Proton,13C and33S coupling constants in the electron resonance spectrum of the 2,4,6-triphenylthiapyryl radical

The E.S.R. spectrum of the 2,4,6-triphenylthiapyryl radical is interpreted by investigating deutero and 33S-enriched derivatives. In some spectra of the latter, several 13C as well as 33S satellite lines were detected and their coupling constants determined. The spin density distribution was calculated by using standard p and d-orbital models. Satisfactory results are obtained if the phenyl groups are assumed to be twisted from the heterocyclic plane.