Synthesis, demetallation, remetallation and transmetallation of new mono- and binuclear schiff base complexes

Abstract

New mono- and binuclear nickel(II) complexes [PyNi(ONS-COPh)] and [PyNi(ONS-CO)] 2-C 6H 4 have been prepared by a nucleophilic substitution reaction of the C—H methine-containing complex, mono-pyridine-S-methyl-N-acetylacetonehydrazine-carbodithioate nickel(II) [PyNi(HONS)], with benzoyl chloride and phthaloyl dichloride, respectively. Reaction of phenylisocyanate and m-xylene diisocyanate to [PyNi(HONS)] also gave new mono- and binuclear nickel(II) complexes, [PyNi(ONS-CONHPh)] and [PyNi(ONS-CONH)] 2- m-xyl, respectively. The demetallation and transmetallation of the prepared nickel(II) complexes with Na 2EDTA and copper(II) acetate monohydrate afford the corresponding mono- and binucleating ligands and mono- and binuclear copper(II) complexes, respectively. The conditions of the reliable demetallation and transmetallation reactions are described. The copper(II) complexes are also synthesized from the reaction of copper(II) acetate with the free ligands. All new compounds are characterized by various physical techniques. The mono- and binuclear nickel(II) and copper(II) complexes display magnetic and spectroscopic behaviour characteristic of square planar complexes. The ESR spectra of the mono- and binuclear copper(II) complexes are similar, indicating the absence of any magnetic coupling between the metal centres.