Insertion of Molecular Oxygen into a Palladium(II) Hydride Bond

Insertion of molecular oxygen into a palladium(II) hydride bond to form an (η-hydroperoxo)palladium(II) complex is reported. The hydroperoxo palladium(II) product has been crystallographically characterized. A second-order rate law (first-order in palladium and first-order in oxygen) is observed for the reaction and a large kinetic isotope effect implicates Pd−H bond cleavage in the rate-determining step. The results of studies with radical inhibitors and light suggest that the reaction does not proceed by a radical chain mechanism.