Synthesis and Magnetism of Neutral, Linear Metallocene Complexes of Terbium(II) and Dysprosium(II)
Synthesis and Magnetism of Neutral, Linear Metallocene Complexes of Terbium(II) and Dysprosium(II)
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DOI：
10.1021/jacs.9b05816
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发表时间：
2019-08-21
影响因子：
15
通讯作者：
Long, Jeffrey R.
中科院分区：
文献类型：
--
作者：
Gould, Colin A.;McClain, K. Randall;Long, Jeffrey R.
二价茂金属配合物Ln-(Cp-iPr5)(2) （Ln = Tb, Dy）是通过KC8还原Ln(Cp-iPr5)(2)I中间体合成的，是这些元素的第一个中性线性茂金属配合物。x射线衍射分析、密度泛函理论计算和磁化率测量表明，4f(n)5d(1)电子构型具有强s/d混合，支持线性配位几何。对比两种二价金属二烯相对于三价金属二烯的盐[Ln-(Cp-iPr5)(2)] [B(C6F5)(4)]的磁弛豫行为，发现镧系还原对镝和铽具有相反的作用，磁弛豫时间从Tb-III增加到Tb-II，从Dy-III减少到Dy-II。这种效应对Tb(Cp-iPr5)(2)的影响最为明显，它对磁弛豫表现出1205 cm（-1）的有效热障和52 K的100 s阻挡温度，这是迄今为止观察到的任何非镝单分子磁体的最高温度。
The divalent metallocene complexes Ln-(Cp-iPr5)(2) (Ln = Tb, Dy) were synthesized through the KC8 reduction of Ln(Cp-iPr5)(2)I intermediates and represent the first examples of neutral, linear metallocenes for these elements. X-ray diffraction analysis, density functional theory calculations, and magnetic susceptibility measurements indicate a 4f(n)5d(1) electron configuration with strong s/d mixing that supports the linear coordination geometry. A comparison of the magnetic relaxation behavior of the two divalent metallocenes relative to salts of their trivalent counterparts, [Ln-(Cp-iPr5)(2)] [B(C6F5)(4)] reveals that lanthanide reduction has opposing effects for dysprosium and terbium, with magnetic relaxation times increasing from Tb-III to Tb-II and decreasing from Dy-III to Dy-II. The impact of this effect is most notably evident for Tb(Cp-iPr5)(2), which displays an effective thermal barrier to magnetic relaxation of 1205 cm(-1) and a 100-s blocking temperature of 52 K, the highest values yet observed for any nondysprosium single-molecule magnet.