Using triazine as coupling unit for intra and intermolecular ferromagnetic coupling .1.

Novel high spin bi- and triradicals composed of triazine coupling units and different kinds of radical centers ((NH2)-N-+., (NH)-N-., (CH2)-C-., HNO., :N, :C), are predicted from AM1-CI calculations. It is found that when (NH)-N-+., and N-. serve as spin centers, the high spin ground states of bi- and triradicals with triazine coupling units are more stable than those with phenylene and benzenetriyl ones, respectively. For a biradical with triazine coupling unit and (NH)-N-+. spin center, intermolecular hydrogen bonds can be formed between this biradical and a diamagnetic cyanuric acid or between two biradicals themselves as well, which may be considered as the basic units of supramolecular aggregates. For these two cases, it is shown that intermolecular hydrogen bonds between high spin molecules and diamagnetic molecules reduce the stability of high spin ground state, but the intermolecular ferromagnetic coupling of biradical dimer can be transferred although weakly through hydrogen bonds.