Metallocorroles with Formally Tetravalent Iron

The unusual oxidation state + IV for iron centers can be stabilized by porphyrin-like corrole ligands in such a way that the compounds 1 (R  Cl, Ph, OFe-corrole) can be isolated at room temperature. The oxygen-bridged binuclear iron(IV) corrole, which can be readily converted into the mononuclear iron(IV) corrole, forms as the only defined product from the reaction of the ligand with [Fe2(CO)9] followed by workup in air. In contrast, only a few iron(IV) porphyrins are known so far, and these are too unstable to be isolated as solids.