Slow Magnetic Relaxation in a High-Spin Iron(II) Complex

被引：470

作者：

Freedman, Danna E. ^{[1
]}

Harman, W. Hill ^{[1
,3
]}

Harris, T. David ^{[1
]}

Long, Gary J. ^{[4
]}

Chang, Christopher J. ^{[1
,2
,3
]}

Long, Jeffrey R. ^{[1
]}

机构：

[1] Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA

[2] Univ Calif Berkeley, Howard Hughes Med Inst, Berkeley, CA 94720 USA

[3] Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA

[4] Univ Missouri, Dept Chem, Missouri Univ Sci & Technol, Rolla, MO 65409 USA

来源：

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY | 2010年 / 132卷 / 04期

关键词：

SINGLE-MOLECULE MAGNETS; ORBITAL ANGULAR-MOMENTUM; JAHN-TELLER DISTORTION; MOSSBAUER; BEHAVIOR; BARRIER; ABSENCE; LEVEL;

D O I：

10.1021/ja909560d

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

Slow magnetic relaxation is observed for [(tpa(Mes))Fe](-), a trigonal pyramidal complex of high-spin iron(II), providing the first example of a mononuclear transition metal complex that behaves as a single-molecule magnet. Dc magnetic susceptibility and magnetization measurements reveal a strong uniaxial magnetic anisotropy (D = -39.6 cm(-1)) acting on the S = 2 ground state of the molecule. Ac magnetic susceptibility measurements indicate the absence of slow relaxation under zero applied dc Field as a result of quantum tunneling of the magnetization. Application of a 1500 Oe dc field initiates slow magnetic relaxation, which follows a thermally activated tunneling mechanism at high temperature to give an effective spin-reversal barrier of U-eff = 42 cm(-1) and follows a temperature-independent tunneling mechanism at low temperature. In addition, the magnetic relaxation time shows a pronounced dc-field dependence, with a maximum occurring at similar to 1500 Oe.

引用

页码：1224 / +

页数：4

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