Choroba Katarzyna, Palion-Gazda Joanna, Machura Barbara, Bieńko Alina, Wojtala Daria, Bieńko Dariusz, Rajnák Cyril, Boča Roman, Ozarowski Andrew, Ozerov Mykhaylo
Institute of Chemistry, Faculty of Science and Technology, University of Silesia, Szkolna St. 9, Katowice 40-006, Poland.
Faculty of Chemistry, Joliot-Curie 14, Wroclaw 50-383, Poland.
Inorg Chem. 2024 Jan 15;63(2):1068-1082. doi: 10.1021/acs.inorgchem.3c03405. Epub 2024 Jan 2.
To get a better insight into understanding the factors affecting the enhancement of the magnetic anisotropy in single molecule (single ion) magnets, two cobalt(II) complexes based on a tridentate ligand 2,6-di(thiazol-2-yl)pyridine substituted at the 4-position with -methyl-pyrrol-2-yl have been synthesized and studied by X-ray crystallography, AC and DC magnetic data, FIRMS and HFEPR spectra, and theoretical calculations. The change of the counteranion in starting Co(II) salts results in the formation of pentacoordinated mononuclear [Co(mpyr-dtpy)Cl]·2MeCN () complex and binuclear [Co(mpyr-dtpy)][Co(NCS)] () compound. The observed marked distortion of trigonal bipyramid geometry in and cationic octahedral and anionic tetrahedral units in brings up a question about the validity of the spin-Hamiltonian formalism and the possibility of determining the value and sign of the zero-field splitting parameter. Both complexes exhibit field-induced slow magnetic relaxation with two or three relaxation channels at = 0.3 T. The high-frequency relaxation time in the reciprocal form τ(HF) = develops according to the Raman relaxation mechanism (for , = 8.8) and the phonon-bottleneck-like mechanism (for , = 2.3). The high-frequency relaxation time at = 2.0 K and = 0.30 T is τ(HF) = 96 and 47 μs for and , respectively.
为了更深入地理解影响单分子（单离子）磁体中磁各向异性增强的因素，我们合成了两种基于三齿配体2,6 - 二（噻唑 - 2 - 基）吡啶且在4 - 位被 - 甲基 - 吡咯 - 2 - 基取代的钴（II）配合物，并通过X射线晶体学、交流和直流磁性数据、FIRMS和HFEPR光谱以及理论计算对其进行了研究。起始钴（II）盐中抗衡阴离子的变化导致形成五配位单核[Co(mpyr - dtpy)Cl]·2MeCN（）配合物和双核[Co(mpyr - dtpy)][Co(NCS)]（）化合物。在中观察到的三角双锥几何结构的明显畸变以及在中阳离子八面体和阴离子四面体单元的情况，引发了关于自旋哈密顿形式主义有效性以及确定零场分裂参数值和符号可能性的问题。两种配合物在 = 0.3 T时均表现出场诱导的慢磁弛豫，具有两个或三个弛豫通道。以倒数形式表示的高频弛豫时间τ(HF) = 根据拉曼弛豫机制（对于， = 8.8）和声子瓶颈状机制（对于， = 2.3）发展。在 = 2.0 K和 = 0.30 T时，对于和，高频弛豫时间分别为τ(HF) = 96和47 μs。
