Exchange Coupling and Magnetic Blocking in Bipyrimidyl Radical-Bridged Dilanthanide Complexes
Exchange Coupling and Magnetic Blocking in Bipyrimidyl Radical-Bridged Dilanthanide Complexes
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DOI：
10.1021/ja308945d
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发表时间：
2012-11-14
影响因子：
15
通讯作者：
Long, Jeffrey R.
中科院分区：
文献类型：
--
作者：
Demir, Selvan;Zadrozny, Joseph M.;Long, Jeffrey R.
报道了三个新的双嘧啶基桥联稀土配合物[（Cp ~*（2）Ln）（2）（mu-bpym（中心点））]（+）（Ln = Gd，Tb，Dy）的合成和磁性。强烈的Ln（III）-bpym（中心点）交换耦合观察到所有物种，在低温下的chi T-M的增加所示。对于含（GdI）-I-II的配合物，数据拟合显示反铁磁耦合，J = -10 cm（-1），得到S = 13/2基态。Tb-III和Dy-III同系物表现出单分子磁体行为，弛豫势垒分别为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，后者复杂的表现出发散的场冷却和零场冷却直流磁化率数据在6.5 K和磁滞低于这个温度。
The synthesis and magnetic properties of three new bipyrimidyl radical bridged dilanthanide complexes, [(Cp*(2)Ln)(2)(mu-bpym(center dot))](+) (Ln = Gd, Tb, Dy), are reported. Strong Ln(III)-bpym(center dot-) exchange coupling is observed for all species, as indicated by the increases in chi T-M at low temperatures. For the (GdI)-I-II-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.