MIXED-LIGAND COMPLEX-FORMATION OF COBALT(II), NICKEL(II) AND ZINC(II)WITH N-BENZENESULFONYL-L-CYSTEINE AS PRIMARY LIGAND AND BIPYRIDINE, ETHYLENEDIAMINE AND GLYCINATE AS SECONDARY LIGANDS

Equilibrium study on the complex formation of M(2+)ions (M=Ca, Ni and Zn) with N-benzenesulphonyl-l-cysteine (NBSCH2) in the presence of bip yridine, ethylenediamine, glycinate (B) indicates the formation of mix ed-ligand complexes of the types M(NBSC)(B), M(H-1NBSC)(B) and M(H-1NB SC)(OH), together with binary M(NBSC) and M(B) complexes. Formation co nstants of the complexes have been determined by potentiometric method at 25 +/- 0.1 degrees in 50% (v/v) ethanol-water medium at a constant ionic strength, l = 0.2 M(NaNo3). Stability of the complexes has been correlated with the modes of coordination of NBSC, basicity of the B ligands and pi-electron delocalisation in the metal-ligands bonds.