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首页> 外文期刊>Acta Crystallographica, Section B. Structural Science >An X-ray diffraction study of partially ordered electron density in clathrates of Dianin's compound that include simple carboxylic acids
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An X-ray diffraction study of partially ordered electron density in clathrates of Dianin's compound that include simple carboxylic acids

机译：Xiann化合物包合物中包含简单羧酸的部分有序电子密度的X射线衍射研究

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摘要

The nature of the inclusions in ten clathrate complexes of Dianin's compound have been investigated by the use of electron-density difference maps. The guest species are the first eight straight-chain carboxylic acids, formic to octanoic, a branched-chain acid (dimethylacetic acid) and trifluoroacetic acid. The point-group symmetry of the clathrate cavity, (3) over bar, is satisfied by partial occupation of symmetry-related sites by two included molecules in the case of formic, acetic and trifluoroacetic acids and by a single molecule in the remainder. Hydrogen-bonding requirements in the case of formic and acetic acids are satisfied by dimer formation; in the trifluoroacetic acid complex the two acid molecules form hydrogen bonds to framework O atoms at either end of the cavity. The adoption of gauche conformations in heptanoic and octanoic acid chains shortens them sufficiently that they fit the cavity with only slight distortion. [References: 12]
机译：通过使用电子密度差图，已研究了Dianin化合物的十个笼形配合物中夹杂物的性质。客体种类是甲酸至甲酸的前八种直链羧酸，支链酸（二甲基乙酸）和三氟乙酸。棒状笼形腔的点群对称性（3）在条形上通过以下方式得到满足：在甲酸，乙酸和三氟乙酸的情况下，两个相关分子部分占据了对称相关位点，其余部分则占据了一个分子。通过形成二聚体可以满足甲酸和乙酸对氢键的要求。在三氟乙酸络合物中，两个酸分子在腔的任一端形成氢键与骨架O原子。在庚酸和辛酸链中采用树胶构象可将它们充分缩短，以使其仅在轻微变形的情况下适合空腔。 [参考：12]

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