Intermolecular C–HBond Activation of Alkanesand Arenes by NCN Pincer Iridium(III) Acetate Complexes ContainingBis(oxazolinyl)phenyl Ligands.

Carbon–hydrogen bond activation of arenes by thepincerIr(III) acetate complex (phebox)Ir(OAc)2(H2O)(1; phebox = bis(oxazolinyl)phenyl) proceeded at 100°C to give the corresponding aryl Ir(III) complexes (phebox)Ir(Ar)(OAc)in high yields. Reactions of the monosubstituted arenes anisole, toluene,chlorobenzene, acetophenone, and nitrobenzene resulted in the formationof meta- and para-substituted aryl complexes in high yields. Competitiveexperiments between two monosubstituted arenes exhibited relativereaction rates in the order C6H5OMe > C6H5NO2> C6H5COMe> C6H5Cl > C6H5Me.Thekinetic isotope effects of C–H bond activation of benzene andnitrobenzene were determined to be 2.9 ± 0.1 and 2.0 ± 0.4,respectively. The Ir complex 1underwent catalytic borylationof arenes with bis(pinacolato)diboron (B2(pin)2) or pinacolborane (HB(pin)), giving the corresponding borylatedproducts. The Ir complex 1was also reactive toward alkaneC–H bond activation, demonstrated by the reactions with n-heptane and n-octane at 160 °C thatcleanly afforded the corresponding alkyl complexes (phebox)Ir(n-CnH2n)(OAc) (n= 7, 8, respectively). [ABSTRACT FROM AUTHOR]