Half-sandwich ruthenium-arene complexes with thiophen containing thiosemicarbazones: Synthesis and structural characterization

Novel conformationally rigid half-sandwich organoruthenium(II) complexes ([(eta(6)-p-cymene)Ru(eta(1)-S-TSC1)CL2], (1); [(eta(6)-p-cymene)Ru(eta(1)-S-TSC2)CL2], (2) and [(eta(6)-p-cymene)Ru(eta(2)-N,S-TSC3)Cl]CI, (3) have been synthesized from the reaction of [{(eta(6)-p-cymene)RuCL}(2)(mu-CL)(2)] with the respective thiosemicarbazones TSC1 (2-acetyl-5-chloro-thiophene thiosemicarbazone), TSC2 (2-acetyl-5-methyl-thiophene thiosemicarbazone) and TSC3 (3-thiophene aldehyde thiosemicarbazone) in a 1: 2 M ratio in methanol and all of the complexes have been characterized by elemental analysis, UV-Vis, FT-IR and H-1 NMR spectroscopy. The crystal structures of TSC1, TSC2 and [(eta(6)-p-cymene)Ru(eta(1)-S-TSC2)CL2], (2) have been determined by X-ray crystallography revealing that TSC1 and TSC2, crystallized in the monoclinic space group P2(1)/c and complex (2) show a distorted octahedral geometry around the ruthenium centre. The mononuclear complex adopts a typical three legged piano-stool geometry (a description commonly used for half sandwich compounds) with the metal centre coordinated by two chlorides and a TSC ligand. The coordination geometry around Ru-II atom is distorted octahedron with three sites occupied by the p-cymene ligand (with an eta(6) coordination mode) while the remaining three sites occupied by the S atom of the TSC ligand and two Cl atoms. The spectroscopic studies showed that TSC1 and TSC2 are coordinated to the central metal as a monodentate ligand coordinating via the thiocarbonyl sulfur atom (C=S) in complexes (1) and (2), whereas TSC3 is coordinated to ruthenium as a bidentate ligand through azomethine nitrogen (C=N) and sulfur atom in complex (3). (C) 2017 Elsevier B.V. All rights reserved.