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

Proton-ligand dissociation and metal-ligand stability constants of tri thiocarbodiglycolic acid (TCGA) with some transition metal ions were c alculated potentiometrically. The order of stability constants was fou nd to be Fe3+ > Cu2+ > Ni2+ > Co2+. The effect of temperature on the s tability of the complexes formed was studied and the corresponding the rmodynamic functions were derived and discussed. Polarographic and cyc lic voltammetric behaviours of TCGA were investigated in B.R. buffer s olutions of pH 2-12. In solutions of pH < 8, the polarograms and cyclo -voltammograms exhibited a single 2-electron diffusion-controlled irre versible step, corresponding to the reduction of the C=S. The mechanis m of the reduction process was postulated and the kinetic parameters o f the electrode process were evaluated.