Structures And Properties Of Mononuclear Multi-Spin Rare Earth-Nitroxide Radicals Complexes

The design and synthesis of rare earth complexes with radical is one of the most attractive fields in the molecular-based magnetic materials. In order to investigate the correlation between the structure and magnetic properties, thirteen novel complexes have been synthesized. All their single crystals have been determined by X-ray diffraction technique. They have been characterized by element analyses, IR, TG and variable- temperature magnetic susceptibility. Some magnetic parameters have been evaluated from magnetic measurements and theoretical methods.The structures of thirteen mononuclear RE(â…¢)-radical complexes [RE(hfac)₃(NITR)₂] are similar. The RE(â…¢) ion is eight-coordinated with six oxygen atoms of three hfac anions and two oxygen atoms from two radicals NITR. The thermal decomposition processes of these complexes are similar.Magnetic studies show that the spin coupling between the Tb(â…¢) ion and the NITPhSMe ligand is ferromagnetic in complex 6. The frequency dependence of the ac susceptibility justifies that complexes Tb(hfac)₃(NITPhOA)₂ (11), Dy(hfac)₃(NITPhOA)₂(12) exhibits some SMM behavior.Many coordination compounds made of rare earth and nitronyl nitroxide radicals have been studied. Their magneto-structural correlations have been explored and the possible magnetic exchange mechanisms are explained. The thermal properties are also discussed.