Insertion of molecular oxygen into a palladium(II) methyl bond: a radical chain mechanism involving palladium(III) intermediates.

The reaction of (bipy)PdMe(2) (1) (bipy = 2,2'-bipyridine) with molecular oxygen results in the formation of the palladium(II) methylperoxide complex (bipy)PdMe(OOMe) (2). The identity of the product 2 has been confirmed by independent synthesis. Results of kinetic studies of this unprecedented oxygen insertion reaction into a palladium alkyl bond support the involvement of a radical chain mechanism.

Investigations of iridium-mediated reversible C-H bond cleavage: characterization of a 16-electron iridium(III) methyl hydride complex.

New iridium complexes of a tridentate pincer ligand, 2,6-bis(di-tert-butylphosphinito)pyridine (PONOP), have been prepared and used in the study of hydrocarbon C-H bond activation. Intermolecular oxidative addition of a benzene C-H bond was directly observed with [(PONOP)Ir(I)(cyclooctene)][PF(6)] at ambient temperature, resulting in a cationic five-coordinate iridium(III) phenyl hydride product. Protonation of the (PONOP)Ir(I) methyl complex yielded the corresponding iridium(III) methyl hydride cation, a rare five-coordinate, 16-valence electron transition metal alkyl hydride species which was characterized by X-ray diffraction.