Functionalization of Corroles: The Nitration Reaction

The reaction of meso-triarylcorroles with AgNO2 proceeds with concomitant metalation and peripheral substitution
to give the corresponding nitro-substituted silver(III) corrole complex. The substitution is highly regioselective, giving
only the corresponding 3-nitro derivative, among the different possible isomers. The results obtained indicate that
the reaction intermediate is the π-cation radical of the complex, which is then attacked by nitrite ion. This was
proven by the reaction of the copper corrole complexes with NaNO2:  in this case, the nitration reaction proceeded
without the addition of an oxidant, because of the π-cation radical character of the copper complex. The reaction
is also successful in the case of 2,3,17,18-tetraethyl-8,12-diacetoxymethyl-7,13-dimethylcorrole (AMCorH3), with
the formation of the meso-substituted silver corrole derivative (NO2)3AMCorAg (fully characterized by X-ray
crystallography), the first of its kind to be reported. Two of the corroles are characterized by cyclic voltammetry and
spectroelectrochemistry in dichloromethane, and the site of electron transfer is elucidated.