The effect of various conformations of 2,2'-bipyridine with respect of the diradicals on ferromagnetic coupling was studied by using quantum chemical ab initio method. The results showed that magnetic coupling of various conformations complied with the spin polarization rule. 2,2'-Bipyridine with different radicals, ·CH2 and ·NH2^+, had the same cou;ling property. Only the strength of magnetic coupling was influenced. The result provided useful information for molecular design of organic magnetic materials.

Key words: BIPYRIDINE, MAGNETISM, COUPLING, SPIN DENSITY, AB INITIO CALCULATION, FREE RADICALS, CONFORMATION