Aerobic oxidation that incorporates both 0 atoms into a substrate (PPh3) is achieved by employing a Cr-III/Cr-V O catalytic couple. A terphenyl trianionic pincer ligand stabilizes a high oxidation state Cr-V O complex, and both the reduced (Cr-III, IR/X-ray) and oxidized (Cr-V O, electron paramagnetic resonance/IR/X-ray) participants in the catalytic cycle are characterized.