Synthesis, X-ray Structure, and Protonation of [Os(C2Ph){NH:C(Ph)C6H4}(CO)(PPr-i3)2]

The bis(alkynyl) complex [Os(C2Ph)2(CO)(PiPr3)2] (1) reacts with benzophenone imine to give [Os(C2Ph)2(CO)(NH=CPh2)(PiPr3) 2] (2) as a mixture of two isomers, cis-bis(alkynyl) (2a) and trans-bis(alkynyl) (2b). In toluene under reflux, this mixture is converted into [Os(C2-Ph){NH=C(Ph)C6H4}(CO)(PiPr 3)2] (3) and phenylacetylene. The X-ray crystal structure of 3 has been determined (triclinic, space group P1 with a = 11.078(1) Å, b = 18.910(2) Å, c = 20.290(2) Å, α = 67.562(7)°, β = 89.427(9)°, γ = 87.289(9)°, and Z = 4). 3 reacts with HBF4 in diethyl ether to give phenylacetylene and [Os{NH=C(Ph)C6H4}(CO)(OH2)(PiPr 3)2]BF4 (4), which by reaction with CH3Li affords [Os(CH3){NH=C(Ph)C6H4}(CO)(PiPr 3)2] (5).