加拿大渥太华大学Murugesu Muralee团队报道了显示慢磁弛豫的具有两个双甲硅烷基酰胺配体的三价4f配合物。相关研究成果发表在2023年5月25日出版的《自然—化学》。

性能最好的单分子磁体（SMMs）历来依赖于在几个配位原子上离域的假轴向配体。已经发现这种配位环境会引发强烈的磁各向异性，但具有低配位数的镧系SMMs仍然是合成上难以捉摸的物种。

该文中，研究人员报道了仅含有两个双甲硅烷基酰胺配体Yb（III）-{N（SiMePh2）2}2][Al{OC（CF3）3}4]的阳离子4f络合物，其表现出缓慢的磁化弛豫。体积庞大的甲硅烷基酰胺配体和弱配位[Al{OC（CF3）3}4]阴离子的组合提供了空间位阻环境，其适当地稳定引发强基态磁各向异性所必需的假三角几何结构。发光光谱对mJ态的分辨率得到了从头计算的支持，该计算显示了大约1850cm^-1的大基态分裂。这些结果提供了一种获得双甲硅烷基酰胺Yb（III）复合物的简单途径，并进一步强调了具有良好定位电荷的轴向配位配体对于高性能SMMs的可取性。

附：英文原文

Title: A trivalent 4f complex with two bis-silylamide ligands displaying slow magnetic relaxation

Author: Errulat, Dylan, Harriman, Katie L. M., Glico, Diogo A., Kitos, Alexandros A., Mansikkamki, Akseli, Murugesu, Muralee

Issue&Volume: 2023-05-25

Abstract: The best-performing single-molecule magnets (SMMs) have historically relied on pseudoaxial ligands delocalized across several coordinated atoms. This coordination environment has been found to elicit strong magnetic anisotropy, but lanthanide-based SMMs with low coordination numbers have remained synthetically elusive species. Here we report a cationic 4f complex bearing only two bis-silylamide ligands, Yb(III)[{N(SiMePh2)2}2][Al{OC(CF3)3}4], which exhibits slow relaxation of its magnetization. The combination of the bulky silylamide ligands and weakly coordinating [Al{OC(CF3)3}4] anion provides a sterically hindered environment that suitably stabilizes the pseudotrigonal geometry necessary to elicit strong ground-state magnetic anisotropy. The resolution of the mJ states by luminescence spectroscopy is supported by ab initio calculations, which show a large ground-state splitting of approximately 1,850cm1. These results provide a facile route to access a bis-silylamido Yb(III) complex, and further underline the desirability of axially coordinated ligands with well-localized charges for high-performing SMMs.

DOI: 10.1038/s41557-023-01208-y

Source: https://www.nature.com/articles/s41557-023-01208-y