Investigations and chemical speciation of ternary complexes of bivalent metal ions with cephalexine as primary ligand and glycine and valine as secondary ligands

Abstract

Studies on ternary complexes of bivalent metal ions viz. Cu, Pb II , Ni, Zn, Co, Cd, Mn, Mg and Ca, hereafter, M(II), with cephalexine (HCEX) as primary ligand and glycine (Gly) and valine (Val) as secondary ligands in 1:1:1 1 ratio, have been investigated by potentiometric technique at μ = 0.1 M (NaClO 4 ) and temp. = 25 ± 0.5° in aqueous medium. The stability constants and S min values of the ternary complexes M(II)-HCEX-Gly (A) and M(II)-HCEX-Val (B) have been calculated. The results have been discussed in terms of electrostatic and metal-ligand interaction. To visualize the nature of equilibrium and to evaluate the calculated stability constants of ternary complexes, species distribution diagrams have been plotted.