Heterocyclic chelating agents. Part I. Metal complexes of 4-2′-pyridylimidazole

Abstract

A study has been made of the metal complexes of 4-2′-pyridylimidazole (A) in aqueous solution at 25·0° and ionic background 0·1M in nitrate ions. The acid dissociation constants of the protonated ligand species H2A2+ and HA+ have been measured. Formation curves have been obtained and accurate formation constants for the complexes MA2+, MA22+, and MA32+(where M = Fe, Co, Ni, Cu, and Zn) have been calculated by a least-squares method on a high-speed digital computer. The results are discussed in relation to metal–ligand π-bonding.