Mono- and bis-chelated nickel(II) complexes of the di-2-pyridylketone Schiff base of S-methyldithiocarbazate and the X-ray crystal structure of the bis[ S-methyl-β- N-(di-2-pyridyl)-methylenedithiocarbazato]nickel(II) complex

Abstract

The di-2-pyridylketone Schiff base of S-methyldithiocarbazate (Hdpksme) reacts with nickel(II) salts giving both mono- and bis-chelated complexes of empirical formulae, [Ni(dpksme)X] (dpksme=anioninc form of the Schiff base; X=NCS −, Cl −) and [Ni(dpksme) 2], respectively. These compounds have been characterized by magnetic and spectroscopic techniques. The mono-ligated nickel(II) complexes are four-coordinate and square-planar but the bis-ligand complex is six-coordinate and octahedral. The crystal and molecular structure of [Ni(dpksme) 2] has been determined by X-ray crystallography. The complex has a distorted mer-octahedral structure in which the ligands are coordinated as uninegatively charged tridentate chelating agents via the pyridine nitrogen atoms, the azomethine nitrogen atoms and the thiolate sulfur atoms. The distortion from regular octahedral geometry is ascribed to the restricted bite angles of the ligands. The ligand and its nickel(II) complexes exhibit weak antimicrobial activity against the pathogenic bacteria, S. dysenteriae, B. cercus, S. aureus and E. coli and the fungi, A. alternata and M. phaseolina.