Molecular solid-state organometallic chemistry of tripodal (polyphosphine)metal complexes. Catalytic hydrogenation of ethylene at iridium

Article abstract of DOI:10.1021/ja00058a021

The solid-gas reactions of [(tripohs)Ir(H)₂(C₂H₄)]BPh₄ (1) with CO, C₂H₄, and H₂ are described [triphos = MeC(CH₂PPh₂)3]. The gaseous reactants promote the elimination of ethane from 1 and the formation of [(triphos)Ir(CO)₂]BPh₄, [(triphos)Ir(C₂H₄)₂]BPh₄, and [(triphos)Ir(H)₂]BPh₄, respectively. The latter 16-electron species is isolable in the solid state at temperatures <70 °C. At higher temperatures, [(triphos)Ir(H)₂]⁺ dimerizes in the solid state to give the tetrahydride [(triphos)HIr(μ-H)₂HIr(triphos)]²⁺. Dimerization is avoided when the unsaturated fragment is incorporated into the lattice of a polyoxometalate cluster such as PW₁₂O₄₀^3-. The complex [(triphos)Ir(H)₂(C₂H₄)]BPh₄ is an effective catalyst for the hydrogenation of ethylene in the solid state at 60 °C. Comparisons are made with analogous fluid solution-phase systems.