Spin Crossover in Tetranuclear Fe(II) Complexes, {[(tpma)Fe(渭-CN)]4}X4 (X = ClO4鈥?/sup>, BF4鈥?/sup>)
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- 作者：Oleksandr Hietsoi ; Paul W. Dunk ; Heather D. Stout ; Alejandra Arroyave ; Kirill Kovnir ; Raechel E. Irons ; Nazira Kassenova ; Rakhmetulla Erkasov ; Catalina Achim ; Michael Shatruk
- 刊名：Inorganic Chemistry
- 出版年：2014
- 出版时间：December 15, 2014
- 年：2014
- 卷：53
- 期：24
- 页码：13070-13077
- 全文大小：386K
- ISSN：1520-510X
文摘
Two Fe(II) complexes, {[(tpma)Fe(渭-CN)]4}X4 (X = ClO4鈥?/sup> (1a), BF4鈥?/sup> (1b); tpma = tris(2-pyridylmethyl)amine), were prepared by reacting the {Fe(tpma)}2+ building block with (Bu4N)CN. The crystal structures of 1a and 1b feature a tetranuclear cation composed of cyanide-bridged Fe(II) ions, each capped with a tetradentate tpma ligand. The Fe4(渭-CN)4 core of the complex is strongly distorted, assuming a butterfly-like geometry. Both complexes exhibit gradual temperature-driven spin crossover (SCO) associated with the high-spin (HS) 鈫?low-spin (LS) transition at two out of four metal centers. The evolution of HS and LS Fe(II) ions with temperature was followed by a combination of X-ray crystallography, magnetic measurements, and M枚ssbauer spectroscopy. Only the Fe(II) ions surrounded by six N atoms undergo the SCO. A comparison of the temperature-dependent SCO curves for the samples stored under solvent and the dried samples shows that the former exhibit a much more abrupt SCO. This finding was interpreted in terms of the increased structural disorder and decreased crystallinity caused by the loss of the interstitial solvent molecules in the dried samples.
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