Potentiometric Studies on Complexation Equilibria between Dimethyltin (IV) and Dioctyltin (IV) Cations with N-N Donor Ligands

The interaction of dimethyltin [DMT] (IV) and dioctyltin [DOT] (IV) cations with 2, 2-bipyridyl and 1, 10-phenanthroline were performed potentiometrically for 11 systems in 10 % alcohol medium at three ionic strengths (= 0.05, 0.10, 0.15M) and at three different temperatures 20C, 30C, 40C. The experimental data are subjected to computational analysis in order to evaluate thermodynamic formation constants [ML, ML (OH) and ML (OH) 2] and other thermodynamic parameters (G, H and S). Stability constants of generalized species (SCOGS) computer program was employed for computation. The concentration distribution of the various complex species in solution has been evaluated as a function of pH and is presented in the form of speciation curves. The studies intimate that 2, 2-bipyridyl formed complexes of low stability than 1, 10-phenanthroline. This is attributed to the difference in ring structure of two ligands.