Chemistry of cyclopentadienyl tricarbonylchromium dimer. Cleavage of bis(thiophosphoryl)disulfanes. Syntheses and X-ray crystal structures of CpCr(CO)2(S2P(OR)2), CpCr(S2P(OR)2)2 and Cr(S2P(OR)2)3 (R=iPr)

Abstract

The facile reaction of [CpCr(CO)3]2 (Cp=η5-C5H5) with one mole equivalent of bis(thiophosphoryl)disulfanes, (RO)2P(S)SSP(S)(OR)2 (R=iPr), at ambient temperature, led to the isolation of dark-purple solids of CpCr(CO)2(S2P(OR)2) (2, yield: 32%) and blue solids of CpCr(S2P(OR)2)2 (3, yield: 30%). At 70-80°C, the reaction gave 3 (yield: 35%) and Cr(S2P(OR)2)3 (4, yield: 11%). 1H-NMR spectral studies demonstrated that 3 and 4 were derived from 2, the primary product. X-ray diffraction analyses showed that 2 possesses cis CO ligands and a bidentate SP(S)(OR)2 ligand, while 3 contains both an unidentate and a bidentate ligand, and in 4 the Cr atom is octahedrally symmetrically coordinated to the three bidentate phosphorylthioato ligand. 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 -65 to 80°C. It is also shown that the CrCr complex [CpCr(CO)2]2 reacted with [(iPrO)2P(S)S]2, albeit much less readily, generating 3 as the eventual product. © 2001 Elsevier Science B.V.