Formation of Iron(III) <i>meso</i>-Chloro-isoporphyrin as a Reactive Chlorinating Agent from Oxoiron(IV) Porphyrin π-Cation Radical

Abstract

Iron­(III) isoporphyrin, a tautomer of porphyrin with a saturated <i>meso</i> carbon, is one of the isoelectronic forms of oxoiron­(IV) porphyrin π-cation radical, which is known as an important reactive intermediate of various heme enzymes. The isoporphyrin has been believed to be incapable of catalyzing oxygenation and oxidation reactions. Here, we report that an oxoiron­(IV) porphyrin π-cation radical can be converted to iron­(III) <i>meso</i>-chloro-isoporphyrin in the presence of trifluoroacetic acid and chloride ion. More importantly, this study shows the first evidence that iron­(III) <i>meso</i>-chloro-isoporphyrin is an excellent reactive agent for chlorinating aromatic compounds and olefins. The results of this study suggest that the mechanism involves electrophilic chlorination of substrate with iron­(III) <i>meso</i>-chloro-isoporphyrin