HIGH-SPIN CATION RADICALS OF METHYLENEPHOSPHORANES

Novel di(cation radical)s and tri(cation radical)s are prepared by oxi dation of the corresponding 4-tert-butylphenyl)methylene]triphenylphos phorane] and -tert-butylphenyl)-methylene]triphenylphosphorane] precur sors. The oligo(cation radical)s are investigated in frozen solutions using ESR spectroscopy. The di(cation radical) has a triplet state as evidenced from a Delta M-s = +/-2 ESR transition exhibiting hyperfine coupling to two identical phosphorus nuclei and is characterized by ze ro-field splitting parameters D = 350 MHz and E = 0 MHz. The correspon ding tri(cation radical) possesses a quartet state with D = 262 MHz an d E = 0 MHz and exhibits a Delta M-s = +/-3 transition. Temperature de pendent studies (4-100 K) reveal that the ESR intensities follow Curie 's law, consistent with high-spin ground states. The stability of thes e oligo(cation radical)s is assessed via cyclic voltammetry at room te mperature in THF solution.