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

Abstract

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.

Keywords:

• Benzazolyl azo ligands
• Direct electrochemical synthesis
• EXAFS
• X-ray diffraction
• Octahedral complexes

Acknowledgments

This work was made possible due to the financial support of the grant of President of Russian Federation (grant NSH 363.2008.3), Russian Foundation for Fundamental Investigation (RFFI, grant nos. 08-03-00154, 07-03-00256, 07-03-00710), grant of Russian Ministry of Education and Science within the project “Development of Scientific Potential” (RNP 2.2.1.1/2348), program “Development of National Universities” (internal SFU grants, 2009), and PAICyT-UANL (Monterrey, Mexico, grant 2009).