Highly Anisotropic Exchange Interactions in a Trigonal Bipyramidal Cyanide-Bridged NiII3OsIII2 Cluster

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• 作者：Andrei V. Palii ; Oleg S. Reu ; Sergei M. Ostrovsky ; Sophia I. Klokishner ; Boris S. Tsukerblat ; Matthew Hilfiger ; Michael Shatruk ; Andrey Prosvirin ; Kim R. Dunbar
• 刊名：Journal of Physical Chemistry A
• 出版年：2009
• 出版时间：June 25, 2009
• 年：2009
• 卷：113
• 期：25
• 页码：6886-6890
• 全文大小：205K
• 年卷期：v.113,no.25(June 25, 2009)
• ISSN：1520-5215

文摘

This article is a part of our efforts to control the magnetic anisotropy in cyanide-based exchange-coupled systems with the eventual goal to obtain single-molecule magnets with higher blocking temperatures. We give the theoretical interpretation of the magnetic properties of the new pentanuclear complex {[Ni^II(tmphen)₂]₃[Os^III(CN)₆]₂}·6CH₃CN (Ni^II₃Os^III₂ cluster). Because the system contains the heavy Os^III ions, spin−orbit coupling considerably exceeds the contributions from the low-symmetry crystal field and exchange coupling. The magnetic properties of the Ni^II₃Os^III₂ cluster are described in the framework of a highly anisotropic pseudo-spin Hamiltonian that corresponds to the limit of strong spin−orbital coupling and takes into account the complex molecular structure. The model provides a good fit to the experimental data and allows the conclusion that the trigonal axis of the bipyramidal Ni^II₃Os^III₂ cluster is a hard axis of magnetization. This explains the fact that in contrast with the isostructural trigonal bipyramidal Mn^III₂Mn^II₃ cluster, the Ni^II₃Os^III₂ system does not exhibit the single-molecule magnetic behavior.