Observation of an iron(II) spin-crossover in an iron octacyanoniobate-based magnet
Observation of an iron(II) spin-crossover in an iron octacyanoniobate-based magnet
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DOI：
10.1002/anie.200802266
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发表时间：
2008-01-01
影响因子：
16.6
通讯作者：
Ohkoshi, Shin-ichi
中科院分区：
文献类型：
--
作者：
Arai, Michio;Kosaka, Wataru;Ohkoshi, Shin-ichi
含八面体配位过渡金属离子的金属配合物的自旋交叉现象已被无机化学家和物理化学家广泛研究。[1-3]利用含磁性过渡金属离子的配位聚合物研究铁磁性已经取得了很大进展。[4]如果自旋交叉和铁磁性同时存在，化合物中会出现多种吸引函数。然而，体磁化已被证明是难以观察到的自旋交叉复合物的报告日期，因为自旋载体分子是孤立的晶体中，这导致在一个非常弱的自旋交叉网站之间的磁耦合。为了在自旋交叉系统中产生磁有序，自旋位点应该通过小配位体直接桥接成三维网络。在这种情况下，氰基桥连的双金属组装体是合适的体系。[5]例如，基于八氰酸酯的网络是很好的候选者[6-10]，因为它们具有通过CN配体进行磁耦合的多个途径，并且可以在晶体结构中采用各种配位几何形状，范围从零维（0 D）[7]到1-，[8] 2-，[9]和3D。[10]本文报道了八氰基桥联Fe-Nb_（13）组装体Fe_2 [Nb（CN）_8]的制备。（3-pyCH2OH）8· 4.6 H2O（3-py= 3-吡啶基），它显示了FeII上的自旋交叉以及FeII和NbIV之间的铁磁有序。粉末样品XRD图案的Rietveld分析（图1a）表明样品具有Ia 3d空间群中的立方晶体结构（a= 35.157（11）;细化Rwp= 0887和Rp= 0685;见辅助资料中的表S1和S2以及图S1）。图1b示出
The spin-crossover phenomenon has been extensively studied for metal complexes containing octahedrally coordinated transition-metal ions by both inorganic and physical chemists.[1–3] The research of ferromagnetism has been developed using coordination polymers containing magnetic transitionmetal ions.[4] A variety of attractive functions should be observed if spin-crossover and ferromagnetism coexist in a compound. However, bulk magnetization has proved difficult to observe in the spin-crossover complexes reported to date because the spin-carrier molecules are isolated in the crystal, which results in a very weak magnetic coupling between the spin-crossover sites. To generate magnetic ordering in a spincrossover system, the spin sites should be directly bridged by a small coordinating ligand into a three-dimensional network. A cyano-bridged bimetallic assembly is a suitable system in this context.[5] Octacyanometalate-based networks, for example, are good candidates [6–10] because they have multiple pathways for magnetic coupling through the CN ligand and can take various coordination geometries in the crystal structure, ranging from zero-dimensional (0D)[7] to 1-,[8] 2-,[9] and 3D.[10] Herein we report the preparation of the octacyanobridged Fe–Nb bimetallic assembly Fe2 [Nb (CN) 8]·(3-pyCH2OH) 8· 4.6 H2O (3-py= 3-pyridyl), which displays both spin-crossover on FeII and ferrimagnetic ordering between FeII and NbIV.Rietveld analysis of the XRD pattern of a powder sample (Figure1a) indicated that the sample has a cubic crystal structure in the Ia3d space group (a= 35.157 (11); refinements Rwp= 0887 and Rp= 0685; see Tables S1 and S2, and Figure S1 in the Supporting Information). Figure 1b shows