Thermodynamic Parameters of the Uncatalyzed Complxation Reaction between Ni (II) Ion and Bioactive Isatin-Bishydrazone

Abstract

The stoichiometries and stability constants of Nickel (II) ions with 2-pyridyl-3-Isatin bishydrazone have been determined spectrophotometrically at different temperatures 20⁰C, 25⁰C, 30⁰C, 35⁰C and 40⁰C by using Job’s continuous variation method.  In all cases, the Job’s curves displayed a maximum at a mole fraction X_ligand =0.5 indicating the formation of complex with 1:1 metal to ligand ratio. It was observed that metal-ligand stability constant decreases with increasing temperature indicating exothermic nature of the reaction. The thermodynamic parameters i.e., ?G⁰, ?H⁰ and ?S⁰ have also been calculated.

Keywords:Isatin-bishydrazone ligands, Ni(II) complexes, thermodynamic parameters, Stability constant, spectrophotometrically.