Chen Shi-Ming, Zhang Yi-Quan, Xiong Jin, Wang Bing-Wu, Gao Song
Beijing National Laboratory of Molecular Science, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China.
Jiangsu Key Laboratory for NSLSCS, School of Physical Science and Technology, Nanjing Normal University, Nanjing 210023, People's Republic of China.
Inorg Chem. 2020 May 4;59(9):5835-5844. doi: 10.1021/acs.inorgchem.9b03264. Epub 2020 Apr 16.
In the series of the adducts of tris(alkyl) Ho complexes, Ho(CHSiMe)(THF) (, Me = methyl) can exhibit slow magnetic relaxation under a zero applied direct current (DC) field with the energy barrier Δ/ of 76 K, which is one of the highest in the non-Kramers ion Ho-based single-ion magnets (SIMs). The DC field-dependence of relaxation time for indicates the occurrence of direct relaxation process at low temperature under certain DC fields. stands out in the series of (Ln = Tb, Dy, Ho, Er, Tm), wherein Dy congener is another SIM in the absence of a DC field with the relaxation barrier of 40 K, while Tb and Er congeners are field-induced SIMs. Further substitutions of the two -THF in by other neutral ligands such as quinuclidine, tricyclohexylphosphine oxide, and 3,5-lutidine afforded Ho(CHSiMe)(quinuclidine) (), Ho(CHSiMe)(OPCy) (), and Ho(CHSiMe)(lutidine) (), respectively. The former two possess analogous structures to with two -arranged neutral ligands, and the latter one has three -lutidine coordinated. The fast quantum tunneling effect swamps the magnetic relaxation for the above three derivatives, so slow relaxation could not be observed under experimental conditions, even when a certain DC field was applied.
在三（烷基）钬配合物的加合物系列中，Ho(CHSiMe)(THF)（，Me = 甲基）在零外加直流（DC）场下可表现出缓慢的磁弛豫，能垒Δ/为76 K，这是基于非克莱默斯离子钬的单离子磁体（SIMs）中最高的之一。对于的弛豫时间的直流场依赖性表明在特定直流场下低温时会发生直接弛豫过程。在（Ln = Tb、Dy、Ho、Er、Tm）系列中很突出，其中镝同系物是在无直流场时具有40 K弛豫势垒的另一种单离子磁体，而铽和铒同系物是场诱导单离子磁体。用其他中性配体如喹核碱、三环己基氧化膦和3,5 - 二甲基吡啶进一步取代中的两个 -THF，分别得到Ho(CHSiMe)(喹核碱)（）、Ho(CHSiMe)(OPCy)（）和Ho(CHSiMe)(3,5 - 二甲基吡啶)（）。前两者具有与两个 -排列的中性配体类似的结构，后者有三个 -3,5 - 二甲基吡啶配位。快速量子隧穿效应掩盖了上述三种衍生物的磁弛豫，所以即使施加一定直流场，在实验条件下也观察不到缓慢弛豫。
