Chemistry of cyclopentadienyl tricarbonylchromium dimer. Cleavage of bis(thiophosphinyl)disulfanes and bis(thiophosphoryl)disulfanes. Syntheses of CpCr(CO)2(S2PPh2) and CpCr(S2PPh2)2. X-ray crystal structure of CpCr(S2PPh2)2

The facile reaction of [CpCr(CO)3]2 with one mole equivalent of bis(diphenylthiophosphinyl)disulfane, Ph2P(S)SSP(S)PPh2, led to the isolation of dark purplish brown solids of CpCr(CO)2(S2PPh2) (2) and blue solids of CpCr(S2PPh2)2 (3) in 50 and 10% yields, respectively. Proton NMR spectral studies demonstrated that 3 is derived from 2, the primary product. IR spectral data indicated that 2 possesses cis CO ligands and a bidentate SP(S)Ph2 ligand, whilst 3 contains both a unidentate and a bidentate ligand, as confirmed by its X-ray diffraction analysis. Variable temperature 1H and 31P spectral studies showed the occurrence of very rapid unidentate–bidentate exchange between the ligands in 3 in the temperature range −80–60°C.