k r’ w LIBRARY Michigen State I University K. _—_ PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINES return on or before date due. DATE DUE DATE DUE DATE DUE MSU Is An Affirmative Action/Equal Opportunity Institution cMchns-q NEW SYNTHETIC APPROACHES TO REACTIVE MIXED-LIGAND COMPLEXES AT THE INTERFACE OF COORDINATION AND ORGAN OMETALLIC CHENIISTRY By Sue-Jane Chen A DISSERTATION submittedto MchiganStateUniversity inpartialfulfillmentoftherequirement fartherbg'reeof DOCTOR OF WPHY Department of Chemistry 1991 ABSTRACT NEW SYNTHETIC APPROACHES TO REACTIVE MIXED-LIGAND COMPLEXES AT THE INTERFACE OF COORDINATION AND ORGAN OMETALLIC CHEMISTRY by Sue-JaneChen The historic distinction between organometallic and coordination chemistry is becoming less clear, and links between ‘classical’ organometallic and coordination chemistry have recently emerged in the form of organometallic compounds with ancillary donor ligands such as halides, nitrenes and alkoxide ligands. These new classes of compounds demonstrate the ability of soft 1r-acceptor ligands such as CO to bond to a metal in the presence of relatively extreme ligand environments. In an effort to unite the two areas of chemistry, we investigated reactions between multiply bonded metal-metal (MAM) dinuclear complexes, namely, ‘highly early transition metals’ and trinuclear carbonyl clusters, namely low valent late transition metals”. We initiated these studies by the reaction between ReZCl4(dppm)2 (ReiRe) (dppm = Sue-Jane Chen PhZPCHzPPhZ) and the electronically and coordinatively unsaturated molecule HZOs3(CO)10 in the presence H2, work that resulted in the isolation of the novel bridging hydride dirhenium species Re2(u-H)(u- Cl)C12(CO)2(dppm)2. The compound Re2(u-H)(u-C1)CIZ(CO)2(dppm)2 exhibits a rich redox activity, with four redox couples representing two oxidations and two reductions being observed in the cyclic voltammegram. A new carbonyl halide cluster, Ru3(CO)8(Cl)2(PBu3")2 , was synthesized from the reaction between the multiply bonded dirhenium complex Re2016(PBu3")2(Re-4—Re) and Ru3(CO)12. These results demonstrate the feasibility of preparing mixed ligand complexes by ligand transfer reactions between two entirely different metal systems; this new synthetic approach provides a promising opportunity for the syntheses of unusual coordination and organometallic compounds. In a second area of investigation, our study of TMZPP chemistry with dinuclear metal-metal bonded systems led to the discovery of unsymmetrical complexes containing an unusual bridging phenoxy— phosphine ligand. The phosphine ligand, TMPP also exhibits novel chemistry with trinuclear cluster complexes. In the chemistry of Group 8 carbonyls of Fe, Ru and Os, we observed facile cluster transformations under extraordinarily mild conditions compared to all previously reported phosphine reactions of these systems. Key results such as facile P-C bond activation by intramolecular oxidative addition and cyclometallation in the triruthenium system, and demethylation of the phosphine to give an open trinuclear phenoxy—phosphine cluster in the triosmium system are presented and discussed. to my family ACKNOWLEDGES I woulk like to express my sincere gratitude to my research advisor, Professor Kim R. Dunbar, for her guidance, support and assistance during my graduate study; as the first group member, I especially appreciate the experience of growing up with the group under her inspiration, encouragement and hard work throughout these years. In particular, I wish to say many thanks for her time and patience in helping me with my project and the accomplishment of dissertation. To all of my group members, Steve Haefner, Anne Quillevéré, Alice Sun, Stuart Bartley, Stacey Berstein, Garry Finniss, John Matonic, Julia Clements, Helen Chifotides, I woulk like to say many thanks for sharing lots of good time with me, and enduring my 'mood shits' in these years. ('I-Ii, Dudes, I love you !') In particular, I wish to express my deep appreciation to John Matonic and 'TMPP patrol' (Steve Haefner, Anne Quillevéré and Alice Sun) for their assistance in my work. ‘ Finally, I would like to thank my parents, my sister and brother; their love, concerns and understanding have always been the radiant support for me on this way. v1 vii TABLE OF CONTENTS LIST OF TABLES ...................................................................... LIST OF FIGURES .................................................................... CHAPTER I. INTRODUCTION .............................................. CHAPTER II. REACTIONS OF TRIPLY BONDED DIRHENIUM COMPLEXES WITH TRINUCLEAR CARBONYL CLUSTERS ....................................................... 1. Introduction .................................................................. 2. Experimental ................................................................. A. Synthesis ................................................................ (1) Preparation of Rez(u-H)(u-C1)C12(CO)2(dppm)2 ...... (i) Reaction of ReZCl4(dppm)2 with (u-H)2083(CO)10 in the presence of H2 .................................... (ii) Reaction of RezCl4(dppm)2 with Os3(CO)12 in the presence of H2 ............................................. (iii) Reaction of Re2C14(dppm)2 with Ru3(CO)12 in the presence of H2 ............................................. (iv) Reaction of Re2014(dppm)2 with an H2/CO gas mixture ...................................................... Page xiv xviii xxviii l 28 29 30 3O 3O 3O 31 31 (v) Reaction of ReZCl4(dppm)2 with (u-H)ZOs3(CO)10 in the absence of H2 ...................................... (vi) Reaction of Re2Cl4(dppm)2 with NaBH4 in the presence of CO ............................................ (vii) Reaction of Re2C14(dppm)2 with NaH in the presence of CO ............................................ (2) Reaction of Re2(u-H)(u-CI)C12(CO)2(dppm)2 with one equivalent of NOBF4 .......................................... (3) Reaction of Re2(p.-H)(u-C1)CIZ(CO)2(dppm)2 with an excess of NOBF4 ................................................ (4) Reaction of Re2(u-H)(u-CI)C12(CO)2(dppm)2 with cobaltocene ...................................................... (5) Electrochemical Oxidation of Re2(u-H)(u-CI)C12(CO)2(dppm)2 ........................... (6) Electrochemical Reduction of Re2(u-H)(u-Cl)Clg(CO)2(dppm)2 ........................... B. X-ray Crystal Structures .......................................... (1) Re2(u-H)(u-Cl)Clz(CO)2(dppm)2 ........................... (2) [Regal-H)(tl-Cl)Clz(CO)2(dppm)2l(BF4) .................. (3) [Rez(u-CO)(u-C1)C12(CO)(NO)(dppm)2](BF4) .......... (4) Rez(il-Cl)(tl-CO)Clz(CO)2(dppm)2 ......................... Results and Discussion ................................................... A. Synthesis ................................................................ B. Spectroscopic Studies ............................................... C. Redox Chemistry ..................................................... 32 33 33 34 34 39 (i) Electrochemical and Chemical Oxidation ............ (ii) Electrochemical and Chemical Reduction ........... D. Molecular Structures ............................................... (1) Re2(u-H)(u-CI)C12(CO)2(dppm)2 ........................... (2) [Re2(u-H)(u-CI)C12(CO)2(dppm)2](BF4) .................. (3) [Regal-CO)(u-Cl)Clz(CO)(NO)(dppm)2](BF4) .......... (4) [Re2(u-Cl)ZClz(CO)2(dppm)2](BF4) ........................ 4. Summary ...................................................................... CHAPTER III. REACTIONS OF QUADRUPLY BONDED DINUCLEAR HALIDE COMPLEXES WITH TRINUCLEAR CARBONYL CLUSTERS .............. 1. Introduction .................................................................. 2. Experimental ................................................................. A. Synthesis ................................................................ (1) Reaction of Ru3(CO)12 with RezCle(PBu3")2 ......... (2) Reaction of (u-H)2083(CO)10 with-(n-Bu4N)2RezCla B. X—ray Crystal Structure of Ru3(CO)3(u-Cl)2(PBu3")2 3. Results and Discussion ................................................... A. Synthetic Methods ................................................... B. Molecular Structure ......... ~ ....................................... 4. Summary ...................................................................... Page 62 68 69 69 70 71 71 72 98 99 100 100 100 100 101 102 102 104 Page CHAPTER N. REACTIONS OF THE MULTIFUNCTIONALIZED PHOSPHINE LIGAND TRIS(2,4,6- TRIMETHOXYPHENYL)PHOSPHINE WITH DINUCLEAR METAL CARBOXYLATE COMPLEXES ................................................... 110 1. Introduction .................................................................. 111 2. Experimental ................................................................. 115 A. Synthesis ................................................................ 115 (1) Reaction of Rh2(02CCH3)4(MeOH)2 with TMPP 115 (i) Synthesis of Rh2(02CCH3)3(TMPP-0)(MeOH) 115 (ii) Chemical Oxidation of Rh2(OZCCH3)3(TMPP-O)(MeOH) .................... 1 16 (2) Preparation of M02(OZCCF3)4 ............................. 116 (3) Reaction of M02(02CCF3)4 with TMPP ................. 117 (4) Preparation of Rh2(02CCF3)4 .............................. 117 (5) Reaction of Rh2(OZCCF3)4 with TMPP .................. 118 . B. X-ray Crystal Structure of Rh2(OchH3)3(TMPP-0)(MeOH) ................................ 1 18 3. Results and Discussion ................. ................................. 119 (1). Reaction of Rh2(OzCCH3)4(MeOH)2with TMPP ............ 119 A. Synthesis ......................................................... 119 B. Spectroscopic Studies ........................................ 120 C. Molecular Structure of Rh2(OgCCH3)3(TMPP-0)(MeOH) ......................... 129 D. Redox Chemistry .............................................. 130 Page (2). Reactions of M2(02CCF3)4 (M = M0, Rh) with TMPP 155 (3). Reactions of [Mz(02CCH3)2(NCMe)6](BF4)2 (M = M0, Rh) with TMPP ............................................................. 165 (4). Reactions of [M02(NCMe)10](BF4)4 with TMPP ............. 166 4. Summary ...................................................................... 166 CHAPTER V. REACTIONS OF TRIS(2,4,6-TRIMETHOXY- PHENYL)PHOSPHINE WI'I'H TRINUCLEAR CARBONYL CLUSTERS .................................... 167 1. Introduction .................................................................. 168 2. Experimental ................................................................. 170 A. Synthesis ................................................................ 170 (1) Reaction of Fe3(CO)12 with TMPP ........................ 170 (2) Preparation of Ru3(CO)u(NCMe) ........................ 171 (3) Reaction of Ru3(CO)n(NCMe) with TMPP ............ 171 (4) Preparation of Ru3(CO)10(NCMe)2 ....................... 172 (5) Reaction of Ru3(CO)10(NCMe)2 with TMPP .......... 172 (6) Preparation of (u—H)2083(CO)10 ........................... 173 (7) Reaction of (u-H)2083(CO)10 with TMPP ............... 173 (8) Preparation of 083(CO)11(NCM8) ........................ 174 (9) Reaction of 033(CO)11(NCMe) with TMPP ............ 174 (10) Preparation of 083(CO)10(NCM8)2 ....................... 175 (11) Reaction of 033(CO)10(NCMe)2 with TMPP ........... 175 B. X-ray Crystal Structure ............................................ 176 (1) [HFe3(CO)11][HTMPP] ....................................... 176 XII (2) Ru3(u-CO)2(CO)6[u3-‘n2-C6H2(0Me)3l[u- P{CGH2(OMe)3}2] ............................................... 177 (3) Os3(u-OH)2(CO)9(TMPP) .................................... 178 (4) O33(u-0H)(CO)9(u-n2-TMPP-0) ........................... 179 3. Results and Discussion ................................................... 180 (1) Triiron carbonyl clusters .......................................... 180 A. Synthesis and Characterization .......................... 180 B. Molecular Structure .......................................... 182 (2) Triruthenium carbonyl clusters ................................ 193 A. Synthesis and Characterization .......................... 193 B. Molecular Structure .......................................... 207 (3) Reactions of Triosmium Carbonyl Clusters ................ 217 A. Synthesis and Characterization .......................... 217 B. Molecular Structure .......................................... 233 (i) 083(u-OH)2(CO)9(TMPP) ............................... 233 (ii) 083(u-OHXCO)9(u-‘n2-TMPP-0) ...................... 238 4. Summary ...................................................................... 238 CHAPTER VI. CONCLUDING REMARKS ................................. 245 REFERENCES ........................................................................... 248 APPENDICES ........................................................................... 263 LIST OF TABLES Page 1H NMR data of phosphine (TMPP) and phosphonium salts (in CDC13). .............................................................................. 22 Various synthetic approach in the preparation of Re2(u-H)(u-C1)C12(CO)2(dppm)2. ........................................... 43 Crystal data for Re2(u-H)(u-Cl)Clz(CO)2(dppm)2 (1) and Re2(u- H)(p.-Cl)Clz(CO)2(dppm)2-MeCN (2). ...................................... 78 Selected bond distances (A) and angles (deg) for Re2(u-H)(u-Cl)Clz(CO)2(dppm)2 (l) and Re2(u-H)(u-Cl)C12(C0)2(dppm)2-MeCN (2). ............................. 79 Crystal data for [Re2(u-H)(u-Cl)Clz(CO)2(dppm)2](BF4) (3) and [Regal-CO)(u-Cl)Clg(CO)(NO)(dppm)2](BF4) (4). ...................... 86 Selected bond distances (A) and angles (deg) for [Re2(u-H)(u-C1)C12(CO)2(dppm)2](BF4). .................................. 87 Selected bond distances (A) and angles (deg) for [Regal-CO)(u-Cl)Clz(CO)(NO)(dppm)2](BF4). ........................... 94 xiv 10. 11. 12. 13. 14. 15. 16. 17. Crystal data for the disordered structure formulated as “RezCl4(CO)2(dppm)2". ......................................................... Crystal data for Ru3(u-Cl)2(PBu3")2(CO)8. .............................. Selected bond distances (A) and angles (deg) for RU3(U’CI)2(PBU3”)2(CO)3. ..................................................... Crystal data for Rh2(OZCCH3)3(TMPP-0)(MeOH). ................... Selected bond distances (A) and angles (deg) for Rh2(OZCCH3)3(TMPP-0)(M60H). .......................................... Bridging v(CO) stretches for various [HFe3(CO)11]' salts. ......... Crystal data for [HTMPPlfFeg(u-H)(u-CO)(CO)10]. ................... Selected bond distances (A) and angles (deg) for [HTMPP][Fe3(u- HXH'COXCOho] ................................................................. Crystal data for Ru3(u-CO)2(CO)6{u3-n2-CGH2(0Me)3}[u- P{CgH2(OMe)3}2]. ................................................................ Selected bond distances (A) and angles (deg) for Ru3(u-CO)2(CO)6{u3-n2-CGH2(OMe)3}[u-P106H2(0Me)3}2]. ......... XV 95 105 106 141 142 183 187 188 209 210 18. 19. 21. 22. Crystal data for 083(u-OH)2(CO)9(TMPP) (l) and Osaw-OH)(CO)9(u-n2-TMPP-O) (2). ........................................ Selected bond distances (A) and angles (deg) for 083(u-OH)2(CO)9(TMPP). ..................................................... Selected bond distances (A) and angles (deg) for Os3(u-OH)(CO)9(u-n2-TMPP-0). ............................................ Atomic positional parameters (A2) and their estimated standard deviations for Re2(u-H)(u-Cl)Clg(CO)2(dppm)2. ....................... Atomic positional parameters (A2) and their estimated standard deviations for [Re2(u-H)(u-CI)C12(CO)2(dppm)2](BF4). .............. Atomic positional parameters (A2) and their estimated standard deviations for [Regal-CO)(u-Cl)Clz(CO)(NO)(dppm)2](BF4). ....... Atomic positional parameters (A2) and their estimated standard deviations for Ru3(u-Cl)2(PBu3")2(CO)8. ................................. Atomic positional parameters (A2) and their estimated standard deviations for Rh2(OzCCH3)3(TMPP-0)(MeOH). ...................... 266 267 270 272 26. 27. Atomic positional parameters (A2) and their estimated standard deviations for [HTMPP][Fe3(u-H)(u-CO)(CO)10]. ...................... Atomic positional parameters (A2) and their estimated standard deviations for Ru3(u-CO)2(CO)6{u3-n2-CGH2(OMe)3}[11- P{CGH2(OM8)3}2]. ................................................................ Atomic positional parameters (A2) and their estimated standard deviations for 083(u-OH)2(CO)9(TMPP). ................................. Atomic positional parameters (A2) and their estimated standard deviations for 083(u-OH)(CO)9(u-n2-TMPP-0). ........................ Page 276 279 284 287 LIST OF FIGURES Schematic diagram depicting the five nonzero d—d overlaps between two metal atoms. .................................................... Conversion of quadruply bonded d4-d4 dinuclear complexes with 621:482 configurations to electron—rich (ds-d5) and electron— deficient (d3-d3) triply bonded dinuclear complexes via a two— electron transfer reduction and oxidation, respectively. ........... Schematic representation of the chemistry occurring during the decomposition of Os3(u-Cl)2(CO)10 on phosphine—functionalized silica, showing the formation of an unsaturated mononuclear compound OsCl(CO)2 which exhibits catalytic activity due to its coordinative unsaturation. ................................................... A plot of cone angles versus the v(CO)A1 stretch for various Ni(CO)3(L) complexes (L = phosphine). .................................. A 500 MHz 1H NMR spectrum of Re2(u-H)(u-CI)C12(CO)2(dppm)2 in Cchlz at 22 OC. .............................................................. xviii Page 13 20 10. 11. A 500 MHz 1H NMR spectra of the methylene region for R6201- H)(u-C1)C12(CO)2(dppm)2 in (a) CD2012 and (b) acetone-d6 at 22 °C. ................................................................................. T1 measurements in CD2012 and at 200 MHz 1H NMR with variable temperatures for the bridging hydride of Re2(u-H)(u- Cl)C12(CO)2(dppm)2. ............................................................ Positive ion FABMS spectrum of Re2(u-H)(u-Cl)C12(CO)2(dppm)2. Cyclic voltammogram of Re2(u-H)(u-Cl)C12(CO)2(dppm)2 in a CH2012 solution with 0.2 M TBAPFG at 200 mV/s using a Pt—disk electrode. ........................................................................... ) and the corresponding oxidation product ( ---------- ) and (b) Regul- H)(u-Cl)C12(CO)2(dppm)2 ( reduction product ( ---------- ). .................... ’ .............................. Infrared spectra of (a) Re2(u-H)(u-Cl)Clz(CO)2(dppm)2 ( ) and the corresponding Electronic absorption spectral changes during electrochemical oxidation of Re2(u-H)(u-CI)C12(CO)2(dppm)2 in 0.1 M TBABF4- CH2012 solution. The total reaction time at ambient temperature was two hours. ................................................................... xix 52 55 57 59 61 12. 13. 14. 15. 16. 17. Positive ion FABMS spectrum of the decomposition product RezCl4(CO)2(dppm)2 isolated from the electrochemical oxidation of Re2(u-H)(u-Cl)Clz(CO)2(dppm)2 in 0.1 M TBABF4—CH2C12 solution, showing (a) the molecular ion - peak [M] = Re2Cl4(CO)2(dppm)2, (b) [M—CO] = ReZCl4(CO)(dppm)2 and (c) [M—ZCO] = Re2Cl4(dppm)2. .................................................. An X—band EPR spectrum taken on a solid sample of [szCo][Re2(u-H)(u-Cl)C12(CO)2(dppm)2l at —150 °C. ............... Schematic diagram depicting the redox reactions of Re2(u-H)(u- Cl)Clz(CO)2(dppm)2. ............................................................ ORTEP drawing of Re2(u-H)(u-Cl)Clz(CO)2(dppm)2, showing the atom labeling scheme. All phenyl—group carbon atoms are represented as small circles for clarity, and all other atoms are represented by their 50% probability ellipsoids. Unlabeled atoms are related to labeled ones by an inversion center at the midpoint of the Re—Re’ bond. ................................. A skeletal ORTEP plot of Re2(u-H)(u-CI)C12(CO)2(dppm)2 view down the Re—Re vector. ...................................................... ORTEP drawing of the [Ream-H)(u-Cl)Clz(CO)2(dppm)2]+ cation showing the atom labeling scheme. All phenyl—group carbon XX 67 75 77 81 83 18. 19. 21. 22. atoms are represented as small circles for clarity, and all other atoms are represented by their 40% probability ellipsoids. ........ ORTEP drawing of [Re2(u-CO)(u-CI)C12(CO)(NO)(dppm)2][BF4]. showing the atom labeling scheme. All phenyl—group carbon atoms are represented as small circles for clarity. .................. Stereoview of the unit cell of the molecule [Re2(u-CO)(u- Cl)C12(CO)(NO)(dppm)2][BF4] along the a axis. ....................... Pluto drawing emphasizing the main features of the cations in the structures of (a) [Re2(u-CO)(u.-Cl)C12(CO)(NO)(dppm)2][BF4] and (b) [Rez(u-H)(u-Cl)Clz(CO)2(dppm)2][BF4]. ........................ Comparison of a series of edge—sharing bioctahedral dirhenium complexes with the syn-Re2C13(dppm)2 core. .......................... ORTEP drawing of Ru3(|.l-Cl)2(PBu3")2(CO)3 showing the atom labeling scheme. All n-butyl carbon atoms are represented as small circles for clarity, and all other atoms are represented by their 50% propability ellipsoids. ............................................ A graph of ligand size versus basicity. The ligand size and basicity are expressed by the cone angle and v(CO) value, respectively. The cone angles and v(CO) values (smaller values xxi 85 89 91 93 97 108 27. indicating greater o—donor and poorer n—acceptor properties) were taken from Tolman's work [22]. ..................................... Schematic diagram of various approaches to the synthesis of Rh2(020CH3)3(TMPP-0)(MeOH). .......................................... A 300 MHz 1H NMR spectrum of Rh2(02CCH3)3(TMPP- OXMeOH) in CD3CN at 22 °C. ............................................... A 500 MHz 1H NMR spectra of the meta proton region of Rh2(02CCH3)3(TMPP-O)(MeOH) in CD3CN at 22 °c with (a) 31p decoupling (b) 31F undecoupling. ......................................... Two-dimensional DQCOSY spectrum of Rh2(OzCCH3)3(TMPP- 0)(MeOH). ......................................................................... 1H NMR spectra of the meta proton of Rh2(02CCH3)3(TMPP- OXMeOH), measured in various solvents (a) THF-dg (b) CD3CN (c) acetone-d6 (d) CD013 (e) CD2C12. .................................... (a) Simulated and (b) experimental 1H NMR spectra of meta- pl‘OtOllS Of Rh2(02CCH3)3(TMPP-OXMBOH). ........................... A 311mm NMR spectrum of Rh2(OZCCH3)3(TMPP-O)(MeOH). xxii 114 122 124 126 128 134 136 138 31. 32. 36. 37. Positive ion FABMS spectrum of Rh2(02CCH3)3(TMPP- O)(MeOl-I). ......................................................................... An ORTEP drawing of Rh2(OZCCH3)3(TMPP-0)(MeOH), showing the atom labeling scheme. All phenyl—group and MeOH carbon atoms are represented as small circles for clarity, and all other atoms are represented by their 50% propability ellipsoids. .......................................................................... Cyclic voltammogram of Rh2(OZCCH3)3(TMPP-0)(MeOH) in 0.2 M TBAPFg—CHsCN at 200 mV/s using a Pt—disk electrode. Varible scan speed cyclic voltammograms of Rh2(OZCCH3)3(TMPP-0)(MeOH) in 0.2 M TBAH—CH3CN. ....... An X—band EPR spectrum (—150 °C) of a 2-MeTHF/CH3CN frozen solution containing 0.1 M TBAPF6 o f Rh2(02CCH3)3(TMPP-0)(MeOH). .......................................... Positive ion FABMS spectrum of Rh2(OzCCH3)3(TMPP-20)(NO). X—band EPR spectra in (a) the solid state and in (b) solution for Rh2(OzCCH3)3(TMPP-20)(NO). ............................................. xxiii 140 144 146 148 150 152 154 38. 39. 41. 42. A 300 MHz 1H NMR spectrum of M02(02CCH3)2(TMPP-0)2. ..... A 300 MHz 19F NMR spectrum of M02(OZCCH3)2(TMPP-0)2. A positive ion FABMS spectrum of M02(02CCH3)2(TMPP-O)2. Schematic diagram of a proposed reaction scheme for the formation of M02(02CCH3)2(TMPP-O)2. ................................. Infrared spectrum in the v(CO) region for [HTMPP][HFe3(CO)11]. The v(CO) stretch at 1748 cm"1 is a bridging mode. ................................................................... An ORTEP diagram of [HTMPP][I-IFe3(CO)1 1], showing the atom labeling scheme. All atoms are represented by their 40% probability ellipsoids. ........................................................... A packing diagram of [I-ITlVlPP][I-IFe3(CO)1‘1], showing there is no ion—pairing interaction present in the molecule. ................ Infrared spectral changes in the v(CO) region for (3) initial product Ru3(CO)n(TMPP) and (b) transformed product with bridging v(CO) bands observed at 1790 and 1800 cm“. .............. xxiv Page 158 162 164 185 190 192 195 47. 49. 51. Infrared spectrum in THF for the molecule Ru3(u-CO)2(CO)6{113- nz-C6H2(0Me)3}[u—P{CGH2(OMe)3]2]. The v(CO) stretches at 1807 and 1866 cm‘1 are bridging modes. ....................................... A 300 MHz 1H NMR spectrum in THF—d8 at 22 °C for Ru3(u- CO)2(CO)61u3-n2-C6H2(0Me)3}[u-PIC6H2(OMe)3}2]. Resonances denoted by (a) and (b) are assigned to both ortho—methoxy groups and two meta protons, respectively, in the cyclometallated ring. Proposed reaction pathway for the formation of Ru3(u-CO)2(CO)6{u3-n2-CGH2(OMe)3}[u—P{CGHZ(OMe)3}2]. ......... Computer generated space—filling model of molecule B of Ru3(u-CO)2(CO)6{pg-nz-C6H2(0Me)3}[u-P1C6H2(0Me)3}2]. The Ru atoms are denoted by the black balls. .......................... ORTEP drawings of (a) molecule A and (b) molecule B of Ru3(u- CO)2(CO)6{u3-n2-CGH2(OMe)3}[u-P1C6H2(0Me)3}2], showing the atom labeling scheme with all atoms represented by their 40% probability ellipsoids. ........................................................... Main features of both enantiomers A end B in the structure of R113(Ll-CO)2(CO)6{113‘112'CGH2(OM8)3}[u-P106H2(OM8)3}2]. Chll‘al carbon atoms in both molecules are denoted by *. .................... XXV 197 200 203 205 212 52. 53. 55. 56. 57. 59. Selected bond distances for molecules A and B in the structure of Ru3(u-CO)2(CO)6{u3-n2-06H2(0Me)3}[u-P{CGH2(OMe)3}2]. ......... Positive ion FABMS spectrum of Os3(u-H)(H)(CO)10(TMPP). Variable—temperature 500 MHz 1H NMR spectra of 083(u-H)(H)(CO)10(TMPP) recorded in CDCl3. ........................ Positive ion FABMS spectrum of 083(CO)11(TMPP). ................ A 300 MHz 1H NMR study depicting spectral changes during the transformation of Os3(CO)11(TMPP). (a) Initial product 033(CO)11(TMPP) with terminal v(CO) stretches only, and (b) transformed product with bridging v(CO) stretches present. A 300 MHz 1H NMR spectrum of 083(u-OH)(TMPP-O)(CO)9 in CDCl3 at room temperature. The doublet denoted by * is due to an impurity of a methyl phosphonium salt. ........................... Schematic diagram outlining a proposed reaction sequence in the formation of 083(u-OH)2(TMPP)CO)9 and Os3(u-OH)(TMPP- 0)(CO)9. ............................................................................. An ORTEP diagram of 083(u-OH)2(TMPP)(CO)9, showing the atom labeling scheme. All phenyl—group carbon atoms of TMPP xxvi Page 216 220 222 225 228 230 232 61. are represented as small circles for clarity, and all other atoms are represented by their 40% propability ellipsoids. ................. ORTEP diagram of 083(u-OHXTMPP-OXCO)9, showing the atom labeling scheme. All phenyl—group carbon atoms of TMPP are represented as small circles for clarity. ................................. Main features of the molecular structures of (a) 053(11- OH)2(TMPP)(CO)9 and (b) 083(u-0H)(TMPP-0)(CO)9. .............. xxvii 244 Ag/AgCl Bu" Calcd cm’1 CV d dppm DQCOSY min mmol LIST OF ABBREVIATIONS angstrom silver-silver chloride reference electrode n-butyl group calculated wavenumber cyclic voltammetry deuterated bis(diphenylphosphine)methane Double-Quantum Correlation Spectroscopy half—wave potential electron spin resonance molar extinction coefficient fast atom bombardment mass spectroscopy grams, ESR g-value hertz infrared metal—metal methyl group milliliter minutes millimoles xxviii MSU n m NMR N TU obs ox Ph PR3 red sh TBABF4 TMPP TMPP-0 TMPP-20 xxix Michigan State University nanometer nuclear magnetic resonance National Taiwan University observed oxidation phenyl group tertiary phosphine ligand reduction shoulder tetra-n-butylammonium hexafluorophosphate tetra-n-butylammonium tetrafluoroborate tri(2,4,6-trimethoxyphenyl)phosphine, P[CGH2(OMe)3]3 P[C6H2(0Me)3]2[CGH2(OMe)2(O)] PICGH2(OMe)3]2[C6H2(OMe)(O)2] volts CHAPTERI INTRODUCTION 2 Transition metal organometallic and coordination complexes comprise a remarkably diverse group of compounds, and among them, polynuclear clusters with two or more metals in close proximity are of great interest [1]. The electronic properties of these compounds reflects the subtle interplay of not only the metal—ligand bonding but also the metal—metal bonding, and the system can display, through mutual metal—metal interactions, chemical and physical properties different from those of the corresponding mononuclear moieties. There are two main classes of polynuclear cluster complexes in transition metal chemistry. One subdivision is “low valent clusters” which typically involve transition metals with n—acceptors such as isocyanides, NO and CO ligands, and ‘classical’ organometallic compounds; metal carbonyl clusters are common members of this family. The dominant role of carbon monoxide as a ligand for stabilizing low oxidation state clusters arises, in part, from the fact that CO is a very flexible ligand which can occupy terminal, edge—bridging, or face—capping locations in a cluster. Furthermore, this ligand functions as a two-electron donor in each of these bonding situations, and therefore terminal to bridging intramolecular exchange processes frequently have very low activation energies. The second class of cluster compounds is the "high valent clusters" which are formed by early transition metal elements and contain classical donor ligands such as 0‘2, 8’2, Cl‘, Br‘, I‘, and OR’. Geometrically these clusters show a strong preference for triangular and octahedral metal skeletal geometries such as Re3019L3 and [M06C16L6]4+. An important feature of this class of complexes is that it includes lower nuclearity 1r- donor clusters that exhibit extensive bonding between the metal atoms. The 3 multiply bonded metal-metal (MB-M) dinuclear complexes have contributed significantly to the development of inorganic chemistry. The past decade has seen remarkable progress towards a broad and deeper understanding of multiply bonded metal—metal dinuclear complexes [2]. The majority of these complexes have been found with the transition metals V, Nb, Ta, Cr, Mo, W and Re, but other metals such as Ru, Os and Rh have also been involved. In these systems, the assigmnent of a formal metal—metal bond order usually rests on the collective data from structural, spectroscopic, and magnetic measurements. For clusters of the earlier transition metals, multiple bonds are frequently observed in compounds without bridging ligands; in these cases, the structural and spectroscopic data are completely consistent with the assignment of a formal bond order on the basis of the number of d electrons associated with each metal atom (one 0, two 1:, and two 5 bonds) as shown in Figure 1, but the maximum bond order in molecular clusters is generally considered to be four because one of the d5 orbitals is required for metal-ligand bonding. The filling of metal-based orbitals in MAM complexes renders a 621t462 ground state configuration. Of importance to note in such systems is that the HOMO and LUMO with 5—symmetries are formed from the weak interaction between two adjacent dxy orbitals from each metal center. The lowest energy absorption band of quadruply bonded dinuclear complexes therefore corresponds to a 3(8 -> 5*) transition with the retention of a strong metal—metal interaction. The M-l-I-M (n = 1—4) dinuclear complexes often exhibit rich redox activity and electronic flexibility, as the presence of two metal atoms united by a multiple bond provides an electron source or sink for multielectron redox reactions [3]. These reactions lead to stepwise changes in M—M Figure 1. Schematic diagram depicting the five nonzero d—d overlaps between two metal atoms. 6 bond order by removing and adding electrons to the metal—metal bond. Figure 2 demonstrates how MAM complexes can either convert to electron-rich M—3-M species by two one—electron reduction, or to electron— deficient M-3—M compounds by two—electron oxidation processes. In theory, the unique structural and electronic properties of M-Q-M complexes can be tailored to promote multielectron transformations by coupling the one— electron redox chemistry of individual metal cores in sequential steps or by exploiting the two—electron activity of a discrete metal core in an effective single step. The redox reactions of these complexes are significantly influenced by coordination geometry and the nature of the coordinated ligands, both of which determine whether such processes are accompanied by ligand rearrangements. For example, the dinuclear complex Re2014(dppm)2 undergoes reversible oxidations by electrochemistry that suggest major structural rearrangement does not take place. On the other hand, two electron oxidized M2X4L4 (M = Mo(II), W(II), Rh(III); X = halide; L = donor ligand including halide) species are best stabilized by adopting a confacial [4] or edge—sharing bioctahedral configuration [5], which enforces octahedral coordination about the oxidized metal core. Finally, the ligands in many multiply bonded molecules exhibit high substitutional lability, thus the coordinatively unsaturated MlM core has the ability to serve as a template for substrate assembly and coupling [6]. In recent years, some organometallic ligands such as alkynes and ethylene have been introduced to the MB-M systems, especially in the metal alkoxide compounds [7], and some important reactions such as carbon—carbon and carbon-hydrogen bond activations were observed [8]. For example, 1,2— R2W2(OR)4 (W—3-W)6+ (R = alkyl group) compounds have been shown to undergo either reductive elimination reactions with loss of alkane and Conversion of quadruply bonded d4—d" dinuclear complexes with 021:452 configurations to electron—rich (d5—d5) and electron—deficient (d3—d3) triply bonded dinuclear complexes via a two-electron transfer reduction and oxidation, respectively. I 2|: II d‘—d‘ Figure2 IJ | I d5_dS ‘1 3.315116 P""" .tdstlc’ prune. sbllvdA-l nun-.1" vJuAru ~ ~ ‘0 $3 on. \b 5,1,4: u‘Li'd‘MA ' v Oops-m a d-coa‘.‘ D. I 41”“; 5 ‘hfi..~ 44.9 L“ '11.“ ’h; \ i ..‘"v-r 9. 4'} “JaLJ Etf'efi “"hn‘ , “inf“: \"" ~.' ‘0 “a,“ an 1 up... 9 alkene and formation of d4—d4 (WiW) compounds, or oxidative addition reactions with elimination of alkane and formation of dl—d1(W—W) containing compounds supported by hydrido and alkylidyne ligands; these competing pathways involve [3— and a-CH activation processes, respectively [9]. In direct contrast to the n—donor ligands, the strong n—acid ligands including CO, NO, and isocyanides only rarely occur in multiply bonded dinuclear complexes; to date, none have been found in quadruply bonded dinuclear complexes. In most cases, the introduction of rt—acceptor ligands into the MAM framework results in M—M bond cleavage, and leads to the formation of mononuclear complexes [10]. For example, reductive or nonreductive Re—Re bond cleavage to afford mononuclear isocyanide complexes of Re(I) and Re(III) was observed in the reactions of alkyl isocyanides with dirhenium(III) complexes containing quadruple bonds such as Re2(02CR)4Clz (R = CH3 or C6H5). Rezxgz‘, and Re2X6(PR3)2 (x = Cl or Br, PR3 = monodentate phosphine ligands) or triply bonded complexes, such as Re2X4(PR3)4 (X = C1 or Br, PR3 = monodentate phosphine ligands). The facile bond cleavage reactions induced by n-acceptors is presumably because the metal d electrons necessary for the formation of the M—M 1t and 6 bonds are involved in n—backbonding 'with the ligands, thus destablizing the M—M bond. In contrast to the facile cleavage of the ReiRe bond in Re2X4(PR3)4 (X = C1 or Br, PR3 = monodentate phosphine ligands) by CO and isocyanide ligands, the analogous phosphine—bridged species Re2X4(dppm)2(Re-1Re) (dppm = thPCHzPth) reacts to give adducts in which a metal-metal bond is preserved [11]. As the scheme below shows, the resulting dinuclear 10 compounds consist of A-frame-like structures or edge-sharing bioctahedral geometries [12]. /'\ A Pm P P P P c1 l on (:1 | C1 (:1 Q I Cl I l\ \ CO v" c“. '1 0“. CO ’ s". 3" \“ a ch /Rc -———> Re Re -———> Rc‘\ (Rs . tel «1 1‘00 a’lsl‘e \j \_/ \_/ Rc2C14(dppm)2 A-framc-hkc geometry Edge—sharing bioctahedron In an effort to unite the two areas of cluster chemistry, we investigated reactions between multiply bonded metal—metal (M-n—M) dinuclear complexes, namely ‘high valent early transition metals’, and ‘classical’ organometallic compounds with n—acceptor CO groups, namely ‘low valent late transition metals’. One predicted outcome of this research was a mild approach to the synthesis of new x-acceptor-containing dinuclear compounds via ligand transfer reactions between the different metal systems. Since the coordinatively unsaturated M-r-LM core is known to behave as a template for substrate assemply and coupling, several other plausible modes of reaction such as mixed—metal assembly via a direct interaction of the early and late transition metal atoms, and redox reactions through outer sphere interactions might also be anticipated. Our initial experiment in this study was the reaction of the phosphine—bridged species Re2X4(dppm)2(Re-1Re) (dppm = PhZPCHzPth) with some reactive organometallic molecules such as HZOs3(CO)10, and the results and discussion are presented in Chapter II. 11 The aforementioned approach describes a possible route for bridging the areas of ‘classical’ organometallic and coordination chemistry. Along this line, we know that the historic distinction between organometallic chemistry and coordination chemistry is becoming less clear, and links between ‘classical’ organometallic and coordination chemistry have recently emerged in the form of organometallic compounds with ancillary donor ligands such as halides, nitrides and alkoxide ligands. These new classes of compounds demonstrate the ability of soft n-acceptor ligands such as CO to bond to a metal in the presence of relatively extreme ligand environments. Some of the new organometallic compounds have been found to exhibit unique electronic properties induced by the combined presence of the dramatically different donor ligands. For example, the chemistry of carbonyl halide clusters has attracted much research interest because facile CO dissociation reactions in these complexes provide a good opportunity to study catalytic applications under mild condition. One example shown in Figure 3 demonstrates the use of an edge double—bridged osmium complex 083(u-Cl)2(CO)10 in surface organometallic chemistry [13]. In this case, 083(u-Cl)2(CO)10 is rendered coordinatively unsaturated by taking advantage of the labile character of CO ligands induced by the bridging chloride atoms, which allows it to be attached to the phosphine— functionalized silica to make the supported osmium catalyst. In general, these complexes with combined ‘hard’ n-donor ligands and ‘soft’ 11:— acceptor CO groups were derived from simple ligand substitution reactions of metal carbonyls with 1c-donor ligands. Often these reactions are not easy to efl’ect, however, and simple substitution of one for another is usually not possible. We postulated that an alternative approach to such compounds via ligand transfer reactions between 'classical' organometallic Figure3. 12 Schematic representation of the chemistry occurring during the decomposition of Os3(u-Cl)2(CO)10 on phosphine— ftmctionalized silica, showing the formation of an unsaturated mononuclear compound OsCl(CO)2 which exhibits catalytic activity due to its coordinative unsaturation. 13 0| — CO 0' co < > Cl C] 0 Cl PPh2 1°th 25 C PPh2 PPh2 thP 105 °C 0| 125 °C Cl CI Cl Pth PPh2 PPh2 PPh2 11 145°C CI PPh2 14 compounds, namely metal carbonyl clusters, and metal halide complexes might be useful. In Chapter III, we report the syntheses of a new class of halide carbonyl clusters derived from the reactions between ReiRe halide complexes with metal carbonyl clusters. An entirely different approach to uniting the distinct properties of ‘high valent early transition metals’ and ‘low valent late transition metals’ involves the use of functionalized ligands. Ligands bearing mixed donor atoms have received special attention because "soft" and "hard" donor ligands complement each other in their preferences for metals [14]. The soft donors stabilize electron—rich metal centers in low oxidation states, whereas the hard donor ligands stabilize electron—poor metals in high oxidation states. These ligands, with the potential to form weak chelate interactions due to these two inherently different coordination abilities, strongly influence the activity, selectivity and stability of a catalytic system via electronic and steric effects. Furthermore, metal chelates containing “hard” and “soft” donors exhibit catalytic potential due to the ligand flexibility and lability. For example, ligands containing P~O chelates exhibit high activity and selectivity in a catalytic process for the manufacture of a-olefins [15]; this process is currently one of the most important applications of homogeneous catalysis in industry. The study of phosphines, especially tertiary phosphines, with the capacity to stabilize a wide range of oxidation states in transition metal complexes, continues to be a field of intense research area in both fundamental and applied chemistry [16]. One of the primary reasons for this interest is that metal phosphine complexes have been found to be good homogeneous catalysts. Recent work has focused on the preparation of new phosphine ligands which may enhance the reactivity of key industrial 15 reactions such as hydrogenation, hydroformylation and hydrosilation. To date, there are two main catagories of heteroatom phosphine ligands bearing both “hard” and “soft” donors that have been investigated: (1) Nitrogen—containing functionalized phosphines, denoted as P~N [17]: Amino—phosphines contain a 'soft' phosphorus atom and a 'hard' primary aromatic amine donor, both of which participate in bonding to the metal as shown below [17(b)]. th [Rh(CO)2X12 P\ /00 Phat—Q = o ., / \ N X H2N H2 (2) Oxygen—containing functionalized phosphines, denoted as P~O [18]: Ether—phosphines are one of the most extensively studied class of oxygen— containing functionalized phosphines [18(a)]. In addition to imparting high reactivity to the metal center, the ligand itself can undergo deprotonation or dealkylation to form rigid unsymmetrical chelates or bridges. Examples of phenoxy—phosphine chelates have been reported in the chemistry of remarkably stable Rh(II) and Ir(II) complexes as shown below [18(j)—(l)lt gs 0 O>M PPh(2,4,6)2 > PPh(2,6)2 > PPh2(2,4,6) > PPh2(2,6) > PPh3 (pKa z 2.3). The mesomeric effect of the multi—methoxy substituents in the trisubstituted phosphine P(2,4,6)3 [tris(2,4,6-trimethoxy)phenylphosphine (TMPP)] results in the highest basicity of any known arylphosphine, on the order of piperdine (pKa = 11.0). The high basicity of TMPP suggested to us that the phosphine would behave as a strong Lewis base. To verify this hypothesis, the value of vA1(CO) in Ni(CO)3(TMPP) was measured and found to be 2048 cm"1 which reveals the highest nucleophilicity ever reported for a phosphine ligand. Furthermore, 1H NMR studies in CDC13 of the phosphine TMPP and several phosphonium salts were measured (Table 1). 31F {1H} NMR studies in CDC13 revealed a singlet at 8 = —68 ppm versus 85% H3PO4. The extreme upfield position of the resonance is in agreement with the high basicity of TMPP. When taken together with the fact that the ligand exhibits a large steric bulk with a cone angle (9) of 184°, we concluded that TMPP would be an excellent ligand for the preparation of coordinatively unsaturated metal complexes. 22 s: 2 u e5 a: n u as A3 a? 3 men 3 men 6v 2c anmotmeaenz a: 2 u as a: n u as me new a was a awe as as namouueaeg a: on u e5 a: n n a: me am.» 3 sen 3 a?“ As to +Etme$.s.§ a: m u as E 5% 3 can as Sc meats Saxons axons :tu oozed costs :13 essensco 308 as sea assessors as age osznaean as see 55 ma 4 2.3. namely ' D Y t . C511 3 characte' "nth bot 3'3. 21168111 Yasmin 1 0‘ G M? ‘o ‘ 11.31:; 23 In our laboratory, some unique metal chelate TMPP complexes [Rh(TMPP)2]n (n = +1, +2, or +3) were discovered in the chemistry of TMPP with [Rh2(NCMe)10]4+ [25]; recently a demethylated TMPP complex, namely the phenoxy—phosphine chelate Ni(II)(TMPP-O)2 [(TMPP-O) = P(C6H2(0Me)3)2(C6H2(OMe)2(O)] was isolated and structurally characterized [26]. Besides chelation, heteroatom functionalized ligands with both “soft” and “hard” donors are capable of coordinating to two different metal centers to form unsymmetrically bridged metal complexes. Unsymmetrical bridging ligands may form mixed—valence complexes by inducing an electronic polarity to the metal—metal bond; these are of considerable interest to synthetic chemists and spectrosc0pists alike. In spite of the promising nature of this chemistry, the designed synthesis of dinuclear metal complexes containing heteroatom functionalized ligands with "soft" and "hard" donor atoms is still in an early stage. Based on these considerations, we extended our studies of tris(2,4,6- trimethoxyphenyl)phosphine to M—n-M complexes in the hopes of providing a systematic synthetic route for the formation of unsymmetrically bridged metal—metal bonded complexes. Metal tetracarboxylate compounds M2(02CR)4 with "paddlewheel" structures were regarded as attractive candidates for the chemistry of TMPP for the following reasons: (1) Carboxylate ligands are important in inorganic and biological chemistry due to their versatile coordination ability [27]. This manifests itself in the form of a wide range of metal bonding modes such as monodentate bridging, bidentate bridging, as well as symmetric and asymmetric chelating; therefore these metal carboxylate complexes in general exhibit higher chemical reactivity due to their ligand flexibility. 244 (2) The complexes M2(OZCR)4 (M = Mo(II), W(II) or Rh(II), R = alkyl or aryl) have been extensively studied from the viewpoints of synthesis, spectroscopy, electrochemistry, and chemical reactivity [28]. In particular, theoretical studies of dirhodium (II,II) compounds confirm the existence of a single 6 bond designated as 02n4625*21t*4 for the electronic configuration of the Rh24+ unit, and M2(02CR)4 (M = Mo(II) or W(II), R = alkyl or aryl) compounds contain quadruply bonded metal—metal cores with the 021:482 configuration. (3) These types of molecules are symmetrical, but if a carboxylate group is substituted by a hetero—bridging ligand such as a phenoxy—phosphine, the electronic enviroment in the equatorial plane will be altered not only because of the presence of ligands with different field strengths, but because of symmetry changes; the result therefore is a degree of electronic polarity in the metal—metal core which may give rise to mixed-valence complexes that are of considerable interest [29]. To this end, Chapter IV reports our investigation of reactions of the functionalized phosphine TMPP with dirhodium and dimolydenum carboxylate metal complexes; in these studies, we discovered several unique molecules containing unsymmetrical phenoxy—phosphine bridges as shown below. 5* 5- M M | | MeO . O O MeO M = Mo(II), Rh(ll) 25 The discussion of the formation of phenoxy—phosphine bridging dinuclear complexes, characterization of these newly synthesized compounds, and the electrochemistry of the dirhodium product are detailed. As part of the investigation of the chemistry of TMPP with various transition metal complexes, we included the study of metal carbonyl clusters. A number of cluster—assisted ligand transformations have been investigated in recent years [30]. Reactions involving transition metal carbonyl clusters and functionalized ligands containing phosphorus, sulfur, oxygen or nitrogen have provided some interesting models. For example, cluster complexes containing oxygen donor ligands are good models for oxide grafted species, and in some cases, they display a comparable chemical reactivity. Alkoxo groups are of particular interest as ancillary ligands due to the stability of the carbon—oxygen bond. The intrinsic properties of coordinated oxygen can facilitate the activation of various ligands including unsaturated hydrocarbons. In other cases, metal-mediated transformations of coordinated phosphines are typical reactions that are facilitated by a cooperative effect of several metal centers. They proceed through sequential oxidative addition reactions (P—C, P—H bond .cleavage and/or acitvation of the C—H bond of the phosphorus substituents) and reductive eliminations involving migration of the phosphorus substituents to other coordinated substrates, generally ending with the stabilization of bridging phosphido or phosphinidene groups. A major problem in cluster chemistry in terms of useful applications is their tendency to undergo thermal or photochemical fragmentation which often involves a preliminary heterolytic or homolytic metal-metal bond cleavage to generate a polynuclear metal unit containing an \( The {'2 26 unsaturated, 16—electron metal center. For example, a heterolytic fission of a metal—metal bond in a trinuclear carbonyl cluster is represented below. 16—electron 18-electron unsaturated unsaturated atom atom A hv The fragmentation arises from the fact that metal-metal and metal carbonyl bond energies are often comparable and hence metal—metal bond breaking is competitive with substitution processes. In the metal cluster carbonyls of Group 8, it is found that reactions of Fe3(CO)12 often lead to cluster break—up, while substitution of CO groups in Ru3(CO)12 occurs only at higher temperatures (ca. 80—100 °C), and in Os3(CO)12 under even more vigorous conditions. The activation of metal cluster complexes of the second and third row metals to permit milder reaction conditions and greater control of kinetic pathway is therefore essential. In order to solve the problem of cluster fragmentation, the use of activated clusters as presursors has provided a breakthrough in cluster chemistry. Recent advances in the chemistry of activated clusters include nucleophilic activation, electron—induced nucleophilic substitution, activation by unsaturated metal clusters, and lightly stabilized metal clusters [31]. The lightly stabilized metal clusters with coordinated solvents have been proven to be excellent precursors in numerous reactions. 27 Among them, the most common solvated clusters are M3(CO)12_n(NCMe)n (M = Os, Ru; n = 1,2) which can be synthesized as following. Mc3N() MeCN MejN + CO2 M3(C0)12 "M3(CO)11" M3(CO)11(NCMe) (M: Ru, Os) Chapter V reports our investigation of the tertiary phosphine TMPP toward Group 8 metal carbonyl clusters. By taking advantage of the flexible coordination ability of the functionalized ligand TMPP, we demonstrated a variety of coordination modes in clusters. Cluster transformations of the phosphine complexes are also observed and discussed therein. 28 CHAPTERII REACTIONS OF TRIPLY BONDED DIRHENIUM COMPLEXES WITH TRINUCLEAR CARBONYL CLUSTERS 11m 1 dE191C :77”)? his «to BHQ‘vI-ql “\n‘t U I ) I’ll. ( t I 1 'h' '0 wt 11 ‘t\ 'np; . ndkila‘ 1 ‘9: “MM! LVH‘P A In! M”;- “eth 29 1. Introduction Multiply bonded dinuclear (M—n—M) complexes have been well developed in the past decade [2]. These compounds exhibit interesting structural and spectroscopic properties, ligand substitution and redox activity. The coordinatively unsaturated MiM core has been proven to serve as a template for substrate assemply and coupling [6]. Furthermore, the ligands in many multiply bonded molecules exhibit high substitutional lability. However, one major point is that strong it—acid ligands including CO, NO, and isocyanides only rarely occur in multiply bonded dinuclear complexes; in most cases, the introduction of n—acceptor ligands into the MLM framework results in M—M bond cleavage, and leads to the formation of mononuclear complexes [10]. Only a few complexes derived from phosphine—bridged species Re2X4(dppm)2 (Re-3—Re) (dppm = thPCHZPPhZ) react with strong n—acid ligands to give adducts in which a metal—metal bond is preserved [11]. In this respect, we are interested in investigating an alternative approach to the synthesis of the x—acceptor containing metal-metal bonded complexes by the reaction between multiply bonded metal-metal dinuclear complexes with metal carbonyl clusters with the ability to serve as a CO source. In this chapter we describe our work in the study of reactions between the multiply bonded dirhenium complex Re2X4(dppm)2 (ReiRe) and the carbonyl clusters H2083(CO)10 and M3(CO)12 (M = Ru, Os) and with H2/CO mixtures. These reactions produce the unusual u-hydrido carbonyl species Re2(u-H)(u-C1)C12(CO)2(dppm)2. 3O 2. Experimental A. Synthesis (1) Preparation of Re2(u-H) (u-C1)C12(CO)2(dppm)2 The following methods involve refluxing a toluene solution of Re2C14(dppm)2 in the presence of various carbonyl clusters (u-H)2033(CO)10, Os3(CO)12 and Ru3(CO)12 with a constant flush of H2 passing through the solution. Os3(CO)12 and Ru3(CO)12 were obtained from commercial sources. Re2Cl4(dppm)2 [39] and (u-H)2053(CO)10 [40] were prepared by literature methods. (i) Reaction of RezCL(dppm)2 with (u-m2053(CO)10 in the presence of H2 A mixture of (u-H)2083(CO)10 (0.10 g, 0.117 mmol) and Re2C14(dppm)2 (0.15 g, 0.12 mmol) was placed in a 50 mL Schlenk tube equipped with a condenser and a stir bar. Toluene (20 mL) was added, and the solution was refluxed with a slow stream of H2 bubbling through the solution. During the course of the reaction, the solution color changed from dark purple to green—brown. The progress of the reaction was monitored by infrared spectroscopy and was judged to be complete after 12 h on the basis of the disappearance of (ll-H)2083(C0)1o. The solVent was removed to give a green-brown residue which was further separated by column chromatography (packed with unactivated silica gel), and the first light yellow band was collected by using hexane/CH2012 (1:1, v/v) as the eluent, and was identified as H4Os4(CO)12 by a comparison of its infrared and 1H N MR spectroscopy to that reported in the literature [41]; yield: 0.05 g (39%). IR (CH2C12)IV(CO) = 2085 (m). 2067(8), 2019 (s), 1995 (m) cm-l. 1H NMR 31 (CD2C12): 5 = —20.44 (s) ppm. EI—MS spectrum: parent ion, m/z = 1101.9 (19205). The second green band was collected with CH2C12 as the eluent, and characterized as Re2(u-H)(u-C1)C12(CO)2(dppm)2 on the basis of spectroscopic and crystallographic data; yield: 0.10 g (70%). IR (Nujol): v(CO) = 1890 (vs), 1854 (s) cm-l. 1H NMR (CD2C12): 5 = 12.75 (1H, s), 7.35 (40H, m), 4.70 (2H, m), 4.27 (2H, m). FABMS spectrum: parent ion, m/z = 1304.5 (187Re). Anal. Calcd for 052H45C1302P4Re2: C, 47.87; H, 3.50. Found: C, 48.34; H, 4.10. (ii) Reaction of Re20h(dppm)2 with 033(0th in the presence of H2 A mixture of Os3(CO)12 (0.10 g, 0.110 mmol) and Re2C14(dppm)2 (0.14 g, 0.110 mmol) in toluene (20 mL) was refluxed with a constant slow stream of H2 passing through the solution. The reaction was monitored by infrared spectroscopy and stopped after 8 h on the basis of the disappearance of Os3(CO)12. The resulting solution was evaporated to dryness, and the residue was redissolved in CH2C12 (5 mL), and purified by column chromatography. Elution with hexane/CH2C12 (1:3, v/v) gave a pale yellow solution containing 0.020 g of H4Os4(CO)12 (yield z 20%) and a small amount of compound (1) (yield z 10%). A brown intractable material was retained at the top of the column. The IR, 1H NMR and mass spectral data for both compounds are given in section A(i). (iii) Reaction of RezCL(dpmn)2 with Rn3(CO)13 in the presence of I12 A mixture of Ru3(CO)12 (0.10 g, 0.156 mmol) and Re2C14(dppm)2 (0.21 g, 0.16 mmol) in toluene (20 mL) was refluxed with a constant slow stream of H2 bubbling through the solution. The reaction was monitored by infrared spectroscopy and was stopped after 8 h on the basis of the 32 disappearance of Ru3(CO)12. The reaction solution was worked—up in the same manner as reaction A(ii). The main product that was isolated is the known compound H4Ru4(CO)12 [42]; yield: 0.018 g (215%). IR (CHzClz): v(CO) = 2080 (s), 2066 (vs), 2022 (s), 2010 (w) cm-l, along with a small amount of compound (1) (yield < 5%). (iv) Reaction of Re2014(dppm)2 with an H2/CO Gas Mixture A solution of ReZCl4(dppm)2 (0.10 g, 0.08 mmol) in toluene (20 mL) was refluxed for 20 h with a rapid stream of H2 and a slow stream of CO passing through the solution. The resulting cloudy green solution contained a small amount of olive green precipitate, which was collected by filtration and identified as RegCl4(CO)2(dppm)2 by its infrared spectrum (Nujol) (v(CO) = 1958 (vs), 1946 (vs), 1722 (m) cm‘l); yield: 0.011 g(17%). The green filtrate was characterized as compound (1) on the basis of IR and 1H NMR spectroscopies; yield 0.050 g (48%). (v) Reaction of RezCl.‘(dppm)2 with (ll-H)2033(CO)10 in the absence of H2 The reaction was performed under the same manner as section A(i) but without the constant flush of H2 through the solution. During the reaction, the solution color changed from dark purple to cloudy green- brown, and after 68 h of reflux, infrared spectroscopy indicated that very little (ll-H)2083(CO)10 remained. After removal of the solvent, the residue was extracted with diethyl ether (20 mL) and filtered to yield a brown precipitate and a brown solution. The brown solid was dissolved in THF (20 mL) and chilled to -10°C to give a green solid that did not contain carbonyl ligands as judged by infrared spectroscopy. The compound was not further investigated. There was no evidence for the presence of the title compound mmer odyide 513111312 )001 mnfinl and tlu' 33 in the remaining brown THF solution or the diethyl ether solution. The only identifiable v(CO) band in these solutions maybe attributed to the starting material (ll-H)2083(C0)10. (vi) Reaction of Re20h(dppm)2 with NaBH., in the presence of CO A suspension of R62C14(dppm)2 (0.10 g, 0.08 mmol) and NaBH4 (0.003 g, 0.08 mmol) was refluxed in toluene (20 mL) for 3 h with a constant slow stream of CO passing through the solution. During this time, an olive green precipitate formed which was identified as RezCl4(CO)2(dppm)2. IR (Nujol): v(CO) = 1958 (vs), 1944 (s), 1721 (m) cm'l. The reaction was then continued after the addition of an excess amount of NaBH4 (0.015 g, 0.4 mmol) into the suspension of RepCl4(CO)2(dppm)2 in toluene. The solution was stirred for 6 h to give a soluble green compound which exhibits a single v(CO) stretch at 1857 cm‘l. No attempt was made to characterize the product. There was no evidence for the presence of (l) in the reaction. (vii) ReactionofRezCl.(dppm)2widiNaHinthepi'eserweofCO A mixture of RepCl4(dppm)2 (0.10 g, 0.08 mmol) and NaH (0.002 g, 0.08 mmol) was refluxed in CH2012 (20 mL) for 24 h with a constant slow stream of CO passing through the solution. An infrared spectrum of the resulting yellow—green solution revealed that the product is Re2Cl4(CO)2(dppm)2. The reaction was continued after addition of an excess amount of NaH (0.10 g, 0.4 mmol) into the reaction solution containing Re2C14(CO)2(dppm)2. The solution was stirred for 24 h to give a dark green solution which exhibits a complicated v(CO) region. IR (CHzClz): 1955 (s), 1945 (s), 1925(8), 1845 (m), and 1724 (m) cm‘l. There was no evidence for the formation of (l) in this reaction. 34 (2) Reaction of Re2(u-H)(u-Cl)C12(CO)2(dppm)2 with one equivalent of NOBF4 Acetonitrile (10 mL) was added into a mixture of Re2(u-H)(ll- Cl)Clg(CO)2(dppm)2 (0.050 g, 0.220 mmol) and NOBF4 (0.008 g, 0.220 mmol). and the green solution turned brown immediately. The mixture was stirred for 15 min with constant pumping to remove N 0 gas. A green solid was collected on a medium—porosity frit under argon and dried in vacuo. The product was recrystallized by slow diffusion of diethyl ether into a CH2C12 solution of the compound; yield z 90 %. IR (Nujol): v(CO) = 2007 (vs), 1851 (w) cm‘l. 711,,”(CH2C12) = 401 nm. (3) Reaction of Re2(u-II)(u-Cl)Clz(CO)2(dppm)2 with an excess of NOBF4 Acetonitrile (10 mL) was added into a mixture of Re2(ll-H)(u- C1)C12(CO)2(dppm)2 (0.050 g, 0.220 mmol) and an excess of NOBF4 (0.016 g, 0.440 mmol), and the green solution turned brown. After the mixture was stirred for 8 h in a close system under argon, a green solid was collected on a medium—porosity frit under argon and dried in vacuo. The product was recrystallized by slow diffusion of diethyl ether into a CH2012 solution of the compound. The compound was further characterized by X—ray diffraction study and revealed to be Re2(u-Cl)(ll-CO)CIZ(CO)(NO)(dppm)2. (4) Reaction of Regal-H) (ll-Cl)Clz(CO)2(dppm)2 with Cohaltocene Acetone (5 mL) was added to the mixture of Re2(u-H)(u- Cl)C12(CO)2(dppm)2 (0.025 g, 0.11 mmol) and cobaltocene (0.005 g, 0.11 mmol) whereupon the green solution turned blue-green. The solution was stirred for 15 min after which time a fine blue-green precipitate was 35 filtered from a clear solution. The solid was collected on a fine—porosity frit under argon and dried in vacuo; yield z 90%. IR (Nujol): v(CO) = 1823 (vs), 1805 (w) cm'l. (5) Electrochemical Oxidation of Re2(u-H) (ll-C1)C12(CO)2(dppm)2 A four compartment electrochemical cell was used for the bulk electrolysis experiment. The working electrode is constructed of Pt mesh approximately 1 cm2 in area. The counter electrode (Pt wire) is separated from the working elctrode by two medium porosity glass frits, and the Ag/AgCl reference electrode is separated from the working electrode by a fine porosity glass frit. A dichloromethane solution containing 0.1 M [n- Bu4N][BF4] as a supporting electrolyte was added to all four compartments, and a small amount of Re2(p.-H)(u-Cl)Clz(CO)2(dppm)2 (= 0.005 g) was added to the working electrode compartment. The potential of the working electrode was set to +1.0 V and the solution was stirred rapidly. The green solution slowly turned yellow—green, and the oxidation process was monitored by UV-visible spectroscopy. During the electrolysis, the original intense absorption band at 423 nm due to the neutral species diminished and an absorption band appeared at 404 nm. After the bulk oxidation proceeded for 2 h, the yellow—green solution was transfered via syringe to a Schlenk tube, and crystallized by slow diffusion of hexane into the solution. IR (Nujol): v(CO) = 1999 (vs), 1973 (vs) cm‘l. lmax (CH2C12) = 404 nm. The compound was structurally characterized as the salt [Re2(u-H)(u- Cl)C12(CO)2(dppm)2](BF4). Prolonged bulk electrolysis at +1.0 V resulted in a decomposition of the yellow-green product to give a brown solution after ca. 2 days. The brown product was worked—up in the same manner as above, and 36 recrystallized by slow diffusion of hexane into the [n-Bu4N][BF4]-CH2012 solution. Brown crystals appeared after 2 days. IR (Nujol): v(CO) = 2007 (vs), 1851 (W) cm“. FABMS spectrum: parent ion, m/z = 1338 (187Re). An X—ray diffraction study of one of the brown crystal revealed the compound to be Re2(u-Cl)(u-CO)C12(CO)2(dppm)2. (6) Electrochemical Reduction of Re2(u-H)(u-CI)C12(CO)2(dppm)2 The same electrochemical cell described in the previous section was also used for bulk reduction. A dichloromethane solution containing 0.1 M [n-Bu4N][BF4] as the supporting electrolyte was added to all four compartments, and a small amount of Re2(u-H)(u-Cl)Clz(CO)2(dppm)2 (a 0.005 g) was added to the working electrode compartment with an applied potential of —1.0 V accompanied by rapid stirring of the solution. The green solution slowly turned blue—green. After the bulk reduction had proceeded for 2 h, the blue—green solution was transfered to a Schlenk tube and recrystallized by slow diffusion of diethyl ether (or hexane) into the solution. The reduction species is very air—sensitive, and it underwent oxidation to the neutral complex during the recrystallization process. IR (Nujol): v(CO) = 1823 (vs), 1805 (w) cm-l. B. X-ray Crystal Structures (1) Re2(u-H)(u-Cl)Clp(CO)2(dppm)2 (i) Data Collection and Reduction 37 A green crystal of dimensions 0.40 x 0.30 x 0.25 mm3 was covered with epoxy cement and mounted at the end of a glass fiber. Geometric and intensity data were obtained on a Nicolet P3/F diffractometer equipped with graphite monochromated MoKa radiation. A rotation photograph indicated that the crystal diffracted well. An automatic search routine was used to locate 25 reflections in the range 20 s 20 S 30°. The reduced cell dimensions indicated that the crystal belongs to the tetragonal crystal system; axial photographs revealed that the Laue class is 4/mmm. Data reduction was carried out by standard methods with the use of well-established computational processures. Systematic absences from the data led to the space group choices of P41212 and P43212. An (0—20 motion was used to scan 8125 data points in the range of 4.5 s 20 5 45°. Structure factors were obtained after Lorentz and polarization corrections. During intensity data collection three check reflections were measured at regular intervals; an average loss in intensity of 4.8% was observed. The program CHORT was applied to correct for this. Azimuthal scans of reflections with Eulerian angle x near 90° (3 curves) were used as a basis for an empirical absorption correction. After avaraging of the equivalent reflections, there remained 4834 unique data and 3319 reflections with F02 > 3 0(F02). (ii) Structure Solution and Refinement The position of the unique Re atom was obtained by the application of MULTAN 11/82. A sequence of successive difference Fourier maps and least—squares cycles led to full development of the coordination sphere. The final full-matrix refinement involved 289 variable parameters and 3319 data, for a data—to—parameter ratio of 11.5. The refinement converged with residuals of R = 0.0304, RW = 0.0368 and quality—of—fit 0.643. A comparison 38 of the refinement in the two enantiomorphs revealed that P41212 is the correct choice for the space group. (2) [Re2(u-H)(ll-Cl)C12(CO)2(dppm)2](BF4) (1) Data Collection and Reduction A plate—like green crystal of approximate dimensions 0.48 x 0.15 x 0.26 mm3 was mounted on a glass fiber with vacuum grease, and data collection was carried out at —98°C on a Nicolet P3/F diffractometer upgraded to a Siemens P3/V equipped with graphite—monochromated CuKa radiation and a low temperature device. A rotation photograph was used to locate 15 reflections from which a preliminary cell was indexed. The reduced cell dimensions indicated that the crystal was triclinic which was confirmed by axial photography. An accurate cell for data collection was measured based on 25 reflections with 40 S 20 S 60°. Intensity data were collected using the (1)—20 scan mode in the range of 4 s 20 5 106° with 1 in 0). Three standard reflections variable scan speed from 3 to 10 min’ measured at constant intervals showed no significant decay in intensities. Data were corrected for Lorentz and polarization effects. The linear absorption coefficient for CuKa was 112.510° cm“, and an empirical absorption correction was applied based on \u scan of three reflection with x near 90°C. (ii) Structure Solution and Refinement The structure was solved by direct methods using the program in SHELXS-86. The heavy atoms were located by a sequence of successive difference Fourier maps, and least-squares cycles led to full development of 39 the coordination sphere. The final full—matrix refinement involved 334 variable parameters and 4841 observed reflections with F02 > 30(F02). The refinement converged with residuals of R = 0.161 and Rw = 0.146. (3) [Rez(ll-CO)(u-Cl)C12(CO)(NO)(dppm)2] (BF4) (i) Data Collection and Reduction A small green crystal of approximate dimensions 0.20 x 0.18 x 0.05 mm3 was mounted on a glass fiber with vacuum grease, and cooled to —95 °C in a nitrogen cold stream on a Nicolet P3/F diffractometer upgraded to a Siemens P3/V equipped with graphiteLmonochromated CuKa radiation and a low temperature device. Cell parameters were determined from 25 reflections with 40 S 20 S 60°. Intensity data were collected using the (1)—20 scan mode in the range of 4 s 20 5 106° with variable scan speed 1.5 - 3.0 min"1 in 0). Three standard reflections measured at constant intervals showed no significant decay in intensities. Data were corrected for Lorentz and polarization effects. The linear absorption coefficient for CuKa was 90.628 °cm’1, and an empirical absorption correction was applied based on w scans of three reflection with 1 near 90°C. (ii) Structure Solution and Refinement The structure was solved by direct methods using SHELXS. The positions of heavy atoms were located, and a sequence of successive difference Fourier maps and least—squares cycles led to the location of the remaining non—hydrogen atoms. The final full-matrix refinement involved 326 variable parameters and 5904 observed reflections with F02 > 40 30(F02). The refinement converged with residuals of R = 0.167 and Rw = 0.214. (4) Regal-Cl)(ll-CO)C12(CO)2(dppm)2 (i) Data Collection and Reduction A brown crystal with approximate dimensions of 0.26 x 0.13 x 0.05 mm3 was mounted on a glass fiber. All measurements were made on a Nicolet P3/F diffractometer upgraded to a Siemens P3/V equipped with graphite monochromated MoKa radiation and a low temperature device. A rotation photograph was used to locate 16 reflections from which a preliminary cell was indexed. Accurate cell constants and an orientation matrix for data collection were obtained from a least—squares refinement using the setting angles of 25 reflections in the range of 20 s 20 5 25°. The cell is monoclinic (C centered) with dimensions : a = 22.945 (5) A, b = 11.322 (3)11, c = 23.406 (8) A and v = 5968 (3)1313. The data were collected using an omega scan mode in the range 4 s 20 S 45° with a scan speed of 4 min“1. The diameter of the incident beam collimator was 1.5 mm. Three standard reflections were measured at constant intervals with no significant loss in intensity. The linear absorption coefficient for MoKa was 43.996 cm‘l. An empirical absorption correction, based on azimuthal scans of three reflections with x near 90°, was applied which resulted in transmission factors ranging from 1.000 to 0.226. The data were corrected for Lorentz and polarization effects. (ii) Structure Solution and Refinement 41 All calculations were performed using the TEXSAN crystallographic software package of Molecular Structure Corporation. The structure was solved by direct methods using SHELXS—86. The positions of heavy atoms were obtained from peaks with the highest electron density. A sequence of successive difference Fourier maps and least— squares cycles led to full development of the coordination sphere. The final cycle of full-matrix least—squares refinement involved 121 variable parameters and 2163 observed reflections with F02 > 30(F02). The refinement converged with residuals of R = 0.210 and RW = 0.241. 3. Results and Discussion A. Synthetic Methods Our study of the reaction between (u-H)2033(CO)10 and Re2Cl4(dppm)2 in the presence of H2 provides a high yield synthetic route for the preparation of a halide carbonyl dinuclear complex that also contains a bridging hydride ligand Re2(ll-H)(u-Cl)Clz(CO)2(dppm)2. The source of the hydride ligand is of considerable interest to us; two plausible reaction routes for the synthesis of the hydride-bridged dirhenium complex are postulated: (a) the bridging hydride ligand was derived from (p.- H)2083(C0)10 via metal hydride coupling, followed by H—Os bond scission [43], and (b) the bridging hydride ligand was derived directly from molecular hydrogen through oxidative addition as shown on the following page. 42 [Rexf—L’Pe] \ H fi/fl‘\p (a) H //_\\ l .0] .0 ”2053(00ho c1 To T c1 RéEEEERgH .thégééng Cl/l n/I co/IYI \m Pd (1)) / P VP [Ref-Re] 92 A second important question is whether the CO ligands in (1) were obtained by ligand transfer reaction from (ll-H)2Osg(CO)10 without any interaction between both metal systems, or via an intermediate with the interaction between the complexes Re2C14(dppm)2 and (ll-H)20s3(CO)10 followed by ligand exchange reaction. These points are important for the understanding of possible formation of heteronuclear complexes in this reaction. In order to probe the role of (u—H)20s3(CO)lo and H2 in the reaction and to further understand the reaction pathway, two alternative reactions were designed (Table 2). One involves the use of carbonyl clusters as precursors to provide the sources of CO, and another one involves the use of CO gas along with various potential hydride sources including molecular hydrogen and hydride reagents such as NaH and NaBH4. In the latter of the two approaches, a significant result was obtained from the direct reaction of Regcl4(dppm)2 with an Hz/CO gas mixture at atmospheric pressure. The yield of ( 1) by this method critically depends on the relative 43 Table2. Various synthetic approach in the preparation of Re2(u-H)(u-Cl)C12(CO)2(dppm)2. Yield (%) (ll-H)2083(CO)10 + H2 = 70 (u-H)2083(CO)10 0 083(CO)12 + H2 3 10 RU3(CO)12 + H2 == 10 44 concentrations of H2 and CO in the reaction. If the CO concentration is in excess, one obtains a high yield of the previously reported compound Re2C14(CO)2(dppm)2 but very little of (1). It is known that the reaction of Re2014(dppm)2 with CO is facile, and it will form an A—frame-like monocarbonyl adduct first, and react further to form an edge—sharing bioctahedral complex ReZCl4(CO)2(dppm)2. The reactions of Re2C14(dppm)2 under a CO atmosphere with sodium borohydride and sodium hydride led to product mixtures which contained Re2C14(CO)2(dppm)2 and some polyhydride complexes, but no evidence for the formation of (l), as determined by IR and 1H NMR spectroscopy A A P P . .. P P 1 “GI “c1 Cl- 1 Q- 1 «Cl (1) “(1‘) C1. l .C! I .0 Rc‘——“ R15“ (1) = "Rg~‘_c "’Re‘“ \\ > ”Re“: "'Ré‘. \ \ \\ I \— \ P P p O P v (i) H2 (ii) NaH or NaBH4 From the aforementioned discussion, it can be ascertained that the control of the CO concentration in these reactions is essential, and higher levels of H2 are necessary in order to favor the formation of (1). This finding suggests that the molecular hydrogen reacts with RezCl4(dppm)2 first, which prevents the formation of the highly unreactive product RezCl4(CO)2(dppm)2. Based on this consideration, we postulate that the product (1) may initially form an edge—sharing bioctahedral dihydride complex via an oxidation addition by molecular hydrogen, followed by a subsequent reductive elimination of HCl as shown on the following page. 45 pp _ P/\P .. =|= PAP 150 1,60 H2 0 13%| ’.H 2 C0 C1 Lag-,1 .50 (Re [Re > (Rev/Rex} > ch_ oomr omNF com? souepunqv eAgle|ea 58 Figure 9. Cyclic voltammogram of Re2(u-H)(ll-Cl)C12(CO)2(dppm)2 in a CH2C12 solution with 0.2 M TBAPFg at 200 mV/s using a Pt— disk electrode. 59 4K +1.5 0.0 V0 LTS vs Ag/AgCl Figure9 -1.5 ) and the corresponding oxidation product ( ---------- ) and (b) Re2(tl-H)(p.-C1)C12(CO)2(dppm)2 ( Figure 10. Infrared spectra of (a) Re2(1l-H)(ll-Cl)Clz(CO)2(dppm)2 ( ) and the corresponding reduction product ( ---------- ). 61 (a) 2000 1900 1800 wavenumber (cm") 10 Figure 62 voltammogram of the compound (1) in a dicholoromethane solution containing 0.1 M [n-Bu4N][BF4] as a supporting electrolyte shows a one— electron reduction couple at E1 ,2 = —-0.80 V with a peak-to—peak separation of 70 mV at 200 mV/sec which confirms the reduction process is reversible. A one—electron reversible oxidation at Em = +0.57 V with a peak-to—peak separation of 70 mV is also observed. In addition, a quasi—reversible reduction couple at E1 ,2 = -1.53 V with the peak—to—peak separation of the couple is ca. 160 mV and an irreversible oxidation near the solvent limit at Ema = +0.96 V vs Ag/AgCl are observed (Figure 9). This extensive redox behavior is characteristic of edge-sharing bioctahedral dirhenium complexes [36, 51 ~52]. (i) Electrochemical andChemical Oxidation The oxidation process at Em = +0.57 V vs Ag/AgCl is accessible and can be achieved chemically by using the salts NO+Y‘ or Ag+Y' (Y: BF4, PFg, etc) as oxidants. Upon addition of one equivalent of [NO][BF4] to an acetonitrile solution of compound (1), an instant color change of the solution from green to green—brown was observed, indicating a facile oxidation had occurred. The infrared spectrum of the oxidation product shows essentially the same pattern for the CO stretching region as the neutral species, R82(H' H)(u-Cl)Clz(CO)2(dppm)2 but at a lower energy of as 60 cm’1 (Figure 10). This result may be taken as an indication of a lesser M—CO it-backbonding upon oxidation from an Reg“ to an R825+ dimetal core. It should be mentioned, that oxidation reactions with nitrosonium salts such as NO+Y" (Y = BF4, PFg, etc) often result in coordination of the NO group to the meatl to form nitrosyl complexes. In the present study, reaction with excess [NO][BF4] with (1) indeed produced the nitrosyl 63 product Re2C13(CO)2(NO)(dppm)2 which was also characterized by an X- ray diffraction study. Another approach to the synthesis of the oxidized species is by an electrochemical method. A controlled—potential bulk oxidation of (l) in a 0.1 M [n-BugN][BF4]—CH2C12 solution, at an applied potential of +1.0 V, resulted in the formation of a dark green solution after ca. 30 min. The electrochemical generation of the cation was monotored by UV—visible spectroscopy, and the original strong absorption band at 416 nm was replaced by the electrogenerated cation with an absorption band at 396 nm (Figure 11). The cyclic voltammogram of the electrolyzed solution was idential to (1) except that the wave at +0.57 V vs Ag/AgCl corresponded to a reduction process, indicating the oxidation product is isostructural to the neutral compound (1). Recrystallization of the product by slow diffusion of hexane into the electrolyzed solution gave a suitable X—ray quality crystal which was confirmed as [Re2(u-H)(u-Cl)Clz(CO)2(dppm)2](BF4) by a crystallographic study. In the course of prolonged bulk oxidation, the green solution gradually turned brown, and the brown decomposition product was analyzed by FABMS spectrum which showed the highest mass peak at m/z = 1338 corresponding to the dirhenium complex Re2C14(CO)2(dppm)2. The result is in a good agreement with an analysis of isotope distributions for the compound (Figure 12). We rationalize the formation of Re2C14(CO)2(dppm)2 as arising from loss of the bridging hydride followed by abstraction of a chloride ligand from the CH2012 solvent. Figure 11. Electronic absorption spectral changes during electrochemical oxidation of Re2(u-H)(u-Cl)C12(CO)2(dppm)2 in 0.1 M TBABF4— CH2C12 solution. The total reaction time at ambient temperature was two hours. 65 com v ' D--------O‘ BOUBQJOsqv Figure 12. Positive ion FABMS spectrum of the decomposition product RezCl4(CO)2(dppm)2 isolated from the electrochemical oxidation of Re2(u-H)(u-C1)C12(CO)2(dppm)2 in 0.1 M TBABF4- CH2C12 solution, showing (a) the molecular ion peak [M] = Re2C14(CO)2(dppm)2, (b) [M—CO] = Re2C14(CO)(dppm)2 and (c) [M—2CO] = Re2C14(dppm)2. 67 oowp 928$ N;— ommp - ocmw _ ommw oouepunqv 911119193 68 (ii) Electrochemical and Chemical Reduction The compound (1) exhibits an accessible reduction couple at -0.8 V vs Ag/AgCl, a process which was chemically achieved by using cobaltocene [szCo] as the reductant. Treatment of an acetone solution of (1) with one equivalent of cobaltocene produced an instantaneous color change from green to blue—green. The blue—green salt [CpZCo][Re2(u-H)(u- Cl)C12(CO)2(dppm)2] is very air—sensitive, and underwent reoxidation back to the neutral species (1) in the presence of a trace amount of water and oxygen present in the solution. The infrared spectrum of the anion product shows the same v(CO) pattern as ( 1) with a shift to lower energies of z 100 cm‘1 (Figure 10). This is consistent with the expected increase in M—CO x—backbonding upon reduction of the dimetal core. The product is nearly insoluble in all organic solvents, which is a severe drawback in the study of its solution behavior. Fortunately, the solid state EPR spectrum at —170 °C showed a well—defined signal with hyperfine coupling to the rhenium (187Re, I = 5/2) and phosphorus (“R I = 1/2) atoms (Figure 13), thereby establishing the compound as a one—electron reduction product as expected. The complex EPR behavior has been noted previously in related dirhenium phosphine complexes and is not unexpected considering the presence of two I = 5/2 nuclei for 187Re and 185Re [53]. Our efforts to isolate the reduction species extended to electrochemical methods as well. A controlled-potential bulk reduction of (1) in a 0.2 M [n-Bu4N][BF4]—CH2012 solution was carried out with an applied potential of —1.0 V. The electrogenerated monoanion [n- Bu4N][Re2(p-H)(u-Cl)C12(CO)2(dppm)2] was highly air sensitive which caused difficluty in monitoring the electrochemical process by UV-visible 69 spectroscopy and also prevented recrystallization. Studies of the redox chemistry of Re2(u-H)(u-Cl)Clz(CO)2(dppm)2 are summarized in Figure 14. D. Molecular Structures (1) Rep(ll-H)(u-Cl)C12(CO)2(dppm)2 Crstallographic data for (1) are listed in Table 3, and the important bond distances and angles for (1) are given in Table 4. An ORTEP plot of the molecular structure with the atom—labeling scheme is shown in Figure 15. The bridging hydrogen atom was not located; thus, it does not appear in the plot. The structure of the dinuclear complex consists of two trans diphosphine ligands bisecting a plane containing the rhenium atoms, two cis terminal CO groups, and the three chloride ligands. The structure is similar to those found for other carbonyl complexes of the [Re2(dppm)2]4"' unit in that the x—acceptor ligands are situated on the same side of the molecule [51]. Also, the conformation of the Re—P—C—P—Re five— membered ring formed by the metal atoms and the dppm ligand is that of a half-chair with the two methylene carbon atoms in a syn rather than anti configuration, in keeping with the 2—fold symmetry of the molecule. As in previously characterized dirhenium complexes containing CO or CNR ligands, the bridgehead carbon atoms are folded to the side of the molecule containing the x-acceptor ligands. The syn structure is preserved in solution , as evidenced by the 1H NMR spectrum in the -CH2- regions of the dppm ligands (vide supra). As the side view of the molecule (Figure 16) clearly shows, the diphosphine ligands are twisted from an 70 eclipsed conformation (x = 85°), resulting in a molecular symmetry of C2 rather than sz. The distances and angles in the molecule are within expected ranges. The metric parameters for (l) are very similar to those exhibited by other edge—sharing bioctahedral molecules such as Re2C16(dppm)2 and RezCl4(CO)2(dppm)2. In RezCl4(CO)2(dppm)2, the Re—Re—Ct angle is 125 (2)° and Re—Re—Clt = 141.3 (7)°. In the present molecule, Re—Re'—Ct = 112.2 (3)° and Re—Re'—Clt = 146.23 (5)°. The unusually small angle that the CO ligand in (1) assumes with respect to the metal-metal bond axis suggests that some attractive interaction may be occurring between the bridging hydride ligand and the CO groups. The Re—Re bond length of 2.605 (1) A is quite long for a complex formally derived from the Rep4+ core. In fact, this distance is close to those values found in Re2°+ compounds such as RezClg(dppm)2 (Re—Re = 2.616 (1) A). The long metal-metal distance in lte2(tt-H)(u-CI)012(00)2(dppm)2 is even more surprising considering that it contains a u—H group, which is known to have the effect of drawing metal atoms closer together. Clearly, more examples of these types of carbonyl-hydrido dinuclear complexes are required to explain the structural parameters of the molecule. (2) [Ream-mm-CIEMCOMW (BFJ Crstallographic data for this compound are listed in Table 5. Bulk oxidation ofa dichloromethane solution of (1) yields [Re2(u-H)(u- Cl)C12(CO)2(dppm)2](BF4) (3), as determined by X—ray crystallography. The ORTEP diagram of (3) (Figure 17) shows that the cation [Re2(p-H)(u- Cl)Clz(CO)2(dppm)2]+ is isostructural to the neutral species. Both compounds exhibit an edge—sharing bioctahedral geometry with a [Re2(u- 71 H)(u-C1)C12(CO)2(dppm)2] core which consists of two dppm ligands in trans position, three chloride ligands located on the same side and two terminal CO trans to the bridging chloride with one bridging hydride occupying the other bridging position. The bond lengths and bond angles for (3) listed in Table 6, compare favorably to those for (l). (3) [Regal-CO)01-Cl)Clg(CO)G\lO)(dppm)2l (BF4) Crystallographic data for this compound are listed in Table 5. Chemical oxidation of compound (1) with the use of NOBF4 led to the isolation of a nitrosyl complex [Rez(u-CO)(u-Cl)Clz(CO)(NO)(dppm)2](BF4) confirmed by an X—ray diffraction study. The dinuclear complex consists of an edge sharing bioctahedral ligation sphere. The molecular structure of (2) represented by the ORTEP diagram is shown in Figure 18. A stereoview of the molecule (2) is illustrated in Figure 19. A listing of selected bond distances and angles are given in Table 7. The good n—accepting properties of the NO and CO ligands reduces the electron density at the metal center, thereby enhancing the Re—Cl x—donating interaction. The synergistic effect between the x—accepting and terminal n—donor ligands may well explain the short terminal bond distances. A comparison of the main features of molecular structres (2) and (3) is shown in Figure 20, and a comparison of a series of edge-sharing bioctahedral dirhenium complexes with "Re2013" ccores is shown in Figure 18. 72 5. SUMMARY The studies described herein were undertaken to gain a more complete understanding of the formation of an unusual hydrido-dirhenium complex. We have verfied that the compound Re2(u-H)(u- Cl)Clz(CO)2(dppm)2 can be prepared by reactions of with carbonyl clusters under an H2 atmosphere and the direct reaction of Re2(u-H)(u- Cl)Clz(CO)2(dppm)2 with a CO/H2 gas misture at atmospheric pressure. The role of H2083(CO)10 as a cluster presursor appears to be an important one in the high-yield synthesis of Re2(p-H)(ll-Cl)C12(CO)2(dppm)2. We have also noted the behavior of H2 in assisting the reaction to form the complex. Attempts to stabilize reactive intermediates might also provide an interesting mixed-metal complex in this reaction. Furthermore, the compound Re2(u-H)(u-Cl)Clz(CO)2(dppm)2 exhibits a high redox activity, and an intensive effort has been made to isolate both oxidation and reduction products, namely [Re2(u— H )(u - Cl)C12(CO)2(dppm)2]+ and [Rez(u-H)(u-CI)C12(CO)2(dppm)2]'; successful attempts were achieved by electrochemical and chemical methods. 74 Figure 13. An X—band EPR spectrum taken on a solid sample of [szCo][Regal-H)(lL-Cl)Clz(CO)2(dppm)2] at —150 °C. 75 l l l l 1300 2100 2900 3700 4500 5300 Field (Gauss) Figurel3 76 Figure 14. Schematic diagram depicting the redox reactions of Regul- H)(u-Cl)C12(CO)2(dppm)2. 77 3 0.53% E 5 Us Us 8 6 co 8 co / _\ I \ / _\r/_ \ eum 30(F02). The refinement converged with residuals of R = 0.0395 and RW = 0.0563. 3. Results and Discussion A. Synthetic Methods The thermal reaction between Ru3(CO)12 and R92C16(PBu3")2 led to the isolation of a double halide—bridged trinuclear carbonyl phosphine cluster Ru3(CO)8(u-Cl)2(PBu3")2 which was confirmed by an X—ray diffraction study. It is obvious that the compound results from a ligand transfer reaction, a situation that was also observed for the reaction between Os3(u-H)2(CO)10 and (n-Bu4N)RezCla to give the known edge doubly—bridged trinuclear carbonyl clusters 083(u-H)(u-Cl)(CO)10 [59]. It is well established that multiply metal-metal bonded dinuclear complexes undergo facile metal- metal bond cleavage upon the reaction with n-acceptor ligands such as carbon monoxide, and isocyanides. It is reasonable to predict that the intractable brown residue contains mononuclear carbonyl halide complexes of Re. 103 The original synthesis of Os3(u-H)(u-Cl)(CO)10 involves the reaction of Os3(p.-H)2(CO)10 with C12. This study simply serves to demonstrate that an alternative source of CI‘ for the preparation of the edge doubly-bridged trinuclear carbonyl cluster Os3(u-H)(u-Cl)(CO)10 can be a dinuclear chloro— phosphine complex. Among the edge doubly—bridged trinuclear carbonyl clusters (Group 8), the three most common are of the types M3(u-H)2(CO)10, M3(u-H)(u-X)(CO)10 and M3(u-X)2(CO)10 (X = halide); these are illustrated below. \ H \ H \ X 7i ; é H g g X g g X M3(u-H)2(CO)10 M3(u-H)(u-X)(CO)10 M2(”'X)2(CO)10 These three structural types also exhibit different electronic properties and reactivities. In the first class, 083(u-H)2(CO)10 is the only known dihydride—bridged species of its kind, as the ruthenium analogue has not yet been observed. The molecule Os3(u-H)2(CO)10 is a 46—electron unsaturated molecule, and it exhibits a high reactivity with great potential for catalytic applications owing to its inherent coordinative unsaturation. The second class of edge doubly-bridged clusters, M3(u-H)(u-X)(CO)10 (M = Os, Ru), comprises the 48—electron saturated clusters which show only moderate reactivity [60, 61]. Additionally, another type of cluster, M3(u-X)2(CO)10 contains an open edge in the molecule with no metal-metal interaction [61]. Although the species has a relatively high stability, the presence of two bridging chlorides results in a labilizing effect on the CO 104 groups in the trans positions. For example, the reaction of Os3(u-Cl)2(CO)10 with triphenylphosphine leads to a disubstituted cluster Os3(CO)3(PPh3)2(u- C1)2 which is formed via CO exchange with triphenylphosphine; the exchange reaction does not occur with Os3(CO)12 under the same mild conditions. B. Molecular Structure The structural data for Ru3(CO)8(u-Cl)2(PBu3")2 are listed in Table 9; selected bond distances and angles are given in Table 10. An Ortep drawing including the labeling scheme is shown in Figure 22. The cluster possesses approximate C2,, symmetry with a triruthenium framework involving two metal—metal bonds [ Ru(1)—Ru(3) = 2.859 (DA; Ru(2)——Ru(3) = 2.871 (1) A] and one open edge Ru(1)-.-Ru(2) supported by two bridging chlorides 01(1) and Cl(2). The metal—metal separation between Ru(l) and Ru(2) is 3.230(1) A, which is in agreement with the prediction for a zero bond order. Similar non—bonding distances have been found in closely related edge double- bridged species such as Ru3(u-NO)2(CO)10 (3.150 (2) A) and Ru3(u-I)2(CO)10 (3.301(1)A ). Atoms Ru(l) and Ru (2) are coordinated to two CO groups and one PBua’f ligand, respectively. Both PBu3" ligands occupy nearly equivalent equatorial sites which are trans to the unique ruthenium atom Ru(2). Carbonyl ligands are located in the positions opposite to the bridging chloride atoms. The trans influence of the Cl atoms results in an average value of metal-carbon bonds trans to 01 of 1.816 (1) A, significantly shorter than the corresponding value found for metal-carbon bonds to Ru(2) (average 1.909A ). 105 Table 9. Crystal Data for Ru3(u-Cl)2(u-PBu3")2(CO)3 Formula Formula weight Crystal system Space group a, A b, A c, A a, deg 13. deg 7. deg v, A3 Z dcalc» g/cm3 Crystal size, mm Ru3C12P203C32H54 1002.8 Monoclinic P21/n 11.093 (2) 20.959 (3) 19.221 (2) 90 95.092 (2) 90 4451 (3) 4 1.532 0.50 x 0.45 x 0.38 Radiation Mo KaOt = 0.71073 A) 11. cm’1 12.187 Data collection instrument Nicolet P3/F Temperature, °C 22 i 2 Scan method 0) — 20 Data col. range, 20, deg. 4.5 — 55 R“ 0.039 .311) 0.056 aR=2llF,|-ch|l/2|F,l bRw=[2wlF,|- IFCI)2/Zw|1=,l2]"2;w=1/02(|F.|) 106 6 NE: 65 6:5 6:5 6 3.5 66 6:5 66 6 an; 66 6:5 6:5 6 mm: 66 6:5 66 6 8.3 66 6:5 6:5 6 55.8 65 6:5 66 6 6.5 66 6:5 6:5 6 2.3 65 6:5 66 6 6.; 66 6:5 6:5 6 6.3 65 6:5 66 6 6.5.: 65 6:5 6:5 6 55.8 65 6:5 66 6 3.6 6:5 6:5 6:5 6 3.: 66 6:5 66 6 6.? 6:5 6:5 6:5 6 mm: 66 6:5 66 6 36 6:5 6:5 6:5 2.5.2 .8. as... m 882 5 :82 25:4 5 as... a 834 H :82 6 6.5 66 6:5 6 6: 66 6:5 6 65.5 66 6:5 6 6: 66 6:5 6 £3 66 6:5 6 63 66 65 6 6.5 66 6:5 6 63 :66 65 6 2.3 65 6:5 6 55: E6 65 6 63 6:5 6:5 6 on: 66 65 6 525 6:5 6:5 6 $3 65 6:5 6 85m 6:5 6:5 853me N 834 H 834 355me N 83¢. a 834 85.555685066565635 .85 653 825.2. 5:: 6 825355 255 5.3855 .2 52:5. 107 Figum22. ORTEP drawing of Ru3(u-Cl)2(PBu3")2(CO)3 showing the atom labeling scheme. All n-butyl carbon atoms are represented as small circles for clarity, and all other atoms are represented by their 50% propability ellipsoids. 108 £\\\(8) ‘ f7 \ ,1" C(4)@, \ C(29) o .- <.§ RUG) 6.. Rum f ‘C(7) 0(4) “1‘, om a5) (1.9 “\ C(9) J C(IO) \ '0’}; C(2) 4‘ C(32) 0(6) “in; C (”’3‘ C(IB) \ CHI) ’5) 0(2) C09) C02) Figurezz 109 4. Summary The work describes a possible route for bridging the area of ‘classical’ organometallic and coordination chemistry. The halide carbonyl clusters derived from the reactions between Ref—Re halide complexes with metal carbonyl clusters demonstrate a promising approach toward the syntheses of a new class of reactive mixed-ligand compounds which may exhibit unique electronic properties induced by the combined presence of the dramatically different donor ligands. 110 CHAPTER IV REACTIONS OF THE MULTIFUNCTIONALIZED PHOSPHINE LIGAND TRIS(2,4,6-TRIMETHOXYPHENYL)PHOSPHINE WITH DINUCLEAR CARBOXYLATE AND SOLVATED METAL COMPLEXES 111 1. Introduction It is well-known that metal phosphine complexes are good catalyst precursors in important reactions such as hydrogenation, hydroformylation, and polymerization. The investigation of bulky and labile phosphine ligands is especially interesting due to the formation of reactive coordinatively unsaturated molecules. One of our recent research interests is to explore the chemistry of the unusually large and basic phosphine ligand tris(2,4,6-trimethoxyphenyl)phosphine (TMPP) with a wide variety of transition metal complexes. The first TMPP metal complex that was prepared in our laboratories is [Rh(TMPP)2](BF4)2, a novel Rh(II) monoclear compound possessing a chelating tridentate arrangement for the PR3 ligand. Since both oxygen and phosphorous atoms are good donors, one may envision a variety of possible multidentate coordination modes for the ligand involving either chelates or bridges. The use of this highly flexible ligand in the series of complexes [Rh(TMPP)2]"+ (n =1, 2, 3) afforded us the rare opportunity to probe the geometrical preferences of a metal center as a function of the electronic configuration. We were intrigued by these results in mononuclear chemistry, and our research interest was further extended to exploring the possibilities that this ligand might have in higher nuclearity metal compounds. It has been known that bidentate phosphine ligands with bridging coordination tendencies are very useful for studying the reactivites of complexes that contain metal—metal bonds because of the variety of structural types that result from binding these molecules. In this respect, one of our research efforts thus focuses on the investigation of the multifunctionalized phosphine TMPP with metal—metal bonded species. Among them, carboxylate—bridged metal complexes M2(OzCCH3)4 (M = 112 Rh(II), Mo(II) ) were chosen as precursors in this study because they have been extensively studied in the past two decades [62]. The intense research interest in rhodium(II) and molybdenum(II) carboxylates has continued to grow in recent years, as more researchers explore structural and spectroscopic properties, ligand substitution, redox reactions [66] in solution and potential practical applications [64-65] of these complexes. In early investigations, we found the low solubility of M2(02CCH3)4 to be a main drawback for the study of its reactivity toward a nucle0phile. The solubility of these systems can be dramatically improved by the use of fluorinated carboxylate ligands. Trifluoroacetate metal complexes M2(OzCCF3)4 with ‘paddlewheel’ structures [63] are isostructural to M2(02CCH3)4, but they demonstrate more facile ligand substitution in many reactions due mainly to their great ligand lability. A series of reactions between trifluoroacetate molybdenum (II) complexes M02(02CCF3)4 and tertiary phosphines were carried out by Anderson and co-workers who concluded that two main types of reactions were occurring, depending on the combined influences of phosphine basicity and their steric bulk. A graph of ligand size versus basicity for various phosphine ligands is given in Figure 23. In general, larger phosphine ligands with low basicity prefer to form bis-adducts in axial positions, and smaller ones with high basicity occupy the equatorial positions along with two bridging and two monodentate dangling trifluoroacetates. Since the TMPP ligand exhibits unique electronic and steric properties with multidentate functionality, namely high basicity and large steric bulk, we explored the reactivity TMPP with trifluoroacetate metal complexes. 113 Figure23. A graph of ligand size versus basicity. The ligand size and basicity are expressed by the cone angle and v(CO) value, respectively. The cone angles and v(CO) values (smaller values indicating greater o-donor and poorer n-acceptor properties) were taken from Tolman's work [22]. ( R = CF3 ) ( L = Phosphine in Class I ) 114 o o/ \o 8 LI 0—0’ I/ / \ 0‘ M0 /M0 0 ,0—0/ I L I R o o \9/ R (R=C&) ( L = Phosphine in Class 1| ) . . e ' P . o CYaP 0 . Class I g, 160 - o O 0 140 r . MePth £139 - - PY o (PhO)3P . MezPhP, 12° ' M93P - Class II . (M60)3P l l L 2060 2070 2080 2080 (cm-1) vM(CO) for LNi(CO)3 Fisure23 115 2. Experimental A. Synthwis (1) Reaction of Rh2(OzCCH3)4 (MeOH) 2with TMPP (i) Synthesis of Rh2(0200H3)2(TMPP-O)M80H) (l) Rh2(02CCH3)4(MeOH)2 was prepared according to a literature method [67]. A suspension of Rh2(OzCCH3)4(MeOH)2 (0.100 g, 0.198 mmol) and TMPP (0.211 g, 0.397 mmol) in ethanol (20 mL) was refluxed for 12 h to give a dark green-brown solution. The solvent was removed in vacuo to ca. 3 mL, and then chromatographed on a silica gel column with CH2C12 as eluent to remove a yellow band. The yellow product was characterized as the [MeTMPP][CH3COO] phosphonium salt. 1H NMR (00013): 8 = 6.13 (d, JHP = 5 Hz, m-H), 3.89 (s, p-OMg), 3.58 (s, o-OMg), 2.45 (d, JHP = 15 Hz, Mg- TMPP) Ppm. A second green band was collected with acetone as eluent, and the product was spectroscopically and structurally characterized as the compound Rh2(02CCH3)3(TMPP-0)(MeOH) (1). Yield: 0.118 g (64%). Recrystallization was carried out by slow diffusion of diethyl ether into a methanol solution of (l), and a crop of green crystals was obtained at room temperature after several days. UV-vis (CH3CN): Am, = 600 nm (e = 174.84 M-lem-l). IR (Nujol): (7,4000) = 1590 can-1. “P NMR (onscm: s = 9.8 ppm ((1, Jp_Rh = 158.9 Hz). Crystalline samples that are subjected to a static vacuum for 24 h lose interstitial ethanol of crystallization and the labile axial methanol ligand, as evidenced by 1H NMR spectroscopy and FABMS spectrum: parent ion, m/z = 900.1 (1°3Rh) corresponding to 116 Rh2(OZCCH3)3(TMPP-0). Anal. Calcd for C32H39015P1Rh2: C, 42.51, H, 4.65. Found: C, 42.68; H, 4.37. (ii) Chemical Oxidation of Rh2(02CCH3)3(TMPP-0)(Me0m A solution of NOPF6 (0.0188 g, 0.107 mmol) in CH3CN (5 mL) was slowly added to Rh2(OzCCH3)3(TMPP-O)(MeOH) (0.100 g, 0.107 mmol) in CH3CN (10 mL). The green solution turned brown immediately, and after the mixture was stirred for ca. 5 min, the solvent was removed in vacuo. The dark greenish—brown residue was extracted with 10 mL of CH2C12 after which time diethyl ether (10 mL) was added to induce precipitation. A brown microcrystalline solid was collected on a medium—porosity frit under argon and dried in vacuo. The product was recrystallized by slow diffusion of diethyl ether into a CH2C12 solution of the compound. UV—vis (CH3CN): 71m, = 330 (sh), 295 nm. IR (Nujol): (7,4000) = 1590 eta-1. v(P— F) = 845 cm'l. 1H NMR: broad and featureless. When an excess of NOPF6 (0.0250 g, 0.143 mmol) was used, a different brown product was obtained. IR (Nujol): (7,4000) = 1590 can-1. v(NO) = 1720 cm-l. 1H NMR : broad and featureless. FABMS spectrum: parent ion, m/z = 915 (1°3Rh) corresponding to the nitrosyl product Rh2(OzCCH3)3(TMPP-20)(NO). . (2) Preparation of Moa(OgCCF3)4 The method is a slight modification of the synthesis reported in the literature [68]. A suspension of M02(02CCH3)4 (1.00 g, 2.336 mmol) in CF3COOH (30 mL) and (CF3COO)20 (5 mL) was refluxed to give a clear yellow solution, and the reaction was stopped after ca. 20 min. The hot solution was immwiately filtered by suction through a medium porosity frit, and the yellow filtrate was subsequently reduced by using a water 117 aspirator to 5 mL. From this procedure, a crop of yellow crystalline solid was obtained. Further purification was carried out by sublimation to give a finely divided sample of M02(02CCF3)4. IR (Nujol): vas(COO) = 1590 cm‘l. 19F NMR (CDCl3) : 8 = -7 3.45 ppm. (3) Reaction of Moz(0200F3)4 with TMPP A yellow solution of M02(02CCF3)4 (0.100 g, 0.155 mmol) and TMPP (0.165 g, 0.310 mmol) in THF or acetone (20 mL) was stirred at room temperature with no apparent color change after ca. 30 min. After the solvent had been reduced in volume, the yellow solution turned reddish— yellow, and a red residue was obtained after complete evaporation of the solvent. The residue was extracted with diethyl ether to give a red solution, leaving behind a pale yellow-brown solid. The yellow-brown product was investigated as a [MeTMPP]+ phosphonium salt with an unidentified counterion. IR (Nujol): Va,(COO) = 1600, 1680 cm‘l. 1H NMR (CDCl3): 8 = 6.13 (d, JHP = 5 Hz, m-H), 3.89 (s, p-OMg), 3.58 (s, o-OMg), 2.45 (d, JHp = 15 Hz, Mg-TMPP) ppm. The red extract was treated with a mixture of toluene and hexane to give a red solid. The red product was investigated by various spectroscopic methods; IR (Nujol): v”(COO) = 1600 cm'l. UV—vis (CH2C12): Am“ = 527, 315 nm. FABMS spectrum: parent ion, m/z = 1452.8 (96Mo). (4) Preparation 0f Rh2(020CF3)4 The method used in our laboratories is a modification of the literature procedure [69]. A suspension of Rh2(OzCCH3)4(MeOH)2 (0.200 g, 0.397 mmol) in CF3COOH (20 mL) and (CF3COO)2O (5 mL) was refluxed for 3 days to give a green solution. Filtration in air led to a clear green filtrate which was reduced in volume on a water aspirator to 5 mL to give a green 118 solid. Sublimation to remove trace amounts of CF3COOH and (CF3COO)2O was carried out, and a fine green powder was obtained. IR (Nujol): vas(COO) = 1650 cm‘l. UV—vis (CH3CN): Am” = 550, 450 nm. (5) Reaction of Rh2(OZCCF3)4 with TMPP A suspension of Rh2(02CCF3)4 (0.100 g, 0.165 mmol) and TMPP (0.275 g, 0.330 mmol) in THF (20 mL) was stirred at room temperature for 30 min to give a clear green solution. The solvent was removed in vacuo to 3 mL, and then chromatographed on a silica gel column with acetone as eluent to lead to a green band. The first green band (1) was collected with acetone as eluent, and a second green band (2) was removed with MeOH. UV-visible spectrum (CH3CN): band (1 ), Am” = 586 nm; band (2), Am” = 594 nm. B. X—ray Crystal Structure of Rha(OZCCH3)3(TMPP-0)(MeOH) (l) (1) Data Collection and Reduction A green crystal of approximate dimension 0.78 x 0.52 x 0.20 mm3 was covered with epoxy cement and mounted at the end of a glass fiber. Geometric and intensity data were obtained on a Nicolet P3/F diffractometer equipped with graphite—monochromated MoKa radiation. A rotation photograph was used to locate 15 reflections from which a preliminary cell was indexed. The reduced cell dimensions indicated that the crystal was triclinic which was confirmed by axial photography. An accurate cell for data collection was calculated from 20 reflections in the range 20 S 20 5 30°. An 00-20 scan motion was used to scan 7053 data points in the range 4 s 20 S 50°. The structure factors were obtained after correction for Lorentz and 119 polarization effects. During data collection, three check reflections were measured every 100 reflections; no loss in intensity was observed. (2) Structure Solution and Refinement The positions of the Rh atoms were obtained from a Patterson Fourier map. A sequence of successive difference Fourier maps and least-squares cycles led to full development of the coordination sphere. The final full- matrix refinement involved 451 parameters and 6209 obsertvations with F02 > 30(F02) for a data—to—parameter ratio of 11.3. The refinement converged with residuals of R = 0.0504 and Rw = 0.0858 and a quality—of-fit of 2.93. The largest shift/esd in the final cycle was 0.96. 3. Results and Discussion (1) WI! Of Rha(020CH9)4(MeOH)2with MP A. Syntheds Reactions of the ether—phosphine ligand tris(2,4,6-trimethoxy- phenyl)phosphine (TMPP) with Rh2(020 CH 3)4(MeOH)2 in refluxing alcohols yield the demethylation product Rh2(OzCCH3)3(TMPP-0)(MeOH). The excess TMPP in solution is methylated to form a phosponium salt as evidenced by 1H NMR spectroscopic studies performed on residues retrieved from the filtrate. The reaction has been successfully carried out in methanol and ethanol with the latter solvent producing a higher yield of (l) (67% verus 40%) for a shorter reflux time (6 h verus 24 h). The identical experiment in THF results in no observed reaction for reflux times up to 120 several days. Further attempts to obtain analogous rhodium complexes in acetic acid proved to be unsuccessful. Since the highly basic TMPP (pKa =- 11) is a good nucleophile, it can easily form a phosphonium salt by either protonation or methylation. A summary of these reactions is shown in Figure 24. B. SpectroscopicStndies The room temperature 300 MHz 1H NMR spectrum of (1) in CD3CN reveals that the TMPP ligand is ligated in a completely unsymmetrical fashion about the two metal centers. Four meta protons are well—resolved quartets, and resonate at 8 = 6.52, 5.96, 5.84, and 5.65 ppm; two ring protons, appear as virtual triplets at 8 = 6.15 and 5.93 ppm (Figure 25). After 31P decoupling, all six meta protons are simplified into doublets (Figure 26). Eight methoxy group resonances were observed, with the most deshielded signal at 8 = 2.57 ppm being assigned to the ring that participates in an axial interaction with the metal center. The absence of a ninth methoxy group suggested that demethylation had occurred, which was subsequently confirmed by a solid state structrual determination. The DQCOSY spectrum of (1) (Figure 27) clearly shows the J— coupling between H1 and H2, H3 and H6, H4 and H5 via their mutual cross— peaks. Due to the strong bonding between ring 1 and Rh(2) via a methoxide interaction, the most deshielded protons H1 and H2 were assigned to this ring. The two meta protons in the free phenyl ring have similar environments, thus we assign protons H4 and H5 to ring 2. Finally, H3 and H6 are in the same ring based on correlated crosspeaks, and a further study reveals that the chemical shift of H3 is very solvent dependent. The meta proton region of (1) between 5.0 and 6.5 ppm, measured in five different 121 Figure 24. Schematic diagram of various approaches to the synthesis of Rh2(02CCH3)3(TMPP-0)(MeOH). 122 68.66.555.256 52685 oz 6885855525556. + A .563 25062255266685.6665 68856655258565 + A .86 60665525665863”. «Nah—ME : N :9.”— 508:6 : VN .xacom E : VN .xsaom :00: n c .53qu loam AEN 5662 u .56 550626558635 9 _\o \o nlfiléln eatex _ C 123 Figure25. A 300 MHz 1H NMR spectrum of Rh2(02CCH3)3(TMPP- OXMeOH) in CD3CN at 22 °C. m._. m.N PFDkPP—lrhlLtPthLrbLbb 5w. 124 111‘--.) 7 j) Wm rL j? mN 959% m6 hbthLLbFPPL-rb it) 06 p h 125 Figure26. A 500 MHz 1H NMR spectra of the meta proton region of Rh2(OzCCH3)3(TMPP-O)(MeOH) in CD3CN at 22 °C with (a) 31P decoupling (b) 31P undecoupling. 126 (a) l , , 3‘ ‘ J V ‘ r L l ‘ - :4, yr V ‘\ fl ‘ J M \Mw'mefi" WWW” "V“ *smV-nfi— ‘95. , wa 6.6 6.4 6.2 6.0 5.8 5.6 PPm “M23 127 Figure 27. Two-dimentional DQCOSY spectrum of Rh2(02CCH3)3(TMPP- OXMeOH). 128 16° MeOH\ / —\0/ Rh / 0’ I>Rh 0M. /' lo I H o P \ H / \0’62’ 0 0 H 5° 0 I H\ 0\ 1L '- 1111 L11 :1 1 1 1 F2 J A LLJ L) g.) 1 2... 3 (ppm) : 5.6- £ db" 8’ 1 ~I';J 5" 33 1 6.0 - S“ a “i a a 5‘6 e 6.2 ‘1 6.4 "‘ l 1 d in t 6.6-1 ‘ a! l i _, 6 6 6 4 6.2 6.0 5 8 5 6 F1 (ppm) 129 deuteriated solvents are shown in Figure 28. The quartet denoted by an asterisk symbol (H3 in CD3CN) shifts to an upfield position. These observations are consistent with axial ether group exchange with the solvent. The ring proton in close proximity to the axial methoxy ligand is expected to be most afi'ected by the chemical enviroment of the position. The Brucker simulation program PANIC was utilized to obtain further coupling constant information (Figure 29): J mm = 1.94 Hz, J Hlp = 4.20 Hz, JHzp = 2.15 Hz, J Han, = 2.37 Hz, J Hap = 4.60 Hz, JHsP = 4.00 Hz, JHm15 = 2.15 Hz, Jmp = 2.70 Hz, and JHsp = 3.91 Hz. The smaller coupling constants J Hzp and Jmp are consistent with the observation that both triplets of H2 and H, are due to a second order effect. 31p {1H} NMR studies in CD3CN revealed a doublet at 8 = 9.8 ppm with J p__Rh = 159 Hz versus 85% H3PO4 (Figure 30). A FABMS spectrum of the compound reveals the higheat observed mass peak at m/z = 900.1 (1°3Rh) corresponding to Rh2(02CCH3)3(TMPP-0). The result supports the idea that the axial ligand MeOH is quite labile (Figure 31). C. Molecular Structure of Rh2(OchH3)3(TMPP-O)(MOOH) (1) Compound (1) was recrystallized from MeOH and diethyl ether to give green crystals, one of which was examined by single crystal X-ray diffraction methods. The crystallographic data are shown in Table 11, and the important bond distances and angles for (l) are given in Table 12. An ORTEP plot of the molecular structure with the atom—labelling scheme is shown in Figure 32. The molecule contains an unusually bonded u-n3— TMPP ligand. Of particular note in this structure, is the transformation of an ether group on the phosphine to an alkoxide thus allowing for a strong 130 Rh(1)—P(1)—-C(7)—C(8)-—0(7)—Rh(2) metallacycle to form. The Rh(2)-— 0(7) bond distance of 2.048 (2) A is substantially shorter than the axial ether interaction Rh(1)—O(10) of 2.351 (2) A. Other metric parameters within the molecule are within usual ranges for dirhodium(II,II) complexes. The Rh—Rh bond distance of 2.4228 (3) A is slightly longer than that found for the complex Rh2(OzCCH3)4(MeOH)2 in which the Rh—Rh distance is 2.377 (1) A. Although ortho-metallation is quite common among mononuclear complexes in which the ortho—metallated tertiary phosphine acts as a chelating ligand with a four—membered ring, it has not been well explored among metal-metal bonded complexes. Until recently, several reports showed that triarylphosphines such as triphenylphosphine can be transformed via ortho—metallation into an unusual tridentate mode of coordination as in 082C12(OAc)2(Ph2PC6H4)2 and Rh2(OAc)2(Ph2PC6H4)2L (L = pyridine or CH3COOH) [70]. D. RedoxChemisry The cyclic voltammogram of Rh2(OzCCH3)3(TMPP-0)(MeOH) in 0.1 M [n-Bu4N][PF6]—CH3CN exhibits a one-electron quasi—reversible oxidation at +0.78 V vs. Ag/AgCl with a peak-to—peak separation of 70 mV at 200 mV/sec which confirms that the reduction process is reversible (Figure 33). Further investigations at various scan speeds revealed a reversible couple at high scan speeds (100 to 10,000 mV/sec) but at slower scan speeds (20 to 100 mV/sec), the wave clearly becomes irreversible (Figure 34). These results suggest that the formation of (2) by the process Rh2(II,II) -) Rh2(II,III) is immediately followed by a chemical reaction 131 which is most likely a ligand substitution reaction at the axial site as depicted below. Me Me Rh—Rh— ’ - e- Rh—Rh— ’ _Me, Rh—Rh— I I l l _ » I | ___.. (I) Fl, OVP *9 OVP v Oxidative bulk electrolysis of complex (1) in 0.1 M [n-Bu4N][PF6]— CH3CN, at an applied potential of +1.0 V, is accompanied by a color change from green to orange-brown. The orange—brown product was charcaterized to be an EPR-active species. The frozen solution EPR spectrum of the electrogenerated cation (Figure 35) in 0.1 M [n-Bu4N][PF6]- CH3CN is comprised of three relatively broad signals at g1 = 2.05, g2 = 2.02, and g3 = 1.996 which are consistent with a metal—centered, unpaired electron; the rhombic nature of the spectrum is due to the low symmetry of [Rh2(OchH3)3(TMPP-O)]+ (~ 02) [71]. The electrolyzed species is quite unstable, and undergoes further decomposition evidenced by the disappearance of the EPR signal over longer periods of time. Chemical oxidation of Rh2(OzCCH3)3(TMPP-O)(MeOH) by reaction with one equivalent of N OPFG yields a brown EPR—active product (2), which was investigated by several spectroscopic methods. The broad and featureless 1H NMR spectrum clearly indicated that the compound is paramagnetic, thus supporting the formulation as a Rh2+6 species. The infrared spectrum of (2) exhibits an absorption at 790 cm-1 which corresponds to the v(P—F) of the PF; counterion. Additional evidence to support the formation of the product as a paramagnetic salt is the 31P NMR 132 spectrum which shows a resonance at ca —100 ppm due to the PF; anion but no resonance for the phosphine ligand. Based on those spectroscopic investigations, the oxidation product is believed to be [Rh2(02CCH3)3(TMPP- 0)](PF6); an exact formulation of the molecule is still not clear without a crystallographic study. If the oxidation reaction is carried out in an excess of NOPFG, a brown product forms which is paramagnetic as evidenced by 1H NMR spectroscopy. A FABMS spectrum of the compound exhibits the highest mass peak at m/z = 931 (1°3Rh) which corresponds to the nitrosyl complex Rh2(OzCCH3)3(TMPP-20)(NO) (Figure 36). Convincing evidence was further provided by both solution and solid-state EPR spectra (Figure 37) which showed signals at g as 2.0. The solution EPR spectrum with better resolution than the solid—state, clearly showed a triplet pattern with a small hyperfine coupling constant, indicating it might be due to an organic radical (NO"’) which would be expected to exhibit a g value close to that of a free electron (as 2.0) [72]. Based on the previous cyclic voltammetric study, the assignment of the nitrosyl formula as Rh2(OzCCH3)3(TMPP-20)(NO) ( TMPP-20 = P[(C6H2(OMe)3l{(CGH22(OMe)(O)2]2} ) is consistent with the idea of ligand substitution at the axial site upon oxidation. The formation of the compound is postulated as below. A + O/ko 0 O I O o Rh2(0AC)s(TM F’P-OXL) [8112(0’ifiisfl'li/lPP-0)(|-)l+ Rl'|2(0!\¢)5(TM PP-20)(NO) 133 Figure28. 1H NMR spectra of the meta proton of Rh2(02CCH3)3(TMPP- 0)(MeOH), measured in various solvents (a) THF-d3 (b) CD3CN (c) acetone-d6 (d) CDCl3 (e)CD2C12. 1 WI 1 1M (d) (e) 135 Figure 29. (a) Simulated and (b) experimental 1H NMR spectra of meta- protons of Rh2(02CCH3)3(TMPP-0)(MeOH). 136 (b) 5.6 5.8 6.0 6.2 6.4 6.6 ppm “801929 137 Figure 30. A “Film NMR spectrum of Rh2(020CH3)3(TMPP-0)(MeOH). 138 Fistula!” A-W 139 Figure 31. Positive ion FABMS spectrum of Rh2(OzCCH3)3(TMPP- 0)(MeOH). 140 69:55 N\ .2 coo? omm com omm com r (41 41b «11 — it - 4: . 1t 4:: _ a: 41.: - 14.—ll 4:—. 1 A 2% u ca: 55526655666635 ‘MPP- eouepunqv eAglelea 141 Table 11. Crystal Data for Rh2(OZCCH3)3(TMPP-O)(MeOH)-EtOH Formula Formula weight Crystal system Space group a, A b, A c, A a, deg 13. deg 7. deg V, A3 Z dcalc: g/cm3 Crystal size, mm Rh2P1017C35H49 978.547 Tliclinic P—l 13.730 (3) 14.396 (5) 11.921 (5) 109.65 (2) 95.65 (2) 64.32 (2) 1997 (l) 2 1.633 0.78 x 0.52 x 0.02 Radiation Mo KaO. = 0.71073 A) 11, cm'1 9.251 Data collection instrument Nicolet P3/F Temperature, °C 22 :t 2 Scan method 00 — 20 Data col. range, 20, deg. 4.4 - 40 R‘“1 0.030 wa 0.036 aR=2llF,|—IF,|l/ZIF,| bizw = [ZwlFol— ch|)2/Zw IF, P11”; w =1/62(|Fs|) 830 142 3 .8: 8:0 8:0 8: 8.88 8:0 3.2 30 3 8.82 8:0 8:0 3.. 8: 8.2.. 30 35. 3.5 3 .8: 30 8:0 30 3 8.88 30 3.2 3.0. 3 8...: 8:0 30 3.. 8: 8.8 8:0 3.2 3.. 3 N8: 880 8:0 3:0 8: 3.: 8:0 3.3 3.8 3 8.2. 8:0 8:0 3.2 8: 8.8 800 35. 3.8 3 8: 8:0 30 3.0. 8: 8.8 30 35. 3.2 3 8.8. 30 3.. 3.2 3 88.88 30 3.2 3.3 3 8.8. 8:0 30 3.8 3 8.88 3.. 3.8 3.8 28...... m as... m as... . 83¢. 285. m as... a as... H as... 3 38.. 8:0 8:0 3 83 8:0 3.2 3 9.8.. 30 30 3 838 30 3.3 3 88.. 8:0 8:0 3 888 8:0 35. 3 SS 800 30 3 83 30 3.2 3 82.. 30 30 3 838 30 3.8 3 a? 8:0 30 3 83 8:0 3.2 3 83... 30 30 3 888 85 35. 3 RS 30 30 3 £3 30 3:0 3 $8.. 880 3.. 3 888 30 3.;— 3 28.. 8:0 3.. 8: 822 3.. 3.8 3 8: 30 3.. 3 83.8 3.8 3.8 8:385 a 83.... a as... 8:385 m 834 H 834 .00.0..m0o20.0-&2.:m.mm00~0Em .8 8%: 8.8.2. 8.... 2: 82.5.5 8.30 8302.00 .fi 2.3. 143 Figure32. An ORTEP drawing of Rh2(OzCCH3)3(TMPP-0)(MeOH). showing the atom labeling scheme. All phenyl-group and MeOH carbon atoms are represented as small circles for clarity, and all other atoms are represented by their 50% propability ellipsoids. C(33) 144 Fisum32 145 Figure33. Cyclic voltammogram of Rh2(02CCH3)3(TMPP-O)(MeOH) in 0.2 M TBAPFs—CH3CN at 200 mV/s using a Pt—disk electrode. 146 T 1011A .1. 311le trade. < L J l l l l l J +1.2 +0.6 0.0 VOLTS vs Ag/AgCI Fizum33 147 Figure34. Varible scan speed cyclic voltammograms of Rh2(OzCCH3)3(TMPP-0)(MeOH) in 0.2 M TBAH—CH3CN. T 20M _.L_ 4 1011A I“ .4 511A 1- a; SOOnA t 148 $ < 2000 mV/sec 7: 100 mV/sec 20 mV/sec 149 Figure 35. An X—band EPR spectrum (—150 °C) of a 2-MeTHF/CH3CN frozen solution containing 0.1 M TBAPF6 of Rh2(02CCH3)3(TMPP-0)(MeOH). 150 V 3136 3239 3342 3445 3548 3651 Field (Gauss) W35 151 Figure36. Positive ion FABMS spectrum of Rh2(02CCH3)3(TMPP- 20)(NO). 152 000.. omm 8250...— N22 com - 41411441 14.—41:1d14 4 1¢—_ :41 11 11——ut 14 41: com eouepunqv eAueleu 153 Figure 37. X—band EPR spectra in (a) the solid state and in (b) solution for Rh2(02CCH3)3(TMPP-20)(NO). 154 I; 50 G i (a) g = 1.97 F 50 G _: (b) g = 2.01 MA A kw v “:2. 0.2:: “4 r...“ ‘42:: 102111937 155 (2) Reaction of M2(02CCF3)4 with TMPP The low solubility of M2(OZCCH3)4 is a main drawback for the study of its reactivity toward a nucle0phile. The solubility of metal complexes can be improved with use of fluorinated groups. The compound M2(02CCF3)4 was synthesized by a carboxylate exchange of trifluoroacetate for the acetate ligands in M2(02CCH3)4. The exchange reaction for M02(OzCCF3)4 is very facile, and is essentially complete after ca. 5 min of reflux. In direct contrast, the corresponding reaction of Rh2(OzCCH3)4 with CF3COOH is stepwise and proceeds much slower; hence prolonged refluxing for one day is required for a complete exchange to give Rh2(02CCF3)4. A mixture of M02(02CCF3)4 and TMPP in THF or acetone remained yellow after the solution was stirred for two hours at room temperature; however upon evacuation, the yellow solution gradually turned red, and a' red product M02(OZCCF3)2(TMPP-O)2 was isolated with extraction by using diethyl ether. The infrared spectrum of the red compound in Nujol shows the antisymmetric carboxylate stretch at 1650 cm‘1 which confirms the presence of the bridging acetate groups. Complicated solution behavior was revealed by 1H and 19F NMR spectra. The 500 MHz 1H NMR in CDCl3 indicated a magnetically inequivalent environment for the three phenyl groups of the phosphine ligand (Figure 38); the meta proton region showed . numerous multiplets at 8 = 5.72 (1H), 5.77 (1H), 5.83 (1H), 5.87 (1H), 5.92 (1H), 6.00 (3H), 6.08 (3H). The ortho and para methoxy groups displayed a complicated pattern in the region of 3.0—4.0 ppm. The 19F NMR spectrum in CDCl3 indicated some association of free trifluoroacetate with the complexes (Figure 39). In the FABMS spectrum of the red compound, the highest observed peak was at m/z = 1452.8, in accordance with the molecular ion [M02(02CCF3)2(TMPP-0)2]+ (Figure 40). Signals 156 corresponding to the [M—(CF3COO)]+ fragment at m/z = 1339.8 were also observed. According to the IR and NMR data, we propose the compound to be the bis-demethylated TMPP complex M02(02CCF3)2(TMPP-O)2. An electronic absorption spectrum (CH3CN) shows Am” values at 550 and 450 nm with the low energy absorption being assigned to the 8 —) 5* transition normally observed at such energies for quadruply—bonded dimolybdenum complexes. Without a crystal structure determination, an exact geometric arrangement of ligands cannot be known, but it is logical to expect that the two bridging TMPP-0 groups are situated in a trans orientation instead of cis based on steric considerations. We postulated that a reasonable reaction pathway for the formation of M02(02CCF3)2(TMPP-0)2 is as shown in Figure 41. The first step of the reaction is expected to be axial coordination of both bulky phosphines, and’ in fact, the yellow color observed in the initial step supports this notion, as other bisphosphine adducts M02(02CCF3)4(L)2 (L = phosphine) are electronically similar [63(c)]. The step following axial ligation is believed to be an intramolecular transformation of the bis—axial phosphine adduct to a second isomer. With both phosphines in equatorial positions, there is a possibility for demethylation to give the volatile organic substrate CF3COOMe. The trifluoroacetate dirhodium complex was also reacted with TMPP in an attempt to synthesize the dirhodium analogue of M02(OZCCF3)2(TMPP-0)2. The reactions of Rh2(02CCF3)4 with TMPP occurred under very mild conditions to give a green product which has been recrystallized from a mixture of hexane and CH2C12. The plate-like green crystal was investigated by a preliminary X—ray diffraction study which showed that the crystal was monoclinic with dimensions : a = 14.511 (9) A, b = 23.63 (1) A, c = 24.68 (1) A , s = 99.52 (4) and v = 8350 (8) A3. 157 Figure 38. A 300 Nle 1H NMR spectrum of M02(02CCH3)2(TMPP-O)2. 158 8288 159 Figm'e 39. A 300 MHz 19F NMR spectrum of M02(OZCCH3)2(TMPP-O)2. 160 8.2.5.... 161 Figure 40. A positive ion FABMS spectrum of M02(OZCCH3)2(TMPP-0)2. 162 comp 32%... N22 omvp oovw _ A 8.8: n 0?: ~83-0x§00~0§2 cmmp eouepunqv eAueleH P905 163 Figure 41. Schematic diagram of a proposed reaction scheme for the formation of M02(02CCH3)2(TMPP-0)2. PR3 —4 164 ama 0\./0 To? \oz \2. 0L. _. .8253 3.00080 m «8.059.030.0682 A .0880 u 0\J0 V .3006; 0.: 80¢ .. 3. _ xiv. a 02 o: E 0A1? \ _ 165 The cell volume corresponds well to a Z = 2 for molecules of Rh2(02CCF3)2(TMPP-O)2. These results suggest that reactions of TMPP with trifluoroacetate complexes such as Rh2(II,II) and M02(II,II) undergo ligand substitution reactions with to form stable doubly bridged— phenoxyphosphine metal complexes. (3) Reaction of W(OZCCH3)2(1‘ICMe)3](BF4)2 (M 8 Mo and Rh) with TMPP The synthesis of the solvated acetonitrile complexes [M2(02CCH3)2(NCMe)6](BF4)2 (M = Mo(II), Rh(II) ) was carried out with the use of [R3O][BF4J (R = Et or Me) as an esterification reagent. The coordinated acetonitrile ligands result in a v(CN) shift to a higher energy (2:2300 cm'l) compared to free acetonitrile (v(CN) z 2260 cm‘l) which is in agreement with the o—donating character of the nitrogen atom. The weak coordination ability of the acetonitrile ligands renders them easily displaced by strong nucleophiles. In agreement with this is a 1H NMR study that has shown that both axial and equatorial acetonitrile ligands in [M02(OZCCH3)2(NCMe)6](BF4)2 freely exchange with coordinated solvent . Corresponding reactions of [M02(02CCH3)2(NCMe)6](BF4)2 with TMPP in MeCN gave a red-purple product with a large amount of unidentified methylphosphonium salt [CH3TMPP]+ observed by 1H NMR spectroscopy. Reactions of [Rh2(02CCH3)2(NCMe)6](BF4)2 with TMPP carried out in various solvents (THF, MeCN, MeOH) produced a similar result, yielding a green product along with a large amount of a methylphosphonium salt [CH3TMPP]+ as judged by 1H NMR spectroscopy. 166 (4) Reaction of [MOg(NCMe)lo] (BFQ4wifli TMPP . The fully solvated dinuclear complexes [M2(N CMe)10](BF4)4 (M = Rh(II), Mo(II) ) have been discovered recently. The reaction of TMPP with the fully solvated dirhodium compound led to a facile metal—metal bond cleavage to give a mononuclear complex [Rh(TMPP)2](BF4)2. The reaction of [M02(NCMe)10](BF4)4 with TMPP turned brown immediately with MeOH as the solvent, suggesting a Mo/oxo species is being formed. Without the support of bridging ligands in the complex, a metal—metal bond cleavage reaction as was found in [Rh2(NCMe)10](BF4)4 also must be considered. If so, a paramagnetic Mo(II) mononuclear complex would form, and indeed, a green product that was isolated from the reaction performed in CH3CN was shown to be paramagnetic by 1H NMR spectroscopy. 4. SUMMARY The aforementioned work resulted in the isolation of the unusual dirhodium compound Rh2(OZCCH3)3(TMPP-0)(MeOH). The identity of the compound was confirmed by an X—ray diffraction study which revealed that the molecule consists of a dirhodium unit bridged by three acetate ligands and one demethylated TMPP ligand that forms two separate metallacycle rings with the rhodium atoms. In this arrangement, the phosphorus atom occupies an equatorial position, and one methoxy group in the ortho position has demethylated to form an alkoxide group. Similar reactions to yield bis-demethylated TMPP complexes are also observed in the chemistry of M2(02CCF3)4 (M = M0, Rh) with TMPP. 167 CHAPTERV REACTIONS OF TRIS(2,4,6-TRJMIETHOXYPHENYDPHOSPHINE WITH , TRINU CLEAR CARBONYL CLUSTERS 168 1. Introduction Chemistry of metal carbonyl clusters complexes has received much attention in inorganic chemistry [73], and major developments are still emerging in this field. Many of these clusters have been found to act as good catalytic precursors in a great variety of industrial processes, thus their use as homogeneous catalysts has been an active area of research for many years. The clusters under investigation for homogeneous catalysis generally consist of multinuclear metal centers surrounded by carbonyls and ancillary ligands, with the crucial role of the secondary groups being to modify the steric and electronic environment of the active species. Along this line, a central theme of organometallic chemistry is to design ligands, especially multifunctionalized ligands, and use their versatile coordination abilities to influence the activity, selectivity and stability of catalytic- systems. Traditional organometallic chemistry has developed largely through the use of soil: n—acceptor ligands such as carbon monoxide, tertiary phosphines, x—olefins, and cyclopentadiene ligands. The use of ancillary hard u—donor ligands such as oxo, imido and alkoxo ligands has only recently attracted attention. It is now well established that polynuclear metal carbonyl complexes may be attached to metal oxide supports with retention of the essential framework of the metal cluster, and in certain cases, catalytic activity of the supported cluster has been observed. For instance, it has been shown that the oxygen-bound triosmium cluster is an efficient catalyst for the hydrogenation of ethylene. Furthermore, the surface oxygen atoms are capable of functioning as either one or three electron donors, with interconversions occurring between these two 169 different coordination modes. One example of this process from a recent literature report is shown below [88]. l \“.o 5" l \“‘g . .Oo,,”’?s\ I,,’?s -—-\Os[H\Os(— = - _}C)O/ / \O / \ P \““w-. / :0 \ P “\\\ In our earlier studies of the reactivity of tris(2,4,6- trimethoxyphenyl)phosphine, we demonstrated that TMPP exhibits a wide variety of bonding modes with various mononuclear and dinuclear metal. complexes. Based on this framework of knowledge, we endeavored to extend our research to higher nuclearity systems, namely trinuclear carbonyl clusters. Chemistry of phosphines with trinuclear carbonyl clusters has been well explored, especially in Group 8 metal systems [74- 76]. Since the tertiary phosphine TMPP is very basic, high reactivity toward metal carbonyl clusters is therefore expected. We postulated that the functionalized nature of the phosphine with its hard and soft donors would provide a promising opportunity for facilitating cluster transformations in multinuclear complexes. 2.8 AS 0531f are prep by K (1)11 clear redis unde be u] a red Yello' ident 170 2. Experimental A. Synthesis The syntheses of Ru3(CO)11(NCMe), Ru3(CO)10(NCMe)2, Os3(CO)n(NCMe), and 033(CO)10(NCMe)2 described in the following section are modifications of those reported by Johnson and Lewis [77]. The preparation of (u-H)2Os3(CO)10 is a modified version of the literature report by Kaesz [78]. (1) Reaction of Fe3(CO)12 with TMPP A solution of Fe3(CO)12 (0.100 g, 0.198 mmol) and TMPP (0.211 g, 0.397 mmol) in THF (20 mL) was stirred at room temperature for 12 h to give a clear red solution. After the solvent was removed, the red residue was redissolved in THF (ca. 3 mL) and chromatographed on a silica gel column under argon. Three bands were observed; the first green band was found to be unreacted starting material Fe3(CO)12; this was followed by a yellow band which was collected with THF/hexane (1:3, v/v) as the eluent. Finally, a red product was eluted with THF/hexane (1 :1 , v/v). The TMPP-containing yellow product was investigated by various spectroscopic methods, and identified to be the mononuclear cluster Fe(CO)5(TMPP). Anal. Calcd for , Fe1P1014C32H33: C, 52.76; H, 4.57. Found: C, 53.04; H, 4.75. IR (THF): v(CO) 2023 (s), 1934 (s), 1916 (vs), 1940 (s) cm-l. 1H NMR (CDC13): 6 = 6.03 (d, JHP = 3 Hz, m-H), 3.78 (s, p-oMa), 3.43 (8, o-oMa). 31? {1H} NMR (CDCI3): 6 = 4.26 ppm. FABMS spectrum: parent ion, m/z = 728 (56Fe). The red product was structurally characterized to be the salt [HFe3(CO)11][HTMPP]. IR (THF): v(CO) = 1998 (vs), 1974 (s), 1952 (w), 1940 (w), 1748 (w). 1H NMR 171 (011013, —50 °C): 6 = 6.08 (d, JHP = 3 Hz, m-H), 3.66 (s, p-oMa), 3.69 (s, o- 0M9). (2) Preparation of Ru3(CO)n(NCMe) A solution of Me3NO (0.017 g, 0.220 mmol) in CH3CN (10 mL) was slowly added to a suspension of Ru3(CO)12 (0.072 g, 0.110 mmol) in CH2C12 (100 mL) and CH3CN (10 mL) at r.t.. The progress of the reaction was monitored by infrared spectroscopy, and stopped after 5 h of stirring at room temperature according to the disappearance of the v(CO) stretch at 2060 cm‘1 due to Ru3(C0)12. The solvent was then removed in vacuo to ca. 5 mL, filtered through a silica gel column , and eluted with CH3CN. The solvent was removed under reduced pressure, leaving behind an orange solid; yield ~ 80%. IR (cyclohexane): v(CO) = 2045(3), 2037(s), 2021(m),‘ 2001(5) and 1994(3) cm‘l. (3) Reaction of Ru3(CO)u(NCMe) with TMPP A yellow solution of Ru3(CO)n(NCMe) (0.100 g, 0.142 mmol) in THF (10 mL) was placed in a 100-mL Schlenk flask and treated with a THF solution (10 mL) of TMPP (0.121 g, 0.142 mmol) whereupon an instantaneous reaction occurred as evidenced by the formation of a clear red solution. The infrared spectrum of the reaction solution revealed the absence of a bridging v(CO) band. The solvent was removed in vacuo to ca. 5 mL, and a red solid precipitated out after hexane was added to the concentrated solution. The red compound was characterized by 1H NMR (CDCl3): 5 = 6.03 (d, JHP = 3 Hz, m-H), 3.78 (s, p-OMe), 3.48 (s, o-OMe) which indicated the product was a monodentate TMPP product, formulated as Ru3(CO)n(TMPP) derived from a ligand substitution of TMPP for a labile dill sch the WC! 172 CH3CN ligand. The red product is quite thermally unstable both in solution and in the solid state, and decomposed to an orange solution in THF after standing overnight at room temperature. Separation of the resulting mixture of transformed products by column chromatography with THF/hexane (1/2) as an eluent led to an isolation of a stable orange product which was characterized to be Ru3(u-CO)2(CO)6[u3-n2-CSH2(OMe)3][u- P{C6H2(OMe)3}2] based on an X—ray crystallographic study. (4) Preparation of Ru3(CO)10(NCMe)a A suspension of Ru3(CO)12 (0.100 g, 0.156 mmol) in CH2C12 (100 mL) and CH3CN (10 mL) was stirred and chilled in a dry ice/acetone bath at —78°C. After a solution of Me3NO (0.030 g, 0.32 mmol) in CH3CN (10 mL) had been added to the stirred suspension, the dry ice/acetone bath was removed, and the reaction mixture was slowly warmed to room temperature. This was accompanied by a color change from orange to bright yellow. The solvent was then removed in vacuo to ca. 3 mL, and a bright yellow solid precipitated from a yellow-brown solution. After the brownish-yellow solution was decanted ofl‘, the bright yellow solid was dried in vacuo for ca. 30 min. (Note: Prolonged stirring of the reaction solution at room temperature for several hours results in decomposition of the yellow compound to an uncharacterized brown product.) IR (THF): v(CO) = 20550311), 2018(vs), 1999(s), 1987(sh) and 1954(m)cm'1. (5) Reaction of Rng(CO)m(NCMe)2 with TMPP A yellow solution of Ru3(CO)10(NCMe)2 (0.100 g, 0.148 mmol) in THF (10 mL) was prepared in a 100-mL Schlenk flask, and then treated with a THF solution (10 mL) of TMPP (0.136 g, 0.148 mmol). The solvent was then 191 by an Rt Spé CID ref. by: 5011 the TBS] 173 removed in vacuo to ca. 5 mL, and chromatographed on a silica gel column by elution with THF/hexane (1:5; v/v). A major orange band was collected and recrystallized from THF/hexane at r.t. to give thin plate—like orange crystals after 2 days. A crystallographic study revealed the compound to be Ru3(u-CO)2(CO)6[u3-n2-C6H2(0Me)3][u-P{C6H2(0Me)3}2]. The infrared spectrum of the product exhibits bridging v(CO) bands at 1807 and 1866 CID—1 . (6) Preparation of (11-H)2Osa(CO)10 A suspension of Os3(CO)12 (1.0 g, 1.10 mmol) in 200 mL of toluene was refluxed for 6 h in a 500—mL three-necked round-bottom flask while hydrogen gas was continuously bubbled through the solution. As the yellow solution turned purple, the reaction was monitored by TLC with hexane as- the eluent. The solvent was removed on a rotary evaporator, and the resulting purple solid was recrystallized from hexane; yield = 0.77 g (z 82%). (7) Reaction of (u-H)2083(CO)10 with TMPP A purple solution of (u-H)2Os3(CO)10 (0.100 g, 0.117 mmol) in THF (10 mL) was added to a solution of TMPP (0.06 g, 0.117 mmol) in THF (10 mL). An instantaneous reaction occurred as evidenced by the formation of a clear yellow solution. After removal of the solvent, purification was carried out by preparative thin layer chromography by using hexane/acetone (10:1 , v/v) as the liquid phase. A yellow band was collected, removed from the plate. and extracted with hexane to give a yellow solution. The product was identified as Os3(u-H)(H)(CO)10(TMPP) based on various spectroscopic methods of characterization as well as by comparison to a series of related 174 compounds [87]; yield = 0.15g (=- 90%). FABMS spectrum: parent ion, m/z = 1385 (1920s). (8) Preparation of 083(CO)11(NCMe) A solution of Me3NO (0.017 g, 0.220 mmol) in CH30N (10 mL) was slowly added to a suspension of OS3(CO)12 (0.100 g, 0.110 mmol) in CH2C12 (100 mL) and CH3CN (10 mL) at r.t. The progress of the reaction was monitored by infrared spectroscopy, and stopped after ca. 5 h stirring at room temperature according to the disappearance of the v(CO) stretch at 2068 cm"1 due to 083(CO)12. The solvent was then removed in vacuo to ca. 5 mL, and filtered through a silica gel column and eluted with CH3CN. The solvent was removed under reduced pressure, leaving behind a yellow solid; yield = 0.082 g (~ 80%). IR (CHzClz): V(CO) = 2107 (sh), 2054 (vs), 2040’ (vs), 2017 (8, sh), 2008 (vs) and 1981 (m) ens-1. (9) Reaction of 083(C0)n(NCMe) with TMPP A light yellow solution of Os3(CO)n(NCMe) (0.100 g, 0.105 mmol) in THF (10 mL) was prepared in a 100-mL Schlenk flask, and then treated with a THF solution (10 mL) of TMPP (0.068 g, 0.105 mmol) whereupon an instantaneous reaction occurred as evidenced by the formation of an orange solution. The reaction mixture was evaporated to dryness in vacuo, the residue was redissolved in 20 mL of THF/hexanes (1:4; v/v) and concentracted until an orange precipitate began to form. The reaction mixture was cooled to ca. —10 °C to effect complete crystallization of the orange complex, which was isolated by removing the supernatant by cannula into another flask. The orange solid was washed with hexanes (20 mL), and then dried in vacuo for 2 h; yield = 0.122 g (.. 82%). FABMS 175 spectrum: parent ion, m/z = 1411 corresponding to Os3P1C37019H35, and a lower mass peak at m/z = 1385 due to [M—COT”. (10) Preparation of 083(CO)10(NCMe)2 A suspension of 083(C0)12 (0.100 g, 0.110 mmol) in CH2C12 (100 mL) and CH3CN (10 mL) was stirred and kept in a dry ice/acetone bath (—78°C). A solution of Me3NO (0.0017 g, 0.220 mmol) in CH3CN (10 mL) was slowly added to the stirred suspension, while the reaction mixture was slowly warmed to room temperature. The reaction was monitored by infrared spectroscopy, and stopped after ca. 5 h of stirring at room temperature on the basis of the disappearance of the v(CO) stretches at 2054 and 2040 cm"1 due to 083(CO)11(NCM6). The solvent was then removed in vacuo to ca. 5 mL, filtered through a silica gel column, and eluted with CH3CN. A bright' yellow band was collected, and the solvent was removed to give a yellow solid; yield = 0.084 g (a: 80%). IR (CH3CN): v(CO) = 2021 (vs), 1983 (s) 1959 (m) cm”1 . (11) Reaction of 083(CO)10(NCM8)2 with TMPP A yellow solution of 083(C0)10(NCM8)2 (0.100 g, 0.095 mmol) in THF (10 mL) was prepared in a 100-mL Schlenk flask, and then treated with a . THF solution (10 mL) of TMPP (0.0525 g, 0.095 mmol). The progress of the subsequent reaction was periodically monitored by infrared spectroscopy, the diminishing of the starting material v(CO) at 2021 cm"1 occurring with the concomitant appearance of a new band at v(CO) = 2005 cm'l. The reaction mixture was evaporated to a small volume (5 mL), and then chromatographed on a silica gel column with THF/hexane (1:2, v/v) as an eluent. An orange band was collected, and recrystallized from 176 CH2C12/hexane at r.t. to give yellow crystals after two days. A yellow crystal was structurally characterized to be O83(u-OH)(CO)9(u-n2-TMPP-O). B. X-ray Crystal Structure (1) [HFe3(CO)u][HTMPP] (i) Data Collection and Reduction A red crystal with approximate dimensions of 0.30 x 0.05 x 0.16 mm3 was mounted on a glass fiber. All measurements were made on a Nicolet P3/F diffractometer with graphite monochromated MoKa radiation and a low temperature device. A rotation photograph was used to locate 16' reflections from which a preliminary cell was indexed. Accurate cell constants and an orientation matrix for data collection, obtained from a least—squares refinement using the setting angles of 25 reflections in the range of 20 s 20 S 25° corresponded to a triclinic cell with dimensions : a = 8.342 (5) A, b = 16.43 (1) A, c = 17.36 (1) A and v = 2149 (3) A3. The data were collected at -110 :1: 2° C by using an 00-20 scan mode in a range of4 S 20 S 45° with a scan speed 4° min-1. Three standard reflections collected at constant intervals. Although no significant decrease in intensity was observed, a decay correction ( program CHORT ) was applied. The linear absorption coefficient for MoKa was 11.366 cm‘l. An absorption correction ( program DIFABS ) was applied. The data were corrected for Lorentz and polarization effects. (ii) Structure Solution and Refinement 177 All calaulations were performed on a VAX 11/750 computer using the program from SDP/VAX. The structure was solved by direct methods using the program MULTAN to give the positions of the heavy atoms. The remaining non-hydrogen atoms were located by a sequence of successive difference Fourier maps and least—squares cycles which led to full development of the coordination sphere. The final cycle of full—matrix least-squares refinement involved 554 variable parameters and 3581 observed reflections with F02 > 30(F02). The refinement converged with residuals of R = 0.0551 and RW = 0.0633. (2) Rusm-CO)2(CO)3[pg-nz-CSH2(OMe)3] [ll-P {03112(0Me)3l 21 (i) Data Collection and Reduction A plate—like red crystal with approximate dimensions of 0.05 x 0.15 x 0.08 mm3 was mounted on the end of a glass fiber and covered with epoxy cement. Geometric and intensity data were collected on a Nicolet P3/F diffractometer with graphite—monochromated MoKa radiation and a low temperature device. The crystal was indexed on 25 intense reflections in the range of 20 S 20 S 25° which gave a triclinic cell with dimensions : a = 11.209 (7) A, b = 15.60 (1) A, c = 24.73 (2) A and V = 4244 (6) A3. The symmetry and lattice dimensions were verfied by axial photography. Least—square analysis was used to refine the cell dimensions and the orientation matrix. The intensity data, gathered by the (1)-20 scan technique at —110 i 2° C, were reduced by routine procedures. Absorption corrections were applied, based on azimuthal scans of three reflections with diffractometer angle x near 90°. The linear absorption coefficient for MoKa was 11.366 cm‘ 178 1. An absorption correction ( program DIFABS ) was applied. The data were corrected for Lorentz and polarization effects. (ii) Structure Solution and Refinement Crystallographic computing was performed on a VAX—11/750 computer with programs from the Enraf-Nonius SDP package. The six unique ruthenium atoms in the structure were located from a Patterson map. The subsequent development of the coordination spheres of the two separate triruthenium molecules was routine. All non—hydrogen atoms were located with an alternating sequence of least—squares refinements and difference Fourier maps. The refinement was completed in two units, with each unit comprising one of the crystallographically independent molecules. The final cycle of full—matrix least—squares refinement converged with residuals of R = 0.0759 and Rw = 0.084. (3) Ossm-OH)2(CO)9(TMPP) (1) Data Collection and Reduction A yellow crystal with approximate dimensions of 0.10 x 0.08 x 0.15 1111!].3 was mounted on the end of a glass fiber. All measurements were made on a Nicolet P3/F diffractometer with graphite—monochromated MoKa radiation and a low temperature device. A rotation photograph was used to locate 16 reflections from which a preliminary cell was indexed. Accurate cell constants and an orientation matrix for data collection, obtained from a least-squares refinement using the setting angles of 25 reflections in the range of 20 S 20 S 25° corresponded to a triclinic cell with dimensions : a = 11.435 (5) A, b = 13.079 (8) A, c = 14.116 (9) A and V = 2085 179 (2) A3. The data were collected using a 03—29 scan mode in the range of 4 S 20 S 40° with a scan speed 3° min-1. The diameter of the incident beam collimator was 1.5 mm. Three standard reflections were measured at constant intervals with no observable decay. The linear absorption coefficient for MoKa was 92.491 cm'l. An empirical absorption correction, based on azimuthal scans of three reflections with )5 near 90°, was applied. The data were corrected for Lorentz and polarization effects. (ii) Structure Solution and Refinement All calaulations were performed on a VAXSTATION 2000 computer using the programs from SDP. The heavy atoms were located by direct methods (MULTAN) a sequence of difference Fourier maps and least— squares cycles resulted in the location of all non—hydrogen atoms. The- final cycle of full—matrix least—squares refinement involved 241 variable parameters and 2806 reflections with F02 > 30(F02). The refinement converged with residuals of R = 0.038 and RW = 0.046. (4) Osam-OH)(CO)9(u-n2-TMPP-O) (i) Data Collection and Reduction A yellow crystal with approximate dimensions of 0.45 x 0.30 x 0.08 1111113 was mounted on the end of a glass fiber. All measurements were made on a Nicolet P3/F diffractometer upgraded to a Siemens P3/V with graphite monochromated CuKa radiation and a low temperature device. A rotation photograph was applied to locate 16 reflections from which a preliminary cell was indexed. Accurate cell constants and an orientation matrix for data collection, obtained from a least-squares refinement using 1S SC at 3F (iii rel Fo- inv 30: 0.01 3.1 180 the setting angles of 25 reflections in the range 20 S 20 S 25° corresponded to an monoclinic cell with dimensions : a = 16.088 (2) A, b = 13.108 (2) A, c = 19.601 (2) A and V = 4133.5 (9) A3. The data were collected using a c0—20 scan mode in the range 4 S 20 S 106° with a variable scan speed of 3° min"1 ( in omega ). The diameter of the incident beam collimator was 1.5 mm. The linear absorption coefficient for CuKoc was 180.610 cm‘l. An empirical absorption correction, based on azimuthal scans of three reflections, was applied which resulted in transmission factors ranging from 1.00 to 0.0988. The data were corrected for Lorentz and polarization effects. (ii) Structure Solution and Refinement The three osmium atoms were located by direct methods, and the remaining non-hydrogen atoms were located by subsequent difference Fourier maps. The final cycle of full—matrix least-squares refinement involved 253 variable parameters and 2980 observed reflections with F,,2 > 30(F02). The refinement converged with residuals of R = 0.089 and Rw = 0.061. 3. Results andDiscussion (I) Triiron carbonyl clusters with TMPP A. Synthesis and Characterization Our investigation of the reaction between Fe3(CO)12 and the highly nucleophilic phosphine TMPP led to the isolation of two TMPP derivatives. A yellow compound was identified as Fe(CO)5(TMPP) based on the evidence 181 from several methods of characterization including an elemental analysis (Anal. Calcd. C: 52.76 %, H: 4.57 %; Found: 53.04 %, H: 4.75 %). A FABMS spectrum of the compound revealed the highest mass peak at m/z = 726 (5°Fe) which is in close agreement with an analysis of isotope distributions for Fe(CO)5(TMPP) (m/z = 728, (5°Fe)). Some structural information was afforded by the 1H NMR spectrum which indicated a symmetrical magnetic environment for the three phenyl groups of the phosphine ligand, as evidenced by the presence of only three resonances corresponding to the ortho and the para methoxy groups; 6 = 6.03 (d) (d, JHP = 3 Hz, m-H), 3.78 (s, p-OMg), 3.48 (s, o-OMg) ppm. 31P{1H} NMR spectroscopy showed a singlet for the product at 8 = 4.26 ppm with a downfield shift from free TMPP which occurs at 6 = -68 ppm. Recrystallization of the yellow compound from a mixture of hexane and THF yielded yellow crystals whose preliminary cell‘ revealed the crystal system to be triclinic with dimensions : a = 15.27 (1) A, b = 16.09 (1) A, c = 13.45 (1) A, a = 90.34 (7). s = 99.52 (4). y = 96.78 (7) and V = 3241 (4) A3; no further data collection was carried out due to severe twinning problems with the crystals. The second product isolated from the reaction and purified by column chromatography is the red salt [HTMPP][HF83(CO)11] characterized by an X—ray difi'raction study as well as by solution spectroscopy. The hydride resonance of [HFe3(CO)n]‘, located at 8 = —15.8 ppm, is close to the values for other [HFe3(CO)11]’ salts reported in the literature. The chemistry of metal carbonyl anions is of special interest in part because they have been discovered to promote hydride migration in the formation of stable metal formyl complexes. This finding has prompted a number of research groups to investigate the reactivity of metal carbonyl hydrides with various Lewis acids [79]. The extent of ion—pairing in salts of metal carbonyl si1 pC C8 de p2 101 fu C0 lig 43 182 hydrides has been correlated to the reactivity of these species. In general, a site on the anion that interacts with the cation is dependent on the charge polarization in the molecule. For example, the interaction of mononuclear carbonyl hydride complexes with Lewis acids usually occurs through the hydride ligands with the degree of interaction depending on the extent of the hydride basicity. On the other hand, in metal cluster anions such as [HFe3(CO)n]', the more basic center is a bridging CO group that dominates the ion-pairing interaction. It has been demonstrated that the v(CO) of the bridging CO group provides a characteristic feature for the study of the ion- pair interactions in these cluster anions [80-81]. The “free” [HFe3(CO)u]’ anion exhibits a v(CO) at ca. 1740 cm‘l, but an interaction of [HFe3(CO)n]" with the counter—cation results in a v(CO) shift to lower energies, with the degree of the shift significantly depending on the strength of the ion-‘ pairing interaction. In our particular study, the v(CO) for the [HFe3(CO)n]‘ anion occurrs at 1780 cm"1 (Figure 42), indicating there is no ion—pairing interaction present in the salt [HTMPP][HFe3(CO)11]; this was further confirmed in the solid state by a crystallographic study. A comparsion of several [HFe3(CO)11]‘ salts with various extents of cation— anion interactions represented by the different absorptions of bridging CO ligands is given in Table 13. B. Molecular Stucture A molecular structure of [HTMPP][HFe3(CO)u] is shown in Figure 43, and a stereoview of the salt is shown in Figure 44. Crystallographic 183 Table 13. Bridging carbonyl stretches of various [HFe3(CO)1 1T salts. SOlid CHCI3 CGHG TI'IF CH3CN [112Et2N] 1550 1656 1640 1745 1725 [H2(n-Bu)2N] 1550 1641 1745 [H2(i-Pr)2N] 1650 1665 1645 1745 1725 [HEt3N] 1660 1640 1642 PPN 1720 TMPP 1740 1748 184 Figure42. Infrared spectrum in the v(CO) region for [HTMPP][HFe3(CO)n]. The v(CO) stretch at 1748 cm“1 is a bridging mode. 185 1748 U I l I l I 2100 2000 1900 1800 1700 wavenumber (cm-1) Fisure42 186 data for the compound are given in Table 14, and selected bond distances and angles are listed in Table 15. The packing diagram clearly shows that the anion [HFe3(CO)11]‘ and the cation [HTMPP]+ are separated by normal van der Waals interactions without any contact ion-pairing. The anion consists of an isosceles triangular framework (Fe(1)—Fe(2) = 2.683 (1) A, Fe(2)—Fe(3) = 2.590 (1) A, Fe(1)—Fe(3) = 2.680 (2) A), wherein the shorter edge between Fe(2) and Fe(3) is symmetrically bridged by a carbonyl group (Fe(2)—C(11) = 1.924 (7) A, Fe(3)—C(11) = 1.946 (7) A) and one hydride ligand; these are located on opposite sides of the trianglar framework. (Note: The hydride is not structurally located, and appears in a calculated position with the use of the “HYDRIDE” program). The symmetrically bridging nature of the carbonyl group suggests that there is an equivalent electronic environment around both iron atoms Fe(2) and Fe(3). Three— terminal carbonyl groups are bonded to atoms Fe(2) and Fe(3), respectively, and atom Fe(l) has four terminal carbonyl groups. The molecule is of approximate C, symmetry; a mirror plane passes through Fe(l), C(l), 0(1), C(2), 0(2), C(11), C(11) and H(1), and bisects the Fe(2)—Fe(3) vector. It is noteworthy that the bond distance of C(11)—O(11) is significantly longer than the value for the bridging CO ligands in the neutral species Fe3(CO)12. The bond—lengthening feature indicates that there is a localization of anionic charge on 0(11). This observation is actually quite consistent with the literature reports that the bridging CO group is the nucleophilic center of cation-anion coupling in anion clusters. 187 Table 14. Crystal Data for [HTMPPllFe3(ll-H)(u-CO)(CO)10] Formula Formula weight Crystal system Space group a, A b, A c, A a, deg 13. deg 7. deg V, A3 Z dcalc» g/cm3 Crystal size, mm Fe31’1020C243H35 1008.19 'I‘liclinic P—l 8.342 (5) 16.43 (1) 17.36 (1) 114.85 (6) 91.95 (5) 93.69 (5) 2149 (3) 2 1.558 0.30 X 0.05 X 0.16 Radiation Mo Kao. = 0.71073 A) 11, cm‘1 11.114 Data collection instrument Nicolet P3/F Temperature, °C -110 i 2 Scan method (0 — 20 Data col. range, 20, deg. 4 —45 R“1 0.055 wa 0.063 aR=Z||F°|—|Fc||/E|Fo| b R, = [zw|F,I- IF,I)2/zw 19,1211”; w = 1/0'2(|F° I) 188 A80..." 3 4.82 2:0 2:0 3 32 8:0 362 8:62 6 3: 8 2.0 3.. 20 8.8 806.2 2:0 36.2 3 N82 «80 80 3.. 3 v.8 30 36.2 36.2 3 8.8. 8 80 2K 3 .8 30 36.2 36.2 3 EN. 8:0 36.8 36.2 3 «.8 30 36.8 36.2 3 :8. 8:0 806.2 36.2 3 8.82 30 36.2 362 3 new. 30 362 36.2 3 8.8 36.2 36.2 39.2 3 0m: 30 362 8:62 3 8.8 8062 36.2 36.2 3 N8: 800 36.2 362 3 8:8 8:62 362 362 032.... m 83¢. N 803.. H 83.3 3954 m 834 N 834 H 834 8: £2 :0 30 80 88.. 80 36.2 3 £2 80 32 8: on: 30 36.2 3 8: 80 3a 8: 88.. 30 36.2 3 03.2 330 38..” a: mm: 30 38am 3 85 8:0 8:62 8: RE 30 36.2 3 85 800 36.2 80 2.: 30 36.2 8: 8: 30 36.8 3 883 36.2 36.2 3 68.. 2:0 362 3 88.8 36.8 36.2 8: mm: 50 38.2 3 S: 38.2 38m 0023me N 834 a SS< 002.8me N ES< H 80.52 .2.0..00x00-axm-n:aoaaazemm .8 88: some... 8.8 3 58:36.2 8.60 «screw .82 836,—. 189 Figure43. An ORTEP diagram of [HTMPP][HFe3(CO)11], showing the atom labeling scheme. All atoms are represented by their 40% probability ellipsoids. 190 30 .01. 30 an36 o ‘1 30 0% a“! ,0; 'x 3.“. 30 .i so“. I \ . N26 0 E: ( .‘ 30 2:0" ~ 30 avg 9ND EC 8:0 fl» 8va \1 Av :- the 40‘; 0'0 191 Figure44. A packing diagram of [HTMPP][HFe3(CO)11], showing there is no ion—pairing interaction present in the molecule. 192 C \ I ‘x . . x. . . v ' I . v. I ‘ ‘ 'there‘ls \ / V ‘& \\/ 1‘ / . Figure“ 193 (II) 'h'iruthenium carbonyl clusters with TMPP A. Synthesis and Characterization Reactions of Ru3(CO)12 with the strong nucleophile TMPP in refluxing THF yields the red product Ru3(CO)11(TMPP) as identified by NMR studies and infrared spectroscopy. The 1H NMR spectrum showed a symmetrical magnetic enviornment for the three phenyl groups of the phosphine ligand in Ru3(CO)11(TMPP), as evidenced by the presence of one resonance in the meta region at 5 = 6.02 (d, JHP = 3 Hz, m-H) ppm, and two singlets for the ortho and the para methoxy groups located at 8 = 3.32 and 3.23 ppm, respectively. 31P {1H} NMR spectroscopy showed a singlet for the product at 8 = —15.6 ppm with a downfield shift from free TMPP (8 = -68 ppm). The infrared spectrum revealed v(CO) bands at 2003 and 2023 cm'1 ,' but no stretches that may be attributed to a bridging CO group (Figure 45(a)). These spectroscopic data support compound (1) as being a monodentate TMPP—containing cluster in which the phosphine most likely occupies an equatorial position based on streic bulk considerations. With Ru3(CO)n(NCMe) as the cluster precursor, the nucleophilic reaction with TMPP proceeds much faster, and yields the same monodentate TMPP product, Ru3(CO)n(TMPP), as in the previous reaction. However, this product is highly thermally unstable both in solution and in the solid state, and undergoes transformation as evidenced by the observation of a color change which is accompanied by spectral changes in the infrared carbonyl region. As the spectra in Figure 45(b) clearly demonstrate, two new bridging v(CO) bands at 1790 and 1800 cm”1 appear after several hours at room temperature. 194 Figure 45. Infrared spectral changes in the v(CO) region for (a) initial product Ru3(CO)11(TMPP) and (b) transformed product with bridging v(CO) bands observed at 1790 and 1800 cm‘l. 195 (a) ia‘) 1mm: iuct “ll-h (b) wavenumber (cm") Figure“ 196 Figune46. Infrared spectrum in THF for the molecule Ru3(u- CO)2(CO)6{u3-n2-C6H2(0Me)3}[u-P{C6H2(0Me)3}2]. The v(CO) stretches at 1807 and 1866 cm“1 are bridging modes. 197 [e RU3'ji1' The v(COI n l I l l 1 2100 2000 1900 1800 1700 wavenumber (cm'1) Fisure46 198 Separation of the decomposition products by column chromatography led to the isolation of a stable red product which exhibits two bridging v(CO) stretches at 1807 and 1866 cm"1 in the infrared spectrum (Figure 46). An X—ray diffraction study of the compound revealed the compound to be Ru3(u-CO)2(CO)6(u3-n2-R)(u-PR2) (R = 2,4,6-CGH2(OMe)3) which consists of a bridging—phosphido group and a triply—bonded cyclometallated trimethoxyphenyl ring. The room temperature 300 MHz 1H NMR spectrum of (2) in CD3CN confirms that the TMPP ligand is ligated in a completely unsymmetrical fashion (Figure 47). Four meta protons are multiplets and resonate at 6 = 5.84 (1H), 6.07 (1H) and 6.17 (2H); two additional signals are doublets at 5 = 5.43 (1H, JHH = 2 Hz) and 5.84 (1H, JHH = 2 Hz) ppm. Both doublets are assigned to the meta protons in the cyclometalled phenyl ring due to the absence of a coupling to the phosphorus nuclei. Seven methoxy group resonances were observed at 6 z 3.80 ppm, with two signals being shifted to the upfield region; these are centered at 8 = 2.98 and 3.10 ppm. Both shielded methoxy resonances are assigned to the ortho—methoxy groups in the cyclometallated ring because the free 2,4,6-trimethoxyphenyl group is expected to exhibit less significant chemical shift deviations from (2,4,6-trimethoxyphenyl)phosphine. The formation of the phosphido—bridged cluster Ru3(u-CO)2(CO)6(H3- nz-R)(u-PR2) (R = 2,4,6-CSH2(OMe)3) is a result of an intramolecular oxidative addition via P—C bond cleavage. Numerous phosphido bridged polynuclear complexes have been explored due to the possibility that u—PR2 bridges might function as strongly bound, flexible but inert ligands. For example, a recent study revealed that u—PRz bridges have the capability of allowing interconversion between “open” (50—electron) and “closed” (48— electron) shell clusters [85]. Figure 47. 199 A 300 MHz 1H NMR spectrum in THF-dB at 22 °C for Ru3(u- CO)2(CO)6{u3-n2-C6H2(0Me)3}[u-P{C6H2(0Me)3}2]. Resonances denoted by (a) and (b) are assigned to both ortho—methoxy groups and two meta protons, respectively, in the cyclometallated ring. MM):_ -.—__ H u _ 200 2 0C for Ruaiic- ‘1’ ]_ Resonant? 1i hm 1 1) vely’ in [he 1 1: 1 ii i 1: ! 1D 1 if i) V‘Iv—v 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 Wm .47 Fi 201 The reaction pathway to prepare many phosphido—bridged polynuclear complexes involves a transition metal mediated P—C bond cleavage which usually occurs for the corresponding tertiary phosphine complexes only under forcing conditions [82]. The first example of cluster—assisted phosphorous ligand transformation via P—C bond cleavage was observed in the course of a prolonged thermal reaction of 083(CO)12 with triphenylphosphine [83]; similar reactions with different tertiary phosphines, but parallel ligand transformations of Ru3(CO)12 were also observed [84]. Mechanistic studies of transition metal mediated P—C bond cleavage are not conclusive, but it appears that the formation of a coordinatively unsaturated intermediate often occurs prior to oxidative addition [ref]. Based on that, we propose a possible reaction pathway for the formation of the molecule Ru3(u-CO)2(CO)6(u3-n2-R)(u-PR2) (R = 2,4,6: CGH2(OMe)3) (Figure 48). In this reaction scheme, the reaction of Ru3(CO)n(NCMe) (I) with PR3 (R = 2,4,6oC6H2(OMe)3) initially produces a monodentate product Ru3(CO)11(PR3) (II) which then further transforms into a didentate product "Ru3(CO)10(u-PR3)” (III) which can further transform, via P—C bond cleavage, into the phosphido—bridged cluster Ru3(|.1-CO)2(CO)6(L13-n2-R)(p.-PR2) (V) with a cyclometallated phenyl ring and a phosphido bridge. The intermediate (IV) is expected to be very unstable. We consider the most significant result obtained from this work to be the synthesis of the 46—electron unsaturated phosphido bridged cluster Ru3(u-CO)2(CO)6(u3-n2-R)(u-PR2) (R = 2,4,6-C6H2(0Me)3). The inherent unsaturation of the molecule is revealed by its space filling model in Figure 49. 202 Figure 48. Proposed reaction pathway for the formation of Ru3(p.-CO)2(CO)6{u3-n2-C6H2(0Me)3}[u-P{C6H2(0Me)3}2]. 203 L | PR3 "I ll Ru“. / I\| I /TU\ R= ——-©~0Me e0 (L=MeCN) OMe MeO o.\ 03 _. ""Rué—C‘fhm‘l‘ ’ \ /\ ,C—Ru Pm". R O I \ I CO H (3) “M48 OMe (1) k co 1! "e lo“ u u z I | \ \/l!iu PR2 OMe Me (2) OMe "or—0M6 so“; I I\\ / \ Ru / I \ Figure 49. Computer generated spacehfilling model of molecule B of Ru3(u-CO)2(CO)6{u3-n2-C6H2(0Me)3}[u-PIC6H2(OMe)3}2]. The Ru atoms are denoted by the black balls. 205 > ;/////t/////.////’ ////I 4 ///,/./,,fl///a WW4, JW/V/ié , x, _‘ y. / _ / / / // , /////.. “M49 206 A number of unsaturated cluster complexes have been prepared [86], and, in general, they are able to undergo associative reactions with a variety of reagents under mild conditions. Based on this consideration, we expect the molecule Ru3(u-CO)2(CO)6(u3-n2-R)(u-PR2) to have similar reactivity to give a saturated molecule. It is reasonable to expect that one possible addition reaction of the molecule involves the opening of the weak ether interaction as shown in the reaction scheme (I). OMe OMe M90 0‘ 0M0 \ _~ L (C0)2 nuéC— =\'-Ru(00)2 : + cc)2 (1) c\ p n “L ° ( )2 | "R R Another consideration that is worth mentioning is that the Ru—Ru bond with the bridging carbon atom exhibits the shortest bond distance (Ru(1)— Ru(2) = 2.669 (3) A in molecule A; Ru(4)—Ru(5) = 2.668 (4) A in molecule B); based on these facts, 6 second possibility for the nucleophilic addition is the opening of one longer C—Ru bonding (Ru(2)—C56 = 2.34 (2) A in molecule A; Ru(5)—C66 = 2.32 (2) A) as shown in the reaction scheme (II). 0M9 0M9 M00 M90 0 0M0 0M0 ‘ ‘0‘ \ + L O. ~c\ I'- (00); Ra‘— =-Ru(00)2 : = (cc)2 Rué— 53mm); (II) \\ / \ - L \\ / \ (fix-Ru Pm...R OC‘RU Pm...R (00h l (00» R 207 B. Molecular Structure A crystallographic study of Ru3(u-CO)2(CO)g(u3-n2-R)(u-PR2) (R = 2,4,6-C6H2(0Me)3) reveals a triclinic space group P-l with Z = 4. Each asymmetric unit contains two independent molecules A and B which are enantiomers that exhibit chiral centers at the bridging carbon atoms C(56) and C(66), respectively, in the cyclometallated phenyl ring. Crystallographic data are summarized in Table 16; important bond distances and angles for this cluster are given in Table 17. The ORTEP plots of both molecules A and B with the atom—labeling schemes are presented in Figure 50. A comparison of the main features of these two molecules is given in Figure 51. Compound (2) consists of a triruthenium framework with a symmetrically disposed phosphido bridge between atoms Ru(l) and Ru(2).. Two bridging carbonyl groups are located on the other two edges of the trinuclear framework. Some important distances in molecule A are Ru(2)—P(1) = 2.334 (3) A, Ru(3)—P(1) = 2.343 (3), and in molecule B; Ru(5)— P(2) = 2.367 (7) A, Ru(6)—P(2) = 2.353 (8) A. By considering the electron— donating characteristics of bridging ligands in metal clusters, an edge— bridging phosphido group PR2 is treated as a threHlectron donor as are SR and OR ligands. Additionally, one cyclometallated (2,4,6- trimethoxy)phenyl ring functions as a capping ligand that is triply bonded to three ruthenium metal centers. The coordination mode is u3-n2-2,4,6- CgH2(OMe)3 wherein the carbon atom doubly bridges two ruthenium atoms (Ru(1)—C(56) = 2.24 (2) A, Ru(2)—C(56) = 2.34 (2) A in molecule A; Ru(4)— C(66) = 2.77 (2) A, Ru(5)—C(66) = 2.32 (2) A in molecule B). The oxygen atom of a methoxy group in the ortho position is bound to the third metal center ( Ru(3)——O(51) = 2.20 (2) A in molecule A; Ru(6)—0(61) = 2.19 (2) A in 208 molecule B ). The cyclometallated phenyl ring which functions as a one electron donor is clearly aromatic with all C—C distances in the range of 1.39—1.49 A as shown in Figure 52. The group, then, functions as a three electron donor in the formation of two five—membered metallacycles which are observed in both molecules: (Ru(1)—Ru(2)—C(51)——C(52)—O(51), Ru(3)—Ru(2)—-C(51)—C(52)—O(51) in molecule A, and Ru(4)——Ru(5)— C(61)—C(62)—0(61), Ru(6)—Ru(5)—C(61)—C(62)—-0(61) in molecule B). Electron counting, by treating both the edge—bridging phosphido group and the cyclometallated trimethoxyphenyl ligand as three—electron donors, gives the compound Ru3(u-CO)2(CO)6(u3-n2-R)(u—PR2) (R = 2,4,6- CgH2(0Me)3) a total of 46 electrons, a count which is in good agreement with the presence of one short metal—metal i.e. Ru(1)——Ru(2) and Ru(4)— Ru(5) in the molecules A and B, respectively. I 209 Table 16. Crystal Data for Ru3(u-CO)2(CO)6 lug-nz-C6H2(OM6)31[u-P{C6H2(OMe)3}21 Formula Formula weight Crystal system Space group a, A b, A c, A a, deg [3, deg 7. deg v, A3 Z dcalc: g/cm3 Crystal size, mm Ru3131017C15H33 1059.83 Tliclinic P—l 11.209 (7) 15.60 (1) 24.73 (2) 85.48 (8) 86.83 (6) 80.16 (7) 4244 (6) 4 1.658 0.10 X 0.12 x 0.08 Radiation Mo Rona = 0.71073 A) u, cm”1 11.366 Data collection instrument Nicolet P3/F Temperature, °C —95 i 2 Scan method 0) Data col. range, 29, deg. 4 - 35 R3 0.075 wa 0.084 aR=2 I IFOI— IFcH/EIFOI bizw = [ZwlFol- IF,|)2/2w |1=o P11”; w =1/02(|Fo|) 210 3 :6: 80 2:0 80 3 2m: 30 28 30 3 2:: 80 2:0 3:2 3 3:2 30 50 3:2 3 6.2. 3:2 80 3:2 3 3:. 3:2 30 3:2 3 32. 3:2 32 3:2 3 QR 3:2 32 3:2 3 3% 3:2 3:2 3:2 3 3.? 3:2 3:2 3:2 3 ~63 3:2 3:2 3:2 3 3.8 3:2 3:2 3:2 3 8.2: 3:2 3:2 3:2 3 3.8 3:2 3:2 3:2 6&2 m :62 m 8:2 2 :62 o2m:< m 8:2 m :62 2 82 3 82 22.0 32 3 32 220 32 3 8.2 2220 32 3 2.2.2 220 22 3 2.2 80 3:2 3 8: 2:0 3:2 3 «2 80 3:2 3 2.3 30 3:2 3 R: 80 3:2 3 3.2 30 20:2 3 $3 32 3:2 3 32m 32 3:2 3 $2.2 32 3:2 3 2.3.2 22 3:2 3 33 3:2 3:2 3 53 3:2 3:2 3 3: 3:2 3:2 3 ~33. 3:2 3:2 3 266.2 3:2 3:2 3 68.2 3:2 3:2 8:522 m :62 2 :62 8:322 u 62 2 :62 .3:62032240232262032230233209200-332 6: ass 632 2:6 3 62668 262 2.3623 2.2 622.2. 211 Figure 50. ORTEP drawings of (a) molecule A and (b) molecule B of Ru3(u-CO)2(CO)6{u3-n2-CGH2(OMe)3}[u-P{CGH2(OMe)3}2], showing the atom labeling scheme with all atoms represented by their 40% probability ellipsoids. .l a...) :6 , wan... . . b) I m— o J, 30 ,\ ' :30 m. y “1., 2 212 3 u u molecule B a: is represen 395.3% I So ,4: “v 30 Vx. also aid \ \.. ‘ ‘ , all v0'. 3 ‘2 33¢ 3 0 Q0 \ J .30 ‘A ‘2 '3”! 9 2 L 3:2 Q) -., So 3m ‘3 or. Q I ‘1 I 30 a . Q ’ . s ; So 80 a ‘Q ~ ) :3 $wa 213 Figure 51. Main features of both enantiomers A snd B in the structure of Ru3(u-CO)2(CO)6{u3-n2-CGH2(OMe)3}[u—P{C6H2(0Me)3}2]. Chiral carbon atoms in both molecules are denoted by *. 214 GEE. 3V E 215 Figure 52. Selected bond distances for molecules A and B in the structure Of RU3(H'CO)2(CO)6{Hg‘n2‘06H2(OMe)3}[H'P{CGH2(OM8)3}2]. an 2&2. 216 a Sud 217 (III) Reactions of Triosmium Carbonyl Clusters with TMPP A. Synthesis and Discussion The trinuclear cluster 083(CO)12 is highly stable, and like reactions with other PR3 ligands, chemistry with TMPP occurs only with a large excess of the phosphine or under forcing conditions with high boiling solvents. In either case, the reactions led to mixtures of products in low yields. Because of these observations, our initial experiments in this study were undertaken with the use of unsaturated molecules such as the 46— electron molecule (u-H)2Os3(CO)10 which exhibits high reactivity due to the electronic unsaturation, and “lightly-stabilized” solvated molecules such as 083(CO)12_,,(NCMe)n (n = 1 or 2) wherein the labile acetonitriles are easily replaced in the presence of stronger nucle0philes. Reactions of 083(u-H)2(CO)10 with TMPP in THF at room temperature showed an instantaneous color change from purple to yellow, similar to that reported for various other tertiary phosphines under the same conditions [87]. This indicated to us that a reaction occurred to form a 48—electron saturated molecule. Further work—up by thin-layer chromatography led to the isolation of a yellow product characterized as 083(u-H)(H)(CO)10(TMPP) on the basis of various spectroscopic methods. A FABMS spectrum of the compound gave the highest mass peak at m/z = 1385 corresponding to the molecular ion [083(H)2(CO)10(TMPP)]+, and a lower mass peak at m/z = 1357 due to the fragment [M—COT" (Figure 53). The molecule 033(11- HXHXCO)10(TMPP) exhibits dynamic behavior in solution as evidenced by a temperature—dependent 500 MHz 1H NMR study in the hydride region. At room temperature, two broad unresolved resonances centered at -15 and - 20 ppm were observed. Upon cooling, both resonances sharpened and then 218 collapsed into two well-resolved resonances by —50°C. A quartet centered at —20 ppm is assigned to the bridging hydride which is coupled to one phosphorus atom (JHP = 3H2) and one terminal hydride ligand (J HH = 3H2). The high—temperature limiting spectrum was not obtained due to the thermal instability of the complex. The 1H NMR spectra in the hydride region at various temperatures are shown in Figure 54. The dynamic phenomenon in solution has also been observed in a series of related compounds such as Os3(u-H)(H)(CO)10(L) ( L = PMeZPh, PPh3 and PhCN [87(a)] and 1‘Bqu’NSNEtBuz, (E , E’ = P, As) [87(b)] ). The behavior is interpreted as a hydride ligand-site exchange involving a bridging and a terminal hydride as well as one axial and one equatorial carbonyl in the molecule as shown below. 0 0 00,, ? “.00 00%?w00 ”'03‘ (I3 I 0 00. H, 0 c 00’ (I: H / (I3 ‘00 00’0 l /| CI)ls‘co 0 0 0 Recrystallization of the compound 033(u-H)(H)(CO)10(TMPP) from a mixture of hexane/THF led to the formation of yellow crystals. A preliminary cell of a single crystal grown from hexane/CHZCIZ showed the crystal system to be monoclinic with dimensions : a = 22.33 (2) A, b = 14.38 (1) A, c = 27.59 (3) A, B = 102.38 (9) and v = 8655 (16) A3. A data set was not collected, however, due to the poor quality of the crystals. 219 Figure 53. Positive ion FABMS spectrum of Os3(u-H)(H)(CO)10(TMPP). 220 omvp seas N22 oowp ommw A 32 u or: 302528833053 comp eouepunqv SMIBIGH Mom. 221 Figure 54. Variable—temperature 500 MHz 1H NMR spectra of 033(u-H)(H)(CO)10(TMPP) recorded in CD013. 222 ,3; Egg 0. cu. m . m T. . — P b . _ . . NImuaxi... axons... am b _ 008- Doom- 00mm- 003.- £115.. 058.. 223 Although a precise structure is not available, several structurally characterized triosmium clusters provide good background information for the compound. Based on the large steric bulk of the phosphine TMPP, it is reasonable to expect that the coordinated TMPP is located in an equatorial position. Reactions of OS3(CO)11(NCM8) with TMPP gave the yellow product 033(CO)11(TMPP) (1) in quantitative yield. Characterization by FABMS showed a molecular peak at m/z = 1411 corresponding to [033(CO)11(TMPP)]+, and a fragment at m/z = 1385 due to [M-CO]+ (Figure 55). A 1H NMR spectrum taken in CD013 indicated a symmetrical magnetic environment for the three phenyl groups of the phosphine ligand, as evidenced by the presence of only three resonances arising from the ortho and the para methoxy groups; 6 = 6.0 (d) (d, JHp = 3 Hz, m-H), 3.5 (s, p-' OMe), 3.8 (s, o-OMe) ppm. The transformation process was monitored by 1H NMR spectroscopy in CD3CN, and symmetrical meta proton resonances due to the initial product with a monodentate TMPP ligand were replaced by multiplets after ca. three days at room temperature. This result indicated that the compound containing monodentate TMPP transformed into a product with an unsymmetrical coordination mode for the phosphine (Figure 56). Unfortunately, in the course of recrystallizing 083(CO)11(TMPP) (1) from a mixture of hexane and CHzClz, hydrolysis occurred, and the cluster transformed to a hydroxy—derivative cluster which was structurally characterized as Os3(u-OH)2(CO)9(TMPP) (3), a species which consists of doubly edge—bridging hydroxy groups similar to other known hydroxy clusters. I a.— 224 Figure 55. Positive ion FABMS spectrum of 053(CO)11(TMPP). 225 comp amass N22 omwp oovw ommp A :2 u or: 8.3.? :00an comp eouepunqv aAllBISH 226 Reactions of 083(CO)10(NCMe)2 with TMPP led to the isolation of two major products; OS3(CO)11(TMPP) (1) and 083(u-OHXCO)9(u-n2-TMPP-O) (2). The latter was confirmed by a crystallographic study. The room temperature 300 MHz 1H NMR spectrum of (2) in CD013 reveals that the TMPP ligand is bonded in a completely unsymmetrical fashion (Figure 57). Six meta protons appear as multiplets and resonate in the range of 5.80— 6.18 ppm. Eight methoxy group resonances appear between 3.35 and 3.85 ppm. The absence of a ninth methoxy group suggested that demethylation had occurred, which was subsequently confirmed by a solid—state structural determination. A schematic diagram depicting the formation of molecule (1) and (2) is shown in Figure 58. [I 227 Figure56. A 300 MHz 1H NMR study depicting spectral changes during the transformation of Os3(CO)11(TMPP). (8) Initial product Os3(CO)11(TMPP) with terminal v(CO) stretches only, and (b) transformed product with bridging v(CO) stretches present. 228 WWW (b) ppm W56 229 Figure 57. A 300 MHz 1H NMR spectrum of Os3(u-OH)(TMPP-0)(CO)9 in CD013 at room temperature. The doublet denoted by * is due to an impurity of a methyl phosphonium salt. 230 231 Figure58. Schematic diagram outlining a proposed reaction sequence in the formation of 033(u-OH)2(TMPP)CO)9 and Os3(u-OH)(TMPP- 0)(CO)9. 232 tv’) 1‘ 083(CO)"(NCM6) TMPP 0 “2 2H,0 CH.+2CO 2C0+Hz MeOH Ifigune58 233 B. Molecular Structure (1) 083(u-0H)2(CO)9(TMPP) The molecular structure of 083(u-0H)2(C0)9(TMPP) is shown in Figure 59. Crystallographic data are given in Table 18, and selected bond distances and angles are listed in Table 19. The molecule contains a triangular arrangement of osmium atoms in which 08(2) is bonded to four terminal carbonyl ligands, 08(1) is attached to three terminal carbonyl groups, and 08(3) is bonded to two terminal carbonyl ligands and one phosphine group. Additionally, the edge 08(1) and 08(2) i8 bridged by two 11- hydroxide ligands. The unbridged metal—metal bond distances are 08(1)—- 0s(2) = 2.833 (1) A and 03(2)—0s(3) = 2.844 (1) A. The doubly—bridged edge with an 08(1)°-°°08(3) separation of 3.114 (2) A would be expected to involve. no significant metal—metal orbital overlap by distance considerations as well as electron count. The two hydroxide ligands form two pseudo— symmetrical bridges across 08(1) and 08(2); the osmium-oxygen distances are 0s(1)—0(10) = 2.10 (1) A, 08(3)—0(10)= 2.13 (1) A, 0s(1)—0(11) = 2.06 (1) A, os(3)—0(11) = 2.09 (1) A, and the angles 0s(1)—0<10)—0s(3) and 08(1)— 0(11)-.—Os(3) are 95.2 (5) and 97.1 (5)°. respectively. An angular distortion observed at the ortho—methoxy group may be explained by the involvement of hydrogen bonding between the hydrogen H(0(11)] and the lone—pair of electrons on the atom 0(12). The ortho—methoxy group interacts significantly with one of the bridging hydroxy groups via hydrogen bonding. The hydrogen atoms were not located during the crystallography refinement, but the distance between the oxygen atom of the hydroxy group and methoxy group is only 2.521 (1) A, clearly indicating the presence of a hydrogen bond. 234 Table 18. Crystal Data for 083(u-0H)2(CO)9(TMPP) (l) and 083(u-0HXCO)9(u-n2-TMPP-0) (2) (1) (2) Formula OS3P1020C36H35 OS3P1019C35H31 Formula weight 1389.24 1357.19 Crystal system Triclinic Monoclinic Space group P—l pzl/n a, A 11.435 (5) 16,033 (2) b, A 13.079 (8) 13,103 (1) c, A 14.116 (9) 19.601 (2) (1, deg 96.44 (5) 90 13. deg 93.08 (5) 90.38 (1) 7, deg 95.23 (4) 90 v. A3 2085(2) 4133.5 (9) Z 2 4 dcalcv g/cm3 2.213 2.181 Crystal size, mm Radiation 11, cm"1 Data collection instrument Temperature, °C Scan method Data col. range, 20, deg. Ra wa aR=z l IFOI— chH/EIFOI 0.10 x 0.08 x 0.15 Mo KaO. = 0.71073 A) 92.491 N icolet P3/F —95 i 2 m-ZO 4—40 0.038 0.046 bRw = [EwlFol- IFc |)2/2w IFo 121‘”; w =1/02(|Fo|) 0.30 x 0.15 x 0.10 Cu Kao. = 1.54184 A) 180.610 Siemens P3/V —95 :1: 2 m-29 4 — 106 0.089 0.061 235 2va 6 :5 a8 8 6 wow 5 a8 68 6 ~65 68 5 68 6 32 6a 88 a8 6 mg 8 68 60 6 $8 68 68 68 6 9% 8 68 2: 6 28 8 68 68 6 has 8 a8 68 6 5w 5 68 68 ease. m :83. a sees. a :82 sass. m 85:. a 834 H 842 6 a: 80 60 6 82 60 a8 6 NM: 28 Em 6 8.2 60 68 6 a: :0 60 6 SN 8 68 6 88 8 68 6 SN 8 68 6 m3 8 68 6 8.2 60 68 6 8.2 60 68 6 £8 60 68 6 as 60 68 6 a: 60 68 6 $8 68 68 6 3.3 68 a8 6 so." 60 68 6 83 8.8 :8 6 3.. 60 68 6 33 68 68 0088me m 88¢ H 83< 3:3me N 83< H 83¢ 3026580560880 .50 Res 885 use 6 $885 88 8828 .2 033,—. Figure 59. 236 An ORTEP diagram of 083(u-0H)2(TMPP)(C0)9, showing the atom labeling scheme. All phenyl-group carbon atoms of TMPP are represented as small circles for clarity, and all other atoms are represented by their 40% propability ellipsoids. 237 (7.; @251 0(7) 7’3, °‘5’ 016703291" 1'» ” 1"@ (73 (781 '8,@ , ;\\y 0(1) C(9)z‘c(< 012) (L- L? “ 0(2) ,. 081 e "13 01 C P26) 014 , 028 018 CW) (@0131 ( k %6’ M 016 ‘\ 5 \3013 ;§ 1 C11 ’ ((54 Pl” 025 012 032 f 012 013) Q c” f , m1 ‘ C(12) ‘32 c1321 0%” 2036 a C, 0222\7‘ C(33) m4 085. 084 C(22) C(34) Ema? 238 (2) 08301-011) (CO)9(u-n2-TMPP-O) The molecular structure of 083(u-0H)(CO)9(u-n2-TMPP-0) is shown in Figure 60. Crystallographic data are listed in Table 18, and selected bond distances and angles are given in Table 20. The cluster consists of a triosmium framework containing two metal—metal bonds, namely 08(1)—— 0s(2) = 2.835 (3) A and os(2)—0s(3) = 2.843 (2) A, and one open edge [08(1)----08(3) = 3.099 (3) A] supported by one hydroxy ligand [08(1)—0(10) = 2.12 (2) A; 0s(3)—0(10) = 2.17 (2) A], and one phenoxide group [0s(1)—0(11) = 2.12 (2) A; 08(3)—C(11) = 2.24 (2) A]. The demethylated TMPP is triply bonded to two osimium atoms 08(1) and 08(3) with the oxygen atom 0(11) as a bridging ligand among the edge of 08(1) and 08(3). The phosphorus atom is bound to 08(3) as a terminal group. The phenoxide group allows for the tridentate coordination mode of u-nz-(TMPP-O) and provides a fiveé membered metallacycle containing 08(3)—P(1)—C(32)—C(32)—0(11) as a chelating group. The main features of both molecular structures (1) and (2) are highlighted in Figure 61 where it can be seen that the molecules contain very similar trinuclear frameworks with one open 08---08 edge bridged by two oxygen atoms. 5. Summary The versatile coordination ability of the tertiary phosphine TMPP has been well—demonstrated in the aforementioned reactions with Group 8 metal carbonyl clusters. In the reaction with Fe3(CO)12, the formation of a new salt [HTMPP][HFe3(CO)n] supports the previous literature report that ion-pair coupling in [HFe3(C0)u]" salts is greatly influenced by the steric bulk of counter cation; in this case, the size of TMPP precludes any interaction. Both reactions of Ru3(CO)12 and also the activated species 239 Ru3(C0)u(NCMe) with TMPP proceed by oxidative addition of the P—C bond, leading to formation of a new 46—electron unsaturated cluster such as Ru3(u-CO)2(C0)6(u3-n2-R)(u-PR2) (R = 2,4,6-C6H2(0Me)3). The cluster- mediated ligand transformation observed in this system is uncharacteristically facile, occurring under very mild conditions compared to previously reported reactions of this type. The reactions of triosmium carbonyl clusters with the phosphine TMPP gave two hydroxy—bridged triosmium carbonyl clusters, namely 083(u-0H)2(C0)9(TMPP) and 083(11- 0H)(CO)9(u-n2-TMPP-0). Structural determinations on the molecules revealed that both clusters consist of similar open frameworks with two oxygen atoms doubly—bridging one 08~~~08 open edge. In this study, the phosphine, tris(2,4,6-trimethoxypheny1)phosphine, exhibits great reactivity toward the low valent metal complexes with TC- acceptors. The presence of mixed-donors, i.e. phosphorus and oxygen atoms, provides the ligand with good chelate tendencies. Reversible coordination of certain interactions, especially the M—ether bonds, of TMPP-containing cluster complexes is considered to be feasible based on the results of this work. 240 a- a x 6 5.8 68 :60 68 6 Ex 860 68 68 6 8a 88 860 68 6 3.2 68 68 68 6 3% :60 68 SE 6 3.3 68 68 68 6 0.3 860 88 68 6 new :60 68 68 6 cam :60 68 68 6 4.8 860 68 68 035» m 83< .0. 83< H 83¢ onc< m 83¢. N 803. H 83¢. 6 6: 60 :8 6 and 60 68 6 a: :60 :8 6 SN 60 68 6 of :60 60 6 NS 60 68 6 ease. 60 68 6 EN 860 68 6 Ca 860 68 6 m: 60 68 6 o? 60 68 6 a: 60 68 6 $8 60 88 6 no." 60 68 6 03 68 68 6 63 68 68 6 88 60 68 6 was 68 68 6 a: 60 68 6 89m 68 68 0083me N 83¢. H 83¢ 08339 N 83< H 83< .:Qdmzbacéaxoox80-3.8 and ass 382 use 6 8885.8 288 8388 .3 038. 241 Figure 60. ORTEP diagram of Os3(u-OH)(TMPP-0)(CO)9, showing the atom labeling scheme. All phenyl-group carbon atoms of TMPP are represented as small circles for clarity. 242 13mm 243 Figure 61. Main features of the molecular structures of (a) 033m- OH)2(TMPP)(CO)9 and (b) Os3(u-OH)(TMPP-O)(CO)9. 244 82.6w: 3 245 CHAPI‘ERVI FINAL REMARKS 246 The aforementioned studies outline new directions in the syntheses of reactive mixed-ligand complexes at the interface of coordination and organometallic complexes. In our initial project, we synthesized a novel bridging hydride dirhenium species Re2(u-H)(u-Cl)Clz(CO)2(dppm)2 by the investigation of the reaction between Re2C14(dppm)2 (Re-a—Re) (dppm = thPCHzPth) and the electronically and coordinatively unsaturated molecule H2033(CO)10 in the presence H2. Further elucidations of various alternative reactions suggested the formation of the bridging hydride dirhenium complex might be achieved by different reaction pathways, namely, by hydride transfer reaction via a metal hydride coupling between the different metal system, or directly from an unprecedented H2 activation reaction. Moreover, a new carbonyl halide cluster, Ru3(CO)8(Cl)2(PBu3")2, was synthesized from the reaction between the multiply bonded dirhenium complex Re2016(PBu3")2 (Refit—Re) and Ru3(CO)12. Both results demonstrate the feasibility of preparing mixed ligand complexes by ligand transfer reactions between two entirely different metal systems; this new synthetic approach provides a promising opportunity for the syntheses of unusual coordination and organometallic compounds. In a second area of investigation, we explored the chemistry of new transition metal phosphine complex with unusual properties. Our study of TMPP chemistry with dinuclear metal-metal bonded systems led to the discovery of unsymmetrical complexes containing an unusual bridging phenoxy—phosphine ligand. Furthermore, the phosphine ligand, TMPP was shown to exhibit novel chemistry with trinuclear cluster complexes. 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Chem. 1984, 23, 1390. Chemistry of metal carboxylate complexes : (a) Rardin, R. L.; Tolman, W. B.; Lippard, S. J. New J. Chem. 1991, 15, 417 . (b) Mehrotra, R. C.; Bohra, R. Metal Carboxylates; Academic: New York, 1983. (c) Catterick, J .; Thronton, P. Adv. 'Inorg. Chem. Radiochem. 1977, 20, 291. (d) Oldham C.; Prog. Inorg. Chem. 1968, 10, 223. Chemistry of trifluoroacetate metal complexes : (a) Santure, D. J .; Huffman, J. C.; Sattelberger, A. P. Inorg. Chem. 1984, 23, 938. (b) Santure, D. J .; McLaughlin, K. W.; Huffman, J. C.; Sattelberger, A. P. Inorg. Chem. 1983, 22, 1877. (c) Girolami, G. S.; Anderson, R. A. Inorg. Chem. 1982, 21, 1318. ((1) Cotton, F. A.; Lay, D. G. Inorg. Chem. 1981, 20, 935. (e) Girolami, G. S.; Mainz, V. V.; Anderson, R. A. Inorg. Chem. 1980, 19, 805. (f) Garner, C. D.; 67. 69. 70. 258 Hughes, C. D. Adv. Inorg. Chem. Radiochem. 1975, 17, 1. (g) Garner, C. D.; Senior, R. G. J. Chem. Soc., Dalton Trans. 1976, 1041. Santure, D. J .; McLaughlin, K. W.; Huffman, J. C.; Sattelberger, A. P. Inorg. Chem. 1983, 22, 1877. Rardin, R. L.; Tolman, W. B.; Lippard, S. J. New J. Chem. 1991, 15, 417. Redox chemistry of Rh2(II,II) complexes : (a) McCarthy, H. J .; Tocher, D. A. Inorg. Chim. Acta. 1988, 145, 171. (b) Tocher, D. A.; Tocher, J. H. Inorg. Chim. Acta. 1987, 131, 69. (c) Tocher, D. A.; Tocher, J. H. Polyhedron, 1986, 5, 1615. (d) Tocher, D. A.; Tocher, J. H. Inorg. Chim. Acta. 1985, 104, L15. Synthesis of Rh2(02CCH3)4(MeOH)2: Jofnson, S. A.; Hunt, H. R.; Neumann, H. M. Inorg. Chem. 1963, 2, » 960. Synthesis of M02(02CCF3)4: Cotton, F. A.; Norman, J. G., Jr. J. Coord. Chem. 1971, 1, 161. Synthesis of Rh2(OzCCF3)4: (a) Bear, J. L.; Kitchens, J .; Willcott, M. R. J. Inorg. Nucl. Chem. 1971, 11, 3479. (b) Jofnson, S. A.; Hunt, H. R.; Neumann, H. M. Inorg. Chem. 1963, 2, 960. Ortho—metallated dirhodium complexes : (a) Morrison, E. C.; Tocher, D. A. Inorg. Chim. Acta. 1989, 157, 139. (b) Barcelo, F.; Cotton, F. A.; Lahuerta, P.; Sanau, M.; Schwotzer, W.; Ubeda, M. A. Organometallics 1987, 6, 1105. (c) Cotton, F. A.; Dunbar, K. R.; Verbruggen, M. G. J. Am. Chem. Soc. 1987, 109, 5498. (d) Cotton, F. A.; Dunbar, K. R. J. Am. Chem. Soc. 1987, 109, 3142. (e) Chakravarty, A. R.; Cotton, F. A.; Tocher, D. A.; Tocher, J. H. Organometallics 1985, 4, 8. (f) Chakravarty, A. R.; Cotton, F. A.; Tocher, D. A. J. Chem. Soc., Chem. Commun. 1984, 501. 71. 72. 73. 74. 75. 259 Recent work on EPR studies of Rh2(II,III) complexes : (a) Yao, C. -L.; Park, K. H.; Khokhar, A. R.; Jun, M. -J.;l Bear, J. L. Inorg. Chem. 1990, 29, 4033. (b) Bear, J. L.; Yao, C. -L.; Capdevielle, F. J .; Korp, J. D.; Albright, T. A.; Kang, S. -K.; Kadish, K. M. Inorg. Chem. 1989, 28, 1254. (c) Lifsey, R. S.; Chavan, M. Y.; Chau, L. K.; Ahsan, M. Q.; Kadish, K. M.; Bear, J. L. Inorg. Chem. 1987, 26, 822. (d) Bear, J. L.; Liu, L. M.; Kadish, K. M. Inorg. Chem. 1987,26, 2927. (e) Chavan, M. Y.; Ahsan, M. Q.; Lifsey, R. 8.; Bear, J. L.; Kadish, K. M. Inorg. Chem. 1986, 25, 3218. (f) Ahsan, M. Q.; Bear, J. L. Inorg. Chem. 1986, 25, 260. (g) Chavan, M. Y.; Lin, X. Q.; Ahsan, M. Q.; Bemal, 1.; Bear, J. L.; Kadish, K. M. Inorg. Chem. 1986, 25, 1281. (h) Kawamura, T.; Katayama, H.; Yamabe, T. Chem. Phys. Lett. 1986, 130, 20. (i) Le, J. C.; Chavan, M. Y.; Chau, L. K.; Bear, J. L.; Kadish, K. M. J. Am. Chem. Soc. 1985, 107, 7195. EPR studies of NO"' complexes : Richter-Addo, G. B.; Legzdins, P. Chem. Rev. 1988, 88, 991. Chemistry of metal carbonyl clusters complexes : (a) Shriver, D. F.; Kasez. H. D.; Adams. R. D. The Chemistry of Metal Cluster Complexes; VCH Publishers: New York, 1990. (b) Atwood, J. D.; Wovkulich, M. J .; Sonnenberger, D. C. Acc. Chem. Res. 1983, 16, 350. (c) Johnson, B. F. G. Transition Metal Clusters; Wiley: New York, 1980, p. 418. (d) Chisholm, M. H.; Rothwell, I. P. Prog. Inorg. Chem. 1982, 29, 1. Foulds, G. A.; Jognson, B. F. G.; Lewis, J. J. Organomet. Chem. 1985, 296, 147. Chemistry of triruthenium carbonyl clusters with phosphines : (a) Bruce, M. I. Coord. Chem. Rev. 1987, 76, 1. (b) Bruce, M. 1. Comprehensive Organometallic Chemistry; Wilkinson, G.; Stine, F. G. A.; Abel, E. W. (Eds.) Pergamen: Oxford, 1982, Vol. 4, p. 843. JFL- ._ 76. 77. 78. 79. 80. 81. 260 Atwood, J. D.; Wovkulich, M. J .; Sonnenberger, D. C. Acc. Chem. Res. 1983, 16, 350. Syntheses of M3(CO)12.,,(NCMe)n (M=Os, Ru, n=1, 2; M=Fe, n=1) : (a) Cardin, C. J.; Cardin, D. J .; Kelly, N. B.; Lawless, G. A.; Power, M. B. J. Organomet. Chem. 1988, 341, 447. (b) Foulds, G. A.; Jognson, B. F. G.; Lewis, J. J. Organomet. Chem. 1985, 296, 147. Synthesis of H2083(C0)10: (a) Johnson, B. F. G.; Lewis, J .; Kilty, P. A. J. Chem. Soc. A . 1968, 2859. (b) Knox, S. A. R.; Koepke, J. W.; Andrews, M. A.; Kaesz, H. D. J. Am. Chem. Soc. 1975, 97, 3942. Ion—pairing of mononuclear metal carbonylates : (a) Kao, S. C.; Darensbourg, M. Y.; Schenk, W. Organometallics 1984, 3, 871. (c) Mclain, S. J. J. Am. Chem. Soc. 1983, 105, 6355. (c) Powell, J .; Gregg, M.; Kuksis, A.; Meindl, P. J. Am. Chem. Soc. 1983, 105, 1064. ((1) Powell, J.; Kuksis, A.; May, C. J .; Nyburg, S. C.; Smith, S. J. J. Am. Chem. Soc. 1981, 103, 5941. (e) Collman, J. P.; Finke, R. G.; Gawse, J. N.; Branman, J. I. J. Am. Chem. Soc. 1978, 100, 4766. (f) Darensbourg, M.; Barros, H.; Borman, C. J. Am. Chem. Soc. 1977, 99, 1647. Interactions of metal carbonyl hydrides with Lewis acids : Richmond, T. G.; Basolo, F.; Shriver, D. F. Organometallics 1982, 1, 1624. Ion—pairing of metal cluster anions : (a) Chen, C. K.; Cheng, C. H.; Hseu, T. H. Organometallics 1987 , 6, 868. (b) Schick, K. -P.; Johns, N. L.; Sekula, P.; Boag, N. M.; Labinger, J. A.; Kasez, H. D. Inorg. Chem. 1984, 23, 2204. (c) Chen, C. K.; Cheng, C. H. Inorg. Chem. 1983, 22, 3378. (d) Collman, J. P.; Finke, R. G.; Matlock, P. L.; Wahren, R.; Komoto, R. G.; Branman, J. I. J. Am. Chem. Soc. 1978, 100, 1119. (e) Wilkinson, J .; Todd, L. J. J. Organomet. Chem. 1976, 118, 199. 82. 261 Chemistry of bridging phosphido polynuclear complexes : (a) Lavigne, G. The Chemistry of Metal Cluster Complexes; Shriver, D. F.; Kasez. H. D.; Adams. R. D. (Eds.) VCH Publishers: New York, 1990, Ch. 5. (b) Lagan, N.; Lavigne, G.; Bonnet, J. -J.; Reau, R.; Neiberker, D.; Tkatchenko, I. J. J. Am. Chem. Soc. 1988, 110, 5369. (c) Nucciarone, D. N .; MacLaughlin, S. A.; Taylor, N. J .; Carty, A. J. Organometallics 1988, 7, 106. (d) Carty, A. J .; MacLaughlin, S. A.; Nucciarone, D. Phosphorus-31 NMR Spectroscopy in Stereochemical Analysis: Organic Compounds and Metal Complexes; Verkade, J. G.; Quin, L. D. (Eds.) VCH Publishers: New York, 1986, Ch. 16, p. 559. (e) Fehlhammer, W. P.; Stolzenberg, H. Comprehensive Organometallic Chemistry; Wilkinson, G.; Stone, F. G. A.; Abel, E. W. (Eds.) Pergamon: Oxford, 1982, Vol. 4, Ch. 31, p. 513. P—C bond cleavage in the reactions of Os3(CO)12 with PR3 : (a) Bradford, C. W.; Nyholm, R. S. J. Chem. Soc., Dalton Trans. 1973, 529. (b) Gainsford, G. J .; Guss, J. M.; Ireland, P. R.; Mason, R.; ‘ Bradford, C. W.; Nyholm, R. S. J. Organometal. Chem. 1972, 40, C70. (c) Deeming, A. J .; Rothwell, I. P.; Hursthouse, M. B.; Backer-Dirks, J. D. J. Chem. Soc., Dalton Trans. 1981, 1879. (d) Deeming, A. J .; Underhill, M. J. Chem. Soc., Dalton Trans. 1973, 2727. (e) Deeming, A. J .; Kimber, R. E.; Underhill, M. J. Chem. Soc., Dalton Trans. 1973, 2727. P—C bond cleavage in the reaction of Ru3(CO)12 with PR3: Bruce, M. 1.; Shaw, G. Stone, F. G. A. J. Chem. Soc., Dalton Trans. 1972, 2094. ‘ Recent work on reactions with P—C bond cleavage : (a) Elliot, D. J .; Holah, D. G.; Hughes, A. N.; Mirza, H. A.; Zawada, E. J. Chem. Soc., Chem. Commun. 1990, 32. (b) Lugan, N.; Lavigne, G.; Bonnet, J. J. Inorg. Chem. 1987, 26, 585. (c) Dubois, R. A.; Garrou, P. E. Organometallics 1986, 5, 466. (d) Dubois, R. A.; Garrou, P. E.; Lavin, K.; Allock, H. R. Organometallics 1986, 5, 473. (e) Garrou, P. E. Chem. Rev. 1985, 85, 171. (f) Garrou, P. E.; Dubois, 86. 87. 88. 262 R. A.; Jung, c. w. CHEMTECH 1985, 123. (g) Dubois, R. A.; Garrou, P. E.; Lavin, K.; Allock, H. R. Organometallics 1984, 3, 649. Unsaturated trinuclear carbonyl clusters : Lavigne, G.; Kasez, H. D. Metal Clusters in Catalysis; Amsterdam: Elsevier, 1986, Ch. IV, p. 43. Reactions of H2083(CO)10 with phosphines : (a) Ehrenreich, W.; Herberhold, M.; Herrmann, G.; Suss-Fink, G. J. Organomet. Chem. 1985, 294, 183. (b) Deeming, A. J .; Hasso, S. J. Organomet. Chem. 1976, 114, 313. . ‘3-“ Recent work on alkoxide and phenoxide complexes : (a) Kraflt, T. E.; Hejna, C. 1.; Smith, J. S. Inorg. Chem. 1990, 29, 2682. (b) Green, L. M.; Meek, D. W. Organometallics 1989, 8, 659. (c) Kim, Y.; Osakada, K.; Sugita, K.; Yamamoto, T.; Yamamoto, A. Organometallics 1989, 7, 2181. (c) Bryndza, H. E.; Fong, L. K.; Paciello, R. A.; Tam, W.; Bercaw, J. E. J. Am. Chem. Soc. 1987, 109, 1444. (d) Kegley, S. E.; Schaverien, C. J .; Freudenberger, J. H.; Bergman, R. G.; Nolan, S. P.; Hoff, C. D. J. Am. Chem. Soc. 1987, 109, 6563. (e) Bryndza, H. E.; Calabrese, J. C.; Marsi, M.; Roe, D. C.; Tam, W.; Bercaw, J. E. J. Am. Chem. Soc. 1986, 108, 4805. (f) Rees, W. M.; CHurchill, M. R.; Fettinger, J. C.; Atwood, J. D. Organomatallics 1985, 4, 2179. (g) Komiya, S.; Akai, Y.; Tanaka, K.; Yamamoto, T.; Yamamoto, A. Organometallics 1985, 4, 1130. (h) 'Bryndza, H. E. Organometallics 1985, 4, 1686. (i) Newman, L. J .; Bergman, R. G. J. Am. Chem. Soc. 1985, 107, 5314. (j) Collman, J. P.; Barnes, C. E.; Brothers, P. J. Collins, T. J .; Ozawa, T.; Gallucci, J. C.; Ibers, J. A. J. Am. Chem. Soc. 1984, 106, 5151. (k) Monaghan. P. K.; Puddephatt, R. J. Organometallics 1984, 3, 444. 263 APPENDICES PHYSICAL MEASUREMENTS (1) Infrared Spectroscopy Infrared spectra were recorded on a Perkin- Elmer 599 or a Nicolet 740 FT-IR spectrophotometer. (2) Electronic Absorption Spectroscopy Electronic absorption spectra were measured on a Hitachi U-2000 (1100-200 nm) or a Cary 17 (2000—200 nm) spectrophotometers. (3) Electrochemistry Electrochemical measurements were performed by using an EG&G Princeton Applied Research Model 352 scanning potentiostat in conjunction with a BAS Model RXY recorder. Cyclic voltammetry experiments were carried out at 22 :t 2 °C in dichloromethane solutions containing 0.1 M TBAH or TBABF4 as supporting electrolyte. Em values [(EN, + Ema/2] were referenced to the Ag/AgCl electrode and are uncorrected for junction potentials. The szFe/szFe+ couple occurs at Em = +0.46 V under the same experimental conditions. (4) NMR Spectroscopy 1H NMR spectra were recorded on a WM 250 Bruker spectrometer with an ASPECT 3000 computer; Gemini 300 MHz; Varian 300 MHz or Varian 500 MHz spectrometer. Resonances were referenced internally to the residual protons in the incompletely deuterated solvent. 31P{1H) NMR spectra were recorded on a Varian 300 MHz spectrometer operating at 121.4 MHz with an internal deuterium lock using aqueous 85% H3PO4 as an external standard. Positive chemical shifts were 264 W?!” 265 measured downfield from H3PO4. 19F NMR spectra were obtained on a Varian VXR 300' MHz spectrometer. An external standard of CF3C6H5 at d —63.9 ppm was used to reference the 19F NMR spectrum. (5) ESR Spectroscopym X—Band ESR spectra of dichloromethane solutions were recorded with the use of a Bruker ER200D spectrometer. To obtain an accurate measure of g-values and line widths, a Bruker ER035M NMR Gaussmeter and a Hewlett-Packard 5245L frequency counter (with a 3-12 GHz adaptor) were used to measure magnetic field strength and the microwave frequency, respectively. (6) Mass Spectrometry Fast atom bombardment (FAB) mass spectrometry studies were performed on a JEOL HX 110 double-focusing mass spectrometer housed in the National Institutes of Health/Michigan State University Mass Spectrometry Facility; samples were dissolved in a 3- nitrobenzyl alcohol matrix. (7) Elemental Analyses Elemental analyses were performed at Galbraith Laboratories, Inc. 266 Table 21. Atomic positional parameters (A2) and their estimated standard deviations for R92(u-H)(u-Cl)C12(CO)2(dppm)2. Atom x y z 8(A2) Re(1) 0.13688(2) 0.21207(2) 0.04002(1) 2.290(3) C1(1) 0.2770(2) 0.277 0.000 2.91(2) C1(2) 0.1321(2) 0.3436(1) 0.09664(6) 3.46(3) P(1) 0.2249(1) 0.1306(1) 0.10556(5) 2.63(3) P(2) 0.0277(1) 0.2936(1) -0.01262(6) 2.70(3) 0(1) -0.0170(5) 0.1000(6) 0.0798(2) 5.9(2) C(l) 0.0380(6) 0.1440(6) 0.0656(3) 3.9(1) C(2) 0.2436(5) 0.0191(5) 0.0779(2) 2.9(1) C(11) 0.1663(5) 0.1065(6) 0.1663(2) 3.2(1) C(12) 0.1864(6) 0.0323(6) 0.1960(3) 4.0(2) C(13) 0.1446(6) 0.0181(6) 0.2449(3) 4.7(2) C(14) 0.0837(8) 0.0770(8) 0.2622(3) 5.2(2) C(15) 0.0640(7) 0.1512(7) 0.2329(3) 5.3(2) C(16) 0.1032(7) 0.1696(7) 0.1835(3) 5.1(2) C(21) 0.3347(5) 0.1714(6) 0.1286(2) 3.6(1) C(22) 0.3568(6) 0.2620(6) 0.1215(2) 3.9(1) C(23) 0.4403(7) 0.2901(9) 0.1398(3) 5.9(2) C(24) 0.4994(7) 0.234(1) 0.1634(3) 6.7(3) C(25) 0.4748(7) 0.1441(9) 0.1687(3) 5.6(2) C(26) 0.3960(6) 0.1104(7) 0.1529(2) 4.2(2) C(31) -0.0859(5) 0.2834(6) 0.0144(2): 3.6(1) C(32) -0.1506(6) 0.2304(7) -0.0068(3) 4.4(2) C(33) -0.2319(7) 0.220(1) 0.0205(3) 7.2(3) C(34) -0.2492(8) 0.266(1) 0.0635(3) 7.5(3) C(35) -0.1834(8) 0.320(1) 0.0850(3) 8.3(4) C(36) -0.1002(7) 0.3312(8) 0.0600(3) 5.5(2) C(41) 0.0369(5) 0.4139(5) -0.0276(2) 3.6(1) C(42) 0.1163(6) 0.4562(6) -0.0233(2) 3.7(2) C(43) 0.1259(9) 0.5471(6) -0.0401(3) 5.2(2) C(44) 0.0501(9) 0.5906(8) -0.0559(4) 6.1(3) C(45) -0.0314(8) 0.5494(7) -0.0576(3) 6.7(2) C(46) -0.0392(8) 0.4596(7) -0.0450(3) 5.1(2) Anisotropically refined atoms are given in the form of the equivalent isotropic displacement parameter defined as u/3Ea15,, + b’B22 + c’8,, + ab(cosY)B,z + ac(cose)8U + bc(cosa)8,,]. ’l‘able22. ato- Ro(1) Ru(2) C1(1) C1(2) C1(3) P(1) P(2) P(3) P(4) 0(1) 0(2) 6(1) 0(2) C(3) C(4) C(11) C(12) C(13) C(14) C(13) C(16) C(21) C(23) C(23) C(24) Atomic positional parameters (A2) and their estimated 267 standard deviations for [Reg(u-H)(u-Cl)Clz(CO)2- (dppm)2](BF4). to c: (o c) to <3 ‘0 <3 0. <> 0» c: <3 0 c: p c> o c) 0 <3 0 .3133(2) .3651(2) 4605(9) .334(1) ,486(1) .465(1) .166(1) .514(1) .225(1) 132(3) .234(3) .183(3) .266(4) .473(4) .113(4) .420(4) .463(4) .423(5) .362(4) .327(3) .359(6) .603(3) .619(4) .7'0(4) .336(4) 0. -O. O. O. O. O. 1174(1) .2711(1) 2815(7) .O4i(1) .4477(u) .069(1) .153(1) .2414(9) .329(1) .080(2) .230(2) .OO7(3) .250(3) .105(3) .222(3) .070(4) .111(3) .215(4) .277(3) .287(4) 137(6) 113(3) 153(3) 137(3) 131(3) 0 O (3 O (D 0 IO 0 C) (3 0 C) (D O C) (3 0 C) (3 O .2914(2) .2007(2) .3664(7) .4150(9) ,2193(9) .272(1) .316(1) .1654(8) .2095(9) .163(2) .004(3) .202(3) .Ob9(3) .163(3) .226(3) .258(4) .361(3) .337(4) .257(3) .173(6) .171(4) .353(3) .441(3) .511(3) .433(4) l(oq) 2.55(9) 2,55(9) 2.4(4) 3.2(4) 2.7(4) 3.4(5) 3.6(7) 4.4(7) 1.6(8) 3(1) 2.7(9) 2(1) 5(1) 3(1) 5(1) 3(1) 5(1) 4(1) 1.3(7) 4(1) 3(1) 4(1) C(25) C(26) C(31) C(32) C(33) (N La .1) C(35) C(36) C(41) C(43) C(44) C(45) C(46) C(51) C(52) C(53) C(54) C(55) C(56) C(61) C(62) C(63) C(64) C(65) O C) (3 O C) (D O C) (3 (3 O 0 Tab 22. Continued. 906(4) .689(4) ,203(3) 119(3) 152(4) 252(4) 123(4) 300(5) .039(4) 045(4) .153(5) .146(5) .O54(4) .045(3) .512(4) .536(3) .524(4) .478(5) .454(4) .463(4) .662(3) .745(4) .360(5) .B9B(4) .flflfl(5) O 0' C) (3 O C) (3 O C) (D O 268 .142(4) .106(3) .229(3) .266(3) .333(3) .354(8) .311(4) .248(4) .049(3) .OO9(4) .O79(5) .122(4) .085(4) .001(8) .272(4) .367(3) .398(3) .314(4) .211(3) .192(3) .306(2) .303(3) .348(4) .399(4) .419(4) 0 O O O C) C) (D O O O 0 0 O C) (3 0 .405(4) .331(3) .415(3) .428(3) .511(3) .531(3) .572(4) .4?2(4) .308(3) .935(4) .243(5) .321(4) .393(4) .387(3) .O55(4) .O37(3) .O50(3) .117(4) .108(3) .O1B(3) .229(2) .192(4) .247(4) .336(4) .377(4) 4(1) 3(1) 1.6(8) 2.2(8) 2.5(9) 3(1) 4(1) 3(1) 3(1) 4(1) 7(2) 5(1) 4(1) 2.4(8) 4(1) 2.3(9) 2.3(9) 5(1) 3(1) 3(1) 0.9(7) 4(1) 5(1) 4(1) 6(1) ato- C(66) C(71) C(72) C(73) C(74) C(75) C(76) C(81) C(82) C(83) C(84) C(85) C(86) C1(4) C1(5) C(5) 000 00000000 0 00 p. p Tabb 22. Continued. 697(3) 156(3) .043(5) .001(5) .054(4) .163(5) .224(5) .258(3) .356(4) .373(4) .287(4) .186(5) .171(4) .979(2) .223(2) .108(8) 0 0 00 00000 0 0 .365(3) .318(4) .347(4) .431(4) .486(4) .462(4) .429(3) .472(3) .542(3) .578(3) .546(4) .472(3) .298(2) .388(2) .371(6) 269 0 0 o 6 6 0000000000 .313(3) .106(3) .052(4) .O33(4) .056(4) .002(4) .087(4) .295(3) .371(4) .438(3) .430(3) .356(4) .292(3) .731(2) .804(2) .753(7) 3(eq) 2.3(8) 1.9(8) 5(1) 5(1) 3(1) 5(1) 5(1) 1 8(8) 4(1) 3(1) 4(1) 5(1) 2.3(9) 14.5(7) 14.5(7) 14(3) 1‘ (‘1 ll ' I . .1 270 ’I‘abb23. Atomic positional parameters (A2) and their estimated standard deviations for [Rez(u-CO)(p-CI)C12(CO)(NO)- (dppm)9J(BF4). atom x y z OOOOOOOOOOOOOOooooooooooooooooooooooor—aooooooooo 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o 1» U) u A NHmmbwNHQU'Iwat-‘ONU‘Ibu)NHmmwat-‘vvvvvvvvvvvvvvvvNun-4NH ooooooooooooooooooooooooooooooooooooooooooooooo I O O O O O C C O C O O O O C C O C C O C O O O C O O C O O C O O O O O O O O O O O O I O 0 U1 0.) u) ooooooooooooooooooooooooooooooooooooooooooooooo O C O C C O C O O C O O C C O O O I O O O O O O O C O O C O O O 0 O O C O O O O O O O O 0 O 0 w (o q A ounce..6..6.6bwwwwwuwNNNNNHHHHHHAwHNHwNH.6.wwwnwmt—‘AAAAA vvvvvvvvvvvvvvvvvvvvvvvvvv 0000000000OOOOOOOOOOOOOOOOOQOOZOOO'11"1"1"‘1'0'0'13'000050$0 271 Tabb 23. Continued. 7‘ y atom )))))))))))))))))))))))))) ((ll‘((((((((((((((((((((((( 08441497046689638988747518 02807337113582170049855846 Qu86I7EDR:bG:bEJ4Aqd:3§:42:51411172401004 .......................... 00000000000000000000000000 ) ))))))))))))))))))))))) 9)) 32221212221222221212212(11 ((((((((((((((((((((((( 9(( 54488381729368453903840046 23563614163528690474970743 33334455542221113333221304 )))))))))))))))))))))))))) ((II‘((((((((((((((((((((((( 98311317193819817605421055 13799337227630047859728980 21001221110122100011119682 OOOOOOOOOOOOOOOOOOOOOOOOO 0 00000000000 0 000 . _ )))))))))))))))))))))) (((((((((((((((((((((((((( 272 Table24. Atomic positional parameters (A2) and their estimated standard deviations for Ru3(u-Cl)2(PBu3")2(CO)3. Atom x y z 8(A2) Ru(l) 0.30145(5) 0.22580(3) 0.39260(3) 3.59(l) Ru(Z) 0.29631(5) 0.23764(3) 0.22483(3) 3.68(1) Ru(3) 0.23734(5) 0.33945(3) 0.31578(3) 4.30(1) Cl(l) 0.1833(2) 0.16656(9) 0.29810(8) 4.02(4) 01(2) 0.4630(1) 0.2095(1) 0.31367(9) 4.17(4) P(1) 0.3538(2) 0.1289(1) 0.45228(9) 4.26(4) 9(2) 0.3463(2) 0.1504(1) 0.15333(9) 4.50(5) 0(1) 0.4564(6) 0.3080(3) 0.4915(3) 7.4(2) 0(2) 0.0932(5) 0.2493(3) 0.4758(3) 7.3(2) 0(3) 0.0773(5) 0.2739(3) 0.1331(3) 7.3(2) 0(4) 0.4405(6) 0.3305(3) 0.1497(3) 8.1(2) 0(5) 0.5092(5) 0.3660(3) 0.3243(4) 7.8(2) 0(6) -0.0198(5) 0.2840(3) 0.3021(3) 7.0(2) 0(7) 0.1950(6) 0.4173(4) 0.4456(4) 9.3(2) 0(8) 0.1796(7) 0.4353(4) 0.2013(4) 10.7(2) C(l) 0.3979(7) 0.2771(4) 0.4543(4) 5.0(2) C(2) 0.1719(7) 0.2402(4) 0.4436(4) 4.8(2) C(3) 0.1627(7) 0.2592(4) 0.1689(4) 5.3(2) C(4) 0.3860(7) 0.2951(4) 0.1791(4) 5.4(2) C(S) 0.4094(7) 0.3553(4) 0.3209(5) 5.5(2) C(6) 0.0768(7) 0.3027(4) 0.3063(4) 5.2(2) C(7) 0.2105(7) 0.3874(4) 0.3973(5) 6.1(2) C(8) 0.2026(8) 0.3997(4) 0.2448(5) 6.6(2) C(9) 0.3365(7) 0.1360(4) 0.5466(3) 4.9(2) C(10) 0.3678(8) 0.0758(5) 0.5893(4) 6.5(2) C(11) 0.341(1) 0.0877(6) 0 6663(4) 9.0(3) C(12) 0.364(1) 0.0215(7) 0.7068(6) 13.0(5) C(13) 0.5098(7) 0.1001(4) 0 4442(4) 5.7(2) C(14) 0.6057(7) 0.1460(5) 0.4730(5) 7.1(3) C(15) 0.7283(9) 0.1209(7) 0.4518(8) 12.1(4) C(16) 0.812(1) 0.1640(8) 0.451(1) 20.1(8) C(17) 0.2634(8) 0.0592(4) 0.4224(4) 6.0(2) C(18) 0.1274(8) 0.0655(5) 0.4341(5) 7.2(2) C(19) 0.055(1) 0.0069(6) 0.4035(6) 11.2(4) C(20) 0.027(1) 0.0101(7) 0.3313(8) 13.6(5) C(21) 0.5010(7) 0.1194(5) 0.1710(5) 6.3(2) C(22) 0.5971(7) 0.1695(6) 0.1587(5) 8.1(3) C(23) 0.722(1) 0.1443(8) 0.1855(9) 14.3(5) C(24) 0 819(1) 0.1891(8) 0.176(1) 15.4(6) C(25) 0.3336(8) 0.1698(4) 0.0597(4) 6.1(2) C(26) 0 3641(9) 0.1143(6) 0.0111(4) 8.2(3) C(27) 0.328(1) 0.1375(7) -0.0661(5) 12.6(4) C(28) 0.354(1) 0.0836(9) -0.1145(8) 14.9(5)* C(29) 0.2537(7) 0.0784(4) 0.1597(4) 5.5(2) C(30) 0.1237(7) 0.0885(5) 0.1290(5) 7.0(2) C(31) 0.059(1) 0.0238(6) 0.1275(7) 10.7(4) C(32) -0.062(1) 0.0295(8) 0.093(1) 16.9(7) 273 Tabh25. Atomic positional parameters (A2) and their estimated standard deviations for Rh2(OzCCH3)3(TMPP-0)(MeOH). Ato- y 2 M42) 35(1) .97704(3) .35229(3) 0.23068(3) 1.515(8) Rh(2) .05222(3) .15371(3) 0.10053(3) 1.633(8) 9(1) .81147(9) .39684(9) 0.1555(1) 1.55(2) 0(1) .0150(3) .1217(3) 0.2341(3) 2.39(8) 0(2) .9525(3) 0.2954(3) 0.3578(3) 2.36(8) 0(3) .1992(3) 0.1453(3) 0.1573(3) 2.59(9) 0(4) .1357(3) 0.3189(3) 0.2908(3) 2.52(9) 0(5) 1.0850(3) 0.2155(2) .0239(3) 2.09(8) 0(5) 1.0172(3) 0.3908(2) 0.0974(3) 2.10(7) 0(7) 0.9073(3) 0.1720(2) .0311(3) 2.13(8) 0(8) 0.7923(3) 0.1995(3) .3559(3) 3.7(1) 0(9) 0.7551(3) 0.5140(3) .0299(3) 2.50(8) 0(10) 0.8996(3) 0.5422(3) .3292(3) 2.37(8) 0(11) 0.5873(4) 0.8837(3) .3734(4) 4.2(1) 0(12) 0.5893(3) 0.5445(3) .1251(3) 2 72(9) 0(13) 0.5559(3) 0.2732(3) .0387(3) 2.37(8) 0(14) 0.5279(3) 0.2753(3) .3873(3) 3.81(9) 0(15) 0.7455(3) 0.4591(3) .4123(3) 2.25(8) 0(15) 1.1357(3) -o.0100(3) 0.0215(3) 2.46(8) C(l) .9731(4) 0.1955(4) 0.3315(4) 2.4(1) C(2) .9455(5) 0.1551(5) 0.4282(6) 4.0(2) C(3) .2114(4) 0.2245(4) 0.2457(5) 2.5(1) c14) .3242(4) 0.2015(5) 0.2902(7) 4.3(2) C(S) .0588(4) 0.3150(4) -o.0009(5) 2.2(1) 0(5) .0794(5) 0.3495(4) -0.1012(5) 3.0(1) Atom W(7) C(8) C(9) C(10) C(11) C(12) C(13) C(14) C(15) C(16) C(17) C(18) C(19) C(20) C(21) C(22) C(ZZB) C(23) C(24) C(25) C(26) C(27) C(28) C(29) C(30) Tabb 25. Continued. X 0.8189(3) 0.8645(4) 0.8584(4) 0.8120(4) 0.7793(4) 0.7836(4) 0.8029(7) 0.7219(5) 0.7455(4) 0.7967(4) 0.7479(4) 0.6410(4) 0.5863(4) 0.6384(4) 0.9575(4) 0.6426(8) 0.490(2) 0.4774(4) 0.7175(4) 0.6604(4) 0.5961(4) 0.5885(4) 0.0198(4) 0.7000(4) 0.6285(4) OOOOOOOOOOOOOOOOOO 274 Y .3459(3) .2302(4) .1762(4) .2400(4) .3520(4) .4054(4) .0907(6) .5767(4) .5449(4) .6035(4) .7165(4) .7717(4) .7171(4) .6050(4) .5982(4) .9450(8) .939(2) .5774(5) .3523(4) .3032(4) .2759(4) .3105(4) .3735(4) .3997(4) .1932(4) 0 00000000000000 -0 Z .0054(4) .0437(4) .1551(4) .2372(4) .1959(4) .0754(4) .3958(5) .1098(5) .2215(4) .3005(4) .3537(5) .3239(5) .2455(5) .1979(4) .4112(5) .4359(9) .350(3) .1505(5) .2251(4) .1605(4) .2170(5) .3404(5) .4100(5) .3493(4) .0299(5) 8(A2) -.... 1.6(1) 1.8(1) 2.2(1) 2.4(1) 2.2(1) 2.0(1) 5.6(2) 3.8(1) 1.8(1) 1.9(1) 2.5(1) 2.8(1) ’2.6(1) 2.0(1) 3.6(1) 4.9(2)* 4.8(6)* 3.2(1) 1.8(1) 2.1(1) 2.5(1) 2.7(1) 2.5(1) 2.0(1) 2.9(1)* 275 Table 25. Continued. Mon at y 2 Mn) C(31) 0.5200(5) 0.3025(5) 0.5141(5) 3.7(1). C(32) 0.7495(4) 0.4954(4) 0.5390(5) 2.8(l)* C(33) 1.1554(5) -0.0244(4) -o.1441(5) 3.2(1). C(34) 0.525 0.995 0.028 32(2) t C(35) 0.525 0.915 0.082 13.1(5)+ 0(17) 0.553 0.875 0.027 28.5(8)+ Starred atoms were refined isotropically. Anisotropically refined atoms are given in the form of the equivalent isotropic displacement parameter defined as u/3Ea‘8H + 038,, 9 c38,, + ab(cos¥)8,, + ac(cose)s,, + bc(cosa)8,,]. f Lattice ethanol which was placed in fixed positions Fats-"- 276 Table %. Atomic positional parameters (A2) and their estimated standard deviations for [I-ITMPP][F83(11-H)()i-CO)(CO)10]. Atom x y z B(A2) Fe(l) 0.4584(2) 0.15172(8) 0 09845(8) 2.92(3) Fe(2) 0.3051(2) 0.23089(8) 0.23945(8) 2.45(3) Fe(3) 0.5099(2) 0.28005(8) 0.24825(8) 2.79(3) 9(1) 0.0429(3) 0.2572(1) 0.7015(1) 1.91(5) 0(1) 0.534(1) 0.1370(5) 0.0328(5) 3.8(2) 0(2) 0.307(1) 0.0898(5) 0.0298(5) 3.3(2) 0(3) 0.509(1) 0.0829(5) 0.1418(5) 3.0(2) 0(4) 0.152(1) 0.2358(5) 0.1703(5) 3 0(2) 0(5) 0.758(1) 0.2024(5) 0.2402(5) 3.8(3) 0(5) 0.428(1) 0.2577(5) 0.0758(5) 3.3(2) C(7) 0.249(1) 0.1225(5) 0.2397(5) 3 1(2) C(8) 0.558(1) 0.3550(5) 0.3540(5) 3.7(3) C(9) 0.705(1) 0.3393(5) 0.1957(5) 3.5(2) C(10) 0.212(1) 0.2924(5) 0.3327(5) 3.1(2) C(11) 0.418(1) 0.3414(5) 0.2492(5) 2.4(2) 012 _0.1715(7) 0.2842(4) 0.8400(3) 2 8(1) 014 0.2108(7) 0.4721(4) 1.0595(3) 2.5(1) 015 0.3355(7) 0.3751(4) 0.7840(3) 2 9(2) 011 0.084(1) 0.3295(5) 0.8127(5) 1.8(2) c12 -0.0252(9) 0.3305(5) 0.8738(5) 2.0(2) 013 0.010(1) 0.3754(5) 0.9511(5) 2.0(2) C14 0.1515(9) 0.4233(5) 0.9872(5) 1.8(2)* C15 0.273(1) 0.4255(5) 0.9300(5) 2.1(2) C16 0.2352(9) 0.3787(5) 0.8450(5) 2.1(2) 277 Tabb M. Continued. Atom x y 3(82) 017 -O.287(1) 0.2789(7) 0.8992(5) 4.9(3) 018 0.109(1) 0.4549(5) 1.1349(5) 2.9(2) 019 0.487(1) 0.4335(5) 0.8141(5) 3.5(3) 022 0.0731(7) 0.1438(4) 0.7903(3) 3.0(1) 024 0.3015(8) —0.0895(4) 0.5544(4) 4 1(2) 025 0.1033(7) 0.1543(4) 0.5325(3) 2.8(1) 021 0.0981(9) 0.1542(5) 0.5515(5) 1.9(2) 022 0.122(1) 0.1053(5) 0.7107(5) 2.3(2) 023 0.189(1) 0.0220(5) 0.5770(5) 2.4(2) 024 0.229(1) -0.0102(5) 0.5929(5) 2 7(2) 025 0.204(1) 0.0332(5) 0.5402(5) 2.4(2) 025 0.1355(9) 0.1137(5) 0.5753(5) 2.1(2) 027 0.118(1) 0.1054(5)' 0.8499(5) 3.5(2) 028 0.327(1) -0.1434(5) 0.5002(5) 5.0(3) 029 0.152(1) 0.1347(5) 0.4472(5) 3.5(2) 032 -0.0383(6) 0.4075(4) 0.5550(3) 2.7(1) 034 -0.5022(7) 0.3111(4) 0.5789(4) 3.5(2) 035 -0.2574(7) 0.1471(4) 0.5718(4) 2.9(1) 031 —o.1519(9) 0.2775(5) 0.5527(5) 1.7(2) 032 —o.1722(9) 0.3502(5) 0.5428(5) 2.0(2) 033 -0.320(1) 0.3542(5) 0.5125(5) 2.4(2) 034 —0.449(1) 0.3025(5) 0.5050(5) 2.8(2) 035 -0.435(1) 0.2283(5) 0.5245(5) 2.5(2) 035 -0.285(1) 0.2152(5) 0.5525(5) 2.2(2) Atom C37 C38 C39 0(1) 0(2) 0(3) 0(4) 0(5) 0(6) 0(7) 0(8) 0(9) 0(10) 0(11) Tabb %. Continued. X .051(1) .631(1) .395(1) .7397(8) .2002(9) .5378(8) .0498(7) .8584(8) .4042(9) .2017(8) .7054(9) .7667(8) .1404(8) .3861(7) 0 OOOCOOO 0 0 0. 0 0 0 278 Y .4851(5) .3932(6) .0883(6) 1237(4) .0451(4) .0277(4) .2414(4) .1563(4) .3128(4) .0579(4) .4069(5) .3813(4) .3338(4) .4141(4) 0 0000000 2 .6350(6) .5703(6) .6725(6) .0106(4) .0151(4) .1632(4) .1266(4) .2368(4) .0555(4) .2438(4) .4230(4) .1636(4) .3898(4) .2569(4) U) fi U‘ U) § U U o o o o o o o Atomic positional parameters (A2) and their estimated 279 standard deviations for Ru3(u-CO)2(CO)6{u3-112- CsH2(OMe)3} [Ll-P {CGH2(OM8)3}2]. Atom Ru(l) Ru(2) Ru(3) P(l) 0(1) 0(2) 0(3) 0(4) 0(5) 0(6) 0(7) 0(8) 012 014 016 022 024 026 051 053 055 C(1) C(2) C(3) C(4) C(5) .2403(3) .3566(3) .1125(3) .2438(8) .133(3) .031(2) .315(2) .518(2) .356(2) .451(2) .139(2) .071(2) .436(2) .244(2) .020(2) .457(2) .254(2) .065(2) .155(2) .502(2) .523(2) .171(3) .060(3) .279(4) .524(3) .352(3) 000 .3305(2) .1731(2) .2214(2) .0979(6) 0.355(2) 0. 0 90000000 .402(1) .507(1) .102(2) .032(1) .254(2) .198(2) .139(1) .049(1) .251(1) .025(1) .117(1) 098(2) .055(1) .289(1) .371(1) .328(1) .349(2) .350(2) .442(3) .131(2) .084(2) OOOOOOOO .5471(1) .5808(1) .5097(1) .5443(4) .437(1) .5593(9) .532(1) .505(1) .5019(9) .4710(9) .550(1) .513(1) .5455(8) .5724(9) .6107(8) .7135(8) .885(1) .7225(9) .5770(8) .7528(8) .5751(9) .478(1) .574(1) .538(2) .595(1) .530(1) 5(l)* 2.6(8)* 1.8(7)* Tabb 27. Continued. Atom C(6) C(7) C(8) C11 C12 C13 C14 C15 C16 C17 C18 C19 C21 C22 C23 C24 C25 C26 C27 C28 C29 C51 C52 C53 C54 C55 .395(3) .046(3) .086(3) .227(3) .339(3) .337(3) .233(3) .124(3) .127(3) .555(3) .137(3) .091(3) .259(3) .357(3) .357(3) .251(3) .152(3) .155(3) .570(3) .149(4) .044(3) .2800) .324(3) .441(3) .518(3) .461(3) 00000 00000 CO 000 280 Y .252(2) .208(2) .172(2) .011(2) .079(2) .160(2) .180(2) .118(2) .037(2) .107(2) .284(2) .000(2) .087(2) .103(2) .108(2) .090(2) .072(2) .069(2) .127(2) .088(3) .030(2) .308(2) .331(2) .350(2) .351(2) .328(2) OOOOO 00000 CO 000 O OO O O O O O O O 0 .511(1) .644(1) .554(1) .627(1) .630(1) .608(1) .591(1) .588(1) .608(1) .643(1) .549(1) .591(1) .719(1) .746(1) .801(1) .830(1) .808(1) .750(1) .740(1) .920(2) .754(1) .675(1) .724(1) .717(1) .668(1) .625(1) 6(1)* 2.6(8)* 2.9(8)* 2.0(8)* 2.6(8)* 3.5(9)* 2.2(8)* 281 Tabb 27. Continued. Atom X y 8(A2) 055 0.337(3) 0.302(2) 0.525(1) 1 8(8)* 057 0.552(3) 0.339(2) 0.570(1) 2.9(8)* 058 0.434(3) 0.380(2) 0.813(1) 3.4(9)* 059 0.093(3) 0.298(2) 0.731(1) 3.0(8)* Ru(4) -0.1518(3) -0.1509(2) 0.8740(1) 2.75(8) Ru(5) -0.0280(3) -0.3217(2) 0.8919(1) 2.35(8) Ru(6) -0.1233(3) -0.2710(2) 0.7907(1) 1.97(7) P(2) 0.0155(8) —0.3980(6) 0.8123(4) 1.9(2) 055 0.053(3) -0.198(2) 0.852(1) 1.7(7)* 051 0.038(2) -0.212(1) 0.7585(8) 2.4(5)* 0(11) -o.205(3) -O.l38(2) 0.795(1) 3.1(8)* C(12) -0.135(3) —0.050(2) 0.897(2) 4(1)* C(13) -0.312(3) -0.144(2) 0.894(2) 5(1)* C(14) -0.124(3) -0.241(2) 0.950(1) 2.7(8)* C(15) -0.121(3) -0.409(2) 0.919(1) 4(1)* 0(15) 0.095(3) -o.359(2) 0.939(1) 2.2(8)* C(17) -0.251(3) -0.314(2) 0 813(1) 4.0(9)* C(18) -0.150(3) -0.279(2) 0.717(1) 4.1(9)* 031 0.155(3) -o.407(2) 0.774(1) 1.7(7)* 041 -0.024(3) -0.509(2) 0.818(1) 2.1(8)* 032 0.057(2) -0.445(1) 0.7042(8) 2.7(5)* 034 0.474(2) -0.4o1(1) 0.5741(9) 3.4(5)* 035 0.271(2) -o.379(1) 0.8482(8) 2.5(5)* 042 -0.179(2) -o.459(1) 0.7537(8) 3.0(5)* 044 -o.123(2) -o.753(2) 0.852(1) 5.3(7)* 045 0.134(2) -0.547(1) 0.8758(9) __3.5(5)* Continued. Atom 063 065 C32 C33 C34 C35 C36 C37 C38 C39 C42 C43 C44 C45 C46 C47 C48 C49 C61 C62 C63 C64 C65 C67 C68 C69 0000000000 1 I O O -0. OOQOOOOOO .393(2) .071(2) .166(3) .269(3) .367(3) .374(3) .270(3) .053(3) .481(3) .386(3) .123(3) .162(3) 091(3) .003(3) .044(3) .282(3) .228(4) .193(4) .107(3) .220(3) .275(3) .235(3) .125(3) .088(3) .452(3) .143(3) 282 Y .128(2) .175(1) .427(2) .428(2) .407(2) .388(2) .394(2) .474(2) .417(2) .372(2) .528(2) .613(2) .669(2) .654(2) .573(2) .486(2) .774(3) .602(3) .193(2) .169(2) .148(2) .148(2) .173(2) .199(2) .128(2) .165(2) OOOOOCOOOOOOOOOOOOOOOOOOO p. .832(1) .9558(9) .720(1) .684(1) .707(1) .760(1) .794(1) .650(1) .617(2) .869(1) .791(1) .799(1) .840(1) .865(1) .854(1) .724(1) .826(2) .920(2) .809(1) .795(1) .837(1) .892(1) .902(1) .713(1) .778(1) .000(2) 4.5(5)* 4.1(5)* 2.6(8)* 3.1(8)* 2.4(8)* 3.0(8)* 1.5(7)* 3.0(8)* 5(1)* 3.5(9)* 2.6(8)* 3.3(9)* 3.7(9)* 3.5(9)* 2.2(8)* 3.8(9)* 5(1)* 5(1)* 2.5(8)* 2.2(8)* 3.0(8)* 3.2(9)* 3.4(9)* 2.4(8)* 4(1)* 5(1)* atom C(31) C(32) C(33) C(34) C(35) C(36) C(37) C(38) OOOOOOOO Tabb 27. Continued. .235(2) .285(2) .287(2) .238(3) .l81(2) .191(2) .272(3) .102(2) 00000000 283 Y .373(3) .425(3) .529(3) .584(4) .544(3) .434(3) .726(4) .447(3) OOOOOOOO .452(2) .SO9(2) .522(2) .474(2) .425(2) .413(2) .542(3) .314(2) B(eq) 2.3(8) 3.5(9) 4(1) 6(1) 4(1) 2.5(8) 10(2) ‘ 4(1) 284 Tabb 28. Atomic positional parameters (A2) and their estimated standard deviations for 083(u-OH)2(TMPPXCO)9. Atom 051 032 083 P1 01 02 C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) 0(1) 0(2) 0(3) 0(4) 0(5) 0(6) 0(7) 0(8) OOCOOOOOOOOOOOOOOOOOOO I O X .31334(8) .29534(9) .1314(5) .342(1) .148(1) .267(2) .468(2) .326(2) .136(2) .265(2) .439(2) .377(2) .063(2) .265(2) .231(2) .567(1) .348(2) .048(1) .245(2) .523(1) .426(2) .017(1) 0. 0. .19481(8) 0. 0 0 0 0 0 0 0 0 0 0 0. 0 0 0 0 0 0 0 0 0 Y 50187(8) 49045(8) 66307(7) .8080(5) .660(1) .551(1) .363(2) .472(2) .523(2) .419(2) .531(2) .588(2) .367(2) 640(2) .752(2) .270(1). .453(2) .526(2) .376(1) .553(2) .642(1) .292(1) .630(2) OOOOOOOOHOOOOOOOOOO H 000 .58184(7) .87981(7) .81475(7) .7321(4) .729(1) .597(1) .550(2) .595(2) .547(2) .839(1) .014(2) .895(2) .880(1) .889(2) .929(2) .543(1) .711(1) .467(1) .818(2) .093(1) .898(1) .877(2) .935(1) \l o O5 \J o a coma) UQGO‘GGUIONUI Tabb 28. Continued. OOOOOOOOO I 0 .305(2) .024(1) .302(1) .366(1) .031(1) .365(1) .073(1) .092(1) .334(1) .293(1) .172(2). .092(2) .l30(2) .253(2) .336(2) .294(2) .104(2) .218(2) .491(2) .021(2) .057(2) .172(2) .252(2) HOO OOOOOOOOO H 00000 285 Y .798(1) .965(1) .170(1) .882(1) .976(1) .830(1) .641(1) .663(1) .844(1) .994(1) .924(2) .991(2) .075(2) .094(2) .033(2) .949(2) .046(2) .240(2) .899(2) .807(2) .897(2) .904(2) .822(2) HOO OOOOOOOOOOOOOO H OOOOO .995(1) .843(1) .025(1) .799(1) .543(1) .580(1) .724(1) .555(1) .344(1) .554(1) .815(1) .854(2) .931(2) .953(2) .915(2) .843(1) .855(2) .073(2) .829(2) .587(2) .545(1) .511(2) .512(2) UIUIbU'l Atom C25 C26 C(22) C(24) C(26) C31 C32 C33 C34 C35 C36 C(32) C(34) C(36) HI 82 Tabb 28. Continued. O 0000 X .227(2) .108(2) .002(2) .451(2) .159(2) .200(2) .169(2) .212(2) .287(2) .319(2) .273(2) .008(2) .292(2) .391(2) .410 .066 ‘<: <3 <3 <3 000000 286 Y .726(2) .724(2) .076(1) .737(2) .550(2) .824(1) .747(2) .743(2) .830(2) .916(2) .912(2) .638(2) .764(2) .072(2) .719 .527 «3 0000 00000000000 .652(2) .687(2) .620(2) .567(2) .723(2) .618(1) .537(1) .442(1) .429(2) .505(2) .595(1) .482(2) .261(2) .653(2) .716 .659 287 Tabb29. Atomic positional parameters (A2) and their estimated standard deviations for 083(u-OHXTMPP-0)(CO)9. at°m x y z B(eq) 05(1) 0.2793(1) 0.3381(1) 0.55171(8) 2.70(9) 05(2) 0.4075(1) 0.19l8(2) 0.55854(8) 3.5(1) 0s(3) 0.3357(1) 0.1938(1) 0.53559(7) 2.32(9) 9(1) 0.2505(5) 0.2373(8) 0.4358(4) 2.4(5) 0((1)) 0.215(2) 0.254(2) 0.790(1) 5.0(8) 0(11) 0.333(1) 0.352(2) 0.555(1) 2.8(5) 0((2)) 0.388(2) 0.494(2) 0.719(1) 5.8(7) 0(10) 0.223(1) 0.218(2) 0.594(1) 2.5(5) 0((3)) 0.140(2) 0.483(3) 0.537(1) 5.7(8) 0((4)) 0.254(2) 0.035(3) 0.701(1) 5.9(8) 0((5)) 0.519(2) 0.013(3) 0.532(2) 11(1) 0((5)) 0.517(2) 0.357(2) 0.598(1) 4.8(5) 0((7)) 0.444(2) 0.238(3) 0.821(2) 10(1) 0((8)) 0.323(2) -0.035(3) 0.525(1) 7.0(8) o((9)) 0.502(2) 0.151(2) 0.459(1) 5.3(5) 0(12) 0.220(2) 0.590(3) 0.485(1) 5.5(7) 0(13) 0.153(1) 0.379(2) 0.351(1) 3.8(5) 0(14) 0.087(1) 0.280(2) 0.494(1) 2.1(5) 0(15) -o.042(2) -0.011(2) 0.402(1) 4.7(7) 0(15) 0.245(2) 0.035(2) 0.391(1) 4.3(6) 0(17) 0.415(1) 0.335(2) 0.411(1) 4.5(5) 0(18) 0.444(2) 0.249(2) 0.159(1) 4.9(7) 0(19) 0.195(1) 0.187(2) 0.291(1) 3.5(5) 0((1)) 0.237(2) 0.284(3) 0.737(2) 4(1) 0((2)) 0.342(2) 0.435(3) 0.595(2) 4(1) atom C((3)) C((4)) C((S)) C((6)) C((7)) C((8)) C((9)) C(11) C(12) C(13) C(14) C(15) C(16) C(17) C(18) C(19) C(21) C(22) C(23) C(24) C(25) C(26) C(27) C(28) C(29) I O Tabb 29. Continued. .l94(3) .314(2) .481(3) .474(2) .429(3) .320(3) .437(2) .163(2) .090(2) .016(2) .026(2) .103(2) .174(2) 00000000000000 .009(2) .121(3) 0.264(3) 0.305(2) 0.386(2) 0.435(2) 0.390(3) 0.313(2) 0.273(2) 0.495(3) 0.534(2) 0.161(2) I O 288 .425(4) .095(3) .O78(4) .296(4) .216(5) .056(4) .178(3) .172(3) .195(3) .l42(3) .054(3) .002(3) .067(3) .336(3) .019(3) .071(4) .246(3) 0.288(3) 0.292(3) 0.251(3) 0.216(3) 0.210(3) 0.384(4) 0.262(3) 0.153(3) OOOOOOOOOOOOOOO 0 0.544(2) 0.594(2) 0.550(2) 0.531(2) 0.757(3) 0.531(2) 0.499(2) 0.435(1) 0.455(1) 0.447(2) 0.418(2) 0.394(2) 0.407(2) 0.495(2) 0.418(2) 0.359(2) 0.349(2) 0.351(2) 0.290(2) 0.229(2) 0.228(1) 0.285(2) 0.409(2) 0.173(2) 0.229(2) 8(eq) 5(1) 3.6(9) 4(1) 4.1(9) 9(2) 6(1) 3.1(8) 2.5(7) 1.7(6) 4(1) 2.8(8) 2.6(8) 3.0(8) 4(1) 5(1) 7(1) 2.2(7) 2.1(7) 3.0(8) 5(1) 2.1(7) 2.7(8) 6(1) 5(1) 4(1) 289 Tabb 29. Continued. Atom x y z 8(A2) 0(11) -0.258(2) -0.082(1) 0.7677(9) 3.6(6) 0(12) -0.125(2) 0.019(2) 0.907(1) 5.7(8) 0(13) -0.4l7(2) -0.137(2) 0.906(1) 10(1) C(14) -0.164(2) -0.238(2) 0.9942(8) 4.0(7) 0(15) -0.167(3) -0.460(2) 0.937(1) 8.4(9) C(16) 0.168(2) -0.398(2) 0.9660(9) 5.0(7) 0(17) -0.340(2) -0.346(2) 0.830(1) 5.8(8) 0(18) ~0.197(2) -0.288(2) 0.676(1) 6.5(8) ‘--‘------~---‘--~-_-----------------------------“--‘-"-------- HICHIGnN STQTE U 3