<b>A six-legged piano stool dysprosium single-molecule magnet</b>
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Dysprosium single-molecule magnets (SMMs) with two mutually <i>trans</i>- anionic ligands have shown large crystal field (CF) splitting, giving record effective energy barriers to magnetic reversal (<i>U</i><sub>eff</sub>) and hysteresis temperatures (<i>T</i><sub>H</sub>). However, these complexes tend to be bent, imposing a transverse field that reduces the purity of the <i>m</i><sub><em>J</em></sub> projections of the CF states and promotes magnetic relaxation; a complex with only one anionic ligand could have more pure CF states, and thus high <i>U</i><sub>eff</sub> and <i>T</i><sub>H</sub>. Here we report the first example of an SMM with this topology, [Dy(C<sub>5</sub>Me<sub>5</sub>)(FPh)<sub>6</sub>][{Al[OC(CF<sub>3</sub>)<sub>3</sub>]<sub>3</sub>}<sub>2</sub>(<i>µ</i>-F)]<sub>2</sub> (<b>1-Dy</b>), which exhibits <i>U</i><sub>eff</sub> = 812(47) K and <i>T</i><sub>H</sub> = 14 K at sweep rates of 22 Oe<i> </i>s<sup>–1</sup>; the C<sub>5</sub>Me<sub>5</sub> ligand imposes a strong axial CF and the five equatorially-bound neutral fluorobenzenes present only weak transverse interactions. We show that complexes such as <b>1-Dy</b> can be useful starting materials for heteroleptic Ln complexes as the fluorobenzenes are easily displaced.
带有两个相互反式（trans）阴离子配体的镝单分子磁体（single-molecule magnets, SMMs）已展现出显著的晶体场（crystal field, CF）分裂，创下了磁反转有效能垒（U<sub>eff</sub>）与磁滞温度（T<sub>H</sub>）的纪录值。然而这类配合物往往易于发生弯折，产生横向磁场，降低晶体场态的*m*<sub>*J*</sub>投影纯度，并加剧磁弛豫；仅含一个阴离子配体的配合物可拥有更纯净的晶体场态，进而实现更高的U<sub>eff</sub>与T<sub>H</sub>。本文报道了首例具有该拓扑结构的单分子磁体配合物：[Dy(C₅Me₅)(FPh)₆][{Al[OC(CF₃)₃]₃}₂(μ-F)]₂（记为**1-Dy**），在22 Oe·s⁻¹的扫描速率下，其U<sub>eff</sub> = 812(47) K，T<sub>H</sub> = 14 K；其中C₅Me₅配体可产生强轴向晶体场，而五个赤道配位的中性氟苯配体仅会带来微弱的横向相互作用。研究表明，此类配合物（如**1-Dy**）可作为合成异配稀土配合物的优质起始原料，因其所含的氟苯配体易于被取代。
