Halobenzenes and Ir(I): Kinetic C−H Oxidative Addition and Thermodynamic C−Hal Oxidative Addition

A (PNP)Ir fragment undergoes facile, room-temperature oxidative addition of C−H bonds in arenes and haloarenes in preference to aromatic carbon−halogen bonds. This preference, however, is determined to be kinetic in nature. Oxidative addition of C−Cl and C−Br is preferred thermodynamically. The products of the C−Cl or C−Br oxidative addition are separated from the C−H oxidative addition products by a high activation barrier and are only accessible at >100 °C. Of the C−H oxidative addition products of chlorobenzene, the isomer with the o-ClC6H4 ligand has the lowest energy.