Reacting parabanic acid with the superacidic systems XF/MF5 (X = H, D; M = As, Sb) in different ratios, led to the formation of the mono‐ and diprotonated species. Salts in terms of [C3H3N2O3][AsF6], [C3H3N2O3][SbF6], [C3H4N2O3][AsF6]2, [C3H4N2O3][SbF6]2, [C3D3N2O3][AsF6] and [C3D4N2O3][AsF6]2 were obtained and characterized by low‐temperature infrared and Raman spectroscopy. Single‐crystal X‐ray structure analyses were performed for [C3H3N2O3][SbF6] and [C3H4N2O3][AsF6]2·4HF. Additionally, quantum chemical calculations were carried out on the B3LYP/aug‐cc‐pVTZ level of theory for the mono‐ and dication. Mapped Electrostatic Potentials together with Natural Population Analysis charges were calculated in order to localize the two positive charges of the diprotonated parabanic acid. The diprotonated parabanic acid can be described as an 1,2‐C,C‐dication, stabilized by electron delocalization over the five‐membered ring.

中文翻译：

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双质子化对羟基苯甲酸：邻位或 1,3-dication？

对羟基苯甲酸与超酸性系统 XF/MF5 (X = H, D; M = As, Sb) 以不同比例反应，导致形成单质子化物质和双质子化物质。获得了 [C3H3N2O3][AsF6]、[C3H3N2O3][SbF6]、[C3H4N2O3][AsF6]2、[C3H4N2O3][SbF6]2、[C3D3N2O3][AsF6] 和 [C3D4N2F6] 的盐类并通过低温红外和拉曼光谱表征。对 [C3H3N2O3][SbF6] 和 [C3H4N2O3][AsF6]2·4HF 进行了单晶 X 射线结构分析。此外，量子化学计算是在 B3LYP/aug-cc-pVTZ 理论水平上进行的。为了定位二质子化对羟基苯甲酸的两个正电荷，计算了映射静电势和自然种群分析电荷。二质子化对羟基苯甲酸可以描述为 1,2-C，