Herchel Radovan, Zoufalý Pavel, Nemec Ivan
Department of Inorganic Chemistry, Faculty of Science, Palacký University 17. Listopadu 12 CZ-771 46 Olomouc Czech Republic
Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacký University Šlechtitelů 27 CZ-783 71 Olomouc Czech Republic.
RSC Adv. 2019 Jan 2;9(1):569-575. doi: 10.1039/c8ra09648a. eCollection 2018 Dec 19.
The objective of this work was the exploration of the effect of the second coordination sphere on the magnetic properties of [Ln(NO)(HO)]·(18C6) (Ln = Dy (1) and Er (2)) compounds comprising co-crystallized 18-crown-6 ethers. Both compounds were identified as field-induced single molecule magnets (SMMs) with estimated magnetization reversal barriers = 66-71 K for 1 and = 21-24 K for 2. Theoretical calculations with the B3LYP functional revealed substantial change and redistribution of the electrostatic potential upon accounting for the second coordination sphere represented by two 18C6 molecules, which resulted in the change of the crystal-field around metal atoms. As a result, the multireference CASSCF calculations exposed significant impact of the second coordination sphere on the energy splitting of the respective (Dy) and (Er) ground states, the magnetization reversal barrier and the magnetic anisotropy parameters. Moreover, the calculated magnetization reversal barriers, = 57 K for 1 and = 16 K for 2, are in good agreement with the experimental values accentuating the importance of the second coordination sphere on the magnetic properties of SMMs.
本工作的目的是探究第二配位层对包含共结晶18-冠-6醚的[Ln(NO)(HO)]·(18C6)（Ln = Dy (1) 和 Er (2)）化合物磁性质的影响。这两种化合物均被鉴定为场诱导单分子磁体（SMMs），估计1的磁化反转势垒 = 66 - 71 K，2的磁化反转势垒 = 21 - 24 K。采用B3LYP泛函的理论计算表明，考虑由两个18C6分子代表的第二配位层后，静电势发生了显著变化和重新分布，这导致了金属原子周围晶体场的改变。结果，多参考CASSCF计算揭示了第二配位层对相应的（Dy）和（Er）基态的能量分裂、磁化反转势垒和磁各向异性参数有显著影响。此外，计算得到的磁化反转势垒，1为 = 57 K，2为 = 16 K，与实验值吻合良好，突出了第二配位层对SMMs磁性质的重要性。
