Cyclopentadienyl-ruthenium and -osmium chemistry. XXVII. X-ray structures of Ru(CCPh)(dppe)(η-C₅H₅) and of [Ru(L)(PPh₃)₂(η-C₅H₅)]X (L = C(OMe)Et, X = PF₆; L = CCMePh, X = I)

Determinations of the crystal structures of the acetylide Ru(CCPh)(dppe)(η-C₅H₅), the vinylidene [Ru(CCMePh)(PPh₃)₂(η-C₅H₅)]I and the carbene [Ru{C(OMe)Et}(PPh₃)₂(η-C₅H₅)][PF₆], have enabled comparison of the RuC(α) bonds in these and a number of related complexes. Cationic complexes have RuC bonds shorter (by 0.05-0.1 Å) than values expected on the basis of normal covalent radii, but in the case of vinyl and acetylide complexes there does not appear to be any significant shortening of the RuC bond which can be ascribed to back-bonding from the metal to the unsaturated carbon-bonded ligand. Ru(CCPh)(dppe)(η-C₅H₅) crystallises in the monoclinic space group P2₁/n, with a 14.642(4), b 14.018(3), c 16.490(4) Å, β 105.08(2)°, Z 4; [Ru(CCMePh)(PPh₃)₂(η-C₅H₅)]I crystallises in the orthorhombic space group P2₁2₁2₁, a 12.612(4), b 15.607(3), c 22.357(6) Å, Z 4; [Ru{C(OMe)Et}(PPh₃)₂(η-C₅H₅)][PF₆ crystallises in the orthorhombic space group P2₁2₁2₁, a 11.999(3), b 14.948(1), c 22.342(3) Å, Z 4. For 4841, 2614 and 3299 data (I > 2.5σ(I), respectively, refinements converged with R, R_w values of 0.038 and 0.048, 0.047 and 0.053, and 0.040 and 0.044 for the three complexes.