A recently developed quantum mechanical approach devoted to the study of structural and magnetic properties of open-shell species was applied to the isoelectronic series formed by benzyl, anilino, and phenoxyl radicals. Hybrid Hartree-Foc/density functional models (here B3LYP) confirm their reliability, whereas, contrary to other cases, vibrational averaging and solvent effects play only a negligible role. The spin dependent properties are interpreted in terms of a new model including first and second order spin polarization effects.