Cluster synthesis. 7. Role of bridging sulfido ligands in the synthesis of platinum osmium carbonyl cluster compounds

Abstract

The four platinum osmium sulfido carbonyl cluster compounds PtOs3(CO)10(PMe2Ph)2(μ 3-S) (I), PtOs3(CO)9(PMe2Ph)3(μ 3-S) (II), PtOs3(CO)9(PMe2Ph)2(μ 3-S) (III), and PtOs3(CO)8(PMe2Ph)3(μ 3-S) (IV) have been obtained from the reaction of Os3(CO)10(μ3-S) with Pt(PMe2Ph)4 at room temperature. All the products were characterized by IR and 1H NMR spectroscopy. Compounds I, II, and IV were also characterized by X-ray crystallographic analyses. All three compounds crystallize in the triclinic space group P1: (I) a = 8.558 (2) Å, b = 13.814 (3) Å, c = 15.214 (5) Å, α = 109.15 (2)°, β = 93.05 (2)°, γ = 95.75 (2)°, Z = 2, ρcalcd = 2.67 g/cm3; (II) a = 10.404 (4) Å, b = 13.746 (7) Å, c = 29.332 (16) Å, α = 85.23 (5)°, β = 88.43 (4)°, γ = 74.25 (4)°, Z = 4, ρcalcd = 2.48 g/cm3; (IV) a = 9.761 (4) Å, b = 11.926 (5) Å, c = 16.412 (6) Å, α = 78.57 (3)°, β = 89.16 (3)°, γ = 87.98 (6)°, Z = 2, ρcalcd = 2.55 g/cm3. All three structures were solved by the heavy-atom method and were refined to the final residuals RF = 0.060 and RwF = 0.071 for I, RF = 0.037 and RwF = 0.039 for II, and RF = 0.032 and RwF = 0.037 for IV. I and II are approximately planar clusters of one platinum and three osmium atoms. They have five metal-metal bonds and a triply bridging sulfido ligand on the PtOs2 triangular face. IV consists of a tetrahedral cluster of one platinum and three osmium atoms with a triply bridging sulfido ligand on the Os3 face. III is believed to be structurally analogous to IV. III and IV can be formed by the decarbonylation of I and II, respectively. This decarbonylation reaction is reversible. UV irradiation of solutions of II yields the compound HPtOs3(CO)7(PMe2Ph)2(PMe 2C6H4)(μ3-S) (V) in addition to IV. V was characterized by X-ray diffraction analysis: space group P1l, a = 10.432 (3) Å, b = 12.727 (6) Å, c = 14.448 (4) Å, α = 98.46 (3)°, β = 93.82°, γ = 91.82 (3)°, Z = 2, ρcalcd = 2.47 g/cm3. The structure of V was solved by the heavy-atom method and was refined to the final residuals RF = 0.037 and RwF = 0.042. V consists of a tetrahedral cluster of one platinum and three osmium atoms and has a triply bridging sulfido ligand on the triosmium face. The phenyl ring of one of the PMe2Ph ligands is orthometalated on a metal atom adjacent to the primary coordination site. © 1984 American Chemical Society.