Synthesis and structural characterization of copper–molybdenum–sulfur and copper–tungsten–sulfur cluster complexes (n-Bu4N)[OMS3Cu3Br2L2] with heterocyclic thiones as ligands

Reaction of (NH4)2[WOS3] or (NH4)2[MoO2S2], n-Bu4NBr, CuCl and Imt in acetone solvent afforded air- and moisture-stable clusters (n-Bu4N)[MOS3Cu3(Imt)2Br2] (M = W or Mo, Imt = imidazolidine-2-thione). These compounds have been characterized by IR, UV–Vis, 1H and 13C NMR spectra and single-crystal X-ray diffraction. They are crystallographically isostructural, with Imt and [MOS3]2− acting as monodentate and bidentate S-donor ligands, respectively. In the anions, the three Cu atoms have different coordination environments, one being distorted tetrahedral with Imt and Br as terminal ligands, the other two being approximately trigonal planar with Imt as a terminal ligand for one and Br as a terminal ligand for the other. W and Mo have approximately tetrahedral coordination geometry, with a terminal O and three triply-bridging S atoms. The NH groups of the Imt ligands serve as donors in intramolecular N–H⋯Br and in intermolecular N–H⋯Br and N–H⋯O hydrogen bonds, linking the anions to form layers with the cations in cavities.

The anions of the title complexes have incomplete cubane core structures, in which the three Cu atoms have different coordination environments, being bonded, respectively, to a Br ligand, a thione ligand, and both of these. The isomorphous crystal structures display intramolecular and intermolecular hydrogen bonding.Figure optionsDownload as PowerPoint slide