Carbon-Carbon Bond Formation at a Diiron Center. 5. Versatile Action of Phosphines on Fe₂(CO)₆(μ-COEt)(μ-CRCR’H) Complexes (R = R’ = Ph, H)

The reaction of Fe2(CO)6(μ-COEt)(μ-CRCR’H) complexes (R = R’ = Ph, H) with the phosphines PPh3 and PMe2Ph is dependent on both phosphine and R. In the case where R = R’ = Ph, reaction with PPh3 leads only to the formation of Fe(CO)3(PPh3)2 in boiling hexane. With PMe2Ph the reaction occurs with CO substitution to give Fe2(CO)5(PMe2Ph)(μ-CPhCPhC(OEt)H) (3), in which the organic fragment is TJV bound through the carbons to the two iron atoms and η1(O) bound through oxygen of the ethoxy group to an iron atom. In the case where R = R’ = H, reaction with PMe2Ph leads to the formation of Fe-(CO)5-n(PMe2Ph)n (n = 1, 2) in boiling hexane. With PPh3, coupling of the two organic bridges is observed and the reaction occurs without CO loss, leading to Fe2(CO)6(PPh3)(μ -C(OEt)CHCH2) (5). Protonation of 5 with HBF4-Et2O gives [Fe2(CO)7(PPh3)Gu-C(OEt)CH(Me))][BF4], the structure of which has been established by an X-ray structure determination: triclinic; space group PI; a = 12.305 Å, b = 16.069 Å, c = 8.210 Å; α = 95.61 (1)°, β = 90.35 (1)°, γ = 87.10 (1)°; Z = 2. The structure was solved and refined to R and Rw values of 0.031 and 0.032, respectively, with use of 3226 reflections. © 1990, American Chemical Society. All rights reserved.