Synthesis, characterization and luminescence of the tetranuclear gold cluster:: [Au4{7,8-(PPh2)2-7,8-C2B9H10}2(PPh3)2]

A tetranuclear gold cluster has been synthesized by the reaction of [Au(PPh3)NO3] with the closo carborane diphosphine 1,2-(PPh2)(2)-1,2-C2B10H10 in THF, and characterized by elemental analysis, FT-IR, H-1 and C-13 NMR spectroscopy and X-ray structure determination. The cluster crystallizes in the triclinic Pi, a= 15.118(8)angstrom, b = 16.057(9)angstrom, c=24.284(13)angstrom, alpha= 80.822(9)degrees, beta=79.624(8)degrees, y=81.938(8)degrees, Z=2, R-1=0.0626, wR(2)=0.1894. A single crystal structure determination showed that four gold atoms form a tetrahedral framework. Among these four gold atoms, two were chelated by two nido carborane diphosphine [7,8-(PPh2)(2)-7,8-C2B9H10](-) anions coming from the degradation of the initial closo ligand 1,2-(PPh2)(2)-1,2-C2B10H10, while the other two were ligated to two PPh3 groups. The luminescence of this cluster was also investigated in dichloromethane solution at room temperature.