Electrochemical Studies Of Novel 3,4-Dichloro-N-((5-ChloroPyridin-2-yl)Carbamothioyl)Benzamide Based On Its Complexes With Copper(II), Cobalt(II), Nickel(II) and Zinc(II) ions

The synthesis of novel N,Nʹ-disubstituted benzoyl thiourea ligand [3,4-dichloro-N-((5-chloropyridin-2-yl)carbamothioyl) benzamide] (L) is achieved in two steps. First step by refluxing KSCN with 3,4-dichloro benzoyl chloride in CH3CN solvent and the other step by the reaction of the resulting filtrate from the first step with 2-amino-5-chloropyridine. The copper(II), Cobalt(II), Nickel(II) and Zinc(II) chloride and acetate salts were coordinated with L ligand in the 1:1 and 1:2 mole ratios (M:L) in the solvent mixture of DMF/H2O or CHCl3/methanol to form the complexes with structural formulas {[LMCl2] and [L2M](CH3COO)2, M= Copper(II), Cobalt(II), Nickel(II) and Zinc(II) ions}. Two mole ratios of the starting materials, 1:1 and 1:2 (M:L) were experimented to form chloride complexes, the product was with structural formula [LMCl2] while acetate complexes with [L2M](CH3COO)2 formula are resulted with the same conditions. Ligand L and its complexes [LCuCl2], [LCoCl2], [LNiCl2], [LZnCl2], [L2Cu](CH3COO)2, [L2Co](CH3COO)2, [L2Ni](CH3COO)2 and [(L)2Zn](CH3COO)2 have been characterized by mass spectrometry, elemental analysis, magnetic moments, conductivity measurements, solubility test, UVvisible, FTIR, H and C NMR spectroscopies. Electrochemical studies were probed by using cyclic voltammetry technique(CV). The data reflect the quasi-reversible reductive nature for the Copper(II) complexes with one electron transfer process while Nickel(II) and Cobalt(II) complexes exhibited two consecutive irreversible reductive nature. The observed UVvisible, elemental analysis, molar conductivity, magnetic moment measurements and solubility test revealed that the metal ion in the all prepared complexes adopted four coordinated square planar structures and [LCuCl2], [LCoCl2], [LNiCl2], [LZnCl2], are formed as neutral complexes while [L2Cu](CH3COO)2, [L2Co](CH3COO)2, [L2Ni](CH3COO)2 and [(L)2Zn](CH3COO)2 adopted anion complexes. The observed magnetic moments show diamagnetic properties of Zinc(II) and Nickel(II) complexes while Copper(II) and Cobalt(II) appeared as paramagnetic species. FT-IR analysis confirmed the coordination sites between the central metal ion with ligand L through two sites, the nitrogen atom in pyridyl ring and the sulphur atom in C=S group.