Title: Interplay of Strongly Anisotropic Metal Ions in Magnetic Blocking of Complexes
Authors: Ungur, Liviu
Thewissen, Maarten
Costes, Jean-Pierre
Wernsdorfer, Wolfgang
Chibotaru, Liviu # ×
Issue Date: 2013
Publisher: American Chemical Society
Series Title: Inorganic Chemistry vol:52 issue:11 pages:6328-6337
Abstract: The key characteristic of single-molecule magnets (SMMs) is the anisotropy-induced blocking barrier, which
should be as efficient as possible, i.e., to be able to provide long magnetic relaxation times at elevated temperatures. The strategy
for the design of efficient SMMs on the basis of transition-metal complexes such as Mn12Ac is well established, which is not the
case of complexes involving strongly anisotropic metal ions such as cobalt(II) and lanthanides (Ln). While strong intraionic
anisotropy in the latter allows them to block the magnetization already in mononuclear complexes, the presence of several such
ions in a complex does not result automatically in more efficient SMMs. Here, the magnetic blocking in the series of isostructural
3d−4f complexes CoII−LnIII−CoII, Ln = Gd, Tb, and Dy, is analyzed using an originally developed ab initio based approach for
the investigation of blocking barriers. The theoretical analysis allows one to explain the counterintuitive result that the Co−Gd−
Co complex is a better SMM than terbium and dysprosium analogues. It turns out that the highly efficient magnetic blockage in
the Co−Gd−Co complex results from a concomitant effect of unexpectedly large unquenched orbital momentum on CoII ions
(ca. 1.7 μB) and the large spin on the gadolinium (S = 7/2), which provides a multilevel blocking barrier, similar to the one of the
classical Mn12Ac. We conclude that efficient SMMs could be obtained in complexes combining strongly anisotropic and isotropic
metal ions with large angular momentum rather than in polynuclear compounds involving strongly anisotropic ions only.
ISSN: 0020-1669
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Quantum Chemistry and Physical Chemistry Section
× corresponding author
# (joint) last author

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