Synthesis, characterization and luminescence property of heterobimetallic trinuclear Mo(W)–Ag–S clusters containing 1,2-bis(diphenylphosphino)-1,2-dicarba-closo-dodecaborane

Reactions of (NH4)2MS4 or (NH4)2MOS3 (M = Mo, W) with AgSCN and closo carborane diphosphine ligand 1,2-(PPh2)2-1,2-C2B10H10 (L) in CH2Cl2 yielded four heterobimetallic trinuclear Mo(W)–Ag–S clusters: [Ag2MoS4L2] (1), [Ag2WS4L2] (2), [Ag2MoOS3L2] (3) and [Ag2WS4L2] (4), respectively. All the new clusters have been characterized by elemental analysis, FT-IR, UV–Vis, 1H and 13C NMR spectroscopy and their molecular structures (except for 3) were further confirmed by single-crystal X-ray diffraction. X-ray crystal structure analysis showed that the closo carborane diphosphine ligand was coordinated bidentately to Ag(I) atom through its two phosphorus atoms, resulting in a stable five-member chelating ring between the diphosphine ligand and the metal. The coordination sphere of the central M atom, as well as all the Ag atoms, was tetrahedron. The skeletons of these clusters could be classified into two types: with (NH4)2MS4, the three metal atoms (two Ag atoms and one M atom) are in a linear conformation, while with (NH4)2MOS3, the conformation of the heterobimetallic trinuclear cluster is butterfly shaped. The luminescence properties of the clusters were investigated in CH2Cl2 solution at room temperature and for the first time the butterfly-shaped Ag–W–S cluster containing the Ag2WS4 core has been proved to show luminescence property.