四配位 Co 单离子磁体中具有强易轴各向异性的零场慢磁弛豫和磁滞回线。
Zero-Field Slow Magnetic Relaxation and Hysteresis Loop in Four-Coordinate Co Single-Ion Magnets with Strong Easy-Axis Anisotropy.
机构信息
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China.
Jiangsu Key Laboratory for NSLSCS, School of Physical Science and Technology , Nanjing Normal University , Nanjing 210023 , China.
出版信息
Inorg Chem. 2019 Oct 7;58(19):12555-12564. doi: 10.1021/acs.inorgchem.9b01175. Epub 2019 Sep 25.
Two mononuclear tetrahedral Co(II) complexes (HNEt)[Co(L)]·HO () and (BuN)[Co(L)]·HO () (HL = ,'-bis(p-toluenesulfony1)oxamide, HL = ,'-diphenyloxamide) have been synthesized, and their structures have been characterized by single-crystal X-ray diffraction. Both complexes adopt distorted tetrahedral coordination geometries surrounding the Co(II) center, which is ligated by two doubly deprotonated oxamide ligands oriented perpendicularly to each other. Their axial magnetic anisotropies were revealed by the direct current (dc) magnetic measurements, high-field and high-frequency electron paramagnetic resonance, and theoretical calculations. Both complexes display slow magnetic relaxation in the absence of an applied dc field. Upon the application of the 0.15 T dc field, the quantum tunneling of magnetization is efficiently suppressed. In addition, both complexes display hysteresis loops with different field sweep rates at 1.8 K, which is rarely observed for Co(II) single-ion magnets (SIMs).
已经合成了两个单核四面体形的 Co(II) 配合物 (HNEt)[Co(L)]·HO () 和 (BuN)[Co(L)]·HO ()（HL =,'-双（对甲苯磺酰基）氧酰胺，HL =,'-二苯氧酰胺），并通过单晶 X 射线衍射对其结构进行了表征。两个配合物都采用扭曲的四面体形配位几何结构，其中 Co(II) 中心由两个彼此垂直的双去质子化的氧酰胺配体配位。它们的轴向磁各向异性通过直流（dc）磁测量、高磁场和高频电子顺磁共振以及理论计算揭示。在没有外加直流场的情况下，两个配合物都显示出缓慢的磁弛豫。施加 0.15 T 的直流场后，磁量子隧穿得到有效抑制。此外，两个配合物在 1.8 K 时以不同的磁场扫描速率显示出滞后回线，这在 Co(II) 单离子磁体（SIM）中很少见。
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