Direct chemical and electrochemical syntheses of coordination compounds of benzazolyl azo ligands

The chelates of 2-hydroxy(aminophenylnaphthyl)-azo-1-alkylbenzimidazoles were obtained from electrochemical (anodic dissolution of zero-valent d-metals) and chemical (from acetates of the same metals) syntheses in methanol. The EXAFS and X-ray single crystal diffraction data revealed the existence of octahedral nickel, zinc, and cadmium complexes containing four five-membered metallocycles with the N4О2 or N6 ligand environments. The formation of five-membered coordination units, non-typical for azo ligands, is explained on the basis of inner-chelate competitive metal binding of ambidentate ligand systems.