Thermodynamics and stability of Co2+, Ni2+, Cu2+ and Zn2+ complexes with DL-2-amino butanedioic acid

pH metric titration technique has been employed to study the formation and composition of complexes of divalent Co, Ni, Cu and Zn with DL-2-amino butanedioic acid. Formation curve reveals the formation of 1: 1 and 1: 2 metal ligand complexes in the pH range 4.30-8.85. Their stability constant have been determined at 20 degrees C, 30 degrees C and 40 degrees C and a different ionic strength viz. 0.05M, 0.1M, 0.15M and 0.2M NaClO4 by Irving Rossotti method which follow the order Co2+ < Ni2+ < Cu2+ > Zn2+ which is in agreement with Irving Williams series. The change in thermodynamic parameter Delta G, Delta H and Delta S accompanying complexation have been evaluated at 30 degrees C. The stability constant and thermodynamic function of these metal complexes are discussed in relation to ionic radii, electronegativity and ionization potential of title metals.