STRUCTURAL STUDIES ON POLYNUCLEAR OSMIUM CARBONYL HYDRIDES .13. MOLECULAR-GEOMETRY OF MU-BROMO-MU-HYDRIDO-DECACARBONYLTRIOSMIUM, (MU-H)((MU-BR)OS3(CO)10, AND A COMPARISON OF OS(MU-H)(MU-X)OS BRIDGES

The structure of (μ-H)(μ-Br)Os3(CO)10 has been elucidated by means of a single-crystal X-ray diffraction study. This complex crystallizes in the centrosymetric triclinic space group PI [formula ommited] p(calcd) = 3.518 g cm-3 for mol wt 931.62 and Z = 4. Diffraction data were collected with a Syntex P21 automated diffractometer using Mo Kα radiation and a coupled θ(crystal)-2θ(counter) scan technique. The structure was solved by conventional techniques and refined to RF = 5.5% and RwF = 4.4% for all 4614 independent data with 3.5° <2θ < 45° (RF = 4.3% and RwF = 4.2% for those 3976 data with I > 3σ(I)). The crystallographic asymmetric unit consists of two independent molecules of (μ-H)(μ-Br)Os3(CO)10. These molecules contain a triangular arrangement of osmium atoms; for each molecule Os(1) and Os(2) are each associated with three carbonyl ligands, while Os(3) is linked to four such ligands. In molecule A, Os(1) and Os(2) are clearly seen to be bridged by a μ-bromide and a μ-hydride ligand. Osmium-osmium distances in this molecule are [formula ommited] Molecule B appears to suffer from a slight disorder problem, wherein the μ-bromide ligand occupies both possible sites above and below the triosmium plane with relative occupancies of 0.917 (4):0.083 (4). Interatomic parameters for this molecule, while consistent with those for molecule A, are regarded as less reliable. © 1979, American Chemical Society. All rights reserved.