Silicon-Oxygen Bond-Forming Reactions upon Addition of Silanes and Silyl Halides to the 16-Electron Alkoxyiridium Complexes trans-ROIr(CO)[P(p-tol)₃]₂(R = Me or Ph; p-tol = p-Tolyl). Crystal and Molecular Structure of H₂Ir(CO)(SiMe₂Ph)[P(p-tol)₃]₂

The reactions of silanes and silyl halides with the 16-electron alkoxyiridium complexes trans-ROIr-(CO)[P(p-tol)₃]₂(R = Me or Ph; p-tol = p-tolyl) are reported. The silanes add oxidatively to the alkoxyiridium complex; the resulting complex undergoes reductive elimination of an alkoxysilane with ultimate formation of H₂Ir(CO)(SiR₃)[P(p-tol)₃]₂. Reactions of silyl halides with the alkoxy complex results in formation of silicon-oxygen bonds. The dihydride H₂Ir(CO)(SiMe₂Ph)[P(p-tol)₃]₂, which is an active hydrogenationcatalyst, was subjected to structural analysis. It crystallizes in the centrosymmetric triclinic space group P1 with a = 10.692 (1) Å, b = 11.199 (2) Å, c = 20.557 (4) Å, α = 75.991 (14)°, β = 84.505 (14)°, γ= 77.503 (11)°, V = 2329 (1) ų, and Z = 2. Diffraction data (Mo Kα, 20 = 4.5-45.0°) were collected with a Syntex P2₁automated diffractometer; the structure was solved and refined to R_F = 4.9% for all 6119 reflections (R_F= 3.6% for those 5094 data with |F_o| > 6σ(|F_o|)). The non-hydride ligands occupy expanded sites in an octahedral iridium(III) complex with Ir-P(1) = Ir-P(2) = 2.366 (2) Å, Ir-Si-2.414 (2) Å, and Ir-CO = 1.900 (8) A. The SiMe₂Ph ligand is trans to a P(p-tol)₃ligand (P(1)-Ir-Si = 146.39 (7)°). The hydride ligands were located and refined; their positions are of limited accuracy, but they lie in mutually cis sites, trans to a P(p-tol)₃ligand (P(2)-Ir-H(1) = 169.2 (21)°) and to the CO ligand (C-(1)-Ir-H(2) = 169.4 (22)°).