High-valent iron–oxo intermediates play central roles as active oxidants in enzymatic and synthetic catalytic oxidations. In this work, the aforementioned photochemical method was investigated with various covalently modified porphyrin ligands. As controlled by the electronic nature of porphyrin ligands, iron(IV)–oxo porphyrin radical cations (Compound I models) and iron(IV)–oxo porphyrin derivatives (Compound II models) were produced, respectively, by visible light irradiation of the corresponding iron(III) bromate complexes. These observations suggest that the photochemical reactions involve a heterolytic cleavage of O–Br in precursors to give a putative iron(V)–oxo intermediate, which might relax to Compound I through electron transfer from electron rich porphyrin to the iron or undergo rapid comproportionation reaction with residual iron(III) to afford the Compound II derivative.

Ligand-controlled photochemical generation of high-valent porphyrin-iron-oxo derivatives

252nd National Meeting (2016)

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