This work presents the crystal structure determination of two elusive polymorphs of furazidin, an antibacterial agent, employing a combination of crystal structure prediction (CSP) calculations and an NMR crystallography approach. Two previously uncharacterized neat crystal forms, one of which has two symmetry‐independent molecules (form I), whereas the other one is a Z′ = 1 polymorph (form II), crystallize in P2₁/c and P1 space groups, respectively, and both are built by different conformers, displaying different intermolecular interactions. It is demonstrated that the usage of either CSP or NMR crystallography alone is insufficient to successfully elucidate the above‐mentioned crystal structures, especially in the case of the Z′ = 2 polymorph. In addition, cases of serendipitous agreement in terms of ¹H or ¹³C NMR data obtained for the CSP‐generated crystal structures different from the ones observed in the laboratory (false‐positive matches) are analyzed and described. While for the majority of analyzed crystal structures the obtained agreement with the NMR experiment is indicative of some structural features in common with the experimental structure, the mentioned serendipity observed in exceptional cases points to the necessity of caution when using an NMR crystallography approach in crystal structure determination.

中文翻译：

---

通过晶体结构预测和NMR晶体学的共同努力揭示了两种呋喃丁啶多晶型物的晶体结构。

这项工作结合了晶体结构预测（CSP）计算和NMR晶体学方法，给出了呋喃丁二酮（一种抗菌剂）的两种难以确定的多晶型物的晶体结构测定。两种以前未表征的纯净晶体形式，其中一种具有两个不依赖于对称性的分子（形式I），而另一种是Z '= 1多晶型物（形式II），在P 2 ₁ / c和P 1中结晶。空间组分别由不同的构象异构体构建，表现出不同的分子间相互作用。结果表明，单独使用CSP或NMR晶体学不足以成功阐明上述晶体结构，尤其是在Z '= 2多晶型的情况下。另外，偶然的情况下以¹ H或^13表示分析和描述了CSP生成的晶体结构所获得的C NMR数据与实验室观察到的结构不同（假阳性匹配）。尽管对于大多数分析的晶体结构而言，与NMR实验所获得的一致性表明某些结构特征与实验结构相同，但在特殊情况下观察到的提及的偶然性表明，在晶体结构中使用NMR晶体学方法时必须谨慎决心。