Light-Driven, Proton-Controlled, Catalytic Aerobic C–H Oxidation Mediated by a Mn(III) Porphyrinoid Complex

The visible light-driven,
catalytic aerobic oxidation of benzylic
C–H bonds was mediated by a MnIII corrolazine complex.
To achieve catalytic turnovers, a strict selective requirement for
the addition of protons was established. The resting state of the
catalyst was unambiguously characterized by X-ray diffraction as [MnIII(H2O)­(TBP8Cz­(H))]+, in
which a single, remote site on the ligand is protonated. If two remote
sites are protonated, however, reactivity with O2 is shut
down. Spectroscopic methods revealed that the related MnV(O) complex is also protonated at the same remote site at −60
°C, but undergoes valence tautomerization upon warming.