Metal complexes of triazine - Schiff bases: Spectroscopic and thermodynamic studies of complexation of some divalent metal ions with 3-(a-acetylethylidenehydrazino)-5,6-diphenyl-1,2,4-triazine

Metal complexes of some divalent metal ions (Co, Ni, Cu and Zn) with 3-(a-acetylethylidenehydrazino)-5,6-diphenyl-1,2,4-triazine (AHDT) as a Schiff-base have been investigated potentiometrically and spectrophotometrically and found to have the stoichiometric formulae 1:1 and 1:2 (M:L). The formation constants of the proton-ligand and metal-ligand complexes have been determined potentiometrically at different temperatures (10, 20, 30, 40 and 50°C) at an ionic strength of 0.1 M KNO3 in 75% (v/v) dioxane-water solution. The standard thermodynamic parameters, viz. DG°, DH°, and DS°, for the proton-ligand and the stepwise metal-ligand complexes have been evaluated.