Synthesis and crystals structure of a carbomethoxy complex of pentacoordinate iridium(I), MeOC(O)Ir(CO)₂(PPh₃)₂

The pentacoordinate complex MeOC(O)Ir(CO)₂(PPh₃)₂, prepared by carbonylation of trans-MeOIr(CO)(PPh₃)₂, crystallizes in the centrosymmetric triclinic space group P1 with a 10.019(2), b 11.828(3), c 16.578(5) Å, α 103.83(2), β 92.71(2), γ 114.27(2)°, V 1715(1) ų and Z = 2. Diffraction data were collected and the structure was solved and refined to R 4.9% for 4504 reflections with 2θ = 4.5-45.0° (Mo-K_α), and R 3.6% for those 3768 data with |F₀| > 6σ(|F₀7z.sfnc;). The iridium(I) atom is in a trigonal-bipyramidal coordination environment. Axial bond lengths are Ir-CO₂Me 2.073(9) and Ir-P(2) 2.360(2) Å; equatorial bond lengths are Ir-P(1) 2.392(2), Ir-CO(1) 1.891(8) and Ir-CO(2) 1.895(10) Å. Isomerism in trigonal-bi-pyramidal molecules is discussed.