I V ’1’ ll J J WI 1 \ HHHHIWNHHII i 'lWlJHl/HH F r 3% WHEN THE ENVESTIGATION OF ZINC (ll), NECKELUI) AND PLATfNUMUI) CHLORWE COMPLEXES WiTH SOME l-SUBSTITUTED TETRAZOLES Tina“ {M {in Dogma of DH. D. MECHIGAN STATE UNEVERSITY George L. Gilbert 1963 .. .atm-ksxv‘um s ' ~ ‘ ‘ _ i of I t 4. ‘5 {fr 3‘?- :1 9'“ ’3 " 42“,; .1: (my! At. .2; a q: a A ‘;‘-A.~‘ c ‘.. -.!'n “Hr-"~51. > m"; in: ’. *1"- V YT... ‘ . U.- ‘ .4025:- ,... ,4. I.“ 3 \ l‘ *3 “-fl. ‘ .“n MICHIGN‘J STATE L'F-STVZRSITY EAST LANSING, MICHIGAN ABSTRACT THE INVESTIGATION OF ZINC(II), NICKEL(II) AND PLATINUM(II) CHLORIDE COMPLEXES WITH SOME l-SUBSTITUTED TETRAZOLES by George L. Gilbert The investigation of the zinc(II) chloride, nickel(II) chloride and platinum(II) chloride complexes of some l-substituted tetrazoles was carried out. The coordination involved the molecular tetrazole coordinating with the metal chloride. The general formula for the solid products was MTZCIZ (where T = l-methyltetrazole, l-cyclo- hexyltetrazole or l-phenyltetrazole). The crystalline products were obtained with the formula Zn(C2N4H‘)plz, Zn(C-,N4H6)ZC12, Zn(C-,N4HIZ)ZC12, Ni(C2N4H4)zClz, Ni(C-,N4H12)ZC12, Pt(CzN4H4)zClz and Pt(C-,N4H12)ZC12. These solids are generally insoluble in common reagents with the exception of the zinc compounds which are moderately soluble in tetrahydrofuran and simple alcohols. Ethanolic solutions of the zinc complexes with l-methyltetrazole and l-phenyltetrazole yielded clear crystals with hexagonal platelet and rhombic shapes respectively. The nickel and zinc complexes decomposed to the free tetrazole and metal chloride in water, but the platinum complexes were un- affected in this medium. The dichlorobis(l-methyltetrazole) platinum(II) compound dissolved with decomposition in concentrated nitric acid and concentrated aqueous ammonia, whereas the l-cyclo- hexyltetrazole platinum(II) complex was not affected by these solvents. George L. Gilbert The solid complexes decompose without melting when heated, often explosively. X-ray diffraction data indicate a large unit cell. Stability constant studies on cobalt and nickel with l-substituted tetrazoles in ethanol and tetrahydrofuran yielded similar values for l-methyltetrazole and l-cyclohexyltetrazole and somewhat larger values with l-phenyltetrazole. THE INVESTIGATION OF ZINC(II), NICKEL(II) AND PLATINUM(II) CHLORIDE COMPLEXES WITH SOME l-SUBSTITUTED TETRAZOLES BY George L. Gilbert A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Chemistry 1963 AC KNOWLEDGMENT The author wishes to express sincere appreciation to Professor Carl H. Brubaker, Jr. , for his counsel and encouragement; and to Lynn, the author's wife, for her aid and understanding. Acknowledgment is made to E. I. duPont de Nemours, and Company, the Atomic Energy Commission, and the Dow Chemical Company for financial aid. >l<>l<*>k>k**>€<**>2<*>1<*>:<* ii TABLE OF CONTENTS I. HISTORICAL. . . . . . . . . . II. EXPERIMENTAL . . . . . . . Materials Used . . . . . . . Preparation of Tetrazoles . Preparation of the Metal Chlorides Analytical Methods . . . . . . . . . Preparation of the Complexes . . . . . . . Nickel chloride-tetrazole complexes Zinc chloride-tetrazole complexes. . Platinum(II) chloride-tetrazole complexes Infraredspectra................ Stability Constants . . . . . . . . . . . . Cobalt-tetrazole complexes . . . . Nickel-tetrazole complexes . . . . Zinc chloride-tetrazole complexes III. RESULTS AND DISCUSSION . . . . . . . . . LITERATURE CITED . . . . . APPENDIX 0 O O O O O O O O O O O O O O O O 0 iii Page 10 10 ll 12 15 20 20 21 21 22 22 32 41 44 TABLE II. III. IV. VI. VII. VIII. LIST OF TABLES Page Infrared Absorption Bands (in cm‘l) of l-Methyltetra- zole, l-Methyltetrazole hydrochloride, Dichlorobis (l-methyltetrazole) zinc(II), Dichlorobis(l-methy1- tetrazole) nickel(II) and Dichlorobis(1-methy1tetrazole) platinum(II). Potassium Bromide Discs. . . . . . . . 13 Infrared Absorption Bands (in cm‘l) of l-Cyclohexyl- tetrazole, 1-Cyclohexy1tetrazole hydrochloride, Dichlorobis(l-cyclohexyltetrazole) zinc(II), Dichloro- bis(l-cyclohexyltetrazole) nickel(II), and Dichlorobis (l-cyclohexyltetrazole) platinum(II). Potassium BromideDiscs...................... 14 Infrared Absorption Bands (in cm-l) of l-Phenyltetra- zole, 1-Pheny1tetrazole hydrochloride and Dichlorobis (l-phenyltetrazole) zinc(II). Potassium Bromide Discs........................... 19 Absorbancies and-n Values for l-Methyltetrazole and 0. 001M Cobalt chloride hexahydrate in Tetrahydro- furanO 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 23 Absorbancies and'r'i Values for l-Cyclohexyltetrazole and 0.0011_\_/l Cobalt chloride hexahydrate in Tetra- hydrOfuranO O O O O O O O O O O O O O O O O O O O O O O O 24 Absorbancies and-n Values for l-Methyltetrazole and 0. 005111 Cobalt chloride hexahydrate in Absolute EthanOIO 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 25 Absorbancies and 3' Values for l-Cyclohexyltetrazole and 0. 005M Cobalt chloride hexahydrate in Absolute Ethanol 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 26 Absorbancies andn Values for l-Phenyltetrazole and O. 005M Cobalt chloride hexahydrate in Absolute Ethanol 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 27 iv LIST OF TABLES - Continued TABLE IX. XI. XII. Page Absorbancies and; Values for l-Methyltetrazole and 0. 01M Nickel chloride hexahydrate in Absolute EthanOI 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 28 Absorbancies and? Values for l-Cyclohexyltetrazole and 0. Ol_l\_/_1 Nickel chloride hexahydrate in Absolute EthanOI 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 29 Absorbancies and; Values for l-Phenyltetrazole and 0. 01M Nickel chloride hexahydrate in Absolute EthanOI 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 30 Table of Formation Constants for Cobalt with 1-Methy1- tetrazole and l-Cyclohexyltetrazole in Tetrahydrofuran, Cobalt with l-Methyltetrazole, l-Cyclohexyltetrazole, and l-Phenyltetrazole in Absolute Ethanol and Nickel with l-Methyltetrazole, l-Cyclohexyltetrazole, and l-Phenyltetrazole in Absolute Ethanol . . . . . . . . 36 FIGURE 1. LIST OF FIGURES Infrared absorption spectra (in microns) of l-methyl- tetrazole. Potassium bromide disc. . . . . . . . . . Infrared absorption spectra (in microns) of l-cyclo- hexyltetrazole. Potassium bromide disc . . . . . . . Infrared absorption spectra (in microns) of l-phenyl- tetrazole. Potassium bromide disc. . . . . . . . . . Infrared absorption spectra (in microns) of dichloro- bis (l-methyltetrazole) zinc(II). Potassium bromide diSCO 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 Infrared absorption spectra (in microns) of dichloro- bis (l-cyclohexyltetrazole) zinc(II)..Potassium bromide disc O O O O O O O O O O O O O O O O O O O O O O Infrared absorption spectra (in microns) of dichloro- bis (luphenyltetrazole) zinc(II). Potassium bromide diSC. 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 Graph offi/(l-fi)[L] vs (LB/(151') [L] for cobalt chloride and l-methyltetrazole in tetrahydrofuran . . Graph of—r'i/(l-HHL] vs (Z-E/(l-Yi) [L] for cobalt chloride and l-methyltetrazole in absolute ethanol . . Graph of 'H/(l—EHL] vs (Z-E/(l-H) [L] for nickel chloride and l-methyltetrazole in absolute ethanol . . vi Page 16 17 18 37 38 39 I. HISTORICAL According to the theory of Sidgwick (l) and Lowry (2), a co- ordinate bond may be formed between any atom or ion which can act as an electron pair donor and any atom or ion which can act as an electron pair acceptor. The class of compounds resulting from this type of interaction is called coordination compounds. It has also been found that certain olefin and ring systems form coordination compounds where the interaction is that of the 1r -electron cloud of the species with the acceptor atom or ion. A full understanding of the nature of this interaction requires the use of a molecular orbital treatment of the system. Azole ring systems containing two or more nitrogen atoms have also been studied as coordinating groups. The ring systems referred to are shown below: - .. .. .. 1 .. 5 \ / 3 5 \ /z 5 \ / 2 5\ / z 1:11 $1 N1 31 H H H pyrazole imidazole ' 1,.2, 3-triazole 1,2,4-triazole 4 N N N 4 3 5 3 5 3 H 2 u I E H I " 3 \N/ z 6 /Z- 6 /N?‘ I 1 7 N1 N1 H H H tetrazole benzimidazole benzotriazole Structurally these rings might be expected to coordinate at the ring nitrogen or by interaction of the Tr-electrons associated with the ring. A review and discussion of some coordination compounds of these ring systems has recently been given (3). A Solid complexes have been prepared between pyrazole and silver and cobalt but they have received little study. The reaction of imidazole with silver and zinc has also produced solid compounds (4, 5) as have substituted imidazoles with Cu(I), Cu(II), Mg, Ni, Co, Zn, Cd, Mn and Pb (6, 7,8, 9, 10, 11). The imidazole system is found to coordinate as the anion, neutral species, or cation, depending on the acidity of the solution. The solid compounds of benzimidazole with silver, platinum(II), copper, mercury, and cobalt are found to form in most instances after the loss of hydrogen from the l-position (12, 13). The stability of the silver salt has led to its use for quantitative precipitation of the silver ion (14). Substitution in the 1-position results in a much weaker coordination species as shown by the lack of interaction of l-phenyl- benzimidazole, 2-benzylimidazole and 1, 6- dimethylbenzimidazole with Cd, Co, Zn or Ag. The silver compound with 1, 2, 3-be nzotriazole (15) and a series of l, 2, 3-benzotriazole compounds with palladium, rhodium, and osmium have been reported (16, 17, 18, 19). In the latter group of compounds the l, 2, 3.benzotriazole is found to coordinate both as the anion and the neutral molecule. In a slightly basic aqueous medium, coordination of 1, 2, 4-tri- azoles with Ni++, Cd”, and Cu++ occurs as the neutral molecule (20, 21) whereas anionic interaction is exhibited in more basic solutions (22, 23). Tetrazole and 5-substituted tetrazoles have been shown to form good compounds with the alkaline earth metals, and early workers reported compounds with mercury, copper and silver (22, 24, 25). More recent studies have yielded crystalline materials from copper, nickel, cobalt and iron(II) with 5-substituted tetrazoles (26, 27, 28, 29). Brubaker and Daugherty prepared a series of copper 5-substituted tetrazole compounds where the tetrazole coordinates as an anion or as the neutral species depending on the nature of the substituent on the ring. The work of Jonassen, utilizing the more basic 5-trifluoromethyltetrazolyl anion, has led to the preparation of cobalt, nickel and iron(II) compounds. Disubstitution or l-substitution on the tetrazole ring appears to give less stable compounds. The only reported instances of compound form- ation being those with Pt(IV), silver and cadmium (30, 31, 32). Polarographic studies by Popov using metrazole was found to yield no interaction with Co ++, Tl+, and Cd++ in aqueous media. The 5-azotetrazole-metal compounds have found uses as detonators while silver salts with 5-thiotetrazole have been used in photography. The interaction of the various azole ring systems with metal ions in solution has also received attention. Stability constant studies and solution studies of imidazole with cobalt, copper, nickel, cadmium and zinc (33, 34, 35) and methylimidazole with cadmium (36) have been reported. The stability constants of tetrazole with various metal ions have yielded meaningful results only in the case of 5-aminotetrazole- copper(II) (26). Infrared studies of the various azole compounds discussed have not elucidated the exact structure of the materials involved. The study of a series of metals with various substituted imidazoles has, however, resulted in the discovery of a regular shift in the 8p. region due to the metal present in the order Cu > Mg > Ni > C0 > Zn, Cd, Mn > Pb (11). The copper-S-aminotetrazole complex has been shown by absence of a shift in the amino NH stretch to involve bonding by the copper to the ring. Studies of the quantitative effect on coordination of various sub- stituents in the 1-position can be hoped to clarify the character of the bond more fully. Investigation of reactions of l-substituted tetrazoles with the view of preparing metal—tetrazolates would also be of scientific interest. II. EXPERIMENTAL Materials Used Reagent grade chemicals were used throughout this investigation with the exception of the following: Sodium azide - Eastman Kodak yellow label Formanilide - Eastman Kodak yellow label N-methylformamide - Eastman Kodak yellow label Tetrahydrofuran - the Baker Analyzed grade chemical was purified by distillation from either CaHz or LiAlH‘. The fraction boiling at 65°C was collected and used. The following chemicals were prepared in this laboratory: Formanilide: The method of Fallon (37) was used with the modifi- cation that after addition of an excess of formic acid to freshly distilled aniline and distillation to remove excess formic acid, water and unreacted aniline, the slightly yellow residue was collected and used without further purification. N-methLlformamide: A slight excess of ethyl formate was added, with cooling, to a 40% aqueous solution of methylamine. The re- resulting solution was refluxed for two hours and then distilled to remove water and ethyl formate. The remaining solution was distilled, the desired N-methylformamide fraction was collected at 195-2160C. N-cyclohexylformamide: A slight excess of ethyl formate was added to newly distilled cyclohexylamine and the resultant solution was refluxed for four hours. This solution was subsequently dis- tilled to remove water and excess ethyl formate. The N-cyclo- hexylformamide was collected at 2600 C. 5 Preparation of Tetrazoles l-Methyltetrazole: The preparation of methyl isocyanide of Ugi and Meyr (38) was utilized. Distillation of the isocyanide-chloroform mixture thus obtained into an 8% solution of hydrazoic acid in toluene was accomplished. This mixture was then refluxed for twenty-four hours to promote reaction. Evaporation to dryness under an air jet gave a crude yield of approximately twenty per cent. Sublimation of the crude material under reduced pressure gave a white crystalline product whose melting point was 37-80 C. The infrared spectra of l-methyltetrazole can be found in Figure l. l-Cyclohexyltetrazole: The cyclohexylisocyanide used was prepared according to the procedure of Ugi St a_._l. (39). A modification of this procedure was made in that the crude product was not distilled, as suggested, but mixed directly with the 8% hydrazoic acid in toluene and this mixture was refluxed for approximately twenty-four hours. Removal of the solvent under an air jet yielded a reddish-brown solid, the color being caused by resinification of cyclohexylisocyanide. The crude product was sublimed under reduced pressure to yield a white crystalline solid melting at 46-70 C. The infrared spectra of l-cyclo- hexyltetrazole can be found in Figure -2. l-Phenyltetrazole: The procedure of Herbst and Fallon'(40) was followed. Purification. of the crude product by recrystallization from, cyclohexane proved to be a lengthy process and gave only nearly-pure material. Sublimation at reduced pressure, however, gave a white crystalline solid melting at 65-60 C. The infrared spectra of 1—pheny1- tetrazole can be found in Figure 3. . .636 opflgonn .H oudwflh .ofioumfiofifnguoana mo Amcouofle cflv .930on GOSQHOmnm commas; m 2.. o m Edflmmmaom w~ pa my D { 3.; fl 2 .omflu oEEOHQ gammmuom .ogosmbouaxogofiotwo; mo Amdouuflh GS .930on GowumHOmnm 9:9“de .N ohfimwh 3 Q NH 3 on o h 1» m m I 1 I «(p .omfip QEEOHQ gammmuom .oHosmuuouacoamuH mo AmGOHUHE EV .930on cofimuonwnm woumnde .m ondwfih «A MA NH 3 OH m w h c m .P i P 2 ‘ d 1 I! d a < I I 10 Preparation of the Metal Chlorides Platinum(II) chloride: The reduction of HthCl6 by hydrazine hydrochloride (41) was carried out. Cobalt chloride: Dehydration of the hexahydrate was accomplished by prolonged heating at 1100 C, to give blue, solid cobalt chloride. Nickel chloride: The anhydrous salt was donated by Mr. R. A. D. Wentworth who had dehydrated the hydrated salt by use of thionyl chloride and subsequent removal of remaining water under vacuum. The analysis reported for chloride was: Anal. calculated for NiClz: Cl, 54.7. Found: Cl, 54.7. Analytical Methods The solid complexes of l-methy1-, 1-phenyl-, and l-cyclohexyl- tetrazole and certain metal chlorides were prepared in this investigation. The solids thus obtained were dried at 600 C under vacuum and analyzed for metal, chloride, and carbon, hydrogen, and nitrogen by the pro- cedures below. Chloride analysis: Samples of the nickel and zinc complexes were dissolved in 50 ml of 0. 1M nitric acid and were titrated potentio- metrically, using a glass electrode-silver-silverchloride electrode system, with 0. IN silver nitrate. The platinum chloride complexes were analyzed for chloride by Spang Microanalytical Laboratory. Zinc analysis: The potentiometric procedure (42) using a platinum- calomel electrode system and titrating-with 0. 1N potassium hexa- cyanoferrate(II) was slightly modified for this work. To the titrating vessel was added the sample, five milliliters of 15M aqueous ammonia, six milliliters of 18M hydrochloric acid, ll 37 ml of water and three drops of 0. 001 potassium hexacyano- ferrate(III). The resulting solution was titrated potentiometrically, using a platinum electrode-calomel electrode system, with 0. IN pota s sium hexacyanofer rate (II) . Platinum analjsis: A weighed portion of the complex was heated carefully in a tared platinum crucible to 6000 C until a constant weight was found. Nickel analysis: The procedure utilized by Daugherty (3) was slightly modified for use here. To the sample was added 20 m1 of 0. 05M potassium cyanide, 5 m1 of concentrated aqueous ammonia and 0. 2 ml of a potassium iodide solution containing 0. 1 g/ml of potassium iodide. The excess cyanide was titrated to turbidity with 0. IN silver nitrate and the nickel was determined by the difference in volume between the sample and a blank prepared in the same manner but lacking the sample. Carbon, hydrogen and nitroien analysis: Samples of the complexes were analyzed by Spang Microanalytical Laboratory for carbon, hydrogen, and nitrogen. Some of the samples exploded on heating and only fair agreement between the two sets of analyses was found. Preparation of the Complexes The technique generally used for the preparation of the complexes was as follows: Add the tetrazole (0. 02 mole) to approximately 75 ml of recently distilled tetrahydrofuran in a round bottomed flask. The metal chloride (0.01 mole) was placed in a soxhlet cup and refluxing of the tetrazole solution to extract the metal chloride as a weak complex with tetrahydrofuran (43) was begun. After twenty-four hours the solu- tion was removed from reflux and the solvent removed by water vacuum. 12 A second technique, used for the preparation of the nickel and zinc complexes involved the addition of the tetrazole and metal chloride in a 2:1 molar ratio to approximately 40 ml of 95% ethanol and refluxing overnight. The resulting solution was allowed to evaporate slowly and the crystals formed dried over calcium chloride in a desiccator. Nickel chloride-tetrazole complexes: These complexes were prepared by both techniques above, the lower solubility of nickel chloride in tetrahydrofuran giving a lower yield for the first method. A similar preparation involving the soxhlet apparatus but with ethanol as the extraction solvent was carried out. 'The infrared spectrum of this compound was found to be similar to that for the product of the tetrahydrofuran preparation. The analytical data for the nickel chloride complexes are shown below: Dichlorobis (l-methyltetrazole) nickel(II) Calculated for NiClzC4N8H3: Ni, 19.7; C1, 23.8; C, 16.1; N, 37.6; H, 2.7. Found: Ni, 19.7; CI, 23.6; C, 16. 1; N, 37.6; H, 2.6. Dichlorobis (l-cyclohexyltetrazole) nickel(II) Calculated for NiC12C14N8Hu:.Ni, 13.5; Cl, 16.3; C, 38.7; N, 25.8; H, 5.6. Found: Ni, 12.0; C1, 13.8; C, 38.3; N, 24.7; H, 6.1. These solids were found to be insoluble in most common solvents, except water, where solution with decomposition to the metal chloride and free tetrazole occurs. They were green to dark green and appeared to be crystalline. The infrared data for these compounds was tabulated and can be found in Tables I and II. 13 Table I. Infrared Absorption Bands (in cm'l) of 1-Methy1tetrazole, l-Methyltetrazole hydrochloride, Dichlorobis(l-methy1tetra- zole) zinc(II), Dichlorobis(l-methy1tetrazole) nicke1(II) and Dichlorobis ( 1 -methyltetrazole) p1atinu1n(II) . Potas sium Bromide Discs C2N4H4 C2N4H4- HCl Zn(CzN4H‘)zClz Ni(C3N4H4)zClz .Pt'(C;N‘I-I4)3C];z 3401 vs 3509-3390 ms 3401 m 3100 vs 3125 3 3096s 3077 s 2900 m 1704 vw 1770-1751 vw 1754 w 1730 W 1637 m 1610 vw 1621 In 1626—1613 w 1497 s 1524 s 1506 s 1517 s 1471 ms 1471 s 1471 m 1460 ms 1460 m 1418 m 1441m 1412 m 1277m 1266w 1311m 1290 ms 1299 ms 1227 w 1236 w 1235 w 1247 w 1170s 1167s 1183s 1171 S 11838 1126 ms 1109 s 1104 s 1105 s 1099 8 1083 w 1078 vw 1064 w 1074 w 1070 m 1053 vw 1027 m 1022 m 1020 m 1018 vw 1012 ms 996 s 993 s 9.66 ms 959 s 890 s 880 s 889 w 877 w 869 s 882 s 862 s 755-749 w 717 m 718 m 709 m 720 ms 719 m 14 Table II. Infrared Absorption Bands (in cm'l) of l-Cyclohexyltetrazole, l-Cyclohexyltetrazole hydrochloride, Dichlorobis(1-cyclohexy1- tetrazole) zinc (II), Dichlorobis(l-cyclohexyltetrazole) nickel(II), and Dichlorobis(1-cyclohexy1tetrazole) platinum(II). Potassium Bromide Discs M C7N4le C7N4le' HCI Zn(C7N4le)zCl_z NI(C7N4H12)2C12 Pt(C7N4HlZ)zC-lz . l 3322 s 3100 m 3096 m 3058 m 3067 m 3077 vs 2899 s 2890 s 2915 s 2899 s 2882 vs 2849 m 2833 m 2833 s 1672 m 1639 w 1634 m 1493 s 1488 m 1490 ms 1470 s 1464 m 1464 w 1441 s 1449 s 1449 s 1439 s 1366 w 1346 w 1368 s 1366 w 1366 w 1346 w 1298 w 1290 m 1266 w 1264 w 1266 w 1167 s 1167 s 1168 s 1174 s 1167 s 1139m 1134 ms 1135 s 1136m 1133m 1101 s 1096 s 1089 s 1093 s 1081 s 1079 w 1054 w 1052 w 1030 w 1027 vw 1014 s 1015 s 1024 ms 999 ms 989 w 970 m 969 w 966 vw 897 w 895 w 893 ms 893 ms 892 m 881 w 879 s 876 m 868 m 818 w 816 w 816 m 814 mw 810 w 749 m 746 ms 743 ms 754 s 743 ms 715w 15 Zinc chloride tetrazole complexes: The solid complexes contain- ing zinc were prepared by the general methods mentioned previously. The latter procedure, addition of the metal chloride and tetrazole to 95% ethanol and refluxing overnight yielded good crystalline products. These were observed to be clear planar hexagonal crystals in the case of 1-methy1tetrazole and clear rhombic needles with 1-pheny1tetrazole. Presently work is under- way at St. Olaf College to determine their structure by X-ray single crystal studies. The analytical data for the zinc chloride complexes are shown below: Dichlorobis “-methyltetrazole) zinc(II): Calculated for ZnClZC4N3H8: Zn, 21.5; CI, 23.3; C, 15.8; N, 36.8; H, 2.6. _ Found: (Zn, 21.6; C1, 23.4; C, 15.8; N, 36.7; N, 2.6. Dichlorobis (l-cyclohexyltetrazole) zinc(II): Calculated for ZnClzCMNBHu: Zn, 14.3; C1, 15.0; C, 40.9; N, 26.5; H, 6.0. Found: Zn, 14.8; C1, 16.1; C, 38.2; N, 25.4; H, 5.5. .Dichlorobis (l-phenjltetrazole) zinc(II): Calculated for ZnClzCMNBHu: Zn, 15.2; C1, 16.7; C, 39.2; N, 26.1; H, 2.8. Found: Zn, 15.1; C1, 16.5; C, 39.3; N, 26.2; H, 2.8. These clear crystalline solids were moderately soluble in tetra- hydrofuran and readily soluble in the simple alcohols. Solution of . these complexes in water causes decomposition to free tetrazole and zinc chloride. Infrared spectra of these compounds have been obtained and are shown in Figures 4,, 5 and 6. .. A tabulation of the absorption maxima is re- ported in Tables I, II and III. l6 . .0330 03593. gammmuonm .ficghu Aoaosmuuouficnguoeni 330.3305 mo 338.335 as .930on :oflmuogum Condumfi 3.; ma . N,“ C S .3. 0.3.9th w a a a a j ; 17 .0330 0350.3. chamomuom .Sdocwu Aofioumuuougxogogawou: manouodfiflp mo Amsouufin :3 .930on 3303930093 Condom”: .m 8&3 m m . F 1 h 0 D 1 Ill ‘ 1‘ «3 mm NH 2 OH 0 m N. 1 a q .006 0350.3. Edflmmmaonm .fidudwu A0Houm30£>G0AQu$ 03.0.3306 mo 6033.335 a: 0300mm ”539.3030 00.30.35 .0 0Hdm3h 3 m2 2 S S a m s w m. 18 4 J 1 I 1‘ 3‘ 1 1 I p b I b b 19 Table III. Infrared Absorption Bands (in cm“) of l-Phenyltetrazole,“ l-Phenyltetrazole hydrochloride and Dichlorobis (l-phenyl- tetrazole) zinc (II) . Potassium Bromide Discs fl 3:: n C7N4H6 C7N4H6 . HCl Zn’(C7N4H6)Z 3436 m 3367 m 3497 w 3025 ms 3077 ms 3077 s 1605 m 1592 me 1600 ms 1504 s 1490 s 1511 s 1471 m 1460 ms 1473 m 1397 mw 1389 m 1416 ms 1337 vw 1330 vw 1311 W 1292 w 1280 vw 1272 w 1211 s 1221 s 1196 m 1198 s 1181 s 1186 m 1185 ms 1172 m 1176 ms 1096 s _ 1083 mw 1086 s 1088 s 1075 w 1053 m 1053 m 1008 s 1000 ms 993 ms 1000 m 966 m 962 m 985 w 919 ms 913 m 917 w 886 m 881 mw 896 mw 832 w 762 s 756 s 763-760 s 717 w 713 w 712 mw 20 P1atinum(II) chloride-tetrazole complexes: The solid platinum complexes were available only by the tetrahydrofuran procedure but were found to be more stable to decomposition than the zinc or nickel complexes. The analytical data for the platinum(II) complexes are shown below: Dichlorobis “-methyltetrazole) platinum(II): Calculated for PtClzC4N8H3: Pt, 44.9; Cl, 16. 3; C, 16.3; -N, 25.8; H, 1.9. Found: Pt, 45.0; C1, 16.2; C, 15.5; N, 26.0; H, 1.6. Dichlorobis (l-cyclohexyltetrazole) platinum(II): Calculated for PtClzC14N8H24: 'Pt, 34.9; C1, 12.4; C, 29.5; N, 19.6; H, 4.2. Found: Pt, 34.2; C1, 12.4; C, 29.4; N, 19.7; H, 4.2. These yellow solids were found to be generally insoluble in common solvents--the 1-methyltetrazole complex being soluble with decomposition in concentrated aqueous ammonia or concentrated nitric acid. The cydlohexyltetrazole complex was unattacked by even these reagents. Purification of these compounds was accomplished due to their very slight solubility in tetrahydrofuran. They were extracted in a soxhlet apparatus and the yellow powder thus obtained dried as previously mentioned. Infrared spectra were obtained for these complexes and the data tabulated in Tables I and II. Infrared Spectra f The infrared spectra of the free tetrazoles, the tetrazole hydro- chlorides and the metal chloride-tetrazole complexes were obtained in potassium bromide salt pellets. A small portion (~0.01 g) was added 21 to approximately 0. 5 g of dried potassium bromide and the mixture ground for one minute in a Wigglebug grinder. The clear pellet was run on a Perkin Elmer Model 221 doublebeam instrument using a potassium bromide pellet in the reference beam. The infrared spectra were also obtained in Nujol mulls to determine to what extent any interaction with the potassium bromide medium may have occurred. The resulting spectra were similar to those in potassium bromide although the peaks appeared broadened in all cases. This was probably due to the larger particle sizes in the mulls. . Stability C on stant s The interaction between cobalt and nickel in absolute alcohol and cobalt in tetrahydrofuran and the tetrazoles were observed spectro- photometrically using a Beckmann DU Spectrophotometer. Cobalt-tetrazole complexes: The determination of a Beer's Law adherence for cobalt in both tetrahydrofuran at 660 rm; and in absolute ethanol at 605 mp. and 650 mg was made. No evidence for a species of composition CoT++ (where T = tetrazole) was found by using varying, but dilute tetrazole and a fixed, but large metal c onc ent ration. A series of solutions containing fixed, high tetrazole concen- trations and low, varying metal concentrations yielded the extinc- tion coefficient for the species CoTz++ in each medium. Absorbancy readings were taken on solutions containing 0. 001 l_\_d CoClz. 6HZO in tetrahydrofuran and tetrazole concentrations from 0. 001 l_\_/i to 0. ll\_/l. Data on the l-phenyltetrazole complex with cobalt was not obtained due to the lack of solubility of this tetrazole in tetrahydrofuran to the extent necessary for definitive measure- ments. 22 The absorbancy measurements in absolute ethanol were made on solutions containing 0. 0051_\_/1 CoClz. 6HzO and tetrazole concentrations varying from 0. 01114 to ‘0. SE. The data from these experiments is tabulated in Tables IV- VIII. Nickel-tetrazole complexes: The solutions of nickel chloride hexahydrate in absolute ethanol were found to obey Beer's Law at 400 mp and 420 mu in theconcentration range used. In accordance with the cobalt data no evidence for any species other than Ni++ and NiTz++ was found. Absorbancy measurements were made at 400 mg and 420 mp on solutions containing 0. 011_\_/I NiClz. 6HZO and tetrazole concen- trations ranging from 0. 002 M to 0. 5 1_\_/I. The data from these experiments are tabulated in Table IX, X and XI. Zinc chloride-tetrazole complexes: An attempt was made to determine the stability constants for complexes between zinc and the tetrazoles in these media. The first technique used was the addition of varying amounts of zinc to solutions of fixed cobalt and tetrazole concentration in tetrahydrofuran--the method of corres- ponding solutions (44). The results obtained were highly scattered and no conclusion concerning the complex could be made. It was observed, however, that a precipitate formed in the solution and a color change from blue to colorless to pink to a yellow brown occurred over a 24 hours period. This latter seems to indicate some interaction between zinc and cobalt in the medium in the presence of tetrazole. ~A second procedure was the addition of an excess of zinc chloride to tetrahydrofuran solutions containing varying amounts 23 Table IV. Absorbancies and‘fi Values for l-Methyltetrazole and 0. 001M Cobalt chloride hexahydrate in Tetrahydrofuran - m —L n [Tz] - Log [Tz] A605 mp. 0.001 3.00 .123 .163 0.002 2.70 .131 .245 0.003 2.52 .138 .316 0.004 2.40 .145 .388 0.005 2.30 .153 .469 0.006 2.22 .159 .530 0.007 2.15 .165 .592 0.008 2.10 .171 .653 0.009 2.05 .174 .683 0.010 2.00 .180 .745 0.030 1.52 .230 1.255 0.050 1.30 .247 1.428 0.060 1.22 .239 1.346 0.100 1.00 .256 1.520 24 Table V Absorbancies and; Values for l-Cyclohexyltetrazole and 0. 0011! Cobalt chloride hexahydrate in Tetrahydrofuran [Tz’] - Log [Tz] A605 mg 0.010 2.00 .185 .773 0.012 1.92 .190 .829 0.014 1.86 .198 .917 0.016 1.80 .202 .961 0.018 1.74 .209 1.028 0.020 1.70 .209 1.028 0.040 1.40 .238 1.359 0.060 1.22 .265 1.657 0.080 1.10 .278 1.801 0.100 1.00 .290 1.934 25 Table VI. Absorbancies and; Values for l-Methyltetrazole and 0. 0051\41 Cobalt chloride hexahydrate in Absolute Ethanol W [Tz] " L08 [Tz] A605 mP 0.050 1.30 .466 .377 0.060 1.22 .460 .407 0.070 1.15 .440 .508 0.080 1.10 .431 .553 0.090 1.05 .413 .644 0.100 1.00 .414 ..639 0.150 0.82 .387 .774 0.200 0.70 .338 1.021 0.250 0.60 .298 1.222 0.300 0.52 .255 1.439 0.350 0.46 .231 1.559 0.400 0.40 .212 1.655 0.450 0.35 .183 1.801 0.500 0.30 .179 1.821 26 Table VII. Absorbancies and'fi' Values for l-Cyclohexyltetrazole and 0. 0051)} Cobalt chloride hexahydrate in Absolute Ethanol [Tz] - Log [Tz] A660 mp '— 0.002 2.70 .253 .120 0.004 2.40 .249 .180 0.006 2.22 .245 .240 0.008 2.10 .239 .330 0.010 2.00 .237 .360 0.020 1.70 .216 .675 0.030 1.52 .202 .885 0.040 1.40 .188 1.095 0.050 1.30 .179 1.230 0.060 1.22 .165 1.440 0.070 1.15 .156 1.575 0.080 1.10 .142 1.785 0.090 1.05 .139 1.830 0.100 1.00 .138 1.845 27 Table VIII. Absorbancies and-n Values for l-Phenyltetrazole and O. 0051_\_/1 Cobalt chloride hexahydrate in Absolute Ethanol sl [T2] " L°8 [Tz] 605 mp. 0.004 2.40 .558 .058 0.006 2.22 .571 .141 0.008 2.10 .567 .116 0.010 2.00 .569 .129 0.020 1.70 .641 .592 0.030 1.52 .669 .772 0.040 1.40 .679 ..836 0.060 1.22 .722 1.112 0.070 s 1.15 .731 1.170 0.080 1.10 .752 1.305 0.090 1.05 .759 1.350 0.100 1.00 .771 1.427 0.150 0.82 .860 2.000 28 Table IX. Absorbancies and; Values for l-Methyltetrazole and 0. 01M Nickel chloride hexahydrate in Absolute Ethanol [Tz] -.Log[Tz] .A420mH E 0.02 1.70 0.096 .265 0.03 1.52 0.094 .313 0.04 1.40 0.090 .410 0.05 1.30 0.085 .530 0.06 1.22 0.079 .675 0.07 1.15 0.074 .795 0.08 1.10 0.070 .892 0.09 1.05 0.066 .988 0.10 1.00 0.063 1.012 0.20 0.70 0.038 1.663 0.30 0.52 0.030 1.856 0.40 0.40 0.026 1.952 0.50 0.30 0.024 2.000 29 Table X. Absorbancies and; Values for 1-Cyclohexyltetrazole and 0. 011:4 Nickel chloride hexahydrate in Absolute Ethanol [Tz] -Log [Tz] A420 mp 71' 0.50 0.30 0.030 2.000 0.45 0.35 0.038 1.792 0.40 0.40 0.033 1.920 0.30 0.52 0.025 2.120 0.25 0.60 0.041 1.715 0.20 0.70 0.048 1.536 0.10 1.00 0.066 1.075 0.09 1.05 0.071 .947 0.08 1.10 0.073 .896 0.07 1.15 0.077 .794 0.06 1.22 0.079 .742 0.05 1.30 0.082 .666 0.04 1.40 0.087 .538 0.03 1.52 0.092 .410 0.02 1.70 0.097 .282 0.01 2.00 0.104 .077 30 Table XI. Absorbancies and-r1 Values for 1-Phenyltetrazole and 0.01131 Nickel chloride hexahydrate in Absolute Ethanol 0. .063 -- 0.002 2.70 .064 -- 0.004 2.40 .070 .119 0.006 2.22 .077 .257 0.008 2.10 .081 .337 0.010 2.00 .087 .455 0.20 0.70 .130 1.307 0.30 0.52 .143 1.564 0.40 0.40 .150 1.703 0.50 0.30 .165 2.000 31 of the tetrazoles. The solutions were allowed to equilibrate in a water bath at 24. 970 C for three days at which point they were removed. After filtration to remove excess solid zinc chloride, the potentiometric titration of an aliquot for zinc with potassium hexacyanoferrate(II) in the manner previously dis- cussed yielded only erratic results. III. RESULTS AND DISCUSSION As a part of this investigation a series of compounds were pre- pared which involved l-methyl-, 1-cyclohexyl-, and l-phenyltetrazole. interacting with nickel chloride, zinc chloride and platinum(II) chloride. The composition for these compounds as dichlorobis (l-sub- stituted tetrazole)metal(ll) was confirmed by the analytical data. The solid species were found to be insoluble in common solvents with the exception of the zinc complexes which were fairly soluble in the lower alcohols and tetrahydrofuran. This solubility was utilized in the purification of the zinc compounds. It was also found that, although the crystallization of the zinc complexes from tetrahydrofuran yielded no well shaped crystalline species, crystallization from alcohol gave excellent crystals with the 1-methy1 and 1-phenyltetrazole complexes. These crystals'were of sufficient purity and definition that they were submitted to Dr. George Hardgrove of St. Olaf College for single crystal studies. Elucidation of their structure by this means may offer valuable information concerning the nature of the bonding within these. complexes- Preliminary x-ray diffraction studies indicate a large unit cell. The nickel complexes were found to be powdery substances insolu- ble in common solvents except water in which they decompose. The platinum complexes were very slightly soluble in tetrahydrofuran as previously mentioned, but extremely insoluble in common solvents. The infrared studies were found to yield no definite information concerning the nature of the bonding within the various complexes. While shifts were observed for certain of the absorbancy maxima, the lack of assignment of the particular vibrations within the ring made correlations impossible. The band at 1470 cm"1 has been assigned to the ring C-H (37) but was not found to vary in the three tetrazoles used 32 33 in this study indicating no great difference in the relative acidities of the ring C-H. Bands assigned to ring vibration (45) were found shifted in the complexes and hydrochlorides of the tetrazoles. The tetrazole-metal complex shift occurred towards higher wave numbers while the hydrochlorides were shifted towards lower wave numbers. The purpose of preparing the hydrochlorides was to establish, if possible, whether the primary bonding was to the substituted ring nitrogen. This is the most likely position for interaction in the hydro- chloride and a similarity in the infrared shift between the metal com- plex and hydrochloride and free tetrazole would lend evidence to this hypothesis. Unfortunately no such similarity in shift was observed. The stability constant studies were performed using spectrophoto- metric measurements on the tetrazoles and nickel chloride or cobalt chloride in absolute ethanol or tetrazoles and cobalt chloride in tetra- hydrofuran. The treatment of the absorbancy data was as follows (46): The degree of formation was found by use of the relationship a = 5:39- where A 2 observed absorbancy, A0 = absorbancy of metal ion solution Am, = limiting absorbancy of tetrazole-metal in solution or o. = M when the interaction was observed by a loss in the absorbancy peak of the metal due to complexation by the tetrazole. The average number of ligands bound per metal, ‘13, ion is (46): ALA _ — A -A = = ———Q- = -_- __Q___ n 2 a ZXAFAO or n 2 0. 2x Ao-Am . Assuming the ligand concentration remaining in solution to be approximately that added, due to the low degree of formation of the 34 complex, and the relatively low concentration of metal ions, the formation constants can be determined. The formation constant, 811 ., for the species 'MLn ,. where M = metal, and L = ligand, is defined by the expression: [3n = [MLn']/[M][L]n(47). The analytical concentration of metal CM can be calculated from the expression n'=N n n5 0 and the total concentration of ligand can be calculated from n=N cL= [10+ 52:0 n Bn[M][L]n- The average number of ligands per metal, '5, can be found as follows: 71 = (CL - [L])/CM or n=N n n:N n -___ n n 13;, 0,111.] / E... 0.110 01‘ n=N z: (it-n) pang.)n = 0. n=0 For the case of the formation of two complexes this expression rearranges to yield 4“" '-' 01+ 132 (2-1131111 (1:5)[13] l - n Thus knowledge of; and -L allows determination of (31 and (52 from a plot of H/(l-EHL] vs (2:11); . The slope of the line obtained is equal to (3;, the intercept of (31. 35 The data obtained for the complexes mentioned was treated in this manner and a least squares treatment of the data thus calculated was carried out. The values for the formation constants are given in Table XII. Typical graphs showing lines obtained from the least squares treatment are given in Figures 7, 8 and 9 for cobalt and 1-methyltetrazole in tetra- hydrofuran, cobalt and l-methyltetrazole in absolute alcohol and nickel and l-methyltetrazole in absolute alcohol, respectively. Whereas a Beer‘s Law relationship had been established for nickel in absolute alcohol up to 0. 011_\_/l and for cobalt in tetrahydrofuran and absolute ethanol up to 0. 001M, it was found that a higher concentrations of cobalt in absolute ethanol a deviation from linearity occurred. The nature of the cause of this deviation is unknown but appears most probably due to the greatly increased activity of water as the concentration of cobalt chloride hexahydrate is increased. The plot of absorbancy vs concentration at these higher cobalt concentrations in absolute ehta'nol is found to deviate slightly from linearity so that plots of the data calculated from absorbancy measurements fits moderately well the line determined by a least squares treatment, as previously mentioned. This deviation does, however, make the values of the stability constants thus calculated of questionable merit. The stability constants indicate a similarity in basicity for the l-methyl- and l-cyclohexyltetrazole. These stability constants have values of an order of magnitude below those of l-phenyltetrazole. This would not be predicted from the lack of shift for the ring C-H band as was mentioned, but may be due to a resonance interaction between the phenyl ring and the tetrazole ring. Expected resonance forms are shown N II N N ‘1" —-—h ——.h- II II 2.... 11-8 ll ‘_— H-C N6 We a 36 Table XII. Table of Formation Constants for Cobalt with 1-Methyltetrazole and l-Cyclohexyltetrazole in Tetrahydrofuran,. Cobalt with l-Methyltetrazole, 1-Cyclohexyltetrazole, and l-Phenyltetra- zole in Absolute Ethanol and Nickel with l-Methyltetrazole, l-Cyclohexyltetrazole, and l-Phenyltetrazol‘e :i'nsAb‘solute Ethanol Metal Chloride Tetrazole (31 (32 . Solvent Cobalt chloride 1 -Methyltetrazole 9 l . 8 2520 Tetrahydro- furan Cobalt chloride 1 -Cyclohexyltetrazole 45. 2 3240 Tetrahydro- furan Cobalt chloride l-Methyltetrazole 4. 15 26. 6 Absolute ethanol Cobalt chloride l-Cyclohexyltetrazole 36 . 3 i 1180 Absolute ethanol Cobalt chloride l-Phen’yltetrazole 45 428 Absolute ethanol Nickel chloride 1 -Methyltetrazole 1 3 . 8 ll 2 Absolute ethanol Nickel chloride l-Cyclohexyltetrazole 3. 7 112 Absolute ethanol Nickel chloride 1 - Phenyiltetrazo'le 42 . 6 3840 Absolute ethanol 37 / / 300“ O / (9’ / zoob O’ /l 14101 / / / / / -.'10 0,1105 0.05 0.10 O / / O / / / 4--100 / / O «"200 Figure 7. graph of fi/(l-YML] vs (am/(LEI) [L] for cobalt chloride and l-methyltetrazole in tetrahydrofur an. .Hocmfio oadHOmnm a: odoumuuouanfiogua paw 0.3.8.30 fimnoo MOM T: AW...3\E.1NV m> aAHam-IC\W mo £920 .w oudwwh 38 . ou—VN . com. . on: IONA -om 1 row vow IONH d u d A db ”(7‘ 39 6:6 63.836 3qu .80 T: fié>mé «5 Ermask mo cameo .e Samara 405330 $300.08 5 oHonmuuouH>£uoEuH 4»w apt» —Ih\o our—In -_¢ ’11-- -—N l L Joe 38 53. do.» den 62:. .11.“) eat—Id" 40 Two of these resonance forms would tend to pull electrons away from the tetrazole ring thus reducing its ability to donate electrons. ~ This effect should manifest itself as weaker complexes which would not be expected to contribute greatly to the species in solution. 10. 11. 12. 13. 14. 15. 16. 17. 18. LITERATURE CITED Sidgwick, N., J. Chem. Soc., _1_2_3_, 725, (1923). Lowry, T., J. Soc. Chem. Ind., 12, 316, (1923). Daugherty, N., Ph. D. Thesis, Michigan State University, 1961. Wyss, C., Ber., _1_0_, 1373,'_(1877). Edsall, J., Felsenfeld, C., Goodgame, D., and Gurd, F., J. Am. Chem. Soc., 16, 3054, (1954). Weitzel, C., Schaeg, W., and Friedhelm, 8., Ann., 632, 124 (1960). . Giesemann, H., Lettau, H., and Mannsfeldt, H., Ber., E, 570 (1960). Andersag, H., and Jung, H., Ger. 578, 488. Montgomery, H., and Lingafelter, E., J. Phys. Chem., 64, 831, (1960). James, B., and Williams, R.,-J. Chem. Soc., 1961, 2007. Harkins, T., Walter, J., Harris, 0., and Frieser, H., J. Am. Chem. Soc., 18, 260 (1956). Shramp, 5., Ann., _2.'_7_0_,419, (1919). Pellizari, C., and Gaiter, A., Gazz. chim. ital., 48, II, 151 (1918). Dutta, R., J. Indian. Chem. Soc., _33, 389, (1956). Cheng, K., Anal. Chem., _2__6_, 1038, (1954). Wilson, R., and Wilson,-L., J. Am. Chem. Soc., :71, 6204, (1955). Wilson, R.,Wilson, L., and Baye, 1..., J. Am. Chem. Soc., Z_8_, 2370 (1956). Wilson, R., and Womach, C., J. Am. Chem. Soc., _8_0_, 2065, (1958). 41 19. —--20. “ 21. ~ 22. - 23. ._ 24. 25. - 26. _ 27. "280 29. - 30. 31. 32. 33. 34. 35. 36. - 37. - 38. 42 Wilson, R., and Baye, L., J. Am. Chem. Soc., 82, 2652 (1958). Paolini, D., and Baj, M., Gazz. chim. ital., 6_1_, 557, (1931). Paolini, D., and Garia, C., Gazz. chim. ital., 63, 1048 (1932). Strain, H., J. Am. Chem. Soc., 42, 1995, (1927). Gehlen, H. and Elchlipp, Ann., 224, 14, (1955). Bladin, J., Ber., -2_5, 1413, (1892). Herbst, R., and Mihina, J., J. Org. Chem., _1_5_, 1082 (1950). Brubaker, C., J. Am. Chem. Soc., 82, 82, (1960). Daugherty, N., and Brubaker, C., J. Am. Chem. Soc., _8__3_, 3779, (1961). Jonassen, H., Terry, J., and Harris, A., Private Communication. Harris, A., Herber, R., Jonassen, H., and Wertheim, C., 7 Private Communication. Oliveri-Mandala, E., and Alagna, E., Gazz. chim. ital., 49, II, 441 (1910). Dister, A., J. Pharm. Belg., _3, 274 (1948). Popov, A., and Holm, R., J. Am. Chem. Soc., .8_1_, 3250, (1959). Li, N., Chu, T., Fuji, C., and White, J., J. Am. Chem. Soc., 11, 859, (1955). Tanford, C., and Wagner, N., J. Am. Chem. Soc., 15, 434, (1953). Terlon, C., and Brigando, J., Compt. Rend., 253, 2069 (1961). Li, N., White, J., and Doody, E., J. Am. Chem. Soc., 16, 6219, (1954). Fallon, F., Ph. D. Thesis, Michigan State University, 1956. Ugi, I., and Meyr, R., Ber., 23, 239, (1960). ’39. ' 40. 41. 42.. 47. '48.. 43 Ugi, I., Meyr, R., Lipinski, M., Bodesheim, F., and Rosendahl, .F., Org. Syn., £1, 13. Fallon, F., and Herbst, R., J. Org. Chem., _2_2, 933,. (1957). Cobley, W., and Busch, D., Inorg..Syn., V, 208. Willard, H. , Merrit, L. , and Dean, J. , "Instrumental Methods of Analysis, " D. Van Nostrand Company, Inc. , Princeton, N- J. , 1958. Herwig, W. and Zeiss, H., J. Org. Chem., _2_3, 1404, (1958). Irving, H. and Mellor, D., J. Chem. Soc., 1955, 3457. Lieber, E., Levering, D., and Patterson, L., Anal. Chem., _2_3, 1594, (1951). Bjerrum, J. , "Metal Ammine Formation in Aqueous Solution,- " P. Haase and Son, Copenhagen, 1957. Rossotti, F., and Rossotti, H., Acta. Chem. Scand., 2, 1166, (1955). Stollé, R., Ehrmann, K., Reider, D., Wille, H., Winter, H., and Henke-Stark, F., J. Prakt. Chem., 134, 282, (1932). APPENDIX Attempted preparation of metal- 1-substituted tetrazolates The initial success in the preparation of the dichlorobis i (l-substituted tetrazole) metal(II) work led to attempts to prepare metal tetrazolate compounds. - Of the possible paths to these compounds, the first utilized was the preparation of the sodium compounds of tetrazole by removal of the ring hydrogen. The reaction of sodium ethoxide with the tetrazole in ethanol was one path used to prepare the desired sodium 1-substituted tetrazolate. Infrared spectra of the solid obtained by removal of the excess ethanol revealed nocharacteristic tetrazole peaks. Reaction of lithium and sodium amide in liquid ammonia with the tetrazoles yielded a solid product which did not dissolve in common solvents except with decomposition and was found to be non-reactive towards the metal halides used in this investigation. The work of Stollé (48) involved preparation of the Grignard reagent of 1-phenyltetrazole (1-pheny1tetrazolemagnesiumiodide)... This was formed when léphenyltetrazole was added tomethylmagnesium iodide in ether. The evolution of methane was noted during this addition. Subsequent addition of benzoyl chloride formed an intermediate which lost nitrogen to yield: C‘H50\N-CN +‘ MgICl This work suggested the addition of the tetrazoles to methyl- magnesium iodide or other Grignard reagents to yield a material which 44 45 could subsequently react with the metal halides to produce the desired tetrazolates. It was found that addition of l-phenyltetrazole to methyMagnesium iodide in ether caused bubbling althoughno attempt to determine the nature of any gas evolved was made. Subsequent reaction of portions of the solution with small amounts of the metal chlorides yielded black solids in all cases. These solids changed in appearance upon exposure to air with the exception of the platinum chloride reaction product. The reaction appeared to have reduced the metal chlorides to the metal in all instances. In order to fully understand the nature of this interaction, work was carried out to prove the existence of the tetrazolemagnesium iodide intermediate. Thus solutions were prepared containing the methyl- magnesium iodide and slightly less than stoichiometric amounts of tetra- zole were added. To these solutions were added carbon dioxide, acetaldehyde, benzaldehyde and excess iodine. Subsequent addition of water to produce the tetrazole derivative gave no new speciesas shown by infrared spectra and melting point determinations. The necessity of determining whether the ring hydrogen was suf- ficiently acid to be removed by this interaction seemed apparent. This was accomplished by utilizing a Zerewittenoff apparatus and adding lithium aluminum hydride in tetrahydrofuran to a tared sample of the solid tetrazole. A blank correction on the data indicates that noquanti- tative conclusion could be made, but a qualitative indication of reaction was found. In order to achieve somewhat higher reaction temperatures, it was decided to use tetrahydrofuran as the solvent medium. The removal of residual water was found to be more critical in this reaction and it was necessary to distill the tetrahydrofuran from lithium aluminum hydride instead of the calcium hydride previously used. 46 Both methylmagnesium iodide and ethyMagnesium bromide were prepared in tetrahydrofuran. To each of these was added the tetrazole and a definite heating and bubbling noted. Once more the attempt to prepare derivatives was found to yield no new species. Similarly, reaction with the metal halides produced the same black reduction products recorded previously. Further work remains since it seems probable that metal-l-sub- stituted tetrazolate compounds should be possible to prepare. One such procedure would be to use n-butyllithium and tetrazole to prepare a lithium tetrazolate which could subsequently react with the metal halides to produce the desired tetrazolate. CHEMISTRY 113mm 3111111111 “21"- Km NMW. Mm u“0 E111 “3 “M9 T“2 31 lllllHHIIHH