SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL-ACTIVITIES OF SOME NICKEL(II) COMPLEXES OF TRIDENTATE NNS LIGANDS FORMED BY CONDENSATION OF 2-ACETYLPYRIDINES AND 2-BENZOYLPYRIDINES WITH S-ALKYLDITHIOCARBAZATES

Nickel(II) complexes of four tridentate NNS Schiff base ligands, deriv ed by condensing 2-acetyl- and 2-benzoyl-pyridine with S-methyl- and S -benzoyldithiocarbazate, have been prepared and characterized. The mon oligated complexes, [Ni(NNS)X] (NNS = anionic ligand; X = Cl, Br, NCS, I) are diamagnetic and square-planar, whereas the bis-ligand complexe s, [Ni(NNS)2] are paramagnetic and tetragonal. The Schiff bases are fu ngitoxic towards A. solani, F. equisetti and M. phaseolina (approachin g the toxicity of the commercial fungicide Nystatin), but the nickel(I I) complexes are less fungitoxic than the free ligands.