Abstract

potentiometric studies are performed in aqueous solution in order to characterize the interaction of dimethyltin(IV) [DMT] and Trimethyltin(IV) [TMT] cation with catecholic ligands. Experiments are performed at three different temperatures (20ºC, 30ºC and 40ºC) and at three ionic strengths (μ = 0.05 ,0.10 and 0.15 M). The analysis of stability constant (log ß) and stability order of investigated metal-ligand species [MHL, ML, ML(OH) and ML(OH)2 ] are obtained by using computer programme SCOGS(stability constants of generalized species). The complex species formed are water soluble in the experimental pH range (3.0-10.5). Thermodynamic stability constants along with thermodynamic parameters i.e. standard free energy change (-Gº) enthalpy change (-Hº) and entropy change(-Sº) are calculated for all the systems. The thermodynamic stabilities of DMT species are found to be more than TMT (IV) species. High stability of 4-methylcatechol complexes is attributed to greater basicity.

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