Trinuclear Pd3O2 Intermediate in Aerobic Oxidation Catalysis

The activation of O2 is a key step in selective catalytic aerobic oxidation reactions mediated by transition metals. The bridging trinuclear palladium species, [(LPdII)3(μ3‐O)2]2+ (L=2,9‐dimethylphenanthroline), was identified during the [LPd(OAc)]2(OTf)2‐catalyzed aerobic oxidation of 1,2‐propanediol. Independent synthesis, structural characterization, and catalytic studies of the trinuclear compound show that it is a product of oxygen activation by reduced palladium species and is a competent intermediate in the catalytic aerobic oxidation of alcohols. The formation and catalytic activity of the trinuclear Pd3O2 species illuminates a multinuclear pathway for aerobic oxidation reactions catalyzed by Pd complexes. Catalytic ménage à trois: A catalytically active trinuclear Pd3O2 complex was identified during Pd‐mediated aerobic oxidation of alcohols. Synthesis, structural characterization, and catalytic studies of the trinuclear compound show that it is a product of oxygen activation by reduced palladium species and is a competent intermediate in the catalytic aerobic oxidation of alcohols. These results illuminate a new pathway for O2 reduction by Pd complexes.