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Cluster condensation reactions. The synthesis and crystal and molecular structures of three hydride-rich hexaosmium clusters formed by the decarbonylation of HOs3(CO)9(μ3-S)(μ-HC-NPh) under hydrogen
Adams, Richard D.,Foust, Donald F.,Segmüller, Brigitte E.
, p. 308 - 314 (2008/10/08)
The thermolytic decarbonylation of HOs3(CO)9(μ3-S)(μ-HC=NPh), I, under an atmosphere of hydrogen has been investigated. Three products, H4Os6(CO)15(μ4-S)(μ 3-S)(μ-HC=NPh)2, II, H6Os6(CO)14(μ4-S)(μ 3-S)(HC=NPh)2, III, and H4Os6(CO)15(μ4-S)(μ 3-S)(μ-HC=NPh)2, IV, formed by the condensation of 2 mol of I and the addition of 1 or 2 mol of H2, have been isolated and characterized by IR, 1H NMR, and single-crystal X-ray diffraction analyses. For II: space group P1, No. 2, a = 10.762 (4) A?, b = 14.850 (5) A?, c = 15.843 (9) A?, α = 63.76 (4)°, β= 87.35 (4)°, γ= 82.04 (3)°, V = 2249 (2) A?3, Z = 2, ρcalcd = 2.78 g/cm3. The structure was solved by a combination of Patterson and difference Fourier techniques. Full-matrix least-squares refinement on 4195 reflections yielded the final residuals R = 0.045 and Rw = 0.052. The molecule consists of two open triangular units of I which are joined by a metal-sulfur donor-acceptor bond and one hydride bridged metal-metal bond. The molecule has four hydride ligands which bridge four of the five metal-metal bonds. For III: space group P1, No. 2, a = 10.926 (5) A?, b = 14.150 (6) A?, c = 15.752 (4) A?, α = 72.48 (3)°, β = 80.92 (3)°, γ = 66.12 (4)°, V = 2122 A?3, Z = 2, ρcalcd = 2.88 g/cm3. The structure was solved by a combination of Patterson and difference Fourier techniques. Full-matrix least-squares refinement on 2789 reflections yielded the final residuals R = 0.051 and Rw = 0.049. The structure of III is analogous to that of II except that one carbonyl ligand has been substituted with two hydride ligands. III has six hydride ligands. One hydride ligand bridges each of the five metal-metal interactions and one is a terminal ligand. For IV: space group P1, No. 2, a = 9.549 (3) A?, b = 10.150 (3), c = 26.495 (12) A?, α = 89.29 (3)°, β = 81.17 (4)°, γ = 64.38 (3)°, V = 2284 (2) A?3, Z = 2, ρcalcd = 2.67 g/cm3. This structure was solved by a combination of Patterson and difference Fourier techniques. Full-matrix least-squares refinement on 3644 reflections yielded the final residuals R = 0.043 and Rw = 0.051. IV is an isomer of III. It contains six metal atoms arranged into groups of four and two. The two groups are held together by bridging sulfido ligands. The isomerization involves a repositioning of two of the hydride-bridged metal-metal bonds and a shift of one carbonyl ligand between two metal atoms. When thermolyzed in refluxing nonane solvent, IV loses all its hydride ligands and is converted into the known Os6(CO)15-(μ4-S) 2(μ-HC=NPh)2, V.
