Coordination enhancement of single-molecule magnet behavior of Tb(III)-Cu(II) dinuclear systems

Tb(III)-Cu(II) based single-molecule magnets (SMMs) were synthesized to investigate the relationship between magnetic anisotropy and the symmetry of the ligand field, by the reaction of [TbCu(o-vanilate)(2)(NO(3))(3)] with 2,2-dimethyl-1,3-propanediamine (3), followed by the reaction of one another equivalent of o-vaniline (4). Both complexes behave as SMM in the temperature range of 2.8-4.0 K (3) and 2.8-5.2 K (4), showing semi-circle shapes of Cole-Cole plots with alpha parameters in the ranges of 0.27-0.41 and 0.11-0.32. The energy barriers Delta/k(B) for the spin flippings were estimated from the Arrhenius plots to be 29(2) K for 3 and 32.2(6) K for 4, respectively. (C) 2009 Elsevier Ltd. All rights reserved.