Carbon-13 Hyperfine Constants, g Factors, and Electronic Structure of m-Benzosemiquinone Radical Anions

Article abstract of DOI:10.1021/j100212a024

The 13C ESR spectra of the carboxylated m-benzosemiquinone radical anions produced in aqueous solution by in situ radiolysis techniques have been observed.Carboxyl substitution does not perturb the spin distribution appreciably so that 13C hyperfine constants can be readily assigned to m-benzosemiquinone.This radical is an odd-alternant species with appreciable spin density at the 4 and 6 positions of the ring system but very little at the 2 position.The large proton and 13C hyperfine constants and relatively low g factors of these radicals show that there is very little spin density on the oxygen atoms.