Δ2- and Δ3-azaosmetine complexes as intermediates in the stoichiometric imination of phenylacetylene with oximes

Article abstract of DOI:10.1021/om010005k

Complexes [Os{(E)-CH=CHPh}Cl(=N=CR₂)(PⁱPr₃)₂] [CF₃SO₃] [CR₂ = CMe₂ (1), C(CH₂)₄CH₂ (2)] react with carbon monoxide to give the Δ²-1,2-azaosmetine derivatives [OsCl(=CHCH(Ph)N=CR₂)(CO)(PⁱPr₃)₂] [CF₃SO₃] [CR₂ = CMe₂ (3), C(CH₂)₄CH₂ (4)], as a result of the coordination of carbon monoxide to the osmium atoms of 1 and 2 and the carbon-nitrogen coupling between the styryl and azavinylidene ligands. The structure of 3 in the solid state has been determined by an X-ray diffraction study. Complexes 3 and 4 can be deprotonated with MeLi to give the Δ³-1,2-azaosmetine compounds Os{CH=C(Ph) N=CR₂}Cl(CO) (PⁱPr₃)₂ [CR₂ = CMe₂(5), C(CH₂)₄ CH₂ (6)], which react with molecular hydrogen to afford the 2-aza-1,3-butadienes CH₂=C(Ph)N=CR₂[CR₂ =CMe₂ (7), C(CH₂)₄CH₂ (8)] and OsH₂(η²-H₂)(CO)(PⁱPr₃ )₂. The carbonylation of the cations of 3 and 4 leads to [Os{(Z)-CH=C(Ph)NH=CR₂}Cl(CO)₂(PⁱPr₃ )₂]⁺ [CR₂ = CMe₂ (9), C(CH₂)₄CH₂ (10)]. The [BF₄]^- salts of 9 and 10 have been obtained by carbonylation of 5 and 6 and subsequent protonation of the resulting η¹-azabutadiene intermediates Os{(Z)-CH=C(Ph)N=CR₂}Cl(CO)₂(Pⁱ Pr₃)₂ [CR₂ = CMe₂ (11), C(CH₂)₄CH₂ (12)]. The structure of the [BF₄]^- salt of 10 in the solid state has also been determined by an X-ray diffraction study.