :55 8&5 20.2.80 .2~ 25.2. 152 4. 1 0‘3) " N13) C(31) C(32) ., -\ f‘. 2 C‘ x , 13(2) T 1 / .(‘2 \ c . o 0(4): “ 0 . « 2 ~\\\\‘ 13.-0 15 N \\\\ Figure 28. ORTEP plot of a molecule of [Re2(CN)6(dppm)2]2‘ with non-hydrogen atoms represented by their 50% probability ellipsoids. 153 ’\ 53 ,{E 0(1) 1 N(2) N(3)‘ 7,5 ' 3 912) cm" Re(1)‘ TIA? "9“) C(2)‘ ‘2 0(3) s1 Ntzr @ "<1 1" Figure 29. View looking down on the equatorial plane of the anion [Re2(CN)6(dppm)2]2‘ emphasizing the unsymmetrical arrangement of the bridging CN group. 154 AD 032 230 CE 5 202.2 280 202 AC mo2.~ 320 22232 28 mm 2.2 280 2872 AC EQN 280 22202 82 2.2.2 CCU A222 62 22m.~ L220 22202 5 092.2 2230 282 5 wood 2220 302 62 2.8.2 2280 52 62 exam 2.2222 €02 6 2292.2 .520 232 5 32 5a 302 E 05.2 2200 322 28 $3 222a 302 62 2.8.2 22220 222a 62 nomad 302 45022 005222. N 805 2 805 00520220 N :85 2 :85 80522220 202205.22580220082:223.82 .2 C 3205. Boa .5 20 38220 252 33200 .3 22s... 155 20 2.02: 200 2002 .200 20 3: Lava 230 20a 20 2:: 200 2002 .200 22 S: 202 200 2 00.2 20 22.82 200 2002 2:0 22 2.0: 202 200 2002 20 2:2 200 2002 200 22.0 ~22 .202 .200 2032 20 020a .2200 2:02 2:0 22 an: 202 200 2002 20 a.; 200 203. 20a 20 haw .2002 200 2002 20 a.; 200 2002 20a 20 0% 2230 200a 2200 20 2.8 .200 203. 20a 20 0.82 2230 20a .2220 20 0.22 200 2:02 20a 20 20.82 200 20a .2200 20 a.; 200 2002 20a 20 «.82 2230 20a 2002 20 22 200 2002 20a 20 S: 2200 20a 2032 20 $0 .200 2002 20a 20 ad: .200 20a 2002 20 08 2200 200a 20a 20 2.22: 2200 220a 2200 22 02: 20a 2002 2 0a 20 4.82 2200 20a 2220 20 $3 200 2:02 .2002 20 022: 2200 20a 2200 20 52 200 2:02 .2002 20 3: 2200 220a 2002 20 20.22. .200 2:02 .2002 20 0.82 2200 220a 2032 20 02V 200 2002 .2002 20 5: 22.00 20a 2022 23 020.25 20a 2002 .2 :02 20 02 200 2002 200 20 25% 20a 2 002 .2002 0&5 m 825 N 825 2 E25 0&5 m 825 N 825 2 E25 8&5 20.252 .3 252. 156 [Rh2(u-CN)(u-C0)(C0)2(dppm)2lC104 and [Mn2H(u-CN)(CO)4(dPPm)2l but full structural details were not available.4(b)t(c) In the Mo structure, however, a disorder associated with the bridging cyanide precluded the reliable determination of bond distances and angles associated with this unusual mode of CN' binding. The bridging angle .20 2282522800 .3 0.2.5.2. 158 analyses (TGA) performed on [Mo2(CN)4(CH3CN)x], [Rh2M02(CN)3(CH3CN)x], and [Re2M02(CN)3(CH3CN)x] shown in figures 30, 31 and 32 exhibit weight losses of 46%, 43% and 35% respectively. The infrared spectra of the solids, after being heated to at least 500°C under a flow of N2 gas, show no v(CEN) bands. Assuming the complete loss of CH3CN and CN' ligands, the amount of CH3CN (x) in each product is calculated to be ca. 3.2, 0.9 and 2.3 equivalents respectively. The TGA of [Fe2M02(CN)3(MeCN)x] (shown in Figure 33) under similar conditions exhibits a weight loss of only 31% which would account for only 5.2 equivalents of CN', and no CH3CN. But this is not possible since the infrared spectrum prior to the TGA clearly shows the presence of v(CEN) bands attributed to CH3CN. The color of the solid after the TGA is orange-brown (not black as seen for the other solids) and the infrared spectrum exhibits a very strong and broad band at 835 cm'1 indicating that a new product has formed as the result of performing the TGA. No v(CEN) bands are present in the spectrum. The TGA exhibited a 2% weight increase between 500 and 600°C indicating a reaction with the N2 gas or possibly 02 (if the TGA system is not absolutely free of 02 contaminant). The decomposed materials would be expected to be highly reactive to 02 forming M-O products. The complex [Bun4N]3[M02(O2CCH3)(CN)6] reacts with [Rh2(NCCH3)1()][BF4]4 to form a black solid precipitate whose infrared spectrum exhibits two intense and broad v(CEN) bands at 2110 and 2042 c m '1. Since there are two types of CN‘ ligands in [Bu’74N]3[M02(02CCH3)(CN)6], nonequivalent M-CN-M' linkages could occur to give different v(CEN) bands. 159 TGA 80.00° \ \ 6000* 1. __'.. ' 1.- 21,2 1 __...L___._L__ 400 00 5300 00 _L l 0 00 100.00 200.00 300.00 Temptfl Figure 30. Thermogravimetric analysis of "M02(CN)4(NCCH3)X". 160 TGA 7. 100.00“ \ 80.00“ \ 60.00- 0.00 200.00 400 00 600 00 Temp[C] Figure 31. Thermogravimetric analysis of "Rh2M02(CN)3(NCCH3)x". ii: 161 TGA IOOOOC \ 80001 \ 60.00- 3 ‘22 1 1 1 1 1 1 1 1 l 1 1 1 1 0.00 200 00 400.00 600 00 Temp[(‘] Figure 32. Thermogravimetric analysis of "Re2M02(CN)8(NCCH3)x". 162 TGA 110.00- 100.00 -—\ 9000- \ 80.00~ \ 60.001~ 0.00 200.00 400.00 600.00 Figure 33. Thermogravimetric analysis of "Fe2M02(CN)3(NCCH3)x". 163 References 99039).“ Michl, J. Science April 26, 1991, 511. (a) Abrahams, B. R.; Hoskins, B. F.; Robson, R. J. Chem. Soc., Chem. Commun. 1990, 60. (b) Abrahams, B. R.; Hoskins, B. F.; Liu, J.; Robson, R. J. Am. Chem. Soc. 1991, 113, 3045. (c) Hoskins, B. F.; Robson, R. J. Am. Chem. Soc. 1990, 112, 1546. (a)Sharpe, A. G. "The Chemistry of Cyano Complexes of the Transition Metals" Academic Press, London. 1976. (b)Ludi, A.; Giidel, H. U. Structure and Bonding 1973, 14, 1-21. (c) Shriver, D. F. Structure and Bonding 1966, I, 32-58. ((1) Griffith, W. P. Coord. Chem. Rev. 1975, 17, 177-247. (e) Iwamoto, T. in, "Inclusion Compounds: Inorganic and Physical Aspects of Inclusion" Eds., Atwood, J. L.; Davies, J. E. D.; MacNicol, D. D. Oxford University Press, Oxford. 1991, 5, Ch. 6, pp. 177-212. (1) Wilde, R. E.; Ghosh, S. H.; Marshall, B. J. Inorg. Chem. 1970, 9, 2512. (a) Curtis, D. M.; Han, K. R.; Butler, W. M. Inorg. Chem. 1980, I6, 2096. (b) Aspinall, H. C.; Deeming, A. J .; Donovan-Mtunzi, S. J. Chem. Soc. Dalton Trans, 1983, 2669. (c) Deraniyagala, S. P.; Grundy, K. R. Inorg. Chim. Acta, 1984, 84, 205. Brignole, A. 8.; Cotton, F. A. Inorg. Synth. 1972, 13, 81. Cotton, F. A.; Norman, J. G.; Coord. Chem. 1971, 1, l4. Dunbar, K. R.; Pence, L. E. Inorg. Synth. 1992, 29, 182. Cotton, F. A.; Wiesinger, K. J. Inorg. Chem. 1991, 30, 871. Bernstein, S. N.; Dunbar, K. R. Angew. Chem. Int. Ed. Engl. 1992, 31, 1359. Hathaway, B. J.; Holah, D. G.; Underhill, A. E. J. Chem. Soc. 1962, 2444. Barder. T. J.; Cotton, F. A.; Dunbar. K. R.; Powell. G. L.; Schwotzer, W.; Walton. R. A. Inorg. Chem. 1985. 24, 2550. Andreades. S.: Zahnow. E. W. J. Am. Chem. Soc. 1969. 9], 4181. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 164 (a) Bino, A.; Cotton, F. A.; Fanwick, P. E. Inorg. Chem. 1979, 18, 3558. (b) Cotton, F. A.; Frenz, B. A.; Deganello, G.; Shaver, A. J. Organomet. Chem. 1973, 227. TEXSAN-TEXRAY Structure Analysis Package, Molecular Structure Corporation 1985. MITHRIL: Integrated Direct Methods Computer Program, Gilmore, C. J. J. Appl. Cryst. 1984, 17, 42. DIRDIF: Direct Methods for Difference Structure, An Automatic Procedure for Phase Extension; Refinement of Difference Structure Factors. Beurskens, R. T. Technical Report 1984. DIFABS: Walker, N.; Stuart, D. Acta Cryst. 1983, A39, 158-166. Sheldrick, G. M. in, "Crystallographic Computing 3 Eds. G. M. Sheldrick, C. Kruger, and R. Goddard, Oxford University Press 1985, pp. 175 - 189. Garner, C. D.; Senior, R. G. J. C. S. Dalton 1975, 1171 Baker, S. L.; Dunbar, K. R. work in progress. Fanwick, P. E.; Martin, D. S.; Cotton, F. A.; Webb, T. R. Inorg. Chem. 1977, 16, 2103. Cotton F. A. Chemical Applications of Group Theory, Third addition, Wiley Interscience, 1990. Anderson, L. B.; Barder, T. J.; Cotton, F. A.; Dunbar, K. R.; Falvello, L. R.; Walton, R. A. Inorg. Chem. 1986, 25, 3629. Barder, T. J.; Cotton, F. A.; Lewis, D.: Schwotzer, W.; Tetrick, S. M.; Walton, R. A. J. Am. Chem. Soc. 1984, 106, 2882. CHAPTER VI REACTIONS OF METAL-METAL BONDED COMPLEXES WITH PHOSPHINE-FUNCTIONALIZED TETRATHIAFULVALENE DONORS 165 166 1. Introduction Since reactions of polycyano-organic acceptor species (i.e. TCNQ and DM-DCNQI) with dinuclear metal complexes led to the formation of covalently linked complexesl, examples in which dinuclear metal complexes are linked to organic donor molecules were thought to be feasable targets. In one reported example, the complex [Rh2(02CCH3)4(TTF)2] contains two axially o-bound TTF (tetrathiafulvalene) donor molecules.2 Other examples in which mononuclear metal complexes are covalently linked to TTF molecules have been reported, but are rare.3 Recently, Fourmiqué and Batail have successfully synthesized a variety of TTF containing phosphines, PPhnTTF3-n (n = 0-3), Me2(PPh3)2'ITF, and (PPh3)4TI‘F.4 Realizing the ability of phosphine ligands to stabilize dimetal centers, we set out to explore the chemistry of these newly synthesized TTF-phosphines with dinuclear metal compounds. We rationalized that the combination of the stacking ability and redox capabilities of 'ITF coupled with the rich redox properties of metal-metal bonded units could result in new materials with interesting magnetic or electrical properties. The products from the reactions of these redox-active TTF-phosphines with various dinuclear species have resulted in a variety of metal/P-TTF complexes. The X-ray crystal structure of [Rh{Me2(PPh2)2TTF}2][BF4] (12) was determined and revealed close intermolecular TTF-TTF contacts in the solid state. 2. Experimental A. Synthesis The metal complexes [Rh2(NCCH3)1()][BF4]4,5 [Butt’lN];>_Re2C18,6 R62C16(PBU3")2.7 M02(02CCH3)4.8 M02(02CCF3)4.9 [MoleOCHshollBme and [V(NCCH3)6][BPh4]2,11 were synthesized according to literature 167 procedures. The phosphines Me3(PPh2)TTF, Me2(PPh2)2TTF, and (PPh2)4TTF were generously provided by Patrick Batail and Marc Fourmiqué.12 (1) Preparation of [Rh{Me2(PPh2)2TTF}2][BF4] (12) A warm solution containing 0.250 g (0.416 mmol) of Me2(PPh2)2TTF and 20 mL of CH3CN was slowly added to a stirred solution containing 0.100 g (0.104 mmol) of [Rh2(NCCH3)1()][BF4]4 and 10 mL of CH3CN whereupon a green solution and a yellow crystalline solid were observed to form. The reaction was stirred for 4 h at room temperature and the yellow solid was collected by filtration, washed with CH3CN (3 x 5 mL) and vacuum dried; yield 0.200 g (69%). The initial green filtrate was heated to reflux for a total of 48 h producing an additional 20 mg of yellow solid; total yield 0.220 g (76%). Anal. Calcd for C64H52B1F4P483Rh11C, 55.28; H, 3.77. Found: C, 55.34; H, 4.06. IR (CsI, Nujol, cm'l): 1505 (w), 1100 (m), 1062 (s), 925 (w), 797 (m), 700 (m), 528 (m), 517 (m), 483 (w), 455 (w), 420 (w). 1H NMR (CD2C12, ppm) 5 = 7.46 (t, C6H5), 5 = 7.20 (t, C6H5), 5 = 7.11 (d, C6H5), 5 = 1.82 (s, -CH3). 31P{ 1H} NMR (CD2C12, ppm) 5 = 50.4 (d). 19F{1H} NMR (CD2C12, ppm) 5 = -154.9 (3). Electronic absorption spectrum (CH2C12) Amax = 270, 318, and~420 nm. MS m/zzl303 (M+, 60). (2) Preparation of ReCl2[Mez(PPh2)2TTF]2 (13) A quantity of [Bu4’1N]2Re2C18 (0.030 g, 0.026 mmol), 0.0340 g (0.057 mmol) of Me2(PPh2)2TTF and 10 mL of ethanol was added to a 100 mL Schlenk flask equipped with a condenser. The mixture was refluxed for 30 min during which time a red precipitate formed. The solid was collected by filtration. washed with ethanol (40 mL) followed by CH3CN (30 mL) to remove any unreacted [Bua’lleRe2C13. washed with 168 diethyl ether (20 mL) to remove any unreacted Me2(PPh2)2TTF, and vacuum dried; yield 0.029 g (71% based on Me2(PPh2)2TTF). IR (CsI, Nujol, cm'l): 1100 (m), 745 (m), 695 (m), 520 (s), 330 (m). 1H NMR (CDC13) broad unresolved resonances at 5 = 9.18, 7.99, and 2.44 ppm. 31P{ 1H} NMR (CDC13) not observed. Electronic absorption spectrum (CH2C12) Amax = 276, 322, 448, and 976 nm. MS m/z: 1457 (M+, 40). (3) Reactions of M02(02CCR3)4 (R = H,F) with Me2(PPh2)2TTF In a typical reaction 0.020 g (0.047 mmol) of M02(O2CCH3)4, 0.056 g (0.093 mmol) of Me2(PPh2)2'1T F, and 10 mL of toluene were added to a 100 mL Schlenk flask followed by the addition of 25 11L (0.19 mmol) of Me3SiCl. No immediate color changes were observed, thus the reaction mixture was heated to reflux for 24 h resulting in the formation of a red precipitate. The solid was collected by filtration, washed with toluene and diethyl ether, and vacuum dried; yield 0.034 g. IR (CsI, Nujol, cm'l): 1190 (w), 1160 (w), 1095 (m), 780 (w), 745 (s), 700 (s), 515 (s), 473 (m). 1H NMR (CDC13) 5 = 6.8 - 7.8 ppm (complicated set of multiplets) 5 = 1.92 ppm (broad unresolved resonance). 31P{ 1H} NMR (CDC13) 5 = 27.1 ppm (3). Electronic absorption spectrum (CH2C12) Amax = 280, 329, and 433 nm. A similar reaction involving M02(O2CCF3)4 and diethyl ether as the reaction solvent under the same reaction conditions and stoichiometries also produced a red solid with similar spectroscopic properties. (4) Reaction of [Rh2(NCCH3)10](BF4)4 with Me3(PPh2)TTF To a 50 mL Schlenk tube was added 0.025 g (0.026 mmol) of [Rh2(NCCH3)1()][BF4]4, 0.045 g (0.104 mmol) of Me3(PPh2)TTF and 10 mL of CH3CN causing an instantaneous dark green solution to form. The mixture was stirred at room temperature for 1 day without any 169 noticeable change in color. Diethyl ether (30 mL) was carefully layered over the solution which effected the precipitation of a black solid. The solid was collected by filtration, washed with diethyl ether, and vacuum dried. IR (CsI, Nujol, cm'l): 1050 (s,br), 890 (w), 750 (w), 720 (m), 695 (m), 530 (s), 475 (m). Electronic absorption spectroscopy (CH2C12) Amax = 510 and 600 nm. (5) Reaction of [Bu4nN]2Re2Cls with Me3(PPh2)TTF To a 50 mL Schlenk flask was added 0.050 g (0.044 mmol) of [Bu4nN]2Re2C13, 0.077 g (0.179 mmol) of Me3(PPh2)'ITF, 5 mL of ethanol and 5 mL of CH2C12. The reaction mixture was refluxed for 16 h at which time it was deduced that no reaction had yet occurred. A quantity of NaBH4 (0.045 g) was dissolved in 5 mL of methanol and added to the reaction mixture to aid in reuction of the Re2 unit which is common in the synthesis of Re2HJICI4(PR3)4 compounds from [Bu4nN]2Re2m~mClg. The resulting mixture was refluxed for 10 minutes whereupon a brown solution and a black precipitate were produced. The solid was collected by filtration, washed with methanol and diethyl ether, and dried in vacuo; yield 0.012 g. IR (CsI, Nujol, cm'l): 1307 (w), 1157 (w), 1170 (w), 1095 (w), 908 (s), 747 (w), 723 (m), 693 (m), 546 (w), 519 (w). (6) Reaction of [Rh2(NCCH3)1o][BF4]4 with (PPh2)4TTF A quantity of [Rh2(NCCH3)1()][BF4]4 (0.054 g, 0.056 mmol) was dissolved in 10 mL of CH3CN and added to a solution of (PPh2)4TTF (0.112 g, 0.119 mmol) in 5 mL of CH2C12 resulting in the immediate formation of a dark brown-yellow solution. The reaction solution was stirred for several days without any noticeable color change. A UV-visible spectrum of the solution exhibited a single absorption band at Amax = 310 nm. The solution was reduced in volume by vacuum and 170 layered with 20 mL of diethyl ether which effected the precipitation of a brown solid. The solid was collected by filtration, washed with diethyl ether, and vacuum dried. A 1H NMR (CD3CN) revealed a set of broad resonances between 5 = 7.0 and 7.8 ppm atuibuted to the phenyl protons in addition to resonances due to residual diethyl ether. A 31P{ 1H} NMR spectrum displayed a doublet centered at 5 = 51.2 ppm with JRh-p = 134.7 Hz which support the equivalencies of the phosphorous nuclei. The solid was dissolved in CH3CN, filtered, and the filtrate was layered with diethyl ether which gave only finely divided solids. (7) Reaction of Re2Cl6(PBu3")2 with (PPh2)4TTF A flask charged with Re2Cl6(PBu3")2 (0.052 g, 0.053 mmol), (PPh2)4'ITF (0.100 g, 0.106 mmol) and methanol (10 mL) was refluxed for 3 days. The mixture was filtered and the resulting yellow-orange solid was washed with methanol and diethyl ether. It was quickly evident that all of the Re2C16(PBu3")2 had reacted as judged by the colorless diethyl ether inwhich Re2C16(PBu3")2 is soluble. The solid was recrystallized from THF; yield 0.090 g. 1H NMR (CDCL3) 5 = 7 -- 8 ppm (complex multiplets due to the phenyl protons). 31P{1H} NMR (CDC13) 5 = 23.1 (5) ppm. There was no evidence of -PBu3" in the NMR indicating complete substitution of these ligands. B. X-ray Crystallography The structure of [Rh{Me2(PPh2)2'I‘TF}2][BF4] (12) was determined by application of general procedures that have been fully described elsewhere.13 Crystallographic data were collected on a Rigaku AFC6S diffractometer equipped with monochromated MOKCX (M; = 0.71069 A) radiation and were corrected for Lorentz and polarization effects. Calculations were performed on a VAXSTATION 4000 computer by using 171 the Texsan crystallographic software package of Molecular Structure Corporation. 14 (1) Data Collection and Reduction Crystals of [Rh{Me2(PPh2)2TTF}2][BF4] (12) were grown from slow evaporation of a CH2C12 solution of the product. A yellow crystal with dimensions of 0.30 x 0.20 x 0.10 mm3 was mounted on the tip of a glass fiber with silicone grease and cooled to -90°C in a cold stream attached to the goniometer. Cell constants and an orientation matrix for data collection obtained from a least squares refinement using the setting angles of carefully centered reflections in the range 20 S 20 S 29° corresponded to a monoclinic cell. A total of 6465 unique data were collected at -90°C using the (1)-scan technique to a maximum 20 value of 50°. The intensities of three representative reflections measured after every 300 reflections decreased by 4.11% thus a linear correction factor was applied to the data to account for this decay. An empirical absorption correction based on azimuthal scans of 3 reflections was applied which resulted in transmission factors ranging from 0.88 to 1.00. (ii) Structure Solution and Refinement Based a statistical analysis of intensity distribution the space group was determined to be C2/c. The structure was solved by SHELXS15 and DIRDIFl6 structure programs and refined by full matrix least-squares refinement. The location of the [BF4]' moiety was ambiguous which resulted in a poor overall refinement of the structure. Residuals R and Rw remained at high values of 0.17 and 0.24 respectively. Repeated attempts higher quality crystals met with failure. A full description of the crystallographic results will. therefore. not be presented. nevertheless 172 valuable information is still available from the refinement in its present form. 3. Results and Discussion The phosphine derivatized TTF compounds Me3(PPh2)TTF, Me2(PPH2)2'ITF, and (PPh2)4'ITF have been found to react with a variety of dinuclear metal complexes. Data from 31P{ 1H} NMR spectroscopy, FAB mass spectroscopy, and X-ray crystallography for the compound [Rh{Me2(PPh2)2TTF}2][BF4] (12), all support the existence of metal- phosphorous bonding. Results from cyclic voltammetry experiments performed on M-[Me2(PPh2)2TI‘F] products are also consistent with coordinated Me2(PPh2)2TTF substituents. The structure of [Rh{Me2(PPh2)2TTF}2][BF4] (12) was determined by X-ray crystallography and displayed a square planar arrangement of the coordinated diphosphines. A Pluto representaion and a packing diagram are depicted in Figures 34 and 35. A full table of positional parameters for compound (12) is located in the Appendix. A. Synthesis and Spectroscopy. (1) Reactions of Me2(PPh2)2TTF The phosphine Me2(PPh2)2TTF reacts with a variety of metal complexes including [Rh2(NCCH3)1()][BF4]4, [M02(NCCH3)10][BF4]4, [Bu4’1N]2Re2C18, Re2Cl6(PBu3")2, Re2(O2CC3H7)4CI2, M02(02CCH3)4, M02(O2CCF3)4, and [V(NCCH3)6][BPh4]2. The reaction of 4 equivalents of Me2(PPh2)2TTF with [Rh2(NCCH3)10][BF4]4 in CH3CN affords the mononuclear complex [Rh{Me2(PPh2)2TTF}2][BF4] (12) as yellow microcrystals. The yellow solid is insoluble in most common solvents and exhibits only limited solubility in CH2C12 and acetone. The infrared spectrum of (12) displays bands attributed to the phosphine ligand along 173 (3(7) 0 0 (3(8) 0(5) 9 0 C(6) 5(3) 5(4) 3 %‘ €$r’\ C(1 1: /C(2) )' 5(2)". anr (3(3)", ,C(4)' saw» fism‘ may» aetsr C(8)’ ’ 5 0(7)‘ Figure 34. Pluto representation of [Rh{Me2(Ph2P)2TTF}2][BF4] (12). 174 Figure 35. Stick packing diagram of [Rh{Me2(Ph2P)2TTF}2][BF4] (12). 175 with stretches assignable to [BF4]- ions. The absence of v(CEN) stretches supports the loss of all CH3CN ligands. A FAB mass spectrum exhibits a peak with m/z = 1303 (M+) representing the Rh[Me2(PPh2)2TTF]2+ fragment. A 19F{ 1H} NMR spectrum exhibits a singlet at 5 = -154.9 ppm which is in the range expected for [BF4]' ion.17 The 1H NMR spectrum of (12) contains resonances assignable only to protons of the Me2(PPh2)2TTF ligands, which includes a set of resonances between 5 = 7.0 and 7.5 ppm due to the phenyl protons, and a singlet at 5 = 1.82 ppm due to the methyl protons. The 31P{ 1H} spectrum displays a doublet at 8 = 50.4 ppm with JRh-p = 134.3 Hz. These values are within the range observed for other RhI-P complexes and also compare well to the value reported for the complex NiC12[Me2(PPh2)2'ITF] characterized by Fourmigué and Batail.4 A cyclic voltammogram (CH2C12, 0.1 M TBABF4) of (12) (Figure 36) exhibits two reversible oxidations at E1/2(ox) = 0.63 and E1/2(ox) = 1.01 V compared to the cyclic voltammogram of Me2(PPh2)2TTF under the same conditions which exhibits oxidations at E1/2(0x) = 0.41 and E1/2(0x) = 0.85 V. The shift to more positive potentials of the values in (12) is the result of strong phosphorous-to-rhodium coordination. The reaction of Me2(PPh2)2TTF and [Rh2(NCCH3)1()][BF4]4 produces the mononuclear product [Rh{Me2(PPh2)2TTF}2][BF4] (12) as a result of reduction of RhII (d7) to Rh1(d8). Thus, a metal-metal bonded complex is unfavorable because a d8-d8 electronic configuration in a typical Mng bonding scheme (i.e. 021t4525*37c*4o*3) results in a zero bond order. As expected. the d8 RhI compound is diamagnetic. The reaction of quadruply bonded R€2C16(PBU3")2 with Me2(PPh2)2TTF in methanol. by a similar approach to that employed with Re2C14(dppm)2 in the attempted synthesis of Re2C14[Me2(PPh2)2TTF]2 176 +1.3 \ .0 l J l ’ 1 1 l J E(+)VOIJ$ _ 50’“ = 0.62 v _ 12““ = 1.01 v Figure 36. Cyclic voltammogram of [Rh{Me2(Ph2P)2TTF}2][BF4] (12) in 0.1 M TBABF4/CH2C12 vs Ag/AgCl at a Pt disk electrode. 177 does not occur. The reaction of [Bu4nN12Re2Clg with Me2(PPh2)2TTF in refluxing ethanol, however, readily produces a red precipitate. The infrared spectrum confirms the presence of the TTF-phosphine unit along with a possible v(Re-Cl) band located at 330 cm'l. The infrared spectrum lacks bands that could be attributed to [Bu4nN]+ cations. The cyclic voltammogram (0.1 M TBABF4, CH2C12) is indicative of a product that contains coordinated phosphine with a reversible oxidation at E1/2(ox) = +0.69 V and a quasi-reversible oxidation at El/2(ox) = +1.02 V. A reversible reduction at 131/urea) = -0.01 V and an irreversible reduction at Bugged) = -0.82 V are also observed. A FAB mass spectrum of this product displays the highest mass peak at m/z = 1457 up to 2500. This is consistent with the formulation of the product as being ReC12[Me2(PPh2)2TTF]2. which would be a rare example of a ReII compound. This ReII (d5) product is paramagnetic which explains the unresolved 1H NMR spectrum and the apparent absence of a 31P NMR resonance. Reactions of [Bu4nN]2Re2Clg with Me2(PPh2)2TTF in either acetone or CH2C12 fail to produce a reaction product, even under refluxing conditions. The reaction between Me2(PPh2)2TTF and M02(02CCR3)4 (R = H, F) in the presence of Me3SiCl causes the precipitation of red solids whose infrared spectra are indicative of the substitution of all four acetate groups by the TTF-phosphine ligand. The 31P{1H} NMR spectrum reveals a resonance at 5 = 27.1 ppm which is shifted considerably from the value observed for unreacted Me2(PPh2)2TTF. The cyclic voltammogram exhibits two reversible oxidations at E1/2(0x) = +0.67 V and 131/3(0)” = +1.03 V. No reaction was observed between [M02(NCCH3)1()][BF4]4 and Me2(PPh2)2TTF in refluxing CH3CN. 178 Likewise, no reaction was observed between Me2(PPh2)2TTF and V(NCCH3)6(BPh4)2. (2) Reactions of Me3(PPh2)TTF The reaction between [Bu4nN]2Re2Clg and Me3(PPh2)'ITF, which does not occur under normal conditions, is facilitated by the addition of NaBH4 which is commonly used as a reducing agent in the synthesis of Re2Cl4(PR3)4 complexes from [Bu4nN]2Re2C13. Unfortunately, the formulation of the resulting black product is not yet known. The reaction between [Rh2(NCCH3)1o][BF4]4 and Me3(PPh2)TTF results in the formation of a dark green solution from which a black solid is obtained by precipitation using diethyl ether. Infrared spectra suggest that [BF4]' is still present and the solid is believed to be paramagnetic because of the broad unresolved resonances that occur in the 1H NMR spectra. (3) Reactions of (PPh2)4TTF The reaction between [Rh2(NCCH3)1o][BF4]4 and (PPh2)4TTF results in the instantaneous formation of a brown-yellow solution from which a solid is isolated by precipitation using diethyl ether. A 31P{1H} NMR spectrum exhibits a doublet at 5 = 51.2 ppm with 11211-1: = 134.7 Hz. This suggests that the phosphorous nuclei are all equivalent and bound to a rhodium center, possibly forming a polymeric framework. A similar result was obtained from the reaction of Re2Cl6(PBu3")2 with (PPh2)4TTF. The 31P{ 1H} NMR of the yellow-orange product in CDC13 exhibits only one resonance at 5 = 23.1 ppm, supporting equivalent, coordinated phosphorous nuclei. The assignment of these products as solids with extended interactions or as polymers is valid considering the strong evidence for the existence of ReC12[Me2(PPh2)2TTF]3 (13), and the crystallographically determined structure of Rh[Me2(PPh3)3TTF]2 (12). 179 No reaction was observed to occur with [Bu4nN]2Re2Clg and (PPh2)4TTF, while the reaction between Moz(02CCF3)4 and (PPh2)4TTF eventually occurs with the addition of Me3SiCl, but produces only oily products. B. X-ray Crystal Structure The X-ray crystal structure of [Rh{Me2(PPh2)2TTF}2][BF4] (12) depicted in Figure 34 reveals a square planar arrangement of ligands around the Rh(I) center. The average Rh-P distance is 2.29 A and the P(1)—Rh-P(2) angle is 852’ while the P(1)-Rh-P(1)' angle is 90° as determined by symmetry. The position of the BF4' ion was not located in the difference map, althought attempts at placing it in as a rigid group were tried. The packing diagram of (12) shown in Figure 35 reveals close intermolecular interactions of ~ 3.5 A between the C(3) atoms on the 'ITF moieties on neighboring molecules resulting in a one-dimensional arrangement. It is apparent from examining the packing diagram that there is considerable bending of the TTF ligands away from the Rh-P plane to accommodate for this interaction. Although not shown in the packing diagram, the bulky phenyl rings prevent a perfect planar TTF-TTF intermolecular interaction. The structure of NiBr2[Me2(PPh2)2TTF]2 reported by Batail et al., unlike that of (12), exhibits a planar structural arrangement with respect to the Ni-Pz-TTF plane.4 There was no report of intermolecular interactions occuring in the nickel complex. 180 References .‘OS’°>J.°‘.U‘:“ 10. 11. 12. 13. 14. 15. Bartley, S. L.; Dunbar, K. R. Angew. Chem. Int. Ed. Engl.l991, 448. Matsubayashi, G.; Yokoyama, K; Tanaka, T. J. Chem. Soc. Dalton Trans. 1988, 3059. Siedle, A. R. in 'Extended Linear Chain Compounds,’ ed. Miller, J. S. Plenum Press, 1982; Ch. 11, pp 477-478. Fourmigué, M.; Batail, P. Bull. Soc. Chim. Fr. 1992, 129, 29. Dunbar, K. R.; Pence, L. E. Inorg. Synth. 1992, 29, 182. Barder, T. J.; Walton, R. A. Inorg. Synth. 1985, 23, 116. San Filippo, J., Jr. Inorg. Chem. 1972, II, 3140. Brignole, A. 8.; Cotton, F. A. Inorg. Synth. 1972, 13, 81. Cotton, F. A.; Norman, J. G.; Coord. Chem. 1971, 1, 14. Cotton, F. A.; Wiesinger, K. J. Inorg. Chem. 1991, 30, 871. Anderson, S. J .; Wells, F. J .; Wilkinson, G.; Hussain, B.; Hursthouse, M. B. Polyhedron 1988, 7, 2615. Laboratoire de Physique des Solides Associé au CNRS(URA 02) Bat. 510, Université Paris-Sud, 91405 Orsay, France. (a) Bino, A.; Cotton, F. A.; Fanwick, P. E. Inorg. Chem. 1979, 18, 3558. (b) Cotton, F. A.; Frenz, B. A.; Deganello, G.; Shaver, A. J. Organomet. Chem. 1973. 50, 227. TEXSAN-TEXRAY Structure Analysis Package, Molecular Structure Corporation 1985. Sheldrick, G. M. In: Crystallographic Computing 3 . Eds., G.M. Sheldrick, C. Kruger. and R Goddard. Oxford U.K.. 1985; pp. 175 - 189. 16. 17. 181 DIRDIF: Direct Methods for Difference Structure, An Automatic Procedure for Phase Extension; Refinement of Difference Structure Factors. Beurskens, R. T. Technical Report, 1984. Matonic, J. H.; Chen, S.-J.; Pence, L. E.; Dunbar, K. R. Polyhedron 1992, 11, 541. CHAPTER VII REACTIONS OF THE ELECTRON-RICH TRIPLY BONDED COMPOUND Re2Cl4(dppm)2 WITH DIOXYGEN. 183 1. Introduction The electron-rich triply bonded species Re2Cl4(dppm)2 is easily oxidized rendering it useful in the reductive coupling of organic molecules,1 in oxidative addition reactions across the triple bond,2 and in the formation of charge-transfer complexes.3 In the course of our investigations of Re2Cl4(dppm)2 in reactions with organocyanide acceptor molecules, we observed that solutions containing Re2Cl4(dppm)2 undergo a color change with eventual production of crystalline solids after exposure to air for several days. To probe this chemistry more carefully, solutions of Re2Cl4(dppm)2 were deliberately exposed to moist air and dry 02. Both experiments led to the formation of Re2(u-O)(u-C1)OC13(dppm)2 (14) and ultimately to Re2(u-O)02Cl4(dppm)2 (15) which have been spectroscopically and structurally characterized. Coincidentally, these same experiments were being performed at the same time by researchers in the Walton group at Purdue University, therefore a collaborative effort was undertaken to jointly report our results. Only the part of the research carried out at Michigan State is provided in this chapter. Details of additional studies can be found in a joint publication. 13 2. Experimental Section A. Synthesis The dirhenium complex, Re2C14(dppm)2, was prepared as described in the literature.4 Glassclad 18 glass treatment to remove surface H20 from silica was purchased from Hills America Inc. The Oz gas was passed through a gas purifier purchased from Alltech Associates Applied Science Labs. 184 (1) Synthesis of Re2(ll'0)(ll-CI)OC13(dppm)2 (14) (i) Method A In a typical reaction, a solution of Re2C14(dppm)2 (0.100 g, 0.078 mmol) in acetone (20 mL) was purged with 02 gas for 2 h. During this period, the solution color changed from purple then to red-wine with deposition of a brown microcrystalline solid. The mixture was allowed to stand undisturbed for 12 h during which time the solution color changed to yellow-brown. The resulting gold-brown precipitate was collected by suction filtration, washed with acetone (3 x 5 mL), and vacuum dried; yield 0.071 g (69%). Anal. Calcd for C50H44Cl4OzP4Re2: C, 45.67; H, 3.35. Found: C, 46.21; H, 3.39. IR (CsI, Nujol, cm'l): 1707 (m), 1219 (m), 1096 (s), 899 (s), 775 (s), 689 (s), 516 (m), 480 (m). Identical results were obtained in benzene and toluene. In a separate reaction Re2Cl4(dppm)2 (0.050 g, 0.039 mmol) in CH2C12 (10 mL) was purged with 02 for 2 h resulting in a red-wine solution. A sample of (14) was obtained by treating the reaction solution with EtzO (20 mL), filtering, washing with acetone (3 x 5 mL), and vacuum drying; yield 0.049 g (95%). IR (CsI, Nujol, cm'l): 1710 (m), 1095 (s), 907 (s), 775 (m), 692(5), 520 (m), 482 (m). (ii) Method B A 50 mL Schlenk tube containing a quantity of Re2C14(dppm)2 (0.100 g, 0.078 mmol) in acetone (20 mL) was exposed to the laboratory atmosphere through an open stopcock for 10 days. During this period of time, large brown crystals of (14) deposited on the bottom of the vessel. The crystals were separated from the green filtrate by suction filtration, washed with acetone (3 x 5 mL), and vacuum dried: yield 0.070 g (68%). Anal. Calcd for C50H44CI4OQP4R€22 C. 45.67; H. 3.35. Found: C. 44.92; 185 H, 3.03. IR (CsI, Nujol, cm'l): 1705 (s), 1100 (s), 908 (s), 778 (s), 694(5), 522 (m), 484 (m). (2) Synthesis of Rez(u-O)02Cl4(dppm)2 (15) (i) Method A A Schlenk tube containing Re2Cl4(dppm)z (0.100 g, 0.078 mmol) in CH2C12 (20 mL) was purged with 02 gas for 1.5 h resulting in an opaque red-wine solution. The solution was set aside whereupon it slowly transformed to a deep olive-green color over a four day period. The solution volume was reduced to ca. 5 mL and then treated with 20 mL of acetone. Within 12 h, a mixture of block-shaped green crystals and feathery green crystals had formed. The feathery crystals slowly redissolved within 3 days. The cr0p of large green crystals was filtered from the yellow-brown filtrate, washed with a minimal amount of cold acetone, and dried in vacuo; yield 0.05 g (45%). To eliminate any contamination of product (2) with (14), the solid was recrystallized by dissolving the solid in ca. 100 mL of hot acetone, filtering, slowly reducing the filtrate volume, and finally chilling the filtrate to 0°C overnight. The green microcrystalline solid was collected by filtration and vacuum dried; yield 0.02 g (18%). Anal. Calcd for C56H50CI4O3P4Re2: C, 46.68; H, 3.50. Found: C, 46.23; H, 3.50. IR (CsI, Nujol, cm“1): 1700 (s), 127 (m), 1154 (m), 1098 (s), 785 (s), 716 (s), 690 (m), 519 (s), 484 (m). (ii) Method B A total of 400 uL of purified H20 was added to a 50 mL Schlenk tube containing a quantity of Re2C14(dppm)2 (0.100 g, 0.078 mmol) in acetone (20 mL). A stream of Oz gas was bubbled through the solution for 2 h. The reaction mixture was allowed to stand for 5 days during which time a large crop of bright green crystals formed. The crystals were 186 collected by filtration, washed with chilled acetone (3 x 5 mL) and vacuum dried; yield 0.074 g (72%). The product was recrystallized from hot acetone (100 mL) to eliminate trace quantities of (14); yield 0.052 g (52%). (iii) Rigorous Exclusion of H20 For this study, all glassware was treated with a 1% solution Glassclad 18 glass treatment5 and oven dried. Tetrahydrofuran was selected as the reaction solvent because it is easily purified by distillation from sodium/potassium benzophenone ketyl radical which is highly effective in eliminating H20. Also, the 02 gas was passed through a gas purifier. A 50 mL Schlenk tube containing 60 mg of Re2C14(dppm)2 and 10 mL of THF was purged with 02 gas for 1.5 h. The solution color turned red- wine. With the reaction mixture kept sealed from atmospheric air over the course of 60 days, the solution color changed from red-wine, to orange- brown, to pale-pink, and finally to a pale yellow solution. This resulting yellow solution was reduced in volume by vacuum and layered with diethyl ether (20 mL) producing a white solid. In a separate reaction, a 50 mL Schlenk tube containing 0.035 g (0.027 mmol) of Re2C14(dppm)2, 10 mL of THF, and 150 uL of H20 was purged with 02 gas for 1.5 h. This solution also turned red-wine, but after 24 h a large crop of green feathery crystals of (15) resulted. These two reactions clearly demonstrate the requirement for H20 in the synthesis of (15). B. X-ray Crystallographic Procedures The structures of Re2(u-O)(u-CI)OC13(dppm)2-(CH3)2C O (14)-(CH3)2CO and Rez(u-0)O2Cl4(dppm)2-2(CH3)2CO (15)-2(CH3)2CO were determined by application of general procedures fully described elsewhere.6 Crystallographic data were collected on a Rigaku AFC6S 187 diffractometer with monochromated MoKa (M = 0.71069 A) radiation and were corrected for Lorentz and polarization effects. Calculations were performed on a VAXSTATION 4000 computer by using the Texsan crystallographic software package of Molecular Structure Corporation.7 (1) Re2(u-0)(u-Cl)0Cls(dme)2°(CH3)2C0 (14)-(CH3)2C0. A single crystal of (14) was carefully selected from the crop of crystals resulting from the reaction in method B. A gold-brown parallelpiped with dimensions 0.30 x 0.20 x 0.30 mm3 was mounted in a quartz capillary tube and sealed with epoxy cement. Indexing and refinement of 20 reflections in the range 6 S 20 S 12 from an automatic search routine gave unit cell parameters for a triclinic crystal system. The cell was further refined by a least-squares fit of 24 reflections in the range 25 S 26 S 29°. Data were collected at 23 3"- 1 °C by using the a) - 29 scan technique. A total of 10777 unique data were collected in the range 4 S 20 S 50°. Intensity measurements of three standard reflections every 150 data points indicated the crystal had not decayed. An empirical absorption correction based upon azimuthal scans of 3 reflections was applied to the data and resulted in transmission factors ranging from 1.00 to 0.73. The structure of (14) was solved by SHELXS-863 and DIRDIF9 structure solution programs within the Texsan software package and was refined by full-matrix least-squares refinement. Hydrogen atoms were not included in the refinement. All non-hydrogen atoms were refined with anisotropic thermal parameters with the exception of 0(2b) and the interstitial acetone molecule. Early in the refinement procedure, it became apparent that a disorder exists between the terminal 0 atom and a Cl atom. This is not surprising in view of the pseudo-symmetry of the molecule. In light of this symmetry, we were curious as to whether the crystal belonged to a 188 monoclinic system rather than a triclinic system, but data collected on two independent crystals (one at Michigan State U. and one at Purdue U.) gave no indication of a higher symmetry cell. Furthermore, we employed several cell reduction programs including the Delaunay reduction TRACERlo and the program MISSYMl 1, neither of which transformed the cell to monoclinic. The Re-0 and Re-Cl distances are quite different, therefore the two peaks appearing in the map in the same approximate vicinity near each Re center were easily assigned. In the case of 0(2b), since it tended to be "absorbed" by the Cl atom after several cycles of refinement, we chose to fix the position as determined in the original difference map after the other atoms had been located. Refinement of the occupancy of the disordered positions of the Cl atom led to an exact 0.5/0.5 population between the two sites. After establishment of this ratio for the C1 atom, the occupancies for the disorderd 0 atom were then fixed to 0.5. The following scheme depicts the arrangement of atoms in the equatorial plane containing the metal atoms: C1\Re/O\ Re/Cl Cl(a) 06» \c1 0(a) ‘C1 36(F02) and 568 parameters. Other data collection and refinement parameters may be found in Table 24. The Re(1)-0(2b) and Re(2)-0(2a) distances of 1.63 A and 1.65 A, respectively are perfectly reasonable for terminal rhenium-oxo bond distances; likewise the Re(l)-Cl(4a) and Re(2)-Cl(4b) separations of 2.33 A and 2.30 A are within the expected range. The presence of the Re=0 terminal moiety is further supported by the observation of a v(Re=0) stretch at 907 (s) cm'1 in the infrared spectrum of (14). (2) Re2(u-0)O2Cl4(dppm)2°2(CH3)2C0 (15)°2(CH3)2C0 Green crystals of (2) were grown by slow evaporation of the yellow- green filtrate from the synthesis of Re2(tt-0)(u-Cl)Cl3(H20)(dppm)2 (14) (method B). A crystal with dimensions 0.50 x 0.40 x 0.40 mm3, was carefully selected from the crop of crystals that were grown and was sealed in a quartz capillary tube. Indexing and refinement of 20 reflections in the range 10 S 20 S 13 from an automatic search routine gave unit cell parameters for a triclinic crystal system. An accurate cell was obtained by a least-squares fit of 23 reflections in the range 20 S 20 S 28°. Data were collected at 23 i 2 °C by using the (1) - 20 scan technique. A total of 5151 unique data were collected in the range 4 S 20 S 50°. Intensity 190 Table 24. Summary of crystallographic data for Re2(ll-0)(u-C1)(0)C13(dPPm)2-(CH3)2O. (l4)°(CH3)20. formula Re2C14P403C53H50 formula weight 1373.1 space group P-l (#2) a, A 16.069(6) b, A 16.5406) c, A 12.214(2) a, deg 109.18(2) [3, deg 99.09(3) 7, deg 101.01(3) v, A3 2923(2) Z 2 dcalc, g/cm3 1.560 )1. (Mo Kat), cm-1 45.23 temperature, °C 23 trans. factors, max., min. 1.00 - 0.73 Ra 0.068 wa 0.082 quality-of-fit indicator 4.68 aR=£ ”Fol' [Foil/Zipol bRw = [M IF. I - IF. bzxzw |1=o 1211/2; w = 1/oz< lFob Cquality-of-fit = [£W( [1:0 I ’ ch bz/(NobS'Nparameters”1/2 191 measurements of three standard reflections every 150 data points indicated no crystal decay. An empirical absorption correction based upon azimuthal scans of 3 reflections was applied to the data and resulted in transmission factors ranging from 1.00 to 0.64. The structure was solved by MITHRIL12 and DIRDIF9 structure solution programs and refined by full-matrix least-squares refinement. With the exception of the six carbon atoms of the acetone molecules in the lattice, all non-hydrogen atoms were refined with anisotropic thermal parameters. A total number of 4449 observations with F02 > 30(F02) were used to fit 302 parameters to give R = 0.029 and Rw = 0.058. The quality-of-fit index was 2.581, and the peak of highest electron density in the final difference map was 1.349 e-IAB. Crystallographic parameters for Re2(u-0)02Cl4(dppm)2 (15) are summarized in Table 25. Positional parameters with the isotropic equivalents of the thermal parameters for (14) and (15) are located in the Appendix. 3. Results and Discussion A. Synthesis The reaction of Re2C14(dppm)2 with 02 in acetone swiftly leads to the formation of Re2(tt-0)(tt-Cl)0Cl3(dppm)2 (14) as brown crystals. The deliberate addition of H20 to an acetone solution of Re2C14(dppm)2 followed by purging with 02 aids in the solubilization of the initial product (1) which then goes on to form Re2(u-O)02Cl4(dppm)2 (15) as green 192 Table 25 . Summary of crystallographic data for Re2(u-0)(0)2C13(dppm)2°2(CH3)20. (15)°2(CH3)20. formula Re2Cl4P405C55H50 formula weight 1441.0 space group P-l (#2) a, A 11.193(2) b, A 12.8820) c, A 10.892(2) a, deg 101.95(1) [3, deg 113.30(1) 7, deg 7552(1) v, A3 1386.3(4) Z 1 dcalc, g/cm3 1.726 p. (Mo Ka), cm-l 47.75 temperature, °C 23 trans. factors, max., min. 1.00 - 0.64 R3 0.029 wa 0.058 guality-of-fit indicator 2.58 311:): llFol- [Fell/ZIFOI. bRW = [2w( [F0 I ‘ ch b2/2W iFo MI”; W = 1/02( IF0 I) Cquality-of-fit = [Zw( It}, I - 1Fc i)2/(Nobs'Nparameters)] ”2 193 R62C14(dppm)2 + 02 ——> Rez(u-O)(u-Cl)(O)Cl3(dppm)2 (14) Rezm-O)(u-Cl)(O)C13(dppm)2 + 1/202 ——-> Rez(u-O)(O)2C14(dppm)2 (14) (15) crystals in high yield. If CH2C12 is used in place of acetone under similar conditions to those described above, the reaction proceeds to form a persistent olive-green solution containing primarily (15). The intermediate, compound (14), which is soluble in CH2C12 and therefore does not precipitate during the course of this reaction, can be isolated by treating the reaction solution with acetone after 2 h of 02 purging. As far as we could tell, in none of the aforementioned systems was water found to be the source of the oxygen in complexes (14) and (15). In one experiment, to rule out the possibility of water being the oxygen atom source for (14), carefully deoxygenated water was deliberately added to a Schlenk tube containing Re2C14(dppm)2 in acetone with strict exclusion of 02. After a period of 60 days, it was evident that no reaction had occurred as indicated by a persistence of the characteristic purple color of the parent complex. When this mixture was then exposed to air, large bright green crystals of (15) formed within several days. Furthuremore, work done at Purdue University showed that when a sample of (14) was dissolved in CD2Cl2 and treated with a trace of H20, H2 was not evolved, thereby ruling out the occurrence of the redox reaction (14) + H20 —> (15) + H2 as being the origin of the conversion of (14) to (15). The reaction of Re2C14(dppm)2 and 02 in THF produced mixtures of (14) and (15), but only in the presence of trace amounts of water. In the absence of H20 under rigorous moisture-free conditions. the reaction of Re2C14(dppm)2 with O2 in THF proceeds by an entirely different route. In this case. the 194 solution changes slowly over the course of 60 days from the initial purple color, through red-wine, orange-brown, pale pink, and finally to a pale yellow solution from which a white solid can be isolated. In one instance, the red-wine solution was reduced in volume and a brown microcrystalline solid of (14) obtained. Identical behavior was found when preformed (14) was reacted with 02 in THF under these exact same anhydrous conditions. The other intermediates in this moisture-free route are currently being investigated. In the absence of 02, compound (14) dissolved in THF and with water added maintained a red-wine color as if no reaction occurred It is evident from these results that H20 plays an important role in the transformation of Re2C14(dppm)2 to complex (15), but the mechanistic interpretation is uncertain. B. Spectroscopy The infrared spectrum of Re2(u-0)(u-Cl)0Cl3(dppm)2 (14) exhibits characteristic v(Re=0) and v(Re-O-Re) modes at 905 (s) and 775 (m)arr1. If the infrared sample of (14) is prepared in air, or if the reaction was carried out in less than moisture-free conditions, the spectra of (14) exhibit an absorption at ca. 3630 cm'1 due to lattice H20. The cyclic voltammogram of Re2(tt-0)(u-Cl)0Cl3(dppm)2 (14), shown in Figure 37, exhibits three reversible electrochemical processes; one reversible oxidation at +0.47 V, and two reversible reductions at -O.85 V and -0.99 V vs Ag/AgCl. A SQUID measurement on a sample of Re2(tt-0)(tt- Cl)0Cl3(dppm)2 (14) indicated that it is weakly paramagnetic. The data indicated antiferromagnetic coupling with a ueff value of 1.13 B.M. at 280 K. The lowest temperature measured (5 K) gave a value of 0.42 B.M. In accord with this behavior we were unable to locate the phosphorus resonance in the 31P{1H} NMR spectrum of the complex. while the 1H 195 I ' ' I | I t I T I W t r 0.80 0.40 0.0 040 Volts U I Figure 37 . Cyclic voltammogram of Re2(u-0)(u-Cl)0Cl3(dppm)2 (14) in 0.1 M TBABF4/CH2C12 vs Ag/AgCl at a Pt disk electrode. 196 NMR spectrum of Rez(ll-O)(u-Cl)0Cl3(dppm)2 (14) in CD2C12 displayed some discernible features at 5 = 12.2, 11.3, and 6.2 ppm, but in general the signals are overlaping in the range of 5 = 6 - 12 ppm. These features are consistent with a Knight-shifted spectrum. Variable temperature spectra down to -90°C did not improve the resolution of the signals. The infrared spectrum of Re2(u-0)02Cl4(dppm)2 (15), like (14), shows v(Re=0) and v(Re-O-Re) bands at 785 (s) and 716 (s) cm‘l. The cyclic voltammogram for (15), shown in Figure 38, exhibits a reversible oxidation at E1/2(ox) = +1.34 V and in irreversible reduction process at 1311.6 = -0.78 V vs Ag/AgCl with a coupled Ep,a process at -0.70 V (ip,3< the). There is an additional process at Epfi = -0.12 V due to the formation of a chemical product following the irreversible reduction at -0.78 V. Although well separated, the relationship between the cathodic and anodic processes is supported by an absence of the wave at -0.12 V when a cyclic scan is taken at potentials positive of the cathodic process. The 31P NMR spectrum of (15) in CD2Cl2 consists of a singlet at 5 = -14.2 ppm, while its 1H NMR spectrum in CDC13 showed complex multiplets at ca. 5 = 7.2 and 5 = 7.7 ppm attributed to the phenyl protons and a pentet at 5 = 4.10 ppm for the -CH2- resonance of the dppm ligands. Additional resonance at 5 = 2.15 ppm were assigned to acetone of crystallization. The electronic spectra of both compounds recorded in CH2C12 in quartz cells exhibit two transitions in the visible region. Characteristic features for complex (14) are located at Amax = 431 nm (5300 M'1 cm'l) and kmax = 537 nm (2700 M‘1 cm'l). The electronic spectrum of (15) consists of an intense transition located at Amax = 441 nm (8800 M"1 cm'l) and a less intense feature at Amax = 693 nm (930 M'1 cm'l). 197 C. Crystal Structures The X-ray structure of R62(|.l-0)(u-Cl)0Cl3(dppm)2-(CH3)2C0 (14)-(CH3)2C0 (Figure 39), is that of an edge-shared bioctahedron in which the Re2(u-dppm)2 unit is preserved. There is one bridging 0 and one bridging Cl atom. The three remaining Cl atoms and one 0 atom are situated in the terminal positions with the 0 atom lying trans to the bridging 0 atom. The chlorine atom Cl(4) and terminal oxygen atom 0(2) were disordered which is a well recognized phenomenon.13 However, we were able to model this dissorder satisfactorily. Selected bond distances and angles are listed in Table 26. The terminal and bridging Re-0 bonds had distances of ca. 1.63 and ca. 1.92 A, respectively. Two trans dppm ligands span the two rhenium centers which are separated by an unusually long distance of 3.363(2) A and is in accord with the absence of any direct Re-Re interaction. This distance is longer than the Re-Re separation of 2.5221(1) A determined for the symmetric dirhenium(IV) complex Re2(02CC2H5)(ll-0)(u-C1)Cl4(PPh3)2 in which there is a strong Re-Re bond.l4 In the di-u-oxo bridged dirhenium(IV) complexes K4[Re2(u- 0)2(C204)4]-3H20,15 [Re2(tt-O)2C12L2]I2-2H20,l6 and [Re2(tt- 0)2I2L2]I2-2H20,17 where L is 1,4,7-triazacyclononane, the Re-Re distances are even shorter at 2.362(1), 2.376(2), and 2.381(1) A, respectively. Work carried out in Professor Waltons group at Purdue University has demonstrated that (14) (represented as I) can be derivatized with isocyanide ligands and acetonitrile to produce the unsymmetrical compounds (11) in which the two metal centers are in quite disparate ligand environments.18 The structure of 11 (L = xyCN) has been determined 198 “1;? I I I T I I I I r I I I I I I I I I I I I I I I I I I I I 1.6 1.2 0.80 0.40 0.0 -0.40 -0.80 -1.2 Volts Figure 38. Cyclic voltammogram of Re2(u-0)02Cl4(dppm)2 (15) in 0.1 M TBABF4/CH2C12 vs Ag/AgCl at a Pt disk electrode. 199 } C(25) C(26) C(19) (3(7) < )C(20) C(8)<> O! \51; Figure 39. ORTEP representation of R62(H-O)(u-C1)OC13(dem)2-(CH3)2CO (14)-(CH3)2CO with 35% probability ellipsoids. Phenyl ring atoms are shown as 0.1 A radius spheres. g/C r " i (3‘2) Cl 3/(11 RN : Table 26. Selected Bond Distances (A) and Bond Angles (°) for Rezm-OXu-CDOCls(dppm)2-(CH3)2O. (l4)'(CH3)20. distances atom 1 atom 2 distance atom 1 atom 2 distance Re( 1) C1( 1) 2.493(6) Re(l) Re(2) 3 .361 (2) Re( 1) Cl(2) 2.337(6) P( 1) C(1) 1.86(2) Re(l) Cl(4a) 2.331(9) P( 1) C(7) 1.84(2) Re(l) P( 1) 2.441(6) P( 1) C(49) 1.84(2) Re( 1) P(4) 2.460(7) P(2) C(13) 1.77(2) Re(l) 0(1) 1.91(1) P(2) C(19) 1.81(2) Re( 1) 0(2b) 1.634(1) P(2) C(49) 1.84(1) Re(2) Cl( 1) 2.557(5) P(3) C(25) 183(2) Re(2) Cl(3) 2.314(5) P(3) C(31) 1 .7 8(2) Re(2) Cl(4b) 2.30(2) P(3) C(50) 1 .87(2) Re(2) P(2) 2.466(6) P(4) C(37) 1.81(2) Re(2) P(3) 2.481(6) P(4) C(43) 1.85(2) Re(2) 0(1) 1.93(1) P(4) C(50) 1.84(2) Re(2) 0(2a) 1.65(4) Etna Eca E6 Eda E32 Eda Eo Eca 53 $30 E3. E0 E32 330 Eca E0 53 980 Eda Ea E98 SEQ Eca Ea E02 Eo Eda Ea Enww Eo Eca Ea E3 380 Eca Ea Eoww 390 Eea Ea Emma E0 5% Ea E?» E0 Eca Ea End: Ea Eda Ea Eve: Ea Eca Ea €52 E0 53. 336 ES: Eo Eca 335 E93 Ea Eca 336 Enoa Ea Eca 35 35.3 Ea Eda BEG Emma Ea Eca 33:0 ENS $80 Eda Ea E32 330 Eca EC Ewaa Eo Eda Ea En; Eo Eca EC m Ewaw Ea Eda EU Ema Ea Eca EC E5 Ea Eda EB Eoda Ea Eca ES Eqma 336 ES. Ea Eta 35 E3. EG ES 35 Eda E6 Ea: 3E0 Eca E6 ENE Eo Eda E6 EEK Eo A Eda A :6 E08 Ea Eda E6 Eada Ea Eca E5 Etoa Ea Eda E6 5wa Ea Eca EC Ea; 3.36 Eda E6 Ewea 3.5 Eca EC E3: Ea Eca E6 Evaea E6 E3. E5 2w§ m 89a N :88 _ 89¢ cha m 89a N ana _ an 8E5 .3283 6N «Ear—t 202 further supporting our assignments in the structure of (14). PAP PAP cu I o I er I or I l- \ I \ I Re—Re CI—Re-O—Re=o \ Cl/I\CI I 0 all Cl/I I II The molecular structure of the dirhenium(V) complex Re2(tt- 0)02Cl4(dppm)2-2(CH3)2C0 (lS)-2(CH3)2C0 (Figure 40), is that of a corner-shared bioctahedron with a linear O-Re-O-Re-O unit. The C1 atoms are nearly perfectly trans to each other in the equatorial positions with Cl-Re-Cl angles of 174.23(8)°. The dppm ligands maintain their original bridging positions despite the Re-Re distance of 3.823 A. The six membered metallacycle consisted of Re-O-Re-P-C-P. Selected bond distances and angles are listed in Table 27. This is a rare example of two dppm ligands bridging a linear M-O—M unit. The only previous example cited in the literature in that of the diosmium complex 052(11- O)Cl6(dppm)2.19 The terminal Re-O distance is 1.708(6) A while the bridging Re-O distance is 1.9115(5) A. These distances are well within the range observed in the structures of other linear Re(V)-O-Re(V) complexes.20 203 C(14)‘ gm . cm Cusr % ’ C(20)‘ ‘ , C(19)‘ “pm ctzsr P(2)' § 0(2) C(l) cru) Cm" €§ Re(l)’ (U: 'Re(1) (‘ 5‘ 1 ‘3 0(2). ~ on) omt Figure 40. ORTEP representation of Re2(tt-O)O2C14(dppm)2-2(CH3)2CO (15)-2(CH3)2CO with 40% probability ellipsoids. Phenyl ring atoms are shown as 0.1 A radius spheres. 204 Table 27 Selected Bond Distances (A) and Bond Angles (°) for Re2(tt-0)ozc14(tt-dppm)2.2(CH3)co, (15)-2(CH3)C0. distances atom 1 atom 2 distance atom 1 atom 2 distance Re( 1) Cl(l) 2.402(2) P( 1) C(1) 1.86(2) Re(l) Cl(2) 2.422(2) P( 1) C(1) 1.836(9) Re(l) P(l) 2.487(2) P( 1) C(7) 1.814(9) Re(l) P(2) 2.489(2) P( 1) C(25) 1.849(8) Re(l) 0(1) 1.9115(5) P(2) C(13) 1.835(9) Re(l) 0(2) 1.708(6) P(2) C(19) 1.828(9) angles atom 1 atom 2 atom 3 angle Cl(l) Re(l) Cl(2) 174.23(8) Cl(l) Re(l) P( 1) 95.77 (8) Cl(l) Re(l) P(2) 8261(8) Cl(l) Re(l) 0(1) 8924(6) Cl(l) Re(l) 0(2) 92.6(2) Cl(2) Re(l) P( 1) 8363(8) Cl(2) Re(l) P(2) 96.5 8(8) Cl(2) Re(l) 0(1) 8499(6) Cl(2) Re(l) 0(2) 93.1(2) P(l) Re(l) P(2) 166.04(7) P(l) Re(l) 0(1) 8224(5) P(l) Re(l) 0(2) 97.6(2) P(2) Re(l) 0(1) 8388(5) P(2) Re(l) 0(2) 96.3(2) 0(1) Re(l) 0(2) 178.1(2) Re(l) 0(1) Re(l)’ 180.00 205 References 10. ll. 12. Esjornson, D.; Derringer, D. R.; Fanwick, P. E.; Walton, R. A. Inorg. Chem. 1989, 28, 1689. (a) Qi, J.-S.; Schrier, P. W.; Fanwick, P. E.; Walton, R. A. Inorg. Chem. 1992, 31 , 258. (b) Shih, K.-Y.; Fanwick, P. E.; Walton, R. A. J. Chem. Soc., Chem. Commun. 1992, 375. (c) Ara, I.; Fanwick, P. E.; Walton, R. A. Polyhedron 1992, II, 1277. (d) Ara, I.; Fanwick, P. E.; Walton, R. A. J. Cluster Sci. 1992, 3, 83. Bartley, S. L.; Dunbar, K. R. Angew. Chem. Int. Ed. Engl. 1991, 30. 448. Barder, T. J.; Cotton, F. A.; Dunbar, K. R.; Powell, G. L.; Schwotzer, W.; Walton, R. A. Inorg. Chem. 1985, 24, 2550. This treatment provides a hydrophobic coating for glass and limits the possibility of H20 adhering to the glass surface. (a) Bino, A.; Cotton, F. A.; Fanwick, P. E. Inorg. Chem. 1979, I8, 3558. (b) Cotton, F. A.; Frenz, B. A.; Deganello, G.; Shaver, A. J. Organomet. Chem. 1973, 227. TEXSAN-TEXRAY Structure Analysis Package, Enraf—Nonious, Delft, The Netherlands, 1979. Sheldrick, G. M. In Crystallographic Computing 3 , Sheldrick, G. M., Kruger, C., Goddard, R.; Oxford University Press: Oxford, U.K., 1985; PP. 175 - 189. DIRDIF: Direct Methods for Difference Structure, An Automatic Procedure for Phase Extension; Refinement of Difference Structure Factors. Beurskens, R. T. Technical Report, 1984. Lawton, S. L.; Jacobson, R. A. The Reduced Cell and Its Crystallographic Applications, United States Atomic Energy Commision, Research and Development Report, TID-4500, 1965. Page, Y. L. J. Appl. Crystallogr. 1988, 21, 983. MITHRIL: Integrated Direct Methods Computer Program, Gilmore, C. J. J. appl. Cryst. 1984, 17. 42. 13. 14. 15. 16. 17. 18. 19. 20. 206 (a) Calviou, L. J.; Arber, J. M.; Collison, D.; Garner, C. D.; Clegg, W. J. Chem. Soc., Chem. Commun. 1992, 654. (b) Yoon, K.; Parkin, G.; Rheingold, A. L. J. Am. Chem. Soc. 1992, 114, 2210. Cotton, F. A.; Foxman, B. M. Inorg. Chem. 1968, 7, 1784. Lis, T. Acta Crystallogr., Sect. B 1975, 31, 1594. B0hm, G.; Weighardt, K.; Nuber, B.; Weiss, J. Angew. Chem. Int. Ed. Engl. 1990, 29, 787. Bfihm, G.; Weighardt, K.; Nuber, B.; Weiss, J. Inorg. Chem. 1991, 30, 3464. (a) Bartley, S. L.; Dunbar, K. R.; Shih, K.-Y.; Fanwick, P. E.; Walton, R. A. Inorg. Chem. 1993, 32, 1341. (b) Bartley, S. L.; Dunbar, K. R.; Shih, K.-Y.; Fanwick, P. E.; Walton, R. A. J. Chem. Soc., Chem. Commun. 1993, 98. Chakravarty, A. R.; Cotton, F. A.; Schwotzer, W. Inorg. Chem. 1984, 23, 99. (a) Backes-Dahmann, G.; Enemark, J. H. Inorg. Chem. 1987, 26, 3960. (b) Glowiak, T.; Lis, T.; Jezowska-Trzebiatowska, B. Bull. Pol. Sci. 1972, 20, 199. (c) Lock, C. J. L.; Turner, G. Can. J. Chem. 1978, 56, 179. (d) Tisley, D. G.; Walton, R. A.; Wills, D. L. Inorg. Nucl. Chem. Let. 1971, 7, 523. (e) Fletcher, S. R.; Skapski, A. C. J. Chem. Soc. Dalton Trans. 1972, 1073. (f) Shandles, R.; Schlemper, E. 0.; Murman R. K. Inorg. Chem. 1971, 10, 2785. CHAPTER VIII CONCLUSIONS 207 208 Reactions of polycyano acceptor species with metal-metal bonded dinuclear donor compounds have led to the isolation of covalently linked complexes. The complexes [Re2C14(dppm)2]2(|.t-L), where L = TCNQ or DM-DCNQI, were isolated and structurally characterized and are precedence for a covalent bonding interaction. While polymeric 1:1 phases are believed to exist, the lack of suitable single crystals has prevented structural determinations. To examine the generality of this approach, a number of hybrid inorganic-organic complexes were synthesized using metal-metal bonded dinuclear complexes of molybdenum and rhenium and a variety of polycyano acceptors. In the majority of the reactions, spontaneous reactivity (as judged from the immediate and dramatic color changes that occur) was observed regardless of oxidation/reduction potentials of the precursors. This, along with the strong and shifted v(CEN) bands in the infrared spectrum and intense charge-transfer bands in the electronic spectra, indicate an overwhelming tendency for these metal-metal bonded compounds to form covalent bonds with the polycyano organic molecules. Except for the complex [Re2C14(dppm)2](TCNE) (3)-A, all of the samples tested were found to be paramagnetic. Also, the products [Re2C14(dppm)2](TCNQ) (1)-A and [Re2C14(dppm)2]2(u-TCNQ) (2) were determined to behave as semiconductors. In addition to the reactions of the donor/acceptor type, reactions involving the fully solvated dinuclear compounds [Rh2(NCCH3)10][BF4]4 and [M02(NCCH3)10][BF4]4 were studied with chemically or electrochemically reduced forms of TCNQ and DM-DCNQI and resulted in 209 the synthesis of covalently bonded polymeric materials. These results clearly demonstrate the potential of constructing large molecular arrays using cyanide-containing species and are mainly attributed to the dimetal units being coordinatively unsaturated along with the bifunctional nature of the cyanide substituent. With the intent to prepare metal-metal bonded precursors which would themselves contain bifunctional ligand sets, the cyanide-containing compounds [Bun4N14lM02(CN)8] (8) and [Bun4Nl3IM02(02CCH3)(CN)6] (9) were prepared. The product [Bun4N]4[M02(CN)3] (8) was the first structurally characterized homoleptic cyanide complex which contained a metal-metal bonded core. These products were reacted with a variety of solvated metal complexes to form mixed metal polymeric materials. In general, it was observed that reactions of CN' with dimetal complexes proceed readily as demonstrated in the synthesis of [Bun4N]2[Re2(CN)6(dppm)2] (11). The X-ray crystal structure of this complex revealed two bridging CN ligands in an unusual side-on o-tt-CEN bonding mode. This is the only well characterized compound to exhibit this bonding mode. In other attempts to form extended molecular arrays, a variety of phosphine-functionalized TTF donors were studied. It was found that the reaction of Me2(PPh2)2TTF with [Rh2(NCCH3)10](BF4)4 led to the formation of [Rh{Me2(PPh2)2TTF}]2[BF4] (12) which, in the solid state crystal structure, exhibits close intermolecular contacts forming an extended molecular network. Attempts to prepare polymeric materials using the tetraphosphine species (PPh2)4TTF were also investigated. Finally, during the course of studying reactions of Re2C14(dppm)2 with organic acceptors, it was observed that solutions of Re2C14(dppm)2 210 underwent color changes in air. Therefore, the chemistry of Re2C14(dppm)2 with air, oxygen, and water was carefully studied and led to the isolation and characterization of Re2(ll-O)(u-CI)OC13(dppm)2-(14) and Re2(u-O)O2Cl4(dppm)2 (15). It was determined that these products are the result of reactions with molecular oxygen and not water and represent a rare example of molecular oxygen activation using a metal- metal bonded complex. APPENDIX 21 1 Table 28. Atomic positional parameters and equivalent isotropic d1splacement parameters (A2) and their estimated standard devratrons for lRe2C14(dppm)2J2(u-TCNQ)°8THF, (2)-8T HF. atom x y z B(eq) Re(l) 0.91930(3) 0.32564(2) 0.82133(3) 2.28(2) Re(2) 0.89354(3) O.28008(2) 0.96107(3) 2.31(2) Cl(l) 0.8207(2) 0.3699(1) 1.0664(2) 3.0(1) Cl(2) 0.8610(2) 0.2236(1) 1.1111(2) 3.5(1) Cl(3) 0.9589(2) 0.2499(1) 0.6775(2) 3.6(1) Cl(4) 0.8929(2) 0.4307(1) 0.8607(3) 3.4(1) P(l) 0.7300(2) 0.2641(1) 0.8492(3) 2.8(1) P(2) 0.7504(2) 0.3483(1) 0.7030(2) 2.8(1) P(3) 1.0948(2) 0.3216(1) 0.9032(2) 2.6(1) P(4) 1.0481(2) 0.2877(1) 1.1061(2) 2.7(1) N(l) 0.9598(5) 0.1899(3) 0.9010(7) 2.2(4) N(2) 1.153(1) 0.0434(6) 0.739(1) 8(1) C(1) 0.6167(8) 0.3065(5) 0.900(1) 3.4(6) C(2) 0.525(1) 0.3272(6) 0.823(1) 4.3(7) C(3) 0.439(1) 0.3591(7) 0.864(2) 5.6(8) C(4) 0.446(1) 0.3727(6) 0.977(2) 5.6(8) C(5) 0.536(1) 0.3525(6) 1.052(1) 5.0(8) C(6) 0.619(1) 0.3197(6) 1.013(1) 4.2(7) C(7) 0.7215(9) 0.1865(5) 0.835(1) 3.9(6) C(8) 0.765(1) 0.1443(6) 0.755(1) 5.5(8) C(9) 0.759(2) 0.0849(7) 0.744(2) 8(1) C(10) 0.711(1) 0.0684(7) 0.812(2) 8(1) C(11) 0.667(1) 0.1098(8) 0.893(2) 7(1) C(12) 0.674(1) 0.1684(6) 0.903(1) 5.3(8) C(13) 0.6443(8) 0.4122(5) 0.732(1) 3.1(5) C(14) 0.5592(9) 0.4313(6) 0.645(1) 4.3(6) C(15) 0.478(1) 0.4744(6) 0.670(1) 5.2(7) C(16) 0.479(1) 0.5005(6) 0.782(1) 4.9(7) C(17) 0.563(1) 0.4825(5) 0.867(1) 3.8(6) C(18) 0.6447(8) 0.4395(5) 0.842(1) 3.2(5) C(19) 0.7505(8) 0.3575(5) 0.557(1) 3.5(6) C(20) 0.763(1) 0.4123(6) 0.536(1) 4.5(7) C(21) 0.768(1) 0.4222(8) 0.430(1) 6(1) C(22) 0.760(1) 0.380(1) 0.347(1) 8(1) C(23) 0.748(1) 0.324(1) 0.361(1) 7(1) C(24) 0.740(1) 0.3150(7) 0.469(1) 5.3(8) C(25) 1.1312(7) 0.3818(5) 0.861(1) 2.9(5) C(26) 1.1429(9) 0.4326(5) 0.928(1) 3.6(6) C(27) 1.168(1) 0.4775(5) 0.888(1) 4.8(7) C(28) 1.182(1) 0.4727(6) 0.778(1) 4.2(7) C(29) 1.170(1) 0.4219(6) 0.708(1) 4.5(7) C(30) 1.1472(8) 0.3769(5) 0.749(1) 3.4(6) C(31) 1.2026(8) 0.2577(5) 0.893(1) 3.1(5) C(32) 1.1919(9) 0.2013(5) 0.847(1) 4.0(6) C(33) 1.282(1) 0.1539(6) 0.841(1) 5.4(8) C(34) 1.374(1) 0.1628(6) 0.879(2) 6.5(9) C(35) 1.385(1) 0.2189(7) 0.927(1) 5.8(8) C(36) 1.300(1) 0.2658(6) 0.931(1) 4.5(7) C(37) 1.1474(8) 0.2186(5) 1.1354(9) 3.1(5) C(38) 1.248(1) 0.2187(6) 1.164(1) 4.7(7) Table 28. (cont'd) atom x C(39) 1.324 C(40) C(41) 00 AA and: N vvvv‘rvvvvvvvvv O O \J O 0 O o k U" 0 C 00000 b h (n O 0000 O) O U1 :1:22:1:32:12:1282:1::1::1::1::1:000000000OODOOOOOOOODOOOOOOODOOOO O H m \0 AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA l—Iv—‘l—lLOCDflO‘U'IwaHmO‘mO‘wfl\1\JmkOO‘O‘O‘NO‘U‘LflWI—‘mmmmmmmhbbkbb NHOvvvvvvvvvmummvNHOKDVDUNHVOOQQVO‘WIBUNHOOQQO‘UTkU O e U 0 H O o o o o o o o o o o O U1 U1 \l b 212 OOOOOOOHHHOOOOOOOOOOOCOOOOOOOOOOHOOOOOHOHHHHHHHHHH onoooooooooooooooooooooooooooooo 0000000000 000. B(GQ) 6.0(8) l—‘l—JN \1 o O 0 I 0 CAR. 0 O O O I 0 0A. 0 O O 0AA. O O 0 0A \OONH\lr—‘OkOleHole-‘NHHNNNNl-‘O-‘kDO‘l—‘Ht—lml-‘U'lUO‘le-‘OU'IOD-‘mt-‘HOHUINHH bu 9.50111100me ~100me tamoxouo vv vvvvvvvv vvvvv vvvvv WHNNWWNNNNH (fl-DON(1)030U'IU'1U1OODHO‘GOOUIU'I0.113:-\OLHO‘l-‘kom\JflmmflbmbmmwabO‘O‘O‘U‘wUO‘ vvvvvvvvvvvAAVVAAAAAAAAVAAAAAVVAAAAA . AAAAAAAAAAA. Table 28. (cont'd) ) 0.4199 ) 0.5640 ) 0.7037 ) 0.7707 ) 0.7789 ) 0.7591 ) 0.7397 ) 0.7304 ) 1.1329 ) 1.1798 ) 1.1980 ) 1.1772 ) 1.1407 ) 1.1254 ) 1.2758 ) 1.4324 ) 1.4524 ) 1.3066 ) 1.2644 ) 1.3947 ) 1.3588 ) 1.1829 ) 1.0532 ) 1.0299 ) l ) ) l ) ) ) l ) ) l l l ) l ) l ) l l l l l ) l :13 H 1.0173 1.0065 1.0090 1.0305 0.7470 0.6396 1.1684 1.0622 1.1115 0.9134 0.2844 0.2202 0.3847 0.3364 0.4992 0.4791 0.3869 0.4493 0.3907 .3665 .5121 .5232 .4894 .4652 .3164 .3407 O\O\O\U‘|U‘lU'IU1U1U'1U1UlU'IU'I15151515hubA1buh“wwwwwwwwUUNNNNNNNNNNHHHHH NHOKOCDNmmDutch-IoomflmmbwNHomeGU‘waNl-JOOQQO‘UIfiUNI—‘OOQNO‘U‘Ik 02:12:11:ncrzzr::r::r::1:ma::1::1::r:ma::1:mmmmmmmmmmmmmmmmmmmmmmmm 0000000 213 Y 0.5329 0.5008 0.4262 0.4448 0.4585 0.3846 0.2957 0.2773 0.4370 0.5139 0.5050 0.4185 0.3412 0.1930 0.1139 0.1287 0.2248 0.3078 0.2559 0.1690 0.0798 0.0763 0.1666 0.4089 0.4463 0.3853 0.2848 0.2419 0.2479 0.2883 0.3351 0.3803 0.1035 0.4504 0.4286 0.4592 0.4219 0.3778 0.3503 0.2929 0.2990 0.1570 0.1638 0.2083 0.1822 0.2862 0.2612 0.2954 0.3207 0.7928 0.9436 0.8990 0.5993 0.4102 0.2730 0.2956 0.4803 1.0053 0.9372 0.7505 0.6298 0.6983 0.8238 0.8063 0.8700 0.9618 0.9550 1.1635 1.2180 1.2170 1.1657 1.1257 1.2279 1.4132 1.5419 1.4897 1.3039 0.6608 0.6662 1.0949 1.0679 0.8748 1.0196 0.2096 0.2724 0.3782 0.4329 0.3299 0.4282 0.3043 0.2206 0.6257 0.4956 0.6624 0.5401 0.6038 0.4780 0.4731 0.5987 B(eq) l—‘H HHOOHHUTUTMNChmmmbDNwammHmbflflwaNmUJbbmbflCOHUOHUQHO‘GQ l—‘l—‘NN mLn00000000oooocoxooxoxooomon»wwwmmmmmqummqumbwmbmbmqwanna)» HH Table 28. (cont'd) =1: 0‘ mmmmmmmmmznmmmm AAAAAAAAAAAAAA \lflflflflflflflfld‘d‘GO‘O‘ mummhuwwoomqmmh 214 Y 0.1965 0.1437 0.2351 0.2004 0.1862 0.1292 0.1010 0.1669 0.1616 0.1523 0.0588 0.0412 0.0626 0.0032 0.0332 0.0515 2 0.1639 0.1843 0.3321 0.3287 0.4845 0.4277 0.4010 0.3884 0.4425 0.5639 0.4529 0.5450 0.3329 0.3910 0.4403 0.3164 B(BQ) 25.9 25.9 26.3 26.3 22.9 22.9 36.7 36.7 19.1 19.1 30.8 30.8 15.6 15.6 25.3 25.3 215 Table 29. Atomic positional parameters and equivalent isotropic displacement parameters (AZ) and their estimated standard deviations for [Re2C14(dppm)2hm-DMDCNQD-41‘ HF (7)41" HF. atom x y z B(eq) Re(l) 0.1165(1) 0.71910(8) 0.5307(1) 2.7(1) Re(2) 0.0892(1) 0.67145(7) O 6701(1) 2.6(1) Cl(l) 0.1863(8) 0.6310(4) 0.4255(8) 3.2(5) Cl(2) 0.153(1) 0.7761(6) 0.377(1) 4.9(7) Cl(3) 0.1073(8) 0.5677(4) 0.630 1) 4.1(5) Cl(4) 0.0541(8) 0.7450(5) 0 8162(9) 4.1(6) P(l) -0.0396(8) 0.7120(5) 0.386(1) 3.0(5) P(2) -0.0874(8) 0.6777(5) 0 589(1) 2.9(5) P(3) 0 2564(8) 0.6487(5) 0.788(1) 3.3(5) P(4) 0.2802(8) 0.7370(5) 0.642(1) 3.4(6) N(l) 0.055(2) 0.796(1) 0.582(3) 3(2) N(2) -0.017(3) 0 904(1) 0.619(3) 4(2) C(1) -0.026(3) 0.677 2) 0.249(3) 3.0(8) C(2) -0.018(4) 0 717(2) 0.170(4) 5(1) C(3) -0.014(4) 0 686(3) 0.045(5) 7(1) C(4) -0.003(5) 0 614(3) 0.028(6) 9(2) C(5) -0.004(4) 0.584(2) 0.101(5) 6(1) C(6) -0.017(4) 0 617(2) 0.221(4) 5(1) C(7) -0.134(3) 0 779(2) 0.367(4) 4(1) C(8) -0.107(5) 0.830(3) 0.355(6) 10(2) C(9) -0.183(4) 0 889(2) 0.323(4) 5(1) C(10) -0.278(5) 0 889(3) 0.299(5) 7(1) C(11) -0.308(4) 0 830(3) 0.289(5) 7(1) C(12) -0.232(3) 0.776(2) 0.324(4) 4(1) C(13) -0.130(3) 0 618(2) 0.637(4) 3.8(9) C(14) -0.139(4) 0 563(2) 0.556(4) 6(1) C(15) -0.180(4) 0.523(2) 0.608(4) 6(1) C(16) —0.187(3) 0.529(2) 0.719(3) 3.6(9) (2(17) -0.177(4) 0.586(2) 0.799(4) 6(1) C(18) -0.144(4) 0.627(2) 0.751(4) 6(1) C(19) —0.191(3) 0.750(2) 0.587(4) 4(1) C(20) -0.171(3) 0.803(2) 0.632(4) 4(1) C(21) -0.250(3) 0.850(2) 0.641(4) 5(1) C(22) -0.349(4) 0.841(2) 0.615(4) 5(1) C(23) -0.366(4) 0.780(2) 0.570(4) 5(1) C(24) -0.289(4) 0.741(2) 0.555(4) 5(1) C(25) 0.260(3) 0.640(2) 0.937(4) 5(1) C(26) 0.249(4) 0.580(3) 0.954(5) 7(1) C(27) 0.228(4) 0.568(3) 1.061(5) 7(1) C(28) 0.238(4) 0.611(3) 1.130(5) 8(1) C(29) 0.261(3) 0.660(2) 1.127(4) 4(1) C(30) 0.264(3) 0.682(2) 1.021(4) 5(1) C(31) 0.359(3) 0.580(2) 0.758(4) 5(1) C(32) 0.448(4) 0.565(2) 0.844(4) 5(1) C(33) 0.526(3) 0.527(2) 0.814(4) 5(1) C(34) 0.518(4) 0.503(2) 0.718(4) 5(1) C(35) 0.435(3) 0.513(2) 0.629(4) 5(1) C(36) 0.361(3) 0.559(2) 0.658(4) 5(1) C(37) 0.285(3) 0.816(2) 0.664(4) 4(1) C(38) 0.329(4) 0.838(2) 0.598(4) 6(1) 216 Table 29. (cont'd) atom x y z C(39) 0.338(4) 0.895(3) 0.599( C(40) 0.297(4) 0.930(2) 0.693( C(41) 0.242(4) 0.920(3) 0.749( C(42) 0.240(4) 0.855(2) 0.732( C(43) 0.394(3) 0.689(2) 0.593( C(44) 0.479(3) 0.676(2) 0.667( C(45) 0.562(5) 0.646(3) 0.596( C(46) 0.561(3) 0.632(2) 0.496( C(47) 0.467(3) 0.646(2) 0.428( C(48) 0.383(3) 0.679(2) 0.469( C(49) -0.0857 0.6550 0.4348 C(50) 0.309(3) 0.716(2) 0.791( C(51) 0.032(3) 0.846(2) 0.597( C(52) -0.008(3) 0.953(2) 0.554( C(53) -0.063(3) 1.015(2) 0.572( C(54) 0.058(3) 0.942(2) 0.482( C(55) -0.135(5) 1.026(3) 0.662( H(1) -0.0143 0.7612 0.1940 8(2) -0.0186 0.7095 -0.0172 H(3) 0.0055 0.5961 -0.0489 8(4) 0.0018 0.5410 0.0814 H(5) -0.0117 0.5900 0.2820 H(6) -0.0260 0.8159 0.3797 H(7) —0.1569 0.9234 0.3167 H(8) -0.3290 0.9310 0.2931 3(9) -0.3772 0.8284 0.2506 H(10) —0.2514 0.7368 0.3234 H(11) -0.1217 0.5554 0.4748 H(12) —0.2085 0.4917 0.5581 H(13) -0.1950 0.4936 0.7525 H(14) —0.1914 0.5925 0.8764 H(15) -0.1316 0.6643 0.7950 H(16) -0.1028 0.8077 0.6592 H(17) -0.2405 0.8916 0.6608 H(18) -0.4050 0.8748 0.6292 H(19) -0.4342 0.7724 0.5515 H(20) -0.2984 0.7031 0.5172 H(21) 0.2501 0.5482 0.8884 H(22) 0.2121 0.5311 1.0777 H(23) 0.2283 0.6054 1.2059 H(24) 0.2758 0.6857 1.1967 H(25) 0.2677 0.7239 1.0113 H(26) 0.4494 0.5807 0.9223 H(27) 0.5907 0.5183 0.8681 H(28) 0.5761 0.4748 0.7003 H(29) 0.4277 0.4906 0.5523 H(30) 0.3047 0.5768 0.5973 H(31) 0.3635 0.8062 0.5498 H(32) 0.3622 0.9112 0.5421 H(33) 0.3148 0.9681 0.7157 .0 H mmmmmmmmmncooooooxmounmcxxiJ:\immmxommqqoqmmwmbhumbmebmmqmq m \D \O 00 VAVVVAVVAVVVVVVVV V O O O O O A. AAA. AA. AAAAAAAA b.)WONv—‘OWNquOCDKOt-‘HOCDHWofi-bxlHONNuD-Oubowt-JNSONNNHHNOHHQHNHHHHHH (D Table 29. (cont'd) atom mammmmmmmmmmmm bhbbbfibbwwwwww b vvvvvvvvvvvvvvv nuwwoomquHOvoxmbuwt-onommumvmqmwhuwwowmqmm 3:52:12EEEEEOOOOOEZEEEEEEOOOOOE AAAAAAAAAAAAAAAAAA C‘O‘O‘O‘O‘U‘U‘U‘lmmm¢~mmmmmmm5mwmm0d§ vvvvvvvvvvvv 0.2036 0.2019 0.4865 0.6310 0.6203 0.4575 0.3174 -0.1514 -0.0423 0.2836 0.3834 0.0997 -0.1826 -0.0938 -001688 0.6880 0.5963 0.5527 0.7007 0.6470 0.5530 0.6126 0.5056 0.5211 0.7697 0.6817 0.6305 0.6813 0.5719 0.5568 0.6688 0.7039 0.6621 0.5291 0.5148 0.6849 0.6873 0.7217 0.7630 0.6916 0.6588 217 0.9495 0.8394 0.6839 0.6340 0.6133 0.6351 0.6943 0.6544 0.6163 0.7489 0.7059 0.9004 1.0008 1.0131 1.0662 0.6359 0.6770 0.6370 0.5863 0.5865 0.6962 0.7069 0.6223 0.6552 0.5721 0.5599 0.5487 0.5962 0.7396 0.7985 0.8068 0.7454 0.6939 0.7973 0.8299 0.8237 0.8285 0.7342 0.7413 0.6748 0.6640 2 0.7983 0.7789 0.7517 0.6499 0.4678 0.3450 0.4146 0.3919 0.4281 0.8422 0.8237 0.4738 0.6429 0.7395 0.6726 0.2798 0.2170 0.1351 0.2319 0.1251 0.2663 0.1816 0.1615 0.0646 0.2309 0.2729 0.1010 0.0739 0.9365 0.8884 0.9164 0.9202 0.9374 0.8085 0.9251 0.8572 0.9869 0.8485 0.9794 1.0075 0.8762 00 (D 10 H H vvvvv HM mmoqqpomuwmmmwmmmmmkmwtflmm O O O O O AAAAA O O O O O O O O O O O O O O HHHAknuHHHmmmmHHHHomepbm 218 Table 30. Atomic positional parameters and equivalent isotropic displacement parameters (.42) and their estimated standard deviations for [BU4"N]4[M02(CN)8]'8CHC13 (8)°8CHCl3. atom x y z B(eq) Mo(1) 0.96425(4) 0.00343(3) 0.03830(5) 2.34(4) N(l) 0.8832(5) 0.1023(3) -0.0001(5) 3.8(6) N(2) 1.0378(6) 0.0679(4) 0.1573(5) 4.4(6) N(3) 0.8336(5) -0.0562(3) -0.0166(5) 3.8(6) N(4) 0.9818(5) -0.0889(4) 0.1426(5) 3.9(6) N(S) 0.3119(5) 0.0465(3) 0.7032(5) 3.6(5) N(6) 0 0664(5) 0.1996(3) 0.0459(6) 4.6(6) C(1) 0.9123(6) 0.0687(4) 0.0104(6) 2.7(6) C(2) 1.0157(6) 0.0457(4) 0.1140(6) 2.9(6) C(3) 0.8787(6) -0.0356(4) —0.0012(6) 2.7(6) C(4) 0.9794(5) -0.0593(4) 0.1053(6) 2.8(6) C(5) 0.2988(6) 0.0357(4) 0 6311(6) 3.3(6) C(6) 0.2310(6) 0.0508(5) 0.6090(7) 4.9(8) C(7) 0.2250(6) 0.0429(4) 0.5302(8) 5.1(8) C(8) 0.1568(7) 0.0554(5) 0.5022(8) 7(1) C(9) 0.2611(7) 0.0237(5) 0.7506(8) 5.4(8) C(10) 0.2544(8) -0.0294(5) 0.7487(8) 6(1) C(11) 0.204(1) -0.0452(7) 0 800(2) 13(2) C(12) 0.148(2) -0.031(1) 0.793(2) 22(3) C(13) 0.3803(6) 0.0270(4) 0.7170(7) 4.1(7) C(14) 0.4049(8) 0.0300(5) 0.7908(7) 5.3(8) C(15) 0.4766(7) 0.0129(6) 0.7951(8) 7(1) C(16) 0 5002(9) 0.0137(7) 0.8664(8) 9(1) C(17) 0 3106(6) 0.0996(5) 0.7174(6) 4.1(7) C(18) 0.3544(6) 0.1295(5) 0.6739(7) 4.6(8) C(19) 0.3459(8) 0.1823(5) 0.6903(7) 6(1) C(20) 0 389(1) 0.2140(5) 0.6487(8) 8(1) C(21) 0.0497(7) 0.2493(6) 0.026(1) 7(1) C(22) 0.0004(7) 0.2576(5) -0.025(1) 7(1) C(23) -0.019(1) 0.3082(7) -0.041(2) 19(2) C(24) 0.028(2) 0.341(1) -0.040(3) 31(5) C(25) 0.0073(6) 0.1734(4) 0.0737(7) 4.8(8) C(26) -0.026(1) 0.1950(6) 0.131(1) 11(1) C(27) -0.0768(8) 0.1628(6) 0.162(1) 9(1) C(28) -0.108(1) 0.185(1) 0.223(1) 20(2) C(29) 0.1210(7) 0.2035(6) 0.0963(9) 6(1) C(30) 0.1473(9) 0.1583(7) 0.1214(8) 7(1) C(31) 0.205(2) 0.164(2) 0.179(2) 17(3) C(32) 0.185(2) 0.179(2) 0.220(3) 36(6) C(33) 0.0873(6) 0.1710(4) -0.0157(7) 4.0(7) C(34) 0.1438(6) 0.1926(5) —0.0565(8) 5.0(8) C(35) 0.1669(7) 0.1577(5) —0.1113(7) 5.2(8) 3:36) 0.2206(8) 0.1796(6) —0.1545(8) 8(1) 01(1) 1.1089(2) 0.1276(2) 0.6880(3) 11.4(4) Cl(2) 1.0613(3) 0.2098(2) 0.7566(3) 11.1(4) Cl(3) 0.9757(2) 0.1555(2) 0.6756(3) 9.5(3) 21(4) 0.3154(2) 0.2317(1) 0.4657(3) 9.7(3) 31(5) 0.2221(2) 0.1824(2) 0 5506(3) 8.7(3) 51(6) 3.2250(2) 0.1649(2) 0 4086(3) 8.8(3) 1!?» 0.3075(2) 0.1582(1) 0 0221(3) 8.0(3) Table 30. (cont'd) atom OQOO Ai-n-n-a 15441,.)t-JLHDJL.)LA)Lawb.)WNNNNNNNNMNHHHt—‘HHHD—‘r—‘HomNO‘U‘bUNP-‘DWUUAAAA :25;:zmm3:3::1::1;:nuz3:33:23::1:mmmzxmmmmmzmmmmmmmmmmnnn HOVOCD\JO\U)-L—-WNHCom\lC‘U‘bLAJNI—‘OKOQQOLDDMNHOVVVVVVVVVOQQQHHHom ’v< >7. 62L. . §¢ .1. . ,. 5L 5“ vvv .4 v'v‘lw—/ _u-_.’vx/vvvvv—rvvvvvvvvvvvvvvvv O O QOOOOOOOOOOOOOOO o o o o 0 o o o o o o o o o o o 219 \lflO‘O‘QQQO‘O‘U‘WDbO‘O‘QQO O O O O O O O O AAAA. Table 30. (cont'd) w r1 0 a x I b :1;:1::2:1:32:1::1::nmznu:mmmmxmmmmmmmmmmmmmmmmmm AAAM-xAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA \1\1\J\1\1\1\Jmmmmmmmmmmmmmmmmmmmmbbbbbbb O‘\U‘|I)ri—‘OOODQO‘U‘bqu—JOOCDQO‘U‘AMNHOKOCDQO‘MDUN OOOOOOOOOOOOOOOOOO 220 -0.0297 -0.0399 -0.0412 0.0237 0.0385 0.0871 0.1648 0.1169 0.1294 0.1738 0.2570 0.2125 0.2416 0.0758 0.1340 0.1409 0.0843 0.1886 0.1616 0.2545 0.2110 0.2381 -0.0009 -0.0448 -0.0773 -0.0270 -0.0901 -0.1392 -0.1267 -0.1878 -0.1754 0.7672 0.4886 0.0138 0.2586 B(GQ) 22.5 33.6 33.6 33.6 5.8 5.8 13.0 13.0 10.7 10.7 o o 0 o O O O bmoommmwuwwooer—‘HNNNNLJLJ N\J(I)CD\O\D\OO\O\O\O\J>J> (A) w 221 Table 31. Atomic positional parameters and equivalent isotropic 2) and their estimated standard A deviations for lBu4nN13lMoz(OzCCH3)(CN)61 (9). displacement parameters ( B(EQ) atom )) 80(())))()())))))))))))(()\I’))))(())\l’))\\.l(l\\ul)))){( .I\\I- 73531111317111111111111511211118512112230121o41o...a... . . . . .(((( .( .(((((((((((( .(((((( O ((((((\. ((((( O (. 44556806585775565465877nw261485770.7 9338501..COSQ.33 0.1.0 1 11 111 1 11 111 114 ng 9|. )) 77))) ) ) ) )) ) ((768)9)8)9)89)))9))))))))) ))))))))))))))))))))))))) 04(((1(1(1(1((111(111111212221111.1112212111124441111111. 10506(7(1(9(42(((5((((((((( (((((((((((((((((((((((( . 15096562106656453138324786319884762.8283445543954452 20085411303101454896228518055365800785754886723171 78885767987056767878988906654777777660011001100000 00000000000000000000000000 oooooooooooooooooooooooo 0000000000000000000000001000000000000000000000000.3.-. __._ 4.— 2))))))))))))))))) ))))))))))))))))))))))))))))))))) (11122111112122212222222223322222233 .i.«42123:.1.m:. .. 78((((((((((((((((((( (((((((((((((((((((((((((( ll Ill/1.1.1) 7499985659832349063334014.904.04551220649.?93.17814. 5 992236535109631396761248986293580863.1080.3821.75.0230 2323313535450323434.22444433433211114.5.0.-.-{0.0 I 0.3CJPD-10 0.....: 0 0 0 0 0 0 0 0 0 0 0 0 ooooooooooooooooooooooooooooooooooo 0000000000000000000000000000000000000003 0003500303.. 3 11 )9 )))))))) ))))))))))))))))))))) . ))))) 1. (l.\l \l \I .1} .1) 11.- 1. ((1...(12111111211212.12121.2221233112222233232254.23O2. 47. ... 80(6((((((((((((( (((((((((((((((((((((((((((((((((( ( 012852221048210371341050.171750883082891.24.322710.8. :.. 87977399290987.623612053750434820770932288271900.311x.l. 00110120124080020022334.34.333344.54.4.4.4.40001001112....4.1 000000000000000000 000 000 ........................ 000000000000000000000000000000000000O00000U00353 -_.-. .. —_ _.-._.________________ 12)))))))))))) )))))))) 0123456789012fixu4—D/bq QUQ 01..4m..11:.,(v_. ((12123456789123456789111111111122.4222222233...32.737.3 oo((((((((((((((((((((((((((((((((((/I\(’l‘(/l((llx;lI I../|\ \I.) MMOONNNNNNNNNCCCCCCCCCCCCCCCCCCCCCCCCCCCCC,Z 3333:: 222 Table 31. (cont'd) G. e 3 atom )(())(())))))))))() 11512821222222112918885588885550077-4.1.55.3007.2.90.1.-..13.. ( o o(( o 0(((((((((( 0II\ 0000000000000000000000000000000 989612070178328700911188994.43338822889997.....833.3.«3335:. 111 122 121 11.1111 111.111 111111111111. 1.1.1.. ))))))))))))))))))) 0000000000000000 (((l\l\l\l\l\l\l\l\ (((((((( 79152257994578685801449385,0532.4 467791278659857988933192539370620275081325035R3300... 87.31818414910203042704326074603818956425784279764.: 001433255555666555699988899900067555544.47678767.-8.0 O 0 )))))))))) ))))))))) 2221222224523532223 ((((((( ((((((((((((9903262727325508510.12233gzlq/OnLQ. 6316683040008589438151941639150970820_/4P3538n36rfi.8373:. 797767606243427083806577785322434.236653547.3597583. 4.33011210100011101021234434Q.5554433344a;4%«4331/4a411001... 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00000000000000000000000000000000 OOOOOOOOOOOOOOOOOOOOOOO03000000300\JN) _. ((((((( ((((I\(((((((60594773648159221O0.085.330.011... 3.3.3.. 7895388755425079353816795329825080323.711816252.....30. 16364.39875791347990636999603117659.107047416083316. 27.3888776558998901.2233224.4.334.5422244.24.325533.5.33....4. O O O O O O O O O O O 0 0 O O o 0 O O 00000000000000000000000000 00000000000000001110000000000000000000030001.10JQ1.. - ....._._.__._._.____._..___. 8901234567890123456 ))))))))) 0.123456790.017.3436:.3..- 33444444444455555551234567891111111l1..11.13/47.5427.7.7..73...: ((((((((((((((((((((((((((((((((((.((ll(1(.(((({({-( )\.( CCCCCCCCCCCCCCCCCCCHHHHHHHHHHHHHHHHHH”nHHHHHHH- Table 31. (cont'd) atom Emil:I112:1:211:1:II:1221:II:IIIEIZIZEZEZEZZIIZIIIIIEEIEIEEIIEI _.—\ ’~‘~«AA‘,fi,fi,A,flAAAAAA.«AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA 21332112 ~81-1nun-10»mmone)ommommwmmmmmmmmbbbAbnbbbbuwuuwwww «.1016ion.)3-CJroHowoo-1mmaumwoomqo‘mbuwwoom\immbuwwoomqmmbuw .,. . . ... ,7. .7. 5.20 0L '0‘. .01 .14 l ‘ 1 ‘ J .1- 4, .4 #4“44.«4,414.4.14’Vvfiuvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv .. .1. .L )-‘ (D X -0.5336 -0.3775 -0.3542 -0.5200 -0.5551 -0.4203 -0.3857 -0.5010 0.0840 -0.0236 -0.0664 0.0421 -0.0983 -0.0422 -0.2248 -0.2350 -0.1684 0.0662 -0 0152 -0 1355 -0.0442 -0.0536 -0.1086 -0.2618 -0.2068 —0.2138 .1365 .2150 .2960 .2255 .3050 .3800 .4712 .3965 .4842 .0856 .1892 .2795 .1760 OQOOOOOOOOOOOOOOO ,. .1.JL1K4/CJL‘J'K_‘J ~ J CD \0 J» L.) r.) Lo t\) ~-)L3t\)\OO.b\J\O tn ,1...L.JQ3CD\J.La>—‘1\)O\ ‘JtDkJ 223 4879 5704 5553 .6255 6329 7278 7205 7571 5919 5597 7002 .7327 7602 6796 .6796 .6551 .5989 .5841 .6446 5377 .4701 .4739 .5614 5073 .4199 .4709 .7122 .6561 .6062 .6718 .7754 .7086 .6854 .7527 .7783 .4643 .5020 .5150 .4769 .3530 .3911 .3730 .3168 .4109 .0542 .0413 .1841 .1975 .1635 -1-.. 0.7388 0.7573 0.6692 0.6248 0.7113 0.7381 0.6515 0.6678 -0.1039 -0.0687 -0.0268 -0.0604 -0.1686 -0.1969 -0.1016 -0.1909 -0.1295 0.1378 0.0914 0.0504 0.0652 0.1937 0.1910 0.1522 0.1550 0.2327 0.0268 0.0807 -0.0376 -0.0863 -0.0045 0.0388 —0.0805 -0.1235 —0.0560 0.0004 -0.0359 .0942 .1302 .0657 .0298 .2038 .1570 .1677 .3886 .3936 .4156 .4122 .2835 an — -..c:... OAK/‘4‘ 0000000000 0) O (D B(GQ) 0 0 O (UCDU1U70303(DCDCDKOKOLAJUJLDUTNNNOOKOKOOOO‘m 224 Table 31. (cont'd) atom x y z B(eq) H(82) 0.8567 0.3034 0.3032 11.3 H(83) 0.7894 0.2714 0.2273 11.3 8(84) 0.7316 0.2815 0.3061 11.3 8(85) 0.7989 0.1024 0.6057 9.8 8(86) 0.7817 0.1626 0.5338 9.8 8(87) 0.6671 0.0547 0.4661 13.4 8(88) 0.6729 0.0060 0.5458 13.4 8(89) 0.5302 0.0222 0.6519 33.8 8(90) 0.5796 -0.0241 0.5817 33.8 H(91) 0.6559 0.0302 0.6389 33.8 8(92) 0.5649 0.1677 0.5733 22.9 H(93) 0.4894 0.1132 0.5157 22.9 8(94) 0.8234 -0.0582 0.4942 11.6 H(95) 0.9507 -0.0540 0.4856 11.6 H(96) 0.9821 -0.0203 0.6337 16.4 H(97) 0.8550 -0.0263 0.6420 16.4 H(98) 0.9782 -0.1353 0.5840 25.0 H(99) 0.9513 -0.1306 0.6726 25.0 H(100) 0.7926 -0.1756 0.6424 21.9 8(101) 0.8198 -0.1805 0.5539 21.9 H(102) 0.8863 -0.2342 0.6174 21.9 H(103) 0.9635 0.1705 0.5250 9.8 8(104) 0.9866 0.1095 0.5956 9 8 H(105) 1.1091 0.0276 0.5123 12.2 8(106) 1.0920 0.0949 0.4465 12.2 8(107) 1.2660 0.1421 0.5202 13.6 8(108) 1.1788 0.1983 0.5574 13.6 H(109) 1.1390 0.0860 0.6509 22.4 H(110) 1.2254 0.0293 0.6133 22.4 H(111) 1.2650 0.1060 0.6637 22.4 225 Table 32. Atomic positional parameters and equivalent isotropic displacement parameters (A2) and their estimated standard deviations for Wdepnmmhoz (10801107, atom x y z B(eq) Re(l) 1.02288(2) 0.08407(1) 1.00331(2) 1.68( P(l) 1.0689(1) 0.0396(1) 0.8275(1) 1.94( P(2) 0.9753(1) 0.1286(1) 1.1790(1) 1.91( N(l) 1.1544(4) -0.0209(3) 1.1368(5) 2.8(2 N(2) 1.2275(4) 0 2155(3) 1.1191(5) 3.0(2 N(3) 0.9342(4) 0.2307(3) 0.9269(5) 3.1(2 N(4) 0.7039(4) 0.3272(3) 0.7869(5) 2.6(2 C(1) 1.1113(5) 0 0207(4) 1.0882(6) 2.2(2 C(2) 1.1545(5) 0.1683(3) 1.0796(6) 2.1(2 C(3) 0.9642(5) 0.1777(4) 0.9526(6) 2.3(2 C(4) 1.0082(5) -0.0611(4) 0.7328(6) 2.1(2 C(11) 1.2036(5) 0.0383(3) 0.8342(6) 2.0(2 C(12) 1.2815(6) 0.0447(4) 0.9412(7) 2.5(2 C(13) 1 3811(6) 0 0395(4) 0.9416(7) 2.8(2 C(14) 1.4031(6) 0 0278(4) 0.8372(7) 3.2(3 C(15) 1.3273(6) 0 0227(4) 0.7308(7) 3.2(3 C(16) 1.2277(5) 0 0286(4) 0.7294(6) 2.7(2 C(21) 1.0266(5) 0.0952(4) 0.7248(6) 2.1(2 C(22) 0.9364(5) 0.0747(4) 0.6275(6) 2.7(2 C(23) 0.9057(6) 0.1241(4) 0.5597(6) 3.2(3 C(24) 0.9670(7) 0.1950(5) 0.5904(6) 3.4(3 C(25) 1.0590(6) 0.2162(4) 0.6866(7) 3.7(3 C(26) 1.0883(6) 0 1679(4) 0.7535(7) 3.1(3 C(31) 1.0510(5) 0 2205(4) 1.2934(6) 2.1(2 C(32) 1.0441(6) 0.2881(4) 1.2625(7) 3.0(2 C(33) 1.1000(7) 0 3598(4) 1.3451(8) 3.8(3 C(34) 1.1626(7) 0 3643(4) 1.4587(7) 4.1(3 C(35) 1.1715(7) 0.2983(5) 1.4903(7) 4.3(3 C(36) 1.1158(5) 0.2263(4) 1.4090(6) 3.0(3 C(41) 0.8457(5) 0.1501(3) 1.1656(6) 2.2(2 C(42) 0.7717(5) 0.1450(4) 1.0565(6) 2.4(2 C(43) 0.6754(5) 0.1622(4) 1.0506(7) 2.9(2 C(44) 0.6483(6) 0.1844(4) 1.1531(7) 3.2(3 C(45) 0.7198(6) 0.1893(5) 1.2631(8) 3.9(3 C(46) 0.8169(6) 0.1726(4) 1.2688(6) 3.2(3 C(47) 0.6410(6) 0.3906(4) 0.7697(8) 3.2(3 C(48) 0.5413(6) 0.3867(5) 0.7968(9) 3.9(3 C(49) 0.4930(8) 0.4567(6) 0.785(1) 5.1(4 C(50) 0.3940(8) 0.4580(7) 0.813(1) 6.2(4 C(51) 0.7273(6) 0.3208(4) 0.9131(6) 2.7(2 C(52) 0.7743(7) 0.3958(5) 1.0172(7) 3.5(3 C(53) 0.7956(7) 0.3819(5) 1.1373(7) 4.3(3 C(54) 0.8563(8) 0.4536(6) 1.2435(9) 5.1(4 C(55) 0.6451(6) 0.2485(4) 0.6953(7) 2.9(3 C(56) 0.7073(6) 0.1831(4) 0.6879(8) 3.8(3 C(57) 0.6388(7) 0.1035(5) 0.6125(8) 3.8(3 C(58) 0.5794(8) 0.0741(6) 0.680(1) 5.3(4 C(59) 0.8064(6) 0.3482(5) 0.7710(7) 2.9(3 C(60) 0.8001(6) 0.3516(5) 0.6468(7) 3.8(3 C(61) 0.9029(7) 0.3902(5) 0.6523(8) 4.3(3 226 Table 32. (cont’d) atom )))))))))))) (((((((((((()))))))))))))))))))))))))))))))))))))) o o o O o o o o o o o o(((((((((((((((((((((((((((((((((((((( )23)33)32856 ))))))))))))))))))))))))))) ) )))))) 1((1(l\1 ((((( 265667566695867667686656797)8)566787)\I (39(63(69315 ((((((((((((((((((((((((((( 1(1 (((((( 11 036272053279308496766799110741655068899(9(121125(( 3662594083506003560940072162874.2528473905222215315 50900103433430086664578135549913386788687999001132 00000000000000000000000 000 00000 0 00000000000000000 01010000000001100000000111110011100000000000111111.. .- 7115225226337 ))))))))))))))))))))))))))))))))))))) (((l\(((((l\(((43444344463544434.46443446466734455566 0521281143920 ((((((((((((((((((((((((((((((((((((( 63672108323633132932541753209867501035808060373205 9385234343455542122127780.1082590749481409708145357 34333221114330000001221244311112143335453432443344 0 000000000000 000 000 000 0000000000000 0000000000 00000000000000000000000000000000000000000000000000 )22622822747 ))))))))))))))))))))))))))))))))))))) 1 (((((((( (((15455645557465555657554557687)55667689 (74800822015((((((((((((( (((((((((((((((( 1|. (((((((( 09945507794963565172901189912073887042672(66758228 06238695535197364884405089028280672054554167344473 90214334333532443188911001217657866555433467877889 00000000000000000000000000000 000 00000000000000000 01110000000001111100011111110000000000000000000000 2123344565786 ))))))))) 0123456789012345678901234567 6((6((6((6((61234567891111111111222222222233333333 (11(11(11(11 (((((( l.\ ((((((((((((((((((((((((((((((( CCCCCCCCCCCCCHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH Table 32. (cont'd) atom H(38) H(39) 8(40) H(41) H(42) H(43) H(44) 8(45) 8(46) 8(47) :1: 01 mmmmmmmmmmmmmmm AAAAAAAAAAAAAAA mmma‘a‘a‘a‘a‘a‘mmmmum mQmeUNl—‘ooa‘thNH QGONGO‘mO‘U‘meU‘LflO‘O‘hO‘Q vvvvvvvvvvvvvvvvvvv 0:934(5) 1.028(4) 227 O‘WO‘LDWMDUIbO‘U‘O‘buD-Uihwmm -0:058(3) -0.077(3) 0:704(5) 0.667(5) In HHmmmkfl\DSOOOHHNNNNHNHNHNHHNNHNN 3 O AAAAAAAAAAAAAAAAAAA vvvvvvvvvvvvvvvvvvv HH NNQQONON\lflO‘O‘QU‘QQO‘O‘thOLflOhwU‘U‘NO‘m AA 0 C C C C O 0 vv 228 Table 33. Atomic positional parameters and equivalent isotropic displacement parameters (A2) and their estimated standard aflm Rh(1) m A H V 00000000OOOOOOOOOOODOOOOOOOOOOOOMWmmm AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA wwwwwwwwmwNNNHHHHHHHHHHmmqmmbuwwwwnww NwoomummbwwwoomqmmAwNH0vvvvvvvvvvvvvv vvvvvvvvvvvvvvvvvvvvvvv deviations for [Rh{Me2(Ph2P)2TTF}2][BF4l (l 2). X 0 0.3040( 03 0‘ 03 k \l N H 0" (A) N N N AAA/K OOOOOOOOOOOOOOOO 00000000000000 N H O A :697( vvvvvv OOOOOOOOOOOOOOOOOOO O O O I O O O O O O O O O O O O :0660 Y .671( .617( .502( .522( .534( .559( .606( .621( .631( .659( OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO 00000000000000000000000000 m w m A Q N‘— (DubU‘O‘O‘MLfl AAAAA O O O O O O O C v mmbmewammmwwmpupbnwwqmwwwwmuwmwwnbuwp A. A. AAAOAOAAOAAOAAAAO HHHHOHwHOHHHQHDHHOHHWHNHHQHHHHHWQOHHWN vvVVAVAVAvvVAVAVVAVVAVVVVAVVVVVAAAAAAA 00 (I) \O \O \O 00 £0 AAAA O 229 Table 34. Atomic positional parameters and equivalent isotro pic starxiarddeviations A2)andtheirestinned for RBXH-OXu-Gmmwmh ((113)2(1) (l4)' (CH3)2CD- displacement parameters ( z B(eq) Y X atom 22)\II)))))))))))))))))))))))))))))))))))))) )))))))) ((111231111378567786566665568676467865489787456686 52((((((((((((((((((((((((((((((((((II\II\II\ ((((((((((( 09403171135527004306718124846613563750655956528725 44 )))))))))) ((3436933337 )))))))))))))))))))))))))))))))))))))) 82 (((((((((( 22112121112111112111112111122121111122 156882310352 (((((((((((((((((((((((((((((((((((((( 85339049115358404901069344088408546468619525899574 16426321772615344343990111190353678097144420679097 23135032332330233211000110557765221101556776210112 O O O O O O O O O O O O O O OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO 00000000000000000000000000000O00000000000000000000 ____ 43 )))))))))) ) ) ) ) ((2326622226 )))))))))))))) 9 ))))) 9 ))))) 9 ))))) 9 ))))) 57 (((((((((( 11111111111111(11111(112117112111(11111 581436642656 (((((((((((((( 5 ((((( 3 ((((( 4 ((((( 5 ((((( 62935333579578903179398528209970201651830458733167 45900019009710649794089242849938212465988022013542 77688778965777900099999988900009900988555666554334 33 )))))))))) ) ((2236622226 )))))))) 8 ))))))))))))))))))))))))))))) 57 (((((((((( 12111111(11111111111111111111111111111. 091900269399 (((((((( 1 ((((((((((((((((((((((((((((( 76530271916716755730516834811385012415651520589158 48890834904085497068772893976801225995911867259062 8669785867885899010977766767766666544.5666677654556 O O O O 0 O O O O O O O O O 00000000000000000000000000000 00000000000000001110000000000000000000000000000000 ))))) AB )) ))))))))))))))))))))))))))) 1212344 11111 AB ))))))))) 012345678901234567890123456 ((((((( 123412212345678911111111111.22222222223333333 e elllll ((((((((((((((((((((((((((((((((((((((((((( RRCCCCCPPPPOOOCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC Table 34. (cont'd) atom C(37) C(38) C(39) C(40) C(41) C(4 000000000000 AAAAAAAAAAAA mmmwmbnpppnb wNHvoomqmman vvv 230 B(GQ) 4.6(5) H N A H v 29(2) HH ON AA H v woqmwwqoqmbwm A. O O O O NNHHmbmHmmO‘mt-‘H VVVVAAAVAAAAAV ham \OxlUIUtm WNHN AAAA. o o 231 Table 35. Atomic positional parameters and equivalent isotropic displacement parameters (A2) and their estimated standard deviations for ReXp-Omdmnb 2(CH3)2CD(15) 2(CH3)2(I). atom x y z B(eq) Re(l) -0.16982(3) 0.04364(3) 0.01642(4) 1.82(2) Cl(l) —0.2719(2) 0.0212(2) -0.2248(2) 2.8(1) Cl(2) -0.0456(2) 0.0611(2) 0.2567(2) 2.9(1) P(1) -0. 1332(2) -0.1504(2) 0.0427(2) 2.04(9 P(2) -0. 1557(2) 0.2236(2) -0.0212(2) l.92(8 0(1) 0 0 0 2.0(3) 0(2) -0.3190(6) 0.0833(5) 0.0367(7) 3.3(3) C(1) -0. 1969(9) -0.1630(7) 0.169(1) 2.3(4) C(2) -0.115(1) -0.1880(7) 0.296(1) 2.8(4) C(3) -0.169(1) -0 1878(9) 0.390(1) 3.9(5) C(4) -0. 304(1) -0 1625(9) 0.355(1) 4.2(5) C(5) -0.385(1) -0 1382(9) 0.228(1) 3.9(5) C(6) -0. 334(1) -0.1373(8) 0.137(1) 3.2(4) C(7) -0. 1982(8) -0.2498(7) -0.0981(9) 2.2(3) C(8) -0. 190(1) -0.2469(8) -0.221(1) 3.0(4) C(9) -0.230(1) -0 3296(9) -0 326(1) 3.8(5) C(10) -0. 277(1) -0 4122(9) -0 310(1) 4.2(5) C(11) -0. 284(1) -0 4128(8) -0.186(1) 4.0(5) C(12) -0.246(1) -0.3331(8) -0.080(1) 3.2(4) C(13) -0. 1146(8) 0.3330(7) 0.117(1) 2.2(3) C(14) -0. 084(1) 0.4234(7) 0.099(1) 2.9(4) C(15) -0. 070(1) 0.5091(8) 0.198(1) 3.7(5) C(16) -0. 088(1) 0.5042(9) 0.315(1) 4.0(5) C(17) -0. 120(1) 0.4169(8) 0.331(1) 3.5(5) C(18) -0. 132(1) 0.3309(7) 0.233(1) 2.8(4) C(19) -0. 3136(8) 0.2907(7) -0.134(1) 2.2(3) C(20) -0. 411(1) 0.3395(9) -0.080(1) 3.4(4) C(21) -0. 531(1) 0.396(1) -0.161(1) 4.4(5) C(22) -0. 555(1) 0.4060(9) -0.294(1) 4.1(5) C(23) -0. 458(1) 0.356(1) -0.345(1) 4.0(5) C(24) -0. 339(1) 0.2960(8) -0.268(1) 3.2(4) C(25) -0. 0463(8) 0.2044(7) -0.116(1) 2.2(3) 0(3) 0.775(1) 0.2822(9) 0.492(1) 7.0(2) C(26) 0.714(1) 0.212(1) 0.426(1) 5.4(3) C(27) 0.763(2) 0.096(1) 0.474(2) 6.8(4) C(28) 0.594(2) 0.249(2) 0.294(2) 9.4(5) H(l) -0.0207 -0.2076 0.3172 3.1 H(Z) -0 1099 -0.2052 0.4816 4.3 H(3) -0 3381 -0 1598 0.4248 4.9 8(4) -0 4784 -0.1160 0.2080 4.5 H(S) -0.3910 -0 1171 0.0483 3.8 8(6) -0.1554 -0 1851 —0.2326 3.8 H(7) —0.2188 -O.3267 -O.4095 5.1 H(8) —0.3078 —0.4700 -0.3856 4.9 8(9) -0.3172 —0.4725 —0.1734 4.7 H(lO) -0.2533 -O.3325 0.0059 3.8 H(ll) -0.0770 0.4230 0.0146 3.6 H(12) —0.0465 0.5716 0.1869 4.6 H(13) —0.0815 0.5584 0.3871 5.8 8(14) -0.1429 0.4078 0.4068 4.5 Table 35. (cont'd) atom x H(15) -0.1500 H(16) -0.3927 H(17) -0.5973 H(18) -0.6331 H(19) -0.4694 H(20) -0.2722 232 Y 0.2646 0.3391 0.4337 0.4534 0.3682 0.2617 2 0.2463 0.0161 -0.1227 -0.3468 -0.4358 -0.3060