Ternary and quaternary metal chelates of some biologically important bivalent transition metal ions viz. Co(II), Ni(II), Cu(II) and Zn(II) formed with biologically significant ligands, viz. Asparagine (A) and Uracil (B) have been investigated. The relevant stability constants and complexation equilibria of quaternary metal chelates in solution at 30 ±1 ºC and at constant ionic strength (I=0.1M NaNO3) have been studied potentiometrically. Equilibrium concentrations of all species in multimetal-multiligand system, concentration of each metal and complexing agent have been calculated. Species distribution curves are obtained by plotting percent (%) concentration of the species obtained through SCOGS computer technique against pH. The distribution curves are finally sketched by running the computer program ORIGIN 4.0. The metal ligand formation constant of MA, MB, MAB and M1M2AB type of complexes follow Irving William order. The order of stability constants of quaternary systems has been observed and solution structures of metal complexes with said ligands have been discussed.
Potentiometrically, Quaternary systems, Stability constants, Chelates