Phenoxaselenin cation-radicals

Phenoxaselenin is oxidized in acetonitrile at a platinum anode to give a cation-radical. However, this radical gave a broad, featureless ESR spectrum from which only a Se hyperfine splitting of 39.5 G could be measured. The radical dimerizes to a diamagnetic product, a process which has been studied in acetonitrile and in concentrated sulfuric acid, The radical is also susceptible to nucleophilic attack at Se by water in these solvents. Galasso s study of -factors in group VI heterocyclic radicals included phenoxaselenin cation-radical. ... 

Dimerization of heterocyclic cation radicals was discovered in recent times. The well known thianthrene cation radical perchlorate forms a dimer in propionitrile solution. This association is, in fact, tetrameric (de Sorgo et al., 1972) that is, the anions are included in the aggregrate (Th +C104)2. Phenoxaselenine cation radical has also been found to form an (M +)2 dimer in sulfuric acid and nitro-methane solutions (Cauquis and Maurey-Mey, 1973). It is not surprising that the very stable metalloporphyrin cation radicals should dimerize, but this was demonstrated only recently with zinc (Fuhrhop et al., 1972), and magnesium (Fajer et al., 1970) octaethyl-porphyrin (MOEP). 

---