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 = Pr-i)

The facile reaction of [CpCr(CO)(3)](2) (CP = eta (5)-C5H5) with one mole e quivalent of bis(thiophosphoryl)disulfanes, (RO)(2)P(S)SSP(S)(OR)(2) (R = ' Pr), at ambient temperature, led to the isolation of dark-purple solids of CpCr(CO)(2)(S2P(OR)(2)) (2, yields 32%) and blue solids of CpCr(S2P(OR)(2)) (2) (3, yield: 30%). At 70-80 degreesC, the reaction gave 3 (yield: 35%) an d Cr(S2P(OR)(2))(3) (4, yield: 11 %). H-1-NMR spectral studies demonstrated that 3 and 4 were derived from 2, the primary product. X-ray diffraction a nalyses showed that 2 possesses cis CO ligands and a bidentate SP(S)(OR), l igand, while 3 contains both an unidentate and a bidentate ligand, and in 4 the Cr atom is octahedrally symmetrically coordinated to the three bidenta te phosphorylthioato, ligand. Variable temperature H-1 and P-31 spectral st udies showed the occurrence of very rapid unidentate-bidentate exchange bet ween the ligands in 3 in the temperature range - 65 to 80 degreesC. It is a lso shown that the C drop Cr complex [CpCr(CO)(2)](2) reacted with [('PrO)( 2)P(S)S](2), albeit much less readily, generating 3 as the eventual product . (C) 2001 Elsevier Science B.V. All rights reserved.