Equilibrium studies of ternary chelates of some divalent metal ions with cephalosporins and α-alanine

Chemical Laboratories, M. V. M., Bhopal-462 002, India Manuscript received 26 October 1999, revised 12 January 2000, accepted 12 February 2000 The formation of bioligand chelates of some divalent metal ions Mn, Co, Ni, Cu, Zn, Cd and Mg with cephaloridine as primary ligand (L) and α-alanine as the secondary ligand (A) has been carried out pH-metrically at 25 and 35° and at constant ionic strength, µ = 0.1 M (NaCIO4). The stability comtanls follow the order : CuII > ZnII > CoII > NiII > CdII > MgII > MnII . The Iog K values are Iess negative than -0.6, suggesting favoured formation of ternary complexes. Stability constants have been evaluated and discussed in terms of the basicity of the ligand, statistical and stereochemical phenomenon and compared with that of cephalexin drug