Multimetal multiligand complex formation equilibria of copper(II), nickel(II) and zinc(II) with L-2-amino-3-methylbutanoic acid (valine) and nitrilotriacetic acid

Department of Chemistry, University of Allahabad, Allahabad-211 002, Uttar Pradesh, India

Manuscript received 7 March 2005, revised 10 August 2005. accepted 29 August 2005

Formation equilibria of homo and heterobinuclear ternary/quaternary complexes of Cu^II , Ni^II and Zn^II with
nitrilotriacetic acid (A) and valine (B) ligands in aqueous solution have been investigated. Stability constants of the complexes and the complex formation equilibria at temperature 30 ± 1° and the ionic strength \(I \) = 0.1 M (NaNO₃) have been determined by potentiometric method. Complexes of the type MAB (2 : 2 : 1) and M₁M₂AB (I1 : 1 : 1 : 1 )/(1 : 1 : 2 : 1) have been discussed from the computer based analysis. Stability constants of binary, ternary and quaternary complexes follow the Irving-Williams order.