SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL-ACTIVITIES OF SOME NEW NICKEL(II), COPPER(II), ZINC(II) AND CADMIUM(II) COMPLEXES OF QUADRIDENTATE SNNS LIGANDS

The quadridentate ligands, prepared by condensation of S-methyl- and S-benzyldithiocarbazate with glyoxal, form stable crystalline complexes of general formula, M(SNNS) (M = Ni(II), Cu(II), Zn(II) and Cd(II); SNNS-2 = ligand dianion). The Ni(II) complexes are diamagnetic but electronic spectral data support a dimeric five-coordinate geometry. Based on magnetic and spectral data, a five-coordinate square-pyramidal structure is also assigned to the copper(II) complexes. The Zn(II) and Cd(II) complexes are polymeric and octahedral. The Schiff bases and metal complexes display good antifungal and antibacterial properties.