STRUCTURAL STUDIES ON POLYNUCLEAR OSMIUM CARBONYL HYDRIDES .11. CRYSTAL-STRUCTURE AND MOLECULAR-GEOMETRY OF (MU-H)OS3(CO)10(CHCH=NET2), A SPECIES CONTAINING A MU-2-HYDRIDE LIGAND AND A MU-2-1,3-DIPOLAR GREATER-THAN C-HCH=N+ET2 LIGAND

The species (μ-H)Os3(CO)10(CHCH=NEt2), previously synthesized by Shapley and co-workers from Os3(CO)10(NCMe)2 and triethylamine, has been unambiguously identified and characterized via a full three-dimensional single-crystal X-ray structural analysis. The complex crystallizes in the centrosymmetric monoclinic space group P21/c with [FORMULA OMMIETD] Mo Kα radiation] were collected with a Syntex P21 automated diffractometer, using graphite-monochromatized radiation. The structure was solved via direct methods (i.e., multan), difference-Fourier techniques, and least-squares refinement techniques, the resulting discrepancy indices being RF=5.03% and RwF=4.59% for 1434 independent reflections. The molecule contains a triangular arrangement of osmium atoms. Os(l) and Os(2) are each associated with three carbonyl ligands, while Os(3) is linked to four such ligands. In addition, Os(l) and Os(2) are mutually bridged by a hydride ligand (which was located and refined in the course of the structural analysis) and by a 1, 3-dipolar>C-HCHN+Et2 ligand. Osmium-osmium bond lengths are [FORMULA OMMITED]. Whereas a single unsupported μ2-hydrido ligand normally causes a lengthening of its bridged metal-metal vector, this effect is counterbalanced by the (M-M) bond-shortening influence of the>C HCHN+Et2 ligand in the present molecule. Osmium-(μ2-hydride) distances are [FORMULA OMMITED]. © 1979, American Chemical Society. All rights reserved.