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  • Base-Promoted, Remote C–H A...
    Moreno, Juan J; Espada, María F; Campos, Jesús; López-Serrano, Joaquín; Macgregor, Stuart A; Carmona, Ernesto

    Journal of the American Chemical Society, 02/2019, Letnik: 141, Številka: 6
    Journal Article

    C–H bond activation at cationic (η5-C5Me5)­Ir­(PMe2Ar′) centers is described, where PMe2Ar′ are the terphenyl phosphine ligands PMe2ArXyl 2 and PMe2ArDipp 2. Different pathways are defined for the conversion of the five-coordinate complexes (η5-C5Me5)­IrCl­(PMe2Ar′)+, 2­(Xyl)+ and 2­(Dipp)+ , into the corresponding pseudoallyls 3­(Xyl)+ and 3­(Dipp)+ . In the absence of an external Brønsted base, electrophilic, remote ζ C–H activation takes place, for which the participation of dicationic species, (η5-C5Me5)­Ir­(PMe2Ar′)2+, is proposed. When NEt3 is present, the PMe2ArDipp 2 system is shown to proceed via 4­(Dipp)+ as an intermediate en route to the thermodynamic, isomeric product 3­(Dipp)+ . This complex interconversion involves a non-innocent C5Me5 ligand, which participates in C–H and C–C bond formation and cleavage. Remarkably, the conversion of 4­(Dipp)+ to 3­(Dipp)+ also proceeds in the solid state.