Bifunctional activation of a carbonyl group in the pentanuclear carbido–clusters [Os5C(CO)15] and [Os5C(CO)15l2] by alcohols: X-ray analysis of [Os5C(CO)14(CO2Et)H] and [Os5C(CO)14(CO2Me)l]

Abstract

The clusters [Os₅C(CO)₁₅](1) and [Os₅C(CO)₁₅l₂](2) react with alcohols (ROH) under mild conditions to give derivatives of the type [Os₅C(CO)₁₄(CO₂R)H](3) and [Os₅C(CO)₁₄(CO₂R)l](4) respectively. X-Ray analysis has confirmed that in both cases the alkoxy-group has attacked a carbonyl ligand in the parent compound to form a C,O-bonded µ-CO₂R group. In contrast, when the species [Os₅C(CO)₁₅-l(X)][X = H or Au(PPh₃)] are heated under reflux in alcohols the complexes [Os₅C(CO)_15–nl(X)][n= 1 or 2, X = H; n= 1, X = Au(PPh₃)] are formed, as had previously been found for the analogous ruthenium compounds. Crystals of [Os₅C(CO)₁₄(CO₂Et)H](3; R = Et) are monoclinic, space group P2₁/n, with a= 15.665(3), b= 16.761(3), c= 10.198(2)Å, β= 90.4(1)°, and Z= 4; refinement of atomic parameters using 3 461 absorption-corrected data converged at R 0.0386. The complex [Os₅C(CO)₁₄(CO₂Me)l](4; R = Me) crystallises in the orthorhombic space group Pna2₁ with a= 17.019(3), b= 10.063(3), c= 15.810(3)Å, and Z= 4; refinement of atomic parameters using 2 460 absorption-corrected data converged at R 0.0487.