Synthesis and electrochemical study of complexes of 2-methylthio-5- (pyridylmethylidene)-3,5-dihydro-4H-imidazol-4-ones with transition metals (Co, Ni, and Cu)

New transition metal (NiII, CoII, and CuII) complexes with 2-methylthio-5-(pyridyl-methylidene)-3,5-dihydro-4H-imidazol-4-ones were synthesized by the reaction of 5-(α-, β-, or γ-)pyridyl-substituted 2-methylthio-3,5-dihydro-4H-imidazol-4-ones with MCl2· nH2O. In the complexes with α-Py-substituted ligands, the metal atom has a tetrahedral coordination environment and is coordinated by the nitrogen atoms of the pyridine and thiohydantoin rings and two chloride anions. The results of electronic spectroscopy and magnetic susceptibility measurements suggest that the complexes with the β-and γ-Py-substituted ligands have polymeric structures, and the metal atoms in these complexes are in an octahedral environment. The molecular and crystal structures of CuIIL1Cl2 (L1 is (5Z)-2-methylthio-3-phenyl-5-(α-pyridylmethylidene)-3,5-dihydro-4H-imidazol-4-one) and CoIIL2Cl2 (L2 is (5Z)-3-methyl-2-methylthio-5-(α-pyridylmethylidene)-3,5-dihydro-4H-imidazol-4-one) were established by X-ray diffraction. Semiempirical quantum-chemical calculations were performed for 2-methylthio-5-(pyridylmethylidene)-3,5-dihydro-4H-imidazol-4-ones. The complexes, starting ligands, and metal chlorides were studied electrochemically. The mechanism of electro-oxidation and electroreduction of 2-methylthio-5-(pyridylmethylidene)-3,5-dihydro-4H-imidazol-4-ones and their cobalt, nickel, and copper complexes was proposed.