Lv Wei, Cui Hui-Hui, Chen Lei, Zhang Yi-Quan, Chen Xue-Tai, Wang Zhenxing, Ouyang Zhong-Wen, Xue Zi-Ling
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China.
Dalton Trans. 2022 May 17;51(19):7530-7538. doi: 10.1039/d2dt00121g.
Recently, the choice of ligand and geometric control of mononuclear complexes, which can affect the relaxation pathways and blocking temperature, have received wide attention in the field of single-ion magnets (SIMs). To find out the influence of the coordination environment on SIMs, two four-coordinate mononuclear Co(II) complexes [NEt][Co(PPh)X] (X = Cl, 1; Br, 2) have been synthesized and studied by X-ray single crystallography, magnetic measurements, high-frequency and -field EPR (HF-EPR) spectroscopy and theoretical calculations. Both complexes are in a cubic space group 3̄ (No. 205), containing a slightly distorted tetrahedral moiety with crystallographically imposed symmetry through the [Co(PPh)X] anion. The direct-current (dc) magnetic data and HF-EPR spectroscopy indicated the anisotropic = 3/2 spin ground states of the Co(II) ions with the easy-plane anisotropy for 1 and 2. calculations were performed to confirm the positive magnetic anisotropies of 1 and 2. Frequency- and temperature-dependent alternating-current (ac) magnetic susceptibility measurements revealed slow magnetic relaxation for 1 and 2 at an applied dc field. Finally, the magnetic properties of 1 and 2 were compared to those of other Co(II) complexes with a [CoAB] moiety.
最近，单核配合物的配体选择和几何控制能够影响弛豫途径和阻塞温度，这在单离子磁体（SIMs）领域受到了广泛关注。为了探究配位环境对单离子磁体的影响，合成了两种四配位单核Co（II）配合物[NEt][Co(PPh)X]（X = Cl，1；Br，2），并通过X射线单晶衍射、磁性测量、高频和高场电子顺磁共振（HF-EPR）光谱以及理论计算对其进行了研究。两种配合物均属于立方空间群$\bar{3}$（编号205），通过[Co(PPh)X]阴离子包含一个稍有畸变的四面体部分，并具有晶体学上的对称性。直流（dc）磁性数据和HF-EPR光谱表明Co（II）离子具有各向异性的$S = 3/2$自旋基态，配合物1和2具有易面各向异性。进行了理论计算以证实配合物1和2的正磁各向异性。频率和温度相关的交流（ac）磁化率测量表明，在施加直流场时，配合物1和2存在慢磁弛豫。最后，将配合物1和2的磁性与其他具有[CoAB]部分的Co（II）配合物的磁性进行了比较。
