A N23- Radical-Bridged Terbium Complex Exhibiting Magnetic Hysteresis at 14 K

The synthesis and magnetic properties of three new N-2(3-) radical-bridged dilanthanide complexes, {[(Me3SO2N](2)(THF)Ln}(2)(mu-eta(2):eta(2)-N-2)(-) (Ln = Tb, Ho, Er), are reported. All three display signatures of single-molecule-magnet behavior, with the terbium congener exhibiting magnetic hysteresis at 14 K and a 100 s blocking temperature of 13.9 K. The results show how synergizing the strong magnetic anisotropy of terbium(III) with the effective exchange-coupling ability of the N-2(3-) radical can create the hardest molecular magnet discovered to date. Through comparisons with non-radical-bridged ac magnetic susceptibility measurements, we show that the magnetic exchange coupling hinders zero-field fast relaxation pathways, forcing thermally activated relaxation behavior over a much broader temperature range.