Transformation of the Bis(diphenylphosphino)methane Ligand on the Ru₃(CO)₉Framework. Synthesis and Characterization of Ru₃(CO)₉(μ₃-η³-P(C₆H₅)CH₂P(C₆H₅)(C₆H₄)), Ru₃(CO)₉(μ-H)(μ₃-η²-P(C₆H₅)CH₂P(C₆H₅)₂), and Ru₃(CO)₁₀(μ-η²-P(C₆H₅)CH₂P(C₆H₅)(C₆H₄))

Several transformations of the dppm ligand on Ru₃ clusters have been established (dppm = bis(diphenylphosphino)methane), starting from the parent complex Ru₃(c6)₁₀(μ-η²-dppm), 1. In compound 2, Ru3(Co)9(μ₃-η3-P-(C6H₅)CH₂P(C₆H₅)(C₆H₄)), the Ru₃(CO)₉ fragment is bridged by the six-electron tridentate phosphine ligand. In compound 3, Ru3(Co)9(μ-H)(μ₃-η²-P(C₆H₅)CH₂P(C₆H₅)₂), the Ru₃(CO)₉H fragment is bridged in a bidentate manner by the five-electron phosphine donor. In compound 4, Ru3(Co)10(μ-η²-P(C6H5)Ch2P(C6H₅)(C₆H₄)), the Ru₃(CO)_l0 fragment is bridged in a bidentate manner by the four-electron phosphine ligand. Thermolysis of 1 at 80 °C in cyclohexane affords 2 in high yield. Thermolysis of 2 in the presence of H₂ affords 3 in high yield. Compound 3 can also be produced directly from 1 at 90 °C in toluene. When CO is bubbled through a solution of 2 in refluxing cyclohexane, compound 4 is produced in high yield. Compound 4 reacts with H₂ under reflux in cyclohexane to yield compound 3. When compound 4 is refluxed in cyclohexane under N₂, compound 2 results. The nature of compounds 2, 3, and 4 has been established by spectroscopic means and by X-ray diffraction methods: crystal data, 2, monoclinic, C_2h⁵-P2₁/c, Z = 4,a = 10.689 (7) Å, b = 11.936 (7) Å, c = 23.281 (18) Å, β = 90.18 (8)° (t = -85 °C), final RiF²) = 3.8%, NO = 7725, NV = 381; 3, monoclinic, C_2h^s-P2_l/n, Z = 4, a = 10.593 (2) Å, b = 13.850 (2) Å, c = 20.720 (3) Å, β= 94.12 (1)° (t = -155 °C), final R(F²) = 3.5%, NO = 7037, NV = 384; 4, monoclinic, C_2h⁵-P2₁/n, Z = 4, a = 12.022 (1) A, b = 15.266 (1) A, c = 17.225 (2) A, β= 105.56 (1)° (t = -155 °C), final R(F²) = 3.5%, NO = 6755, NV = 400.