Ammeline is a simple, readily available, molecular compound, which has been known for nearly 200 years. Despite that, no proper structural characterization of ammeline has been conducted so far. For this reason, the prevalent tautomeric form of ammeline in the solid remained unknown to this date. In the course of this study, its crystal structure was finally established by single‐crystal X‐ray diffraction. In this structure, ammeline is exclusively found as its 4,6‑diamino‐1,3,5‐triazin‐2(1H)‐one tautomer and adopts layered structure with an exceptionally high hydrogen bond density. Ammeline shows an interesting amphoteric behavior. Therefore, the synthesis and structural characterization of some of its salts were carried out to investigate the influence of the protonation degree on its molecular structure. In particular, the crystal structure of silver ammelinate monohydrate was solved as the first reported structure containing deprotonated ammeline. Moreover, the crystal structures of three different modifications of ammelinium perchlorate were elucidated and the transformation conditions between them were studied. Lastly, the crystal structure of ammelinediium diperchlorate monohydrate, containing unprecedented doubly protonated ammeline, was determined. The products’ thermal behavior was studied by differential thermal analysis and thermogravimetric analysis. The perchlorate salts were additionally examined for their potential as insensitive high‐energy‐density materials.

中文翻译：

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关于互变异构和两性：Ammeline 及其一些盐的深入结构和物理化学表征


Ammeline 是一种简单、容易获得的分子化合物，为人所知已近 200 年。尽管如此，迄今为止尚未对ammeline进行适当的结构表征。因此，迄今为止，固体中普遍存在的三聚氰胺互变异构形式仍然未知。在本研究过程中，最终通过单晶X射线衍射确定了其晶体结构。在该结构中，ammeline仅以其4,6-二氨基-1,3,5-三嗪-2(1H)-one互变异构体被发现，并采用具有极高氢键密度的层状结构。 Ammeline 显示出有趣的两性行为。因此，对其部分盐进行了合成和结构表征，探讨质子化程度对其分子结构的影响。特别是，三聚氰酸银一水合物的晶体结构被解析为第一个报道的含有去质子化三聚氰胺的结构。此外，还阐明了高氯酸氨的三种不同变体的晶体结构，并研究了它们之间的转化条件。最后，确定了含有前所未有的双质子化的氨美啉二高氯酸二氨美二钠一水合物的晶体结构。通过差热分析和热重分析研究了产品的热行为。另外还检查了高氯酸盐作为不敏感高能量密度材料的潜力。