Ligand-Controlled Magnetic Interactions in Mn4 Clusters

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• 作者：Erik Kampert ; Femke F. B. J. Janssen ; Danil W. Boukhvalov ; Jaap C. Russcher ; Jan M. M. Smits ; Ren de Gelder ; Bas de Bruin ; Peter C. M. Christianen ; Uli Zeitler ; Mikhail I. Katsnelson ; Jan C. Maan ; Alan
• 刊名：Inorganic Chemistry
• 出版年：2009
• 出版时间：December 21, 2009
• 年：2009
• 卷：48
• 期：24
• 页码：11903-11908
• 全文大小：816K
• 年卷期：v.48,no.24(December 21, 2009)
• ISSN：1520-510X

文摘

A method is presented to design magnetic molecules in which the exchange interaction between adjacent metal ions is controlled by electron density withdrawal through their bridging ligands. We synthesized a novel Mn₄ cluster in which the choice of the bridging carboxylate ligands (acetate, benzoate, or trifluoroacetate) determines the type and strength of the three magnetic exchange couplings (J₁, J₂, and J₃) present between the metal ions. Experimentally measured magnetic moments in high magnetic fields show that, upon electron density withdrawal, the main antiferromagnetic exchange constant J₁ decreases from −2.2 K for the [Mn₄(OAc)₄] cluster to −1.9 K for the [Mn₄(H₅C₆COO)₄] cluster and −0.6 K for the [Mn₄(F₃CCOO)₄] cluster, while J₂ decreases from −1.1 K to nearly 0 K and J₃ changes to a small ferromagnetic coupling. These experimental results are further supported with density-functional theory calculations based on the obtained crystallographic structures of the [Mn₄(OAc)₄] and [Mn₄(F₃CCOO)₄] clusters.