无序示例-N-四氢吡咯基乙基吲哚二重无序

DJ_Tokyo

相关软件或概念：Olex2[1] (Version: Olex2-1.5); SHELXL[2] (Version: SHELXL-2019/3); PLATON[3] (Version: 60124)

案例来源：CCDC2346008, DOI: 10.5517/ccdc.csd.cc2jr6p6.

该结构中-CH2CH2-基团附近最大的两个残余峰与其呈交叉状，N1、C1等原子椭球明显形变拉长，如图1所示。

▲图1 残余峰及原子椭球情况

将吲哚环1号位取代基（四氢吡咯基乙基）、3号位取代基（醛基）和吲哚的吡咯环绕C3–C8键旋转做二组分无序，随后用SAME指令（参阅推文“SHELXL指令之SAME”）和SIMU指令（参阅推文“SHELXL指令之SIMU”）分别对两个无序组分的几何结构和原子各向异性位移参数进行限制，结果如图2所示，残余峰（Max Peak从0.6降为0.1，Min Peak从-0.5降为-0.1）和R因子（R1从8.26%降为4.93%，wR2从24.75%降为13.84%）得到极大改善，两个无序组分原子椭球也较为正常。

▲图2 无序处理结果

视频操作演示请参阅：

单晶结构解析练习145(数据还原)：https://www.bilibili.com/video/BV1Wm42177g6

参考文献

[1]Dolomanov, O. V.; Bourhis, L. J.; Gildea, R. J.; Howard, J. A. K.; Puschmann,H. OLEX2: A complete structure solution,refinement and analysis program. J. Appl. Cryst. 2009, 42, 339–341.

[2](a) Sheldrick, G. M. SHELXL-2019/3, Program for Crystal Structure Refinement,University of Göttingen, Germany, 2019. (b) Sheldrick, G. M. A short history ofSHELX. Acta Cryst. 2008, A64, 112–122. (c) Sheldrick, G. M.Crystal structure refinement with SHELXL.Acta Cryst. 2015, C71, 3–8. (d)Lübben, J.; Wandtke, C. M.; Hübschle, C. B.; Ruf, M.; Sheldrick, G. M.;Dittrich, B. Aspherical scattering factors for SHELXL – model, implementation and application. Acta Cryst. 2019, A75, 50–62.

[3] (a) Spek, A. L. Single-crystal structure validationwith the program PLATON. J. Appl.Cryst. 2003, 36, 7–13. (b) Spek,A. L. Structure validation in chemical crystallography. Acta Cryst. 2009, D65, 148–155. (c) Spek, A. L. What makes a crystal structure reportvalid? Inorg. Chim. Acta 2018, 470, 232–237. (d) Spek, A. L. checkCIFvalidation ALERTS: what they mean and how to respond. Acta Cryst. 2020, E76, 1–11.

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