Gupta Sandeep K, Nielsen Hannah H, Thiel Andreas M, Klahn Emil A, Feng Erxi, Cao Huibo B, Hansen Thomas C, Lelièvre-Berna Eddy, Gukasov Arsen, Kibalin Iurii, Dechert Sebastian, Demeshko Serhiy, Overgaard Jacob, Meyer Franc
Universität Göttingen, Institut für Anorganische Chemie, Tammannstraße 4, D-37077Göttingen, Germany.
Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000Aarhus C, Denmark.
JACS Au. 2023 Jan 23;3(2):429-440. doi: 10.1021/jacsau.2c00575. eCollection 2023 Feb 27.
A comprehensive understanding of the ligand field and its influence on the degeneracy and population of -orbitals in a specific coordination environment are crucial for the rational design and enhancement of magnetic anisotropy of single-ion magnets (SIMs). Herein, we report the synthesis and comprehensive magnetic characterization of a highly anisotropic Co SIM, LCo (L is an ,'-chelating oxanilido ligand), that is stable under ambient conditions. Dynamic magnetization measurements show that this SIM exhibits a large energy barrier to spin reversal > 300 K and magnetic blocking up to 3.5 K, and the property is retained in a frozen solution. Low-temperature single-crystal synchrotron X-ray diffraction used to determine the experimental electron density gave access to Co -orbital populations and a derived , 261 cm, when the coupling between the and orbitals is taken into account, in very good agreement with ab initio calculations and superconducting quantum interference device results. Powder and single-crystal polarized neutron diffraction (PNPD, PND) have been used to quantify the magnetic anisotropy via the atomic susceptibility tensor, revealing that the easy axis of magnetization is pointing along the N-Co-N' bisectors of the ,'-chelating ligands (3.4° offset), close to the molecular axis, in good agreement with complete active space self-consistent field/N-electron valence perturbation theory to second order ab initio calculations. This study provides benchmarking for two methods, PNPD and single-crystal PND, on the same 3d SIM, and key benchmarking for current theoretical methods to determine local magnetic anisotropy parameters.
全面理解配体场及其在特定配位环境中对 - 轨道简并度和占据情况的影响,对于单离子磁体(SIMs)磁各向异性的合理设计和增强至关重要。在此,我们报道了一种高度各向异性的钴单离子磁体LCo(L是一种 ,'- 螯合草酰苯胺配体)的合成及全面磁学表征,该磁体在环境条件下稳定。动态磁化测量表明,这种单离子磁体表现出较大的自旋反转能垒 > 300 K,磁阻塞温度高达3.5 K,且该性质在冷冻溶液中得以保留。用于确定实验电子密度的低温单晶同步辐射X射线衍射能够获取钴 - 轨道占据情况,并且在考虑 和 轨道之间的耦合时,得出 ,261 cm,这与从头算计算和超导量子干涉装置结果非常吻合。粉末和单晶极化中子衍射(PNPD,PND)已被用于通过原子磁化率张量量化磁各向异性,结果表明易磁化轴沿着 ,'- 螯合配体的N - Co - N'平分线方向(有3.4°偏移),接近分子轴,这与完全活性空间自洽场/N - 电子价微扰理论二阶从头算计算结果相符。本研究为在同一3d单离子磁体上使用PNPD和单晶PND这两种方法提供了基准,也为当前确定局部磁各向异性参数的理论方法提供了关键基准。