Ab initio MO study of m-phenylenediamine and 2,4-diamino-1,3,5-triazine dication diradicals

Ab initio MO calculations of m-phenylenediamine (1) and 2,4-diamino-1,3,5-triazine (2) dication diradicals, which are the model molecules of two possible high-spin polymers (poly(m-aniline) and poly(imino-1,3,5-triazinediyl) cation radicals), have been carried out with the 6–31G* basis set at the ROHF, GVB and CASSCF levels. In accordance with qualitative MO considerations, the electronic structures of 12+ and 22+ were quite different from each other. In the planar C2V geometry, the singlet-triplet splittings (ΔES-T) of 12+ and 22+ were calculated to be 0.7 and 12.5 kcal/mol, respectively, at the CASPT2 level. m-1,3,5-triazinediyl is another effective ferromagnetic coupler for the aza-substituted systems.