A Combined Synthetic, Magnetic, and Theoretical Study on Enhancing Ligand-Field Axiality for Dy(III) Single-Molecule Magnets Supported by Ferrocene Diamide Ligands.
A Combined Synthetic, Magnetic, and Theoretical Study on Enhancing Ligand-Field Axiality for Dy(III) Single-Molecule Magnets Supported by Ferrocene Diamide Ligands.
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DOI：
10.1021/acs.inorgchem.3c00896
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发表时间：
2023-06
影响因子：
4.6
通讯作者：
Kexin Yang;Rong Sun;Jingliang Zhao;Chong Deng;Bingwu Wang;Song Gao;Wenliang Huang
中科院分区：
文献类型：
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作者：
Kexin Yang;Rong Sun;Jingliang Zhao;Chong Deng;Bingwu Wang;Song Gao;Wenliang Huang
分子设计是提高单分子磁体性能的关键。对于镝（III）SMM，增强配体场轴性是实现高性能SMM的非常合适的策略。我们合成了一系列镝（III）配合物，（NNTIPS）DyBr（THF）2（1，NNTIPS = fc（NSiiPr 3）2; fc = 1，1 '-二茂铁二基，THF =四氢呋喃），[（NNTIPS）Dy（THF）3][BPh 4]（2），（NNTIPS）DyI（THF）2（3），和[（NNTBS）Dy（THF）3][BPh 4]（4，NNTBS = fc（NSitBuMe 2）2），由二茂铁二酰胺配体支撑。X-射线晶体学表明，刚性二茂铁骨干强制执行一个近轴向配位场与弱配位赤道配体。镝（III）配合物1-4在零磁场下都表现出缓慢的磁弛豫，并在1000 K左右具有高的有效势垒（Ueff），与先前报道的（NNTBS）DyI（THF）2（5）相当。我们通过理论计算探讨了结构变化对SMM行为的影响，发现由rq定义的负电荷分布，即，轴向配体上的电荷与赤道配体上的电荷的比率起决定性作用。此外，对一系列不含赤道配体的模型配合物1 ′-5 ′的理论计算揭示了轴向晶场参数B20与N-Dy-N角成正比，支持了增强配体场轴向度可以改善SMM性能的假设。
Molecular design is crucial for improving the performance of single-molecule magnets (SMMs). For dysprosium(III) SMMs, enhancing ligand-field axiality is a well-suited strategy to achieve high-performance SMMs. We synthesized a series of dysprosium(III) complexes, (NNTIPS)DyBr(THF)2 (1, NNTIPS = fc(NSiiPr3)2; fc = 1,1'-ferrocenediyl, THF = tetrahydrofuran), [(NNTIPS)Dy(THF)3][BPh4] (2), (NNTIPS)DyI(THF)2 (3), and [(NNTBS)Dy(THF)3][BPh4] (4, NNTBS = fc(NSitBuMe2)2), supported by ferrocene diamide ligands. X-ray crystallography shows that the rigid ferrocene backbone enforces a nearly axial ligand field with weakly coordinating equatorial ligands. Dysprosium(III) complexes 1-4 all exhibit slow magnetic relaxation under zero fields and possess high effective barriers (Ueff) around 1000 K, comparable to previously reported (NNTBS)DyI(THF)2 (5). We probed the influences of structural variations on SMM behaviors by theoretical calculations and found that the distribution of negative charges defined by rq, i.e., the ratio of the charges on the axial ligands to the charges on the equatorial ligands, plays a decisive role. Moreover, theoretical calculations on a series of model complexes 1'-5' without equatorial ligands unveil that the axial crystal-field parameters B20 are directly proportional to the N-Dy-N angles and support the hypothesis that enhancing the ligand-field axiality could improve SMM performance.