Combined X-ray and neutron diffraction study of [Os4(CO)11H3(CHCHPh)]

Abstract

The title complex has been prepared by the photolytic reaction of styrene with [Os₄(CO)₁₂H₄]. It crystallises in the monoclinic space group P2₁/c with a= 8.720(3), b= 16.338(5), c= 18.144(6)Å, β= 111.60(3)°, and Z= 4. Simultaneous refinement of a single parameter set to fit 2 155 X-ray [(sin θ)/λ > 0.352] and 935 neutron data has led to R 0.058 (X-ray) and 0.096 (neutron). The Os₄ unit is tetrahedral with three long (mean 2.956 Å) and three short (mean 2.806 Å) Os–Os edges. The styrenyl ligand σ bonds to one Os atom and π bonds to another, asymmetrically bridging a short Os–Os edge. The three hydride ligands bridge two long and one short metal–metal bond with O–H distances in the range 1.77 to 1.86 Å. The eleven carbonyl ligands are all terminal.