THE CRYSTAL STRUCTURE OF ANHYDROUS SILICOTUNGSTIC ACID AND RELATED COMPOUNDS AND THEIR PROBABLE MOLECULAR FORMULAS.
THE CRYSTAL STRUCTURE OF ANHYDROUS SILICOTUNGSTIC ACID AND RELATED COMPOUNDS AND THEIR PROBABLE MOLECULAR FORMULAS.
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无水硅钨酸及相关化合物的晶体结构及其可能的分子式。
DOI：
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发表时间：
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影响因子：
11.1
通讯作者：
G. Clark
中科院分区：
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作者：
A. Scroggie;G. Clark
硅钨酸以多种形式结晶，具有不同量的水合水。它以八面体形式存在，具有以下组成，2H20.SiO2.12W03.30H20和以菱面体形式存在，2H20I.SiO2。12WO0.24H20。已经描述了具有22个水合水分子的同分异构的三斜晶型，也描述了含有17个水合水分子的同分异构的三斜晶型，但是通过将水合形式加热到2200 ℃获得的无水酸是作为细粉末获得的，并且其晶体结构还没有通过光学方法令人满意地确定。原子在分子中的排列一直是罗森海姆、阿希和阿希等人推测的主题，但所提供的证据在任何情况下都不是决定性的。本研究的目的是对硅钨酸的晶体结构进行X射线衍射分析，并将这些结果与化学数据联合收割机结合起来，试图推断出正确的分子结构，并将这些结果与以前提出的结构进行比较。1.研究酸的结构。A.化学检验。在这部分工作中，我们将经典的分子降解和分解产物的分离鉴定方法应用于硅钨酸。酸被过量的KOH分解，这导致K2 WO 4分子的分裂。这些可以被检测到，因为它们在强无机酸的存在下产生黄色至白色的WO 3沉淀。引起酸分子分裂所需的酸的量通过实验确定如下：制备一系列含有已知量的酸的溶液，并加入等于8、9、10、11、12或14当量碱的KOH溶液;在水解达到等当量后，
Silicotungstic acid crystallizes in a number of forms with different amounts of water of hydration. It occurs as octahedrons with the following composition, 2H20.SiO2.12W03.30H20 and as rhombohedrons, 2H20I.SiO2. 12WO0 .24H20. An isomeric triclinic form with 22 molecules of water of hydration has been described, and also one containing 17 molecules of water of hydration, but the anhydrous acid obtained by heating the hydrated forms to a temperature of 2200, is obtained as a fine powder and its crystal structure has not been satisfactorily determined by optical means. The arrangement of the atoms in the molecule has been the subject of speculation by Rosenheim, Asch and Asch, and others,3 but the evidence offered has not been conclusive in any case. The aim of the present research was to make an x-ray diffraction analysis of the crystal structure of silicotungstic acid and to combine these results with chemical data in an attempt to deduce the correct molecular structure, and to compare these results with previously suggested structures. 1. Investigation of the Structure of the Acid.-A. Chemical Examination. In this part of the work, the classical method of degrading the molecule and isolating and identifying the decomposition products was applied to silicotungstic acid. The acid was decomposed by an excess of KOH which causes the splitting off of molecules of K2WO4. These could be detected since they gave a yellow to white precipitate of W03, in the presence of strong mineral acids. The amount of acid necessary to cause the splitting of the acid molecule was established experimentally as follows: a series of solutions were prepared containing a known amount of acid, and a volume of KOH solution equal to 8, 9, 10, 11, 12, or 14 equivalents of alkali was added; after hydrolysis had reached an equi-