Metal complexes of cyanoimidazolates: Synthesis and characterization.

Abstract

Two cyanoimidazoles, 4-cyanoimidazole (HMCI) and 2-(2<super>'</super>-pyridyl)-4,5dicyanoimidazole (HDCIPy) have been synthesized and their coordination chemistry examined. The crystal structure of 4-cyanoimidazole was observed for the first time [P_c (a = 5.7230(13) A, b = 3.6965(9) A, c = 10.244(2) A and beta = 97.689(7)&deg;)]. The solid state structure was observed to have a net dipole moment. 4-cyanoimidazole binds metals exclusively as the anionic species and most often acts as an exobidentate bridge, generating polymers of the formula [M<super>2+</super>(MCl)₂]_n &bull; X H₂O. Thermal characterization and magnetic susceptibility studies were conducted on materials with M = Co<super>2+</super>, Ni<super> 2+</super>. Similar products and data were obtained when 4,5-dicyanoimidazolate was employed as the ligand. Single crystal X-ray diffraction was performed on the compound (Bu₄N)₄ Ni(MCI)₆ &bull; 2H₂O, the first hexakis imidazolate compound reported [P2(1)/c (a = 14.9380(18) A, b = 21.368(3) A, c = 16.926(2) A and beta = 115.863(2)&deg;)]. Nine compounds containing vanadium, ruthenium, cobalt, nickel, palladium, copper or zinc ligated by DCIPy<super>-</super> were synthesized and characterized. Six structures, Co(DCIPy)₃ &bull; 3EtOAc [P-1 (a = 10.775(4) A, b = 14.519(5) A, c 15.732(6) A and alpha = 65.543(5)&deg;, beta = 85.106(6)&deg;, gamma = 84.408(6)&deg;)], HDCIPyZn(DCIPy)₂ &bull; MeOH [P2_1/n (a = 9.5538(12) A, b = 17.508(2) A, c = 18.436(2) A and beta = 95.210(2)&deg;)], (MeOH)₂Ni(DCIPy)₂ &bull; 2 MeOH [P1 (a = 9.755(5) A, b = 11.462(7) A, c = 14.861(8) A and alpha = 70.262(16)&deg;, beta = 83.885(17)&deg;, gamma = 65.313(16)&deg;)], (H₂O)VO(DCIPy)₂ &bull; 2 MeOH [P2_1/n (a = 11.6017(9) A, b = 17.9435(13) A, c = 12.0775(9) A and beta = 102.7430(10)&deg;)], (H₂O)Cu<super>2+</super>(DCIPy)₂ [P2_1/n (a = 7.296(3) A, b = 19.994(8) A, c = 13.014(5) A and beta = 92.640(9)&deg;)], [P(C₆H₅)₃]₂Cu<super>I</super>(DCIPy) [P2_1/n (a = 12.8981(6) A, b = 19.9043(10) A, c = 15.1140(7) A and beta = 90.3580(10)&deg;)], were determined by single crystal X-ray diffraction. Both Co(DCIPy)₃ and (bpy)₂Ru(DCIPy)Cl have been tested for application in dye sensitized solar cells and have shown sufficient promise to warrant further evaluation. (H₂O)VO(DCIPy)₂ has shown itself to be an effective human spermicide, affecting both motility and viability of the cell.