A Highly Oxidized Cobalt Porphyrin Dimer: Spin Coupling and Stabilization of the Four-Electron Oxidation Product

A highly oxidized cobalt porphyrin dimer is reported. Each cobalt(II) ion and porphyrin ring underwent 1e oxidation with iodine as the oxidant to give a 4e-oxidized cobalt(III) porphyrin -cation radical dimer. The bridging ethylene group allows for substantial conjugation of the porphyrin macrocycles, thus leading to a strong antiferromagnetic coupling between the -cation radicals and to stabilization of the singlet state. X-ray crystallography clearly showed that the complex may be considered as a real supramolecule rather than two cobalt(III) porphyrin -cation radicals that interact through space.