Physico-chemical investigation on the complexes of indium(III) with Mercapto-, Hydroxy-, and Amino-substituted propionic acid

Abstract

Potentiometric studies have been carried out on the metal complexes of indium(111) with β-mercaptopropionic, β-hydroxypropionic, and β-aminopropionic acid. The Calvin-Bjerrum pH-titration technique, as used by Irving and Rossotti, has been applied to determine the stepwise formation constants of the complexes. The logK values have been computed by alternative methods. Thermodynamic formation constants have been obtained by extrapolation of the values at various ionic concentrations. The values of overall changes in ΔG, ΔH, and ΔS accompanying complex formation have been evaluated at three different temperatures at an ionic strength of 0.lM (NaClO₄). The stability constant of the indium(111) complex decreases as the subsituted group changes from SH to OH to NH₂.