Faculty of Chemistry , University of Wroclaw , Joliot-Curie 14 , 50-383 Wroclaw , Poland.
Faculty of Chemistry , Wroclaw University of Technology , Wybrzeze Wyspiańskiego 27 , 50-370 Wroclaw , Poland.
Inorg Chem. 2018 Oct 15;57(20):12740-12755. doi: 10.1021/acs.inorgchem.8b01906. Epub 2018 Oct 2.
Three pentacoordinate complexes of the type [Co( pypz)X], where pypz is a tridentate ligand 2,6-bis(pyrazol-1-yl)pyridine and X = Cl (1), NCS (2), and NCO (3), have been synthesized, and their structures have been determined by X-ray analysis. The DC magnetic data show a sizable magnetic anisotropy, which was confirmed by high-field high-frequency electron paramagnetic resonance (HF EPR) measurements. Well-resolved HF EPR spectra of high spin cobalt (II) were observed over the microwave frequency range 100-650 GHz. The experimental spectra of both complexes were simulated with axial g tensor components, a very large positive D value, and different E/ D ratios. To determine the exact D value for 2 (38.4 cm) and 3 (40.92 cm), the far-infrared magnetic spectroscopy method was used. Knowledge of the zero field splitting parameters and their signs is crucial in interpreting the single-molecule magnet or single chain magnet behavior. The AC susceptibility data confirm that these complexes exhibit a slow magnetic relaxation under small applied DC field with two (1 and 3) or three (2) relaxation modes.
已合成了三种五配位配合物[Co(pypz)X]，其中 pypz 是一种三齿配体 2,6-双（吡唑-1-基）吡啶，X=Cl（1）、NCS（2）和 NCO（3），并通过 X 射线分析确定了它们的结构。直流磁数据显示出相当大的磁各向异性，这通过高频电子顺磁共振（HF EPR）测量得到了证实。在微波频率范围 100-650 GHz 上观察到了高自旋钴（II）的高分辨率 HF EPR 光谱。用轴向 g 张量分量、非常大的正 D 值和不同的 E/D 比对两个配合物的实验光谱进行了模拟。为了确定 2（38.4 cm）和 3（40.92 cm）的确切 D 值，使用了远红外磁光谱法。了解零场分裂参数及其符号对于解释单分子磁体或单链磁体行为至关重要。交流磁化率数据证实，这些配合物在施加小直流场时表现出缓慢的磁弛豫，其中 2（1 和 3）或 3（2）种弛豫模式。
