THERMODYNAMICS OF THE COMPLEXATION OF SOME TRANSITION-METAL IONS WITH TRITHIOCARBODIGLYCOLIC ACID - POTENTIOMETRIC AND VOLTAMMETRIC STUDIES

Proton-ligand dissociation and metal-ligand stability constants of trithiocarbodiglycolic acid (TCGA) with some transition metal ions were calculated potentiometrically. The order of stability constants was found to be Fe3+ > Cu2+ > Ni2+ > Co2+. The effect of temperature on the stability of the complexes formed was studied and the corresponding thermodynamic functions were derived and discussed. Polarographic and cyclic voltammetric behaviours of TCGA were investigated in B.R. buffer solutions of pH 2-12. In solutions of pH < 8, the polarograms and cyclo-voltammograms exhibited a single 2-electron diffusion-controlled irreversible step, corresponding to the reduction of the C=S. The mechanism of the reduction process was postulated and the kinetic parameters of the electrode process were evaluated.