X-ray crystallography is an important method used to confirm the three-dimensional structure of a chemical compound. In this study, the crystal structure of endosulfan sulfate was investigated. Endosulfan sulfate is the major metabolite of the insecticide endosulfan, which is composed of two stereoisomers (α and β). From GC–MS analysis, α- and β-endosulfan each gave a single peak in the endosulfan sample, but only one peak was observed for endosulfan sulfate. Interestingly, in X-ray crystallography, two conformers of endosulfan sulfate (A and B) were observed at a ratio of 2(A):1(B). A heterocyclic seven-membered ring of conformer B assumed a horizontal-chair form, differing from two twisted forms of α-endosulfan while a vertical-chair form was observed for conformer A, showing the very similar structure to β-endosulfan; this difference in conformation is caused by differing bond angles at O(1)–C(8)–C(3) and O(2)–C(9)–C(4). In space packing, two asymmetric units were obtained, and three molecules were aligned in the order of A–A–B conformers in each unit. The total potential energy of A was slightly lower (approximately 4 kcal/mol) than B, possibly resulting in the two molecules of A that exist in a rigid crystal state. However, A and B conformers should not exist at room temperature in a solution state for GC–MS analysis, likely due to the small energy difference.

中文翻译：

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硫酸硫丹的X射线晶体结构

X射线晶体学是用于确认化合物的三维结构的重要方法。在这项研究中，研究了硫丹硫酸盐的晶体结构。硫酸硫丹是杀虫剂硫丹的主要代谢物，它由两种立体异构体（α和β）组成。通过GC-MS分析，硫丹样品中的α-硫丹和β-硫丹各有一个峰，但硫酸硫丹仅观察到一个峰。有趣的是，在X射线晶体学中，以2（A）：1（B）的比例观察到两个构象的硫丹硫酸盐（A和B）。构象异构体B的杂环七元环假定为水平椅形式，不同于α-硫丹的两种扭曲形式，而对于构象异构体A观察到垂直椅形式，其结构与β-硫丹非常相似。这种构象差异是由O（1）–C（8）–C（3）和O（2）–C（9）–C（4）处不同的键角引起的。在空间包装中，获得了两个不对称单元，并且三个分子在每个单元中按A–A–B构象体的顺序排列。A的总势能略低于B（约4 kcal / mol），可能导致A的两个分子以刚性晶体状态存在。但是，在室温下，对于GC-MS分析，在溶液状态下不应存在A和B构象异构体，这可能是由于能量差较小所致。可能会导致两个A分子以刚性晶体状态存在。但是，在室温下，对于GC-MS分析，在溶液状态下不应存在A和B构象异构体，这可能是由于能量差较小所致。可能会导致两个A分子以刚性晶体状态存在。但是，在室温下，对于GC-MS分析，在溶液状态下不应存在A和B构象异构体，这可能是由于能量差较小所致。