Synthesis,13C and15N NMR and infrared studies of cyano(ligand) cobaloximes

Abstract

Mixed ligand complexes of [CNCo(D2H2)L ] (where L = imidazoles, benzimidazoles, thiourea or hydroxylamine) were prepared by treating the [CNCo(D2H2)SCN] with 'L' in alcohol. Imidazoles and benzimidazoles bind to Co(Ill) through N3, thiourea through S and hydroxylamine through N of NH2. The analogous series of complexes enriched in 1 aC and 15N of the cyanide ligand have been used to locate the cyanide's ~3C and 15N NMR resonances and the cyanide stretching frequencies in the infrared spectra. As the trans axial ligand is varied, an inverse dependence of the x 5 N chemical shift on the 13 C chemical shift is observed. This data together with trends in ~ ~ 5N, 6 ~ 3C and v CN with the basicity of the trans axial ligand are interpreted to indicate that the cobalt to cyanide bonding is important in these cyano (ligand) complexes.