Metal-induced cleavage of carbon-sulfur bonds in thiolato ligands. Thermolysis of HOs₃(CO)₁₀(μ-SC₆H₅) under CO pressure. The synthesis and crystal and molecular structures off Os₄(CO)₁₃(μ₃-S) and Os₅(CO)₁₅(μ₄-S)

The thermolysis of HOs₃(CO)₁₀(μ-SC₆H₅), I, has been studied under carbon monoxide pressures of 200 and 1800 psi at 150°C. At 200 psi, I eliminates C₆H₆ and forms the new compounds Os₄(CO)₁₃(μ₃-S), II, and Os₅(CO)₁₅(μ₄-S), III, and the known compounds Os₃(CO)₉(μ₃-S)₂, IV, and Os₃(CO)₁₂. Compounds II and III have been characterized by X-ray crystallographic methods. For II: space group P1, No. 2, a = 9.608 (2) Å, b = 15.402 (2) Å, c = 15.703 (3) Å, α = 113.29 (2)°, β = 99.04 (2)°, γ = 95.52 (2)°, V = 2077 (2) ų, Z = 4, ρ_calcd = 3.70 g/cm³. The structure was solved by the heavy-atom method. For 3998 reflections (F² ≥ 3.0σ(F²)) R_F = 0.040 and R_wF = 0.046. The structure consists of a butterfly cluster of four osmium atoms with a triply bridging sulfido ligand on one triangular group of three. There are 13 linear terminal carbonyl ligands. When heated in the absence of CO, II loses 1 mol of CO and forms the Os₄(CO)₁₂(μ₃-S) which contains a closed tetrahedron of four metal atoms. For III: space group Pna2₁, No. 33, a = 19.119 (4) Å, b = 7.724 (6) Å, c = 16.417 (4) Å, V = 2424 (3) ų, Z = 4, ρ_calcd = 3.84 g/cm³. The structure was solved by direct methods. For 1520 reflections (F² ≥ 3.0σ(F²)) R_F = 0.037 and R_wF = 0.042. The structure consists of a square-pyramidal cluster of five osmium atoms with a quadruply bridging sulfido ligand spanning the square base. Each metal atom contains three linear terminal carbonyl ligands. At 1800 psi of CO pressure thermolysis of I yields C₆H₆, Os₃(CO)₉(μ₃-S)₂, and Os(CO)₅ only. A reaction mechanism involving Os₃-(CO)₉(μ₃-S) and Os(CO)₄ intermediates is proposed and discussed. © 1983 American Chemical Society.