C−C Formation and C−O Cleavage Reactions on Hemilabile Arene−Phosphine Ligands in Route to η5-Cyclohexadienyl Iridium Compounds

Abstract

9 páginas, 3 figuras, 1 tabla, 6 esquemas.Complexes of the type [Ir{η5-3-(CH3COCH2)C6H5OCH2CH2Pt-Bu2-k-P}(alkene)] (alkene = C2H4, 4, C3H6, 5) were prepared by nucleophilic addition of acetone enolate to the “ansa” π-arene/phosphine-type compounds [Ir(alkene)(η6-C6H5OCH2CH2Pt-Bu2-k-P)][BF4] (alkene = C2H4, 1, C3H6, 2) where the arene−phosphine is acting as a formal eight-electron-donor chelate ligand. On the other hand, the related [Ir{η5-3-(C6H5C C)C6H5OCH2CH2Pt-Bu2-k-P}(C2H4)] complex (6) was obtained by addition of phenylacetylide to compound 1, but the reaction was not fully completed. Compounds 4 and 5 react with methanol with a C−O bond cleavage process, producing the vinylphosphine complexes [Ir(η5-C6H5O)(alkene)(t-Bu2PCHCH2)] (alkene = C2H4, 7, C3H6, 8). Compounds 7 and 8 are also obtained by treatment of 1 and 2, respectively, with a basic solution in methanol. The vinyl group in 7 adds methanol to render an ether phosphine, which coordinates in a chelate form, and the final compound isolated was [Ir(OC6H5)(C2H4)(t-Bu2PCH2CH2OMe-k2-O,P)] (9). In addition, the molecular structures of complexes 4 and 7 have been determined by X-ray diffraction methods.The financial support from Ministerio de Educación y Ciencia (MEC/FEDER) (Project CTQ2006- 03973/BQU) and CONACYT-México for a postdoctoral fellowship to I.I.R. are gratefully acknowledged.Peer reviewe