Using triazine as coupling unit for intramolecular ferromagnetic coupling of multiradicals

Novel high spin tri-, tetra-, pentaradicals, composed of triazine coupling units and cationic amino radical spin centers (+ . NH) under various config urations and linkages, are predicted from AM1-CI calculations. It is found that for charged planar multiradicals the stability of high spin ground sta tes depends on both the molecular configuration and the number of end group s. Generally, cyclic 1,3-bridged charged multiradicals (S less than or equa l to 5/2) possess more stable high spin ground states than their isomers un der the branched 1,3,5,-bridged configuration. Therefore, it is suggested t hat in the design of planar high spin molecules with stable high spin groun d states, less end groups and all the supposed spin centers and/or the coup ling units should be under the same structural situation. (C) 1999 Elsevier Science B.V. All rights reserved.