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

The stoichiometries and stability constants of Nickel (II) ions with 2-pyridyl-3-Isatin bishydrazone have been determined spectrophotometrically at different temperatures 20 0 C, 25 0 C, 30 0 C, 35 0 C and 40 0 C 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., ?G 0 , ?H 0 and ?S 0 have also been calculated. Keywords: Isatin-bishydrazone ligands, Ni(II) complexes, thermodynamic parameters, Stability constant, spectrophotometrically.