Face-Sharing Heterotrinuclear MII−LnIII−MII (M = Mn, Fe, Co, Zn; Ln = La, Gd, Tb, Dy) Complexes: Synthesis, Structures, and Magnetic Properties

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• 作者：Tomoka Yamaguchi ; Jean-Pierre Costes ; Yukana Kishima ; Masaaki Kojima ; Yukinari Sunatsuki ; Nicolas Brfuel ; Jean-Pierre Tuchagues ; Laure Vendier ; Wolfgang Wernsdorfer
• 刊名：Inorganic Chemistry
• 出版年：2010
• 出版时间：October 18, 2010
• 年：2010
• 卷：49
• 期：20
• 页码：9125-9135
• 全文大小：999K
• 年卷期：v.49,no.20(October 18, 2010)
• ISSN：1520-510X

文摘

Trinuclear linear 3d−4f−3d complexes (3d = Mn^II, Fe^II, Co^II, Zn^II and 4f = La^III, Gd^III, Tb^III, Dy^III) were prepared by using a tripodal nonadentate Schiff base ligand, N,N′,N′′-tris(2-hydroxy-3-methoxybenzilidene)-2-(aminomethyl)-2-methyl-1,3-propanediamine. The structural determinations showed that in these complexes two distorted trigonal prismatic transition metal complexes of identical chirality are assembled through 4f cations. The Mn and Fe entities crystallize in the chiral space group P2₁2₁2₁ as pure enantiomers; the cobalt complexes exhibit a less straightforward behavior. All Mn, Fe, and Co complexes experience M^II−Ln^III ferromagnetic interactions. The Mn−Gd interaction is weak (0.08 cm⁻¹) in comparison to the Fe−Gd (0.69 cm⁻¹) and Co−Gd (0.52 cm⁻¹) ones while the single ion zero field splitting (ZFS) term D is larger for the Fe complexes (5.7 cm⁻¹) than for the cobalt ones. The cobalt complexes behave as single-molecules magnets (SMMs) with large magnetization hysteresis loops, as a consequence of the particularly slow magnetic relaxation characterizing these trinuclear molecules. Such large hysteresis loops, which are observed for the first time in Co-Ln complexes, confirm that quantum tunnelling of the magnetization does not operate in the Co−Gd−Co complex.