Oxidative Coupling of an Enaminoporphyrin: C−C, N−N Linkages or Both?

A symmetrical bis-nickelporphyrin was prepared in very good yield by oxidative coupling of a nickel(II) enaminoporphyrin. This dimer was obtained by the intermolecular reaction of the starting enamine (acting as nucleophile) with the porphyrin radical cation (acting as electrophile) generated in situ. Alternatively, by using different reaction conditions, an N-N linked porphyrin dimer was obtained in moderate yield. The monomeric extended porphyrin leading to the N-N linked dimer was obtained by the intramolecular reaction of the same radical cation with the neighbouring meso-aryl group (acting as nucleophile).