title: Cationic Ir(III) alkylidenes are key intermediates in C-H bond activation and C-C bond-forming reactions.
abstract: This work describes the chemical reactivity of a cationic (η(5)-C(5)Me(5))Ir(III) complex that contains a bis(aryl) phosphine ligand, whose metalation determines its unusual coordination in a κ(4)-P,C,C',C" fashion. The complex (1(+) in this paper) undergoes very facile intramolecular C-H bond activation of all benzylic sites, in all likelihood through an Ir(V) hydride intermediate. But most importantly, it transforms into a hydride phosphepine species 4(+) by means of an also facile, base-catalyzed, intramolecular dehydrogenative C-C coupling reaction. Mechanistic studies demonstrate the participation as a key intermediate of an electrophilic cationic Ir(III) alkylidene, which has been characterized by low-temperature NMR spectroscopy and by isolation of its trimethylphosphonium ylide. DFT calculations provide theoretical support for these results.
authors.affiliation: Departamento de Química Inorgánica, Instituto de Investigaciones Químicas, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas, Avda. Américo Vespucio 49, 41092 Sevilla, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Campos
authors.forename: Joaquín
authors.initials: J
authors.lastname: López Serrano
authors.forename: Eleuterio
authors.initials: E
authors.lastname: Álvarez
authors.forename: Ernesto
authors.initials: E
authors.lastname: Carmona