Complexes containing the unit Rh2P 'down curve sign' PM (M=Cr or Mn, P 'down curve sign' P = bis(diphenylphosphino) alkane) ; the independence of the metal centres

Article abstract of DOI:10.1016/S0022-328X(96)06534-5

Treatment of (η⁵-C₅H₅)₂Rh₂(CO){η¹-Ph₂P(CH₂)_nPPh2}(μ-η¹:η¹-CF₃C₂CF₃) (I) with (η⁵-CH₃C₅H₄)Mn(CO)₂(thf) or Cr(CO)₅(thf) gives the hetero-trinuclear products (η-C₅H₅)₂Rh₂(CO)(μ-CF₃C₂CF₃){μ:η¹:η¹-Ph₂P(CH₂)nPPh₂}(η-CH₃C₅H₄)Mn(CO)₂ (II, n = 1-4) and (η⁵-C₅H₅)₂Rh₂(CO)(μ-CF₃C₂CF₃){μ:η¹:η¹-Ph₂P(CH₂)_nPPh₂}Cr(CO)₅ (IV, n = 1-4) in good yields. In these products, the configuration of the CO and bisphosphine units on the Rh-Rh bond is trans. Related reactions between (η⁵:η⁵-C₅H₄CH₂C₅H₄)Rh₂(CO){η¹-Ph₂P(CH₂)_nPPh2}(μ-η¹:η¹-CF₃C₂CF₃) (V) and the same solvated manganese and chromium complexes give (η⁵:η⁵-C₅H₄CH₂C₅H₄)Rh₂(CO)(μ-CF₃C₂CF₃){μ:η¹:η¹-Ph₂P(CH₂)_nPPh₂}(η-CH₃C₅H₄)Mn(CO)₂ (VI, n=1, 2 or 4) and (η⁵:η⁵-C₅H₄CH₂C₅H₄)Rh₂(CO)(μ-CF₃C₂CF₃){μ:η¹:η¹-Ph₂P(CH₂)₃PPh₂}(CrCO)₅ (VIII). The complexes (VI) and (VIII) have a mutually cis arrangement of CO and the bisphosphine on the Rh-Rh bond. Attempts to induce the complexes (IV), (V), (VI), and (VIII) to form clusters by loss of CO and Rh-M bond formation were not successful. Treatment with trimethylamine oxide or sunlight irradiation generally resulted in loss of the hetero-metal and formation of the dirhodium phosphine oxide complexes (III, n = 2 or 4) and (VII, n = 2, 3).