Structural characterization of a copper(II) complex containing oxidative cyclization of N-2-(4-picolyl)- N′-(4-methoxyphenyl)thiourea, new ligands of 4-picolylthiourea derivatives and the precursor molecular structure of oxidative cyclization of N-(2-pyridyl)- N′-(4-methoxyphenyl)thiourea

Abstract

Three new compounds of aryl thiourea derivatives, namely N-2-(4-picolyl)- N′-(4-methoxyphenyl)thiourea ( L1), N-2-(6-picolyl)- N′-(4-methoxyphenyl)thiourea ( L2) and N-2-(4-picolyl)- N′-(4-nitrophenyl)thiourea ( L3), and the new copper(II) complex [Cu(4PicTz4OMePh)(OAC)(EtOH)] ( C1), as a result of oxidative cyclization of the ligand ( L1), were synthesized. In addition, pure precursor ( P1), as the product of the oxidative cyclization of N-(2-pyridyl)- N′-(4-methoxyphenyl)thiourea ( L4), was isolated and characterized. Ligands ( L1) and ( L2) were characterized by 1H and 13C NMR and single crystal X-ray analysis. 1H NMR spectroscopy showed strong hydrogen bonding interactions between N′H-functionalities and the pyridine nitrogen atoms as well as weak intermolecular hydrogen bonding between the thione sulfur and the NH hydrogen. Structural studies of complex ( C1) showed that the copper ion is five-coordinated with a square-pyramidal environment. The oxidative cyclization of ligand ( L1) results in an anionic bidentate ligand in complex ( C1). Both ligand ( L1) and precursor ( P1) crystallize as centrosymmetric dimers.