Synthesis , Characterization and physical studies of Some New Co(II), Ni(II), Cu(II) and Zn(II) Complexes with (E)-4-methyl-3-nitro-N-(2-(1-(pyridin-2-yl)ethylidene)hydrazine-1-carbonothioyl) benzamide Ligand

Abstract

New series complexes of Cu(II), Ni(II), Zn (II) and Co(II) ions were derived from the novel thiosemicarbazone compound, (E)-4-methyl-3-nitro-N-(2-(1-(pyridin-2-yl)ethylidene)hydrazine-1-carbonothioyl) benzamide (MNEC-H) ligand was prepared in three steps. The step one  the reaction between acetyl pyridine with hydrazine hydrate at room temperature to obtain (E) - 2 -(1 -hydrazonoethyl)pyridine.  The Second step  3-nitro 4- methy- benzoyl chloride was refluxed with potassium thiocyanate in acetonitrile solvent forming 3-nitro 4- methy- benzoyl isothiocyanate. The third step of the reaction is summarized by the refluxing the mixture of (E) - 2 -(1 -hydrazonoethyl) pyridine and 3-nitro 4- methy- benzoyl isothiocyanate in acetonitrile solvent to form the desired free ligand (MNEC-H). Two types of the element complexes were synthesized and investigated, the chloride as well as acetate compounds through employing different mole ratios 1:1 (L:M) and 2:1 (L:M) whereas L and M represent the (MNEC-H) ligand and metal salt respectively via using metal chloride and metal acetate salts to gaining [(MNEC-H)MCl]Cl and [(MNEC-H)2M] structures. The various available spectroscopies and techniques were used to characterize and confirm the formula of the free ligand (MNEC-H) and its element compounds. ¹HNMR, ¹³CNMR, IR, UV-vis, mass spectra, CHNS, magnetic effective moment, conductance values. The cyclic voltammetry of the prepared element complexes were recorded in DMSO solvent to investigate their redox behavior. The Cu(II) compounds showed quasi reversible process at the cathodic potential whereas the Co(II) and Ni(II) complexes displayed one irreversible system at the oxidative potential. All the employed techniques and measurements confirmed together that the chloride compounds arranged as tetrahedral four coordinated [(MNEC-H)MCl]Cl in neutral formula whereas the acetate compounds adopted octahedral six coordinated [(MNEC-H)₂M] in neutral structure too. The Zn(II) chloride and acetate complexes were confirmed as diamagnetic species according to the effective magnetic data. While Cu(II), Ni(II), Co(II) and Zn(II) chloride and acetate compounds appeared as paramagnetic species.