Ferromagnetic Interaction between Aminium Radical Centers through m-Phenylene and m-1,3,5-Triazinediyl

Ab initio MO study (at the ROHF, GVB, and CASSCF levels) of m-phenylenediamine (1) and 2,4-diamino-1,3,5-triazine (2) dication diradicals, which are model molecules of two possible high-spin polymers, poly(m-aniline) and poly(imino-1,3,5-triazinediyl) cation radicals, is presented. On the basis of qualitative MO considerations, it was seen that the electronic structures of 1(2+) and 2(2+) differed considerably. The singlet-triplet splittings (DeltaE(S)(-)(T)) of 1(2+) and 2(2+) were calculated to be 0.7 and 12.5 kcal/mol, respectively, at the CASPT2 level. m-1,3,5-Triazinediyl is shown to be a strong ferromagnetic coupler for aza-substituted systems.