Department of Chemistry, University of California, Berkeley, 94720, United States.
J Am Chem Soc. 2012 Nov 14;134(45):18546-9. doi: 10.1021/ja308945d. Epub 2012 Nov 5.
The synthesis and magnetic properties of three new bipyrimidyl radical-bridged dilanthanide complexes, (Cp*(2)Ln)(2)(μ-bpym(•)) (Ln = Gd, Tb, Dy), are reported. Strong Ln(III)-bpym(•-) exchange coupling is observed for all species, as indicated by the increases in χ(M)T at low temperatures. For the Gd(III)-containing complex, a fit to the data reveals antiferromagnetic coupling with J = -10 cm(-1) to give an S = (13)/(2) ground state. The Tb(III) and Dy(III) congeners show single-molecule magnet behavior with relaxation barriers of U(eff) = 44(2) and 87.8(3) cm(-1), respectively, a consequence of the large magnetic anisotropies imparted by these ions. Significantly, the latter complex exhibits a divergence of the field-cooled and zero-field-cooled dc susceptibility data at 6.5 K and magnetic hysteresis below this temperature.
报道了三种新型联吡啶基自由基桥联双镧系元素配合物(Cp*(2)Ln)(2)(μ-bpym(•))（Ln=Gd、Tb、Dy）的合成和磁性。所有物种均表现出强的 Ln(III)-bpym(•-)交换耦合，这表明在低温下χ(M)T 增加。对于含 Gd(III)的配合物，拟合数据表明存在反铁磁耦合，J=-10 cm(-1)，给出 S = (13)/(2)基态。Tb(III)和 Dy(III)同系物表现出单分子磁体行为，弛豫势 U(eff)=44(2)和 87.8(3)cm(-1)，这是这些离子赋予的大磁各向异性的结果。值得注意的是，后一种配合物在 6.5 K 以下的磁场冷却和零场冷却直流磁化率数据以及低于该温度的磁滞回线出现发散。
