C−H Oxidative Addition to a (PNP)Ir Center and Ligand-Induced Reversal of Benzyl/Aryl Selectivity

The (PNP)Ir fragment displays a thermodynamic preference for the oxidative addition of aromatic vs benzylic C−H bonds. However, in the case of the mesitylene activation products, the benzylic isomer is kinetically accessible and can be trapped by an external donor ligand. The preference for the benzylic isomer in the six-coordinate Ir(III) adduct of mesitylene activation is ascribed to steric factors.