Polynuclear Iron(II)鈥揂minotriazole Spincrossover Complexes (Polymers) In Solution

详细信息    查看全文

• 作者：Irene Br盲unlich ; Antoni S谩nchez-Ferrer ; Matthias Bauer ; Rahel Schepper ; Philippe Kn眉sel ; Julia Dshemuchadse ; Raffaele Mezzenga ; Walter Caseri
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：April 7, 2014
• 年：2014
• 卷：53
• 期：7
• 页码：3546-3557
• 全文大小：488K
• 年卷期：v.53,no.7(April 7, 2014)
• ISSN：1520-510X

文摘

Polynuclear spincrossover (SCO) complexes prepared by the combination of [Fe(DMF)₆]²⁺ and NH₂trz (NH₂trz = 4-amino-1,2,4-triazole) were studied (2ns^{鈥?/sup> = counterion 2-naphthalenesulfonate). It is demonstrated that these [Fe(NH₂trz)₃](2ns)₂ complexes can be dissolved鈥攃ontrary to common reported experience鈥攊n N,N-dimethylformamide (DMF) and, therefore, can be conveniently processed by simple means. The resulting solutions were examined with UV/vis and X-ray absorption spectroscopy (XANES and EXAFS) as well as with small-angle X-ray scattering (SAXS). At a molar NH₂trz/Fe2+ ratio of 3/1, corresponding to the stoichiometric ratio of the ideal coordination compound, [Fe(NH₂trz)₃]2+ in the low-spin state was found to be in equilibrium with polynuclear species in the high-spin state. The equilibrium can be shifted virtually completely to the side of low-spin Fe2+ by an excess of the ligand. The polymer therewith formed contains 100 or more Fe2+ ions and is of a pronounced rigid-rod structure, with Fe鈥揊e distances around 3.32 脜 (in comparison to 3.94 脜 of the polynuclear species in the high-spin state). Reversible spin crossover takes place in solution upon a temperature increase to around 60 掳C; this process is associated with a shift in equilibrium toward species shorter than the initial polynuclear species.}