Reactions of polyhomofunctional organic compounds: 2-Kinetics of hydrolysis of four azomethine sites in a trinuclear cobalt(II) complex

482-488Kinetic studies on the hydrolysis of a novel trinuclear cobalt(II) complex, (CoBAMC-Sal)2 Co(DMF)2+2(2) in buffered 90 : 10 aqueous /DMF (v/v) mixtures are reported. Repetitive spectral scans of the reaction mixture exhibit isosbestic points at all pH’s. The hydrolysis follows pseudo - first order kinetics with respect to the complex. The rate constants are compared to those reported earlier for the ligand, BAMC - Sal (1) under similar conditions. The difference between the rates of hydrolysis of complex and those of the pure ligand is found to be due to steric factors and stability of the complex. The studies indicate different modes of cleavage of the trinuclear complex at different pH's before the ligand moieties undergo hydrolysis at their azomethine sites. Activation energy, E a, and thermodynamic parameters such as ΔH#, ΔG# and ΔS# are evaluated by Arrhenius and Eyring methods