Novel stable high spin molecules possessing three differently arranged fashions are designed using -·N- S- as spin-containing (SC) fragment, phenylene as end groups and various aromatic, such as benzene (1), 2,6-pyridine (2), 3,5-pyridine (3), pyridazine (4), 4,6- pyrimidine (5), 2,6-pyrimidine (6), pyrazine (7), triazine (8) as a ferromagnetic coupling (FC) unit. The effect of the different coupling units on the spin multiplicities of the ground states and their stabilities was investigated by means of AM1-CI approach. It is found that the spin densities on the two atoms of the SC are different from delocalization results in the specific stability of -·N-S-. In these molecules, the stabilities of the triplet states decrease when the distance between the atoms of central SC (-N-) increases. It is shown that nitrogen-containing aromatic rings as coupling unit influence the stabilities of high-spin ground states.

Key words: HETEROCYCLIC COMPOUNDS, FREE RADICAL, BENZENE, PYRIDINE, PYRIDAZINE, PYRIMIDINE, PYRIMIDINE, TRIPLET