Gruene Tim, Clabbers Max T B, Luebben Jens, Chin Jia Min, Reithofer Michael R, Stowasser Frank, Alker André M
Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Austria.
Department of Materials and Environmental Chemistry, Stockholm University, Sweden.
J Appl Crystallogr. 2022 Apr 29;55(Pt 3):647-655. doi: 10.1107/S160057672200276X. eCollection 2022 Jun 1.
Electron diffraction enables structure determination of organic small molecules using crystals that are too small for conventional X-ray crystallography. However, because of uncertainties in the experimental parameters, notably the detector distance, the unit-cell parameters and the geometry of the structural models are typically less accurate and precise compared with results obtained by X-ray diffraction. Here, an iterative procedure to optimize the unit-cell parameters obtained from electron diffraction using idealized restraints is proposed. The cell optimization routine has been implemented as part of the structure refinement, and a gradual improvement in lattice parameters and data quality is demonstrated. It is shown that cell optimization, optionally combined with geometrical corrections for any apparent detector distortions, benefits refinement of electron diffraction data in small-molecule crystallography and leads to more accurate structural models.
电子衍射能够使用对于传统X射线晶体学来说太小的晶体来确定有机小分子的结构。然而，由于实验参数存在不确定性，特别是探测器距离，与X射线衍射得到的结果相比，晶胞参数和结构模型的几何形状通常不太准确和精确。在此，提出了一种使用理想化约束来优化从电子衍射获得的晶胞参数的迭代程序。晶胞优化程序已作为结构精修的一部分得以实现，并且证明了晶格参数和数据质量有逐步改善。结果表明，晶胞优化（可选择地与针对任何明显探测器畸变的几何校正相结合）有利于小分子晶体学中电子衍射数据的精修，并能得到更准确的结构模型。
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