Catalytic Aerobic Oxidation by a Trianionic Pincer CrIII/CrV Couple

Aerobic oxidation that incorporates both O atoms into a substrate (PPh3) is achieved by employing a CrIII/CrV≡O catalytic couple. A terphenyl trianionic pincer ligand stabilizes a high oxidation state CrV≡O complex, and both the reduced (CrIII, IR/X-ray) and oxidized (CrV≡O, electron paramagnetic resonance/IR/X-ray) participants in the catalytic cycle are characterized.