晶体结构解析案例56(空间群)

DJ_Tokyo

相关软件或概念：Olex2[1] (Version: Olex2-1.5); PLATON[2] (Version: 241123); SHELXL[3] (Version: SHELXL-2019/3); SHELXT[4]; XPREP[5](Version 2014/2)

最近，南京某高校友友求助晶体结构解析，拿到数据后，用Olex2打开其ins文件，显示空间群为I2，如图1所示。

▲图1 数据初始状态

在Olex2中运行SHELXT求解初始结构，给出的结果空间群为I2/m，结构中主体结构存在大量无序，且结构的键长键角均不合理，如图2所示。

▲图2 SHELXT求解的初始模型

遂运行XPREP，查看情况，XPREP给出的空间群为C2，如图3所示。

▲图3 XPREP给出的空间群

随后再用SHELXT求解，给出的结果是空间群为Cm，主体结构有序，只有末端的叔丁基存在无序，精修后无AB级警报，结果如图4所示。

▲图4 最终结果

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) 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.

[3](a) Sheldrick, G. M. SHELXL-2019/2, 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.

[4]Sheldrick, G. M. SHELXT – Integratedspace-group and crystal structure determination. Acta Cryst. 2015, A71, 3–8.

[5]Bruker (2014). XPREP (Version2014/2), Program for Space GroupDetermination. Bruker AXS Inc., Madison, Wisconsin, USA.

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