Abstract: Five new complexes of binuclear rare earth(Nd, Gd, Dy, Ho, Er)pentafluoropropionate with μ-2-(4'-chlorobenzoyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide were synthesized and characterized.According to hypersensitive transitions of the complexes (Nd(Ⅲ), Dy(Ⅲ), Ho(Ⅲ), Er(Ⅲ)), it was discussed that for the same ligand the covalency decreases as the atomic number of the rare earth metal atom increases, The observed variable-temperature(4～300 K)susceptibility data for Gd(Ⅲ)complex were fitted to those from theoretical magnetic equation by least-square method.The exchange integral, J, was found to be positive, indicating a weak ferromagnetic spin-exchange interaction between the radical and Gd(Ⅲ)ion.

Key words: Stable radical, Binuclear rare earth complexes, Magnetlsm