Electrochemical synthesis and structural characterization of copper and silver complexes of imidazolidine-2-thione ligands

• Published in: Polyhedron 2005-10, Vol.24 (15), p.2043-2054
• Main Authors: García-Vázquez, José A., Sousa-Pedrares, Antonio, Carabel, Maximiliano, Romero, Jaime, Sousa, Antonio
• Format: Article
• Language: English
• Subjects: Copper; Crystal structures; Electrochemical synthesis; Heterocyclic thione; N,S ligands; Silver
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2005.06.016

New multinuclear copper (I) and silver (I) 1-R-imidazolidine-2-thionates of the general formula [Cu(1-RImS)] and [Ag(1-RImS)] (where R = Me, Et, Pr, i Pr) have been synthesized and characterized. The crystal structures of [Cu(1-EtImS)] ( 1), [Cu(1-PrImS)] ( 2), [Ag(1-PrImS)] ( 3) and [Ag(1- i PrImS)] ( 4) were determined by X-ray diffraction. Compounds ( 1) and ( 2) are tetranuclear and the complexes ( 3) and ( 4) are hexanuclear. In all these compounds each metal atom has a distorted trigonal [MS 2N] environment with each ligand acting as a μ 2-N,S(η 2-S; η 1-N) bidentate S-bridging ligand. The electrochemical oxidation of anodic metal (copper and silver) in acetonitrile solutions of the appropriate 1-R-imidazolidine-2-thione (1-RImSH) afforded complexes of composition [M(1-RImS)], M = Cu, Ag, R = Me, Et, Pr, i Pr. The compounds have been characterized by microanalysis, IR, NMR and mass spectroscopy and, in the case of [Cu(1-EtImS)] ( 1), [Cu(1-PrImS)] ( 2), [Ag(1-PrImS)] ( 3) and [Ag(1- i PrImS)] ( 4), by X-ray diffraction. Compounds ( 1) and ( 2) are tetranuclear with an array of four copper atoms at the vertices of a tetrahedron bridged by four sulfur atoms. Each copper atom has a distorted trigonal [CuS 2N] environment with each ligand acting as a μ 2-N,S(η 2-S; η 1-N) bidentate S-bridging ligand. Complexes 3 and 4 are hexanuclear with six silver atoms at the vertices of a distorted octahedron and the ligand acting as a μ 2-N,S(η 2-S; η 1-N) bidentate S-bridging five-electron donor. In the crystals the copper molecules are interconnected by weak intermolecular C–H⋯S and C–H⋯π interactions but, in contrast, the silver molecules are linked by weak intermolecular C–H⋯N and C–H⋯π interactions.