Synthesis of Os3(CO)10(CNR)(NCMe) and its reaction with propynoic acid

Article abstract of DOI:10.1021/om00059a055

The nitrile derivatives Os₃(CO)₁₀(CNR)(NCMe) (2) have been prepared by the reaction of isocyanide complexes Os₃(CO)₁₁(CNR) (1) with Me₃NO in the presence of CH₃CN. The labile complex 2 on reaction with two-electron donor ligands L (L = CO, PPh₃, PMePh₂) gives Os₃(CO)₁₀(CNR)L (3). Treatment of 2 with propynoic acid (HC≡CCO₂H) in CH₂Cl₂ yields the hydrido complexes (μ-H)Os₃(CO)₁₀(μ₂-OCOC≡CH)(CNR) (4); however, complex 2 reacts with propynoic acid in acetonitrile to form complex 4 and the bridging aminocarbyne species Os₃(CO)₁₀(μ₂-OCOC≡CH)(μ ₂-C=NHR) (5) containing a unique bridging unidentate (μ₂-η¹-oxo) carboxylate ligand. Molecular structures of Os₃(CO)₁₀(CNPr)(PPh₃) (3a) and Os₃(CO)₁₀(η₂-OCOC≡CH)(η ₂-C=NHPr) (5a) have been determined by X-ray diffraction studies. Crystal data are as follows. 3a: P1; a = 11.4611 (14), b = 11.6963 (19), c = 14.9661 (22) A?; α = 93.635 (12), β = 73.633 (11), γ = 117.325 (11)°; V = 1705.0 (4) A?³, Z = 2; R = 4.2%, R_w = 5.1%. 5a: P2₁2₁2₁; a = 9.4241 (23), b = 15.414 (4), c = 15.972 (3) A?; V = 2320.2 (9) A?³, Z = 4; R = 3.2%, R_w = 3.5%.