Magneto-structural correlations in arsenic- and selenium-ligated dysprosium single-molecule magnets.
Magneto-structural correlations in arsenic- and selenium-ligated dysprosium single-molecule magnets.
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DOI：
10.1039/c5sc03755g
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发表时间：
2016-03-01
期刊：
影响因子：
8.4
通讯作者：
Layfield RA
中科院分区：
文献类型：
--
作者：
Pugh T;Vieru V;Chibotaru LF;Layfield RA
本文报道了一系列砷化、砷化、砷化和硒配位的镝单分子磁体。砷化物和硒酸盐连接的SMM显示各向异性障碍高达300 cm-1时，磁稀释。报道了砷和硒配位的镝单分子磁体[Cp′3Dy（AsH 2 Mes）]（3-Dy），[（η5-Cp′2Dy）{μ-As（H）Mes}]3（4-Dy），[Li（thf）4]2[（η5-Cp ′2Dy）3（μ3-AsMes）3Li]（[Li（thf）4]2[5-Dy]）和[（η5-Cp′2Dy）{μ-SeMes}]3（6-Dy）的结构和磁性.砷配位配合物4-Dy和5-Dy是第一个以类金属元素为供体原子的配体为特征的SMM。砷化物配位的配合物4-Dy和硒化物配位的配合物6-Dy在零直流电场下在250 cm-1区域显示出大的各向异性势垒，在5%磁稀释时增加到300 cm-1。理论研究表明，这些SMM中的热弛豫发生通过第二激发Kramers的双峰。相比之下，砷化酶连接的SMM 5-Dy提供了23 cm-1的小得多的屏障，稀释后增加到35 cm-1。在1.8 K时，4-Dy和5-Dy的磁化强度与磁场的依赖关系在10 kOe附近显示出不寻常的平台，这是由于砷介导的交换在偶极交换中占主导地位。交换相互作用的影响在5-Dy中更明显，这是对主要离子镝-砷键的共价贡献的小但显著增加的结果。而磁性非稀释镝SMM显示只有非常窄的磁化强度与场磁滞回线在1.8 K，磁稀释的影响是戏剧性的，蝴蝶形的回路被观察到高达5.4 K的情况下，4-Dy。我们的研究结果表明，具有较重的p-区元素供体原子的配体具有相当大的潜力，被开发更广泛的应用在分子磁性。
A series of arsine-, arsenide, arsinidene and selenium-ligated dysprosium single-molecule magnets (SMMs) are described. The arsenide- and selenolate-ligated SMMs show anisotropy barriers up to 300 cm–1 upon magnetic dilution. The structures and magnetic properties of the arsenic- and selenium-ligated dysprosium single-molecule magnets (SMMs) [Cp′3Dy(AsH2Mes)] (3-Dy), [(η5-Cp′2Dy){μ-As(H)Mes}]3 (4-Dy), [Li(thf)4]2[(η5-Cp′2Dy)3(μ3-AsMes)3Li] ([Li(thf)4]2[5-Dy]), and [(η5-Cp′2Dy){μ-SeMes}]3 (6-Dy) are described. The arsenic-ligated complexes 4-Dy and 5-Dy are the first SMMs to feature ligands with metalloid elements as the donor atoms. The arsenide-ligated complex 4-Dy and the selenolate-ligated complex 6-Dy show large anisotropy barriers in the region of 250 cm–1 in zero d.c. field, increasing to 300 cm–1 upon 5% magnetic dilution. Theoretical studies reveal that thermal relaxation in these SMMs occurs via the second-excited Kramers' doublet. In contrast, the arsinidene-ligated SMM 5-Dy gives a much smaller barrier of 23 cm–1, increasing to 35 cm–1 upon dilution. The field-dependence of the magnetization for 4-Dy and 5-Dy at 1.8 K show unusual plateaus around 10 kOe, which is due to the dominance of arsenic-mediated exchange over the dipolar exchange. The effects of the exchange interactions are more pronounced in 5-Dy, which is a consequence of a small but significant increase in the covalent contribution to the predominantly ionic dysprosium-arsenic bonds. Whereas the magnetically non-dilute dysprosium SMMs show only very narrow magnetization versus field hysteresis loops at 1.8 K, the impact of magnetic dilution is dramatic, with butterfly-shaped loops being observed up to 5.4 K in the case of 4-Dy. Our findings suggest that ligands with heavier p-block element donor atoms have considerable potential to be developed more widely for applications in molecular magnetism.
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