MO studies on the33S hyperfine splittings andg-factors of dithiin cation radicals

Abstract

The spin distribution and g-factors have been calculated for a number of dithiin cation radicals. The s-spin densities on sulphur calculated by the open-shell unrestricted INDO method both with and without annihilation of the quartet component have been correlated satisfactorily with the observed 33S hyperfine splittings. The g-factors calculated according to the Stone theory by an open-shell restricted version of the INDO method are found in good agreement with observation; their deviation from the free-spin comes from the large spin density localized on the sulphur atoms and the small excitation energy from the ‘NB’ sulphur orbitals to the odd MO. Comparative calculations with the sp and spd basis sets demonstrate the modest effect of the 3d(S) orbitals on the considered physical constants of the dithiin cations.