Binary and ternary complex formation of zirconium(IV) in dioxane-water medium with aminopolycarboxylic acids as primary ligands and aroyl hydrazone schiff bases as secondary ligands

Abstract

The complex equilibria of Zr(IV) with 2-hydroxy-1-naphthalidene benzoylhydrazone (NABHZ) and 2-hydroxyl-naphthalidene salicyloylhydrazone (NASHZ) have been studied in 75% (v/v) dioxane-water at different temperatures. The ternary systems with NTA, HEDTA and EDTA as primary ligands and the schiff bases as secondary ligands are also studied. Zr(IV) complexes are lessprone to hydrolysis, polymerisation etc. in this medium than in water in presence of the complexing ligands. The enthalpy and entropy are favourable in the formation of binary complexes but only enthalpy favours the ternary complex formation which is not favoured by entropy.