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Δ2- and Δ3-Azaosmetine Complexes as Intermediates in the Stoichiometric Imination of Phenylacetylene with Oximes

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journal contribution
posted on 04.05.2001, 00:00 by Ricardo Castarlenas, Miguel A. Esteruelas, Enrique Oñate
Complexes [Os{(E)-CHCHPh}Cl(NCR2)(PiPr3)2][CF3SO3] [CR2 = CMe2 (1), (2)] react with carbon monoxide to give the Δ2-1,2-azaosmetine derivatives [CR2 = CMe2 (3), (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 [CR2 = CMe2 (5), (6)], which react with molecular hydrogen to afford the 2-aza-1,3-butadienes CH2C(Ph)NCR2 [CR2 = CMe2 (7), (8)] and OsH22-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), (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(PiPr3)2 [CR2 = CMe2 (11), (12)]. The structure of the [BF4]- salt of 10 in the solid state has also been determined by an X-ray diffraction study.