THEORETICAL DESIGN OF A HIGH-SPIN ORGANIC-MOLECULE

Quantum chemistry calculations may rationalise the search for pure org anic ferromagnets. Neutral molecules based on two rings coupled throug h a central C-C bond were tested. The triplet ground state is evidence d by a positive singlet-triplet splitting, which ranges between 0.2 an d 2 eV. Using dimer geometries found in organic radicals as a model fo r the intermolecular interactions, it was found that a triplet or a qu intet ground state is stable against the low-spin state of the dimer. Consequently, this series of molecules, were its synthesis possible, a ppears to be attractive for building new organic ferromagnets. (C) 199 8 Elsevier Science B.V.