Synthesis, characterization and reactivity of new (m-aminocarbyne)diruthenium complexes containing alkynylimino ligands

Addition of acetylides R′C≡CLi [R′ = Tol, Ph, Me3Si, nBu, C(Me)=CH2] to the diruthenium complexes [Ru2{μ-CN(Me)(R)}(μ-CO)(CO)(NCCMe3)(Cp)2]+ (R = Xy, 2a; Bz, 2b; Me, 2c) results in the formation of [Ru2{μ-CN(Me)(R)}(μ-CO)(CO){N(H)=C(CMe3)(C≡CR′)}(Cp)2]+ (R = Xy, R′ = Tol, 3a; R = Bz, R′ = Tol, 3b; R = Me, R′ = Tol, 3c; R = Xy, R′ = Ph, 4a; R = Bz, R′ = Ph, 4b; R = Me, R′ = Ph, 4c; R = Bz R′ = H, 5; R = Xy, R′ = nBu, 6; R = Xy, R′ = [C(Me)=CH2], 7), which contain an alkynylimino ligand, formed from addition of the acetylide to the Me3CCN ligand. Structural and spectroscopic studies show that all these complexes contain the two Cp ligands in a relative cis arrangement, whereas two isomers arise from the different orientation of the substituents on the bridging aminocarbyne μ-CN(Me)(R) when R ≠ Me. Addition of secondary amines to 3−7 results in a stereo- and regioselective cis amination of the C−C triple bond to give the new complexes [Ru2{μ-CN(Me)(R)}(μ-CO)(CO){N(H)=C(CMe3)C(H)=C(NMe2)(Tol)}(Cp)2]+ (R = Xy, 8a; Bz, 8b; Me, 8c), [Ru2{μ-CN(Me)(Xy)}(μ-CO)(CO){N(H)=C(CMe3)C(H)=C(NC5H10)(Tol)}(Cp)2]+(9) and [Ru2{μ-CN(Me)(Xy)}(μCO)(CO){N(H)=C(CMe3)C(H)=C(NMe2)C(Me)=CH2)}(Cp)2]+ (10) containing the hitherto unknown new imino-2-en-3-amine ligand. The solid-state structures of these products have been analyzed by X-ray analysis and, in solution, by NOE spectroscopic studies.