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

The complex equilibria of Zr(IV) with 2-hydroxy-1-naphthalidene benzoy lhydrazone (NABHZ) and 2-hydroxy-1-naphthalidene salicyloylhydrazone ( NASHZ) have been studied in 75% (v/v) dioxane-water at different tempe ratures. The ternary systems with NTA, HEDTA and EDTA as primary ligan ds and the schiff bases as secondary ligands are also studied. Zr(IV) complexes are less prone to hydrolysis, polymerisation etc. in this me dium than in water in presence of the complexing ligands. The enthalpy and entropy are favourable in the formation of binary complexes but o nly enthalpy favours the ternary complex formation which is not favour ed by entropy.