title: Cyclometalated iridium complexes of bis(aryl) phosphine ligands: catalytic C-H/C-D exchanges and C-C coupling reactions.
abstract: This work details the synthesis and structural identification of a series of complexes of the (η(5)-C5Me5)Ir(III) unit coordinated to cyclometalated bis(aryl)phosphine ligands, PR'(Ar)2, for R' = Me and Ar = 2,4,6-Me3C6H2, 1b; 2,6-Me2-4-OMe-C6H2, 1c; 2,6-Me2-4-F-C6H2, 1d; R' = Et, Ar = 2,6-Me2C6H3, 1e. Both chloride- and hydride-containing compounds, 2b-2e and 3b-3e, respectively, are described. Reactions of chlorides 2 with NaBArF (BArF = B(3,5-C6H3(CF3)2)4) in the presence of CO form cationic carbonyl complexes, 4(+), with ν(CO) values in the narrow interval 2030-2040 cm(-1), indicating similar π-basicity of the Ir(III) center of these complexes. In the absence of CO, NaBArF forces κ(4)-P,C,C',C″ coordination of the metalated arm (studied for the selected complexes 5b, 5d, and 5e), a binding mode so far encountered only when the phosphine contains two benzylic groups. A base-catalyzed intramolecular, dehydrogenative, C-C coupling reaction converts the κ(4) species 5d and 5e into the corresponding hydrido phosphepine complexes 6d and 6e. Using CD3OD as the source of deuterium, the chlorides 2 undergo deuteration of their 11 benzylic positions whereas hydrides 3 experience only D incorporation into the Ir-H and Ir-CH2 sites. Mechanistic schemes that explain this diversity have come to light thanks to experimental and theoretical DFT studies that are also reported.
authors.affiliation: Departamento de Química Inorgánica, Instituto de Investigaciones Químicas, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas, Avda. Américo Vespucio 49, 41092, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Campos
authors.forename: María F
authors.initials: MF
authors.lastname: Espada
authors.forename: Joaquín
authors.initials: J
authors.lastname: López-Serrano
authors.forename: Ernesto
authors.initials: E
authors.lastname: Carmona
mesh_terms: D002384:Catalysis; D003500:Cyclization; D007495:Iridium / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry*
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D010720:Phosphines; D007495:Iridium