147713-21-1Relevant articles and documents
Cyclometalated iridium complexes of bis(aryl) phosphine ligands: Catalytic C-H/C-D exchanges and C-C coupling reactions
Campos, Jesus,Espada, Maria F.,Lopez-Serrano, Joaquin,Carmona, Ernesto
, p. 6694 - 6704 (2013/07/19)
This work details the synthesis and structural identification of a series of complexes of the (η5-C5Me5)Ir(III) unit coordinated to cyclometalated bis(aryl)phosphine ligands, PR′(Ar) 2, for R′ = Me and Ar = 2,4,6-Me3C6H 2, 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-C 6H3(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 κ4-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 κ4 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-CH 2 sites. Mechanistic schemes that explain this diversity have come to light thanks to experimental and theoretical DFT studies that are also reported.
