MOLECULAR-STRUCTURE OF H4RU4(CO)12 AND H4RU4(CO)10(PPH3)2

The structures of H4Ru4(CO)12 and H4Ru4(CO)10(PPh3)2 have been solved by single-crystal x-ray diffraction methods. Their geometries, like that of the closely related H4Ru4(CO)uP(OMe)3 reported earlier, consist of a distorted tetrahedral core (D2d symmetry) with four long Ru-Ru distances and two short Ru-Ru distances. It is believed that the four H atoms, which were not unambiguously located in this study, bridge the four long edges of the Ru4 cluster. In H4Ru4(CO)12, H4Ru4(CO)nP(OMe)3, and H4Ru4(CO)10(PPh3)2 the two short (nonbridged) Ru-Ru bonds are opposite each other, unlike those in H4Ru4(CO)10(Ph2PCH2CH2PPh2) which are ajacent to each other. All H4Ru4(CO)12-nLn molecules investigated so far show carbonyl groups staggered with respect to the M-M edges of the M4 cluster, in contrast to those in H4Re4(CO)12 which are eclipsed. The structural analysis of H4Ru4(CO)12 is complicated by packing disorder, which is commonly found in crystals of dodecacarbonyl metal cluster complexes. Structural details: in H4Ru4(CO)12, the average long (Ru-H-Ru) and short (Ru-Ru) metal-metal distances are 2.950 (1) and 2.786 (1) Å, respectively; in H4Ru4(CO)l0(PPh3)2 they are 2.966 (2) and 2.772 (2) Å, respectively. Crystal details: H4Ru4(CO)12 crystallizes in the triclinic space group Pῑ, with a = 9.838 (7) Å, b = 10.087 (6) Å, c = 9.659 (6) Å, a = 82.77 (4)°, β = 88.99 (4)°, γ = 85.08 (3)°, Z = 2, and V = 947.4 Å3; the final R factor was 6.3% for 4361 reflections (7 > 3σ) collected at -175 °C. H4Ru4(CO)10(PPh3)2 crystallizes in the monoclinic space group P2√c, with a = 15.922 (5) Å, b = 17.888 (7) Å, c = 17.916 (5) Å, β = 112.04(2)°, Z = 4, and V = 4729.8 Å3; the final R factor was 6.5% for 3512 reflections (I > 3σ) collected at room temperature. © 1978, American Chemical Society. All rights reserved.