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Magnetic and 57Fe Mossbauer Study of the Single Molecule Magnet Behavior of a Dy3Fe7 Coordination Cluster
被引:91
作者:
Abbas, Ghulam
[2
]
Lan, Yanhua
[2
]
Mereacre, Valeriu
[2
]
Wernsdorfer, Wolfgang
[3
]
Clerac, Rodolphe
[4
,5
]
Buth, Gernot
[6
]
Sougrati, Moulay T.
[7
]
Grandjean, Fernande
[7
]
Long, Gary J.
[1
]
Anson, Christopher E.
[2
]
Powell, Annie K.
[2
]
机构:
[1] Univ Missouri, Missouri Univ Sci & Technol, Dept Chem, Rolla, MO 65409 USA
[2] Univ Karlsruhe, Karlsruhe Inst Technol, Inst Anorgan Chem, D-76131 Karlsruhe, Germany
[3] CNRS, Inst Neel, F-38042 Grenoble, France
[4] Ctr Rech Paul Pascal, Equipe Mat Mol Magnet, CNRS, UPR 8641, F-33600 Pessac, France
[5] Univ Bordeaux, UPR 8641, F-33600 Pessac, France
[6] Forschungszentrum Karlsruhe, Karlsruhe Inst Technol, Inst Synchrotronstrahlung, D-76344 Eggenstein Leopoldshafen, Germany
[7] Univ Liege, Dept Phys, B-4000 Sart Tilman Par Liege, Belgium
关键词:
LADDER-TYPE COMPOUNDS;
GROUND-STATE SPINS;
MIXED-VALENT;
EXCHANGE INTERACTIONS;
LANTHANIDE ELEMENT;
ION LN;
FE-III;
DY-III;
COMPLEXES;
MANGANESE;
D O I:
10.1021/ic901248r
中图分类号:
O61 [无机化学];
学科分类号:
070301 ;
081704 ;
摘要:
The reaction between N-methydiethanolamine (mdeaH(2)), benzoic acid, FeCl3, and DyCl3 yields a decanuclear coordination cluster, [Dy3Fe7(mu(4)-O)(2)(mu(3)-OH)(2)(mdea)(7)(mu-benzoate)(4)(N-3)(6)]center dot 2H(2)O center dot 7CH(3)OH (1) whose single crystal structure exhibits three and seven crystallographically distinct Dy(III) and Fe(III) ions; six of the Fe(III) ions are pseudo-octahedrally coordinated, whereas the seventh has a trigonal-bipyramidal coordination geometry. Both direct current (dc) and alternating current (ac) magnetic susceptibility studies indicate that, upon cooling, intracluster antiferromagnetic interactions are dominant in 1, yielding a ferrimagnetic spin arrangement. The out-of-phase (chi '') ac susceptibility reveals that 1 undergoes a slow relaxation of its magnetization mainly resulting from the anisotropy of the Dy(III) ions. This slow relaxation has been confirmed both by magnetization measurements on an oriented single crystal of 1 and by the observation of hysteresis loops below 1.9 K. The macroscopic magnetic studies yield an effective energy barrier, U-eff, of 33.4 K for this relaxation, a barrier that is the highest yet reported for a lanthanide(III)-Fe(III) single molecule magnet. The Fe-57 Mossbauer spectra of 1 obtained between 3 and 35 K are consistent with the presence of Fe(III) intracluster antiferromagnetic coupling with slow magnetic relaxation relative to the Larmor precession time, thus confirming, on a microscopic scale, the presence of a barrier to the magnetic relaxation below 35 K. Between 55 and 295 K the Mossbauer spectra reveal paramagnetic behavior with six partially resolved quadrupole doublets, one for the trigonal-bipyramidal Fe(III) site and five for the six pseudo-octahedral Fe(III) sites.
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页码:9345 / 9355
页数:11
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