New Iron(II) Spin Crossover Coordination Polymers [Fe(渭-atrz)3]X2路2H2O (X = ClO4炉, BF4炉) and [Fe(渭-atrz)(渭-pyz)(NCS)2<

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• 作者：Yu-Chun Chuang ; Chi-Tsun Liu ; Chou-Fu Sheu ; Wei-Lun Ho ; Gene-Hsiang Lee ; Chih-Cheh Wang ; Yu Wang
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：April 16, 2012
• 年：2012
• 卷：51
• 期：8
• 页码：4663-4671
• 全文大小：481K
• 年卷期：v.51,no.8(April 16, 2012)
• ISSN：1520-510X

文摘

A potential bridging triazole-based ligand, atrz (trans-4,4鈥?azo-1,2,4-triazole), is chosen to serve as building sticks and incorporated with a spin crossover metal center to form a metal organic framework. Coordination polymers of iron(II) with the formula [Fe(渭-atrz)₃]X₂路2H₂O (where X = ClO₄^{鈥?/sup> (1路2H₂O) and BF₄鈥?/sup> (2路2H₂O)) in a 3D framework and [Fe(渭-atrz)(渭-pyz)(NCS)₂]路4H₂O (3路4H₂O) in a 2D layer structure were synthesized and structurally characterized. The magnetic measurements of 1路2H₂O and 2路2H₂O reveal spin transitions near room temperature; that of 3 exhibits an abrupt spin transition at 200 K with a wide thermal hysteresis, and the spin transition behavior of these polymers are apparently correlated with the water content of the sample. Crystal structures have been determined both at high spin and at low spin states for 1路2H₂O, 2路2H₂O, and 3路4H₂O. Each iron(II) center in 1路2H₂O and 2路2H₂O is octahedrally coordinated with six 渭-atrz ligands, which in turn links the other Fe center forming a strong three-dimensional (3D) network; counteranion and water molecules are located in the voids of the lattice. The FeN₆ octahedron of 3路4H₂O is formed with two atrz, two pyrazine (pyz) ligands, and two NCS鈥?/sup> ligands, where the ligands atrz and pyz are bridged between iron centers forming a 2D layer polymer. A zigzag chain of water molecules is found between the layers, and there is a distinct correlation between the thermal hysteresis with the amount of water molecules the exist in the crystal.}