Oxygen-Promoted C-H Bond Activation at Palladium

[Pd(P(Ar)(tBu)(2))(2)] (1, Ar = naphthyl) reacts with molecular oxygen to form Pd-II hydroxide dimers in which the naphthyl ring is cyclometalated and one equivalent of phosphine per palladium atom is released. This reaction involves the cleavage of both C-H and O-O bonds, two transformations central to catalytic aerobic oxidizations of hydrocarbons. Observations at low temperature suggest the initial formation of a superoxo complex, which then generates a peroxo complex prior to the C-H activation step. A transition state for energetically viable C-H activation across a Pd-peroxo bond was located computationally.