Structural and Electronic Dependence of the Single-Molecule-Magnet Behavior of Dysprosium(III) Complexes

详细信息    查看全文

• 作者：Victoria E. Campbell ; H茅l猫ne Bolvin ; Eric Rivi猫re ; Regis Guillot ; Wolfgang Wernsdorfer ; Talal Mallah
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：March 3, 2014
• 年：2014
• 卷：53
• 期：5
• 页码：2598-2605
• 全文大小：490K
• 年卷期：v.53,no.5(March 3, 2014)
• ISSN：1520-510X

文摘

We investigate and compare the magnetic properties of two isostructural Dy^III-containing complexes. The Dy^III ions are chelated by hexadentate ligands and possess two apical bidendate nitrate anions. In dysprosium(III) N,N鈥?bis(imine-2-yl)methylene-1,8-diamino-3,6-dioxaoctane (1), the ligand鈥檚 donor atoms are two alkoxo, two pyridine, and two imine nitrogen atoms. Dysprosium(III) N,N鈥?bis(amine-2-yl)methylene-1,8-diamino-3,6-dioxaoctane (2) is identical with 1 except for one modification: the two imine groups have been replaced by amine groups. This change has a minute effect on the structure and a larger effect the magnetic behavior. The two complexes possess slow relaxation of the magnetization in the presence of an applied field of 1000 Oe but with a larger barrier for reorientation of the magnetization for 1 (U_eff/k_B = 50 K) than for 2 (U_eff/k_B = 34 K). First-principles calculations using the spin鈥搊rbit complete active-space self-consistent-field method were performed and allowed to fit the experimental magnetization data. The calculations gave the energy spectrum of the 2J + 1 sublevels issued from the J = ¹⁵/₂ free-ion ground state. The lowest-lying sublevels were found to have a large contribution of M_J = 卤¹⁵/₂ for 1, while for 2, M_J = 卤¹³/₂ was dominant. The observed differences were attributed to a synergistic effect between the electron density of the ligand and the small structural changes provoked by a slight alteration of the coordination environment. It was observed that the stronger ligand field (imine) resulted in complex 1 with a larger energy barrier for reorientation of the magnetization than 2.