Terbium Triangle Bridged by a Triazole Nitronyl Nitroxide Radical with Single-Molecule-Magnet Behavior.

An unprecedented cyclic TbIII-radical cluster, [Tb3(hfac)6(4-Me-3-NITtrz)2(OH)3] (1), has been self-assembled from Tb(hfac)3·2H2O and 4-Me-3-NITtrz in the presence of Cu(hfac)2·2H2O. Alternating-current magnetic studies show that the Tb3 cluster displays a dual slow relaxation of magnetization behavior under a zero direct-current (dc) field and a single relaxation process under an induced dc field with an effective energy barrier of 14 K, representing the first triangle 2p-4f cluster with a slow magnetic relaxation property.