57Fe标记的八甲基铁四二酸. 构造性异构体的X射线晶体结构,高精度相互作用,以及摩斯尔光谱学的自旋格子放松
Herwig Schottenberger1, Klaus Wurst, Ulrich J Griesser
1Faculty of Chemistry and Pharmacy, University of Innsbruck, 6020 Innsbruck, Austria. herwig.schottenberger@uibk.ac.at
Journal of the American Chemical Society
|May 5, 2005
概括
八甲基铁四甲酸 (OMFc(+) BF(4)(-)) 由于晶格能量差异小,因此表现出形态多态性. 与中性OMFc不同,OMFc(+) BF(4)(-) 没有显示金属原子运动的突然增加,表明不同的动态.
科学领域:
- 有机金属化学 有机金属化学
- 固态化学 固态化学
- 晶体学 晶体学是指结晶学.
背景情况:
- 八甲基铁四二酸 (OMFc(+) BF(4)(-)) 是一种有机金属化合物,在材料科学中具有潜在的应用.
- 了解其固态特性,包括多态和动态,对于其技术利用至关重要.
研究的目的:
- 为了研究OMFc ((+) BF ((4) ((-)) 的形态多态性.
- 为了研究OMFc ((+)) BF ((4) ((-)) 中铁原子的温度依赖动力学.
- 描述OMF中的旋转放松过程和固体-固体过渡的特征c(+) BF(4)(-).
主要方法:
- 单晶的X射线结构的确定.
- 对 (57) Fe-标记的OMFc ((+) BF ((4))) 的温度依赖的莫斯尔光谱.
主要成果:
- 确定了两种不同的OMFc (((+) BF (((4))) 的晶体形式,它们在连接体扭转角度 (180°和108°) 中存在差异,这归因于微小的格子能量差异 (3.2 kJ mol ((-1)).
- 莫斯勒光谱检测显示,金属原子运动在370K之前没有异常增加,与中性OMFc.不同.
- 放松光谱表明旋转放松最好用奥巴赫过程来描述,Moessbauer格子温度为89K.
- 在400 K发生了可逆的固体-固体过渡到塑料晶体介质相.
结论:
- OMFc(+) BF(4)(-) 呈现出由微妙的格子能量变化驱动的形态多态.
- 在OMFc ((+) BF ((4))) 中,铁中心的动态与其中性对应物显著不同,具有独特的旋转放松机制.
- 在高温下,该化合物经历可逆相转换,变成塑性晶体半相.
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