Synthesis, characterization and crystal structure determination of (NEt4)2[MS4(CuBp′)2]·X (M=Mo, X=(CH3)2CO; M=W, X=CH3CN); Bp′=H2B(3,5-Me2Pz)2

Two new copper(I) complexes containing the [MS4]2− core (M=Mo or W) and anionic Bp′ ligands have been prepared from the reaction system consisting of (Et4N)2[MS4], CuCl and KBp′ in acetone; their IR, UV–Vis, 1H and 13C NMR spectra have been studied. The structures of the complexes have been determined by X-ray crystallography. The trinuclear dianions, [Bp′CuS2MS2CuBp′]2−, are isostructural, and their tetraethylammonium salts are isomorphous, despite the presence of different solvent molecules in the two crystal structures. In both complexes, the coordination environment around each copper atom is distorted tetrahedral with two N donors of the bidentate bispyrazolylborate and two S donors of the central MS4 group, offering a structural model for some copper proteins. The W and Mo atoms essentially retain the tetrahedral geometry of the free [MS4]2− anion.