Amaro Hernández Aldo Guillermo, Rodríguez Tzompantzi Tomasa, Dávila García Álvaro, Meza-León Rosa Luisa, Bernès Sylvain
Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, 14 Sur Esq. Av. San Claudio, 72570 Puebla, Pue., Mexico.
Instituto de Física, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue., Mexico.
IUCrdata. 2020 Jun 16;5(Pt 6):x200788. doi: 10.1107/S2414314620007889. eCollection 2020 Jun.
The title compound, CHNO·CHCl, was obtained as a product of a double aza-Michael addition of hydroxyl-amine on a Chiron with a known absolute configuration. The enanti-opure compound crystallized as a chloro-form solvate, in space group 1, and diffraction data were collected at room temperature with Ag α radiation. The Flack parameter refined to = -0.01 (16); however, the Flack and Watkin 2 plot clearly shows that differences between Friedel opposites (the component of the plot) do not carry any reliable information about resonant scattering of Cl atoms, and are rather dominated by random and systematic errors. The factor calculated using 1941 acentric Friedel pairs is = 0.995. On the other hand, the 2 component of the plot, related to average intensities of Friedel pairs, shows that data are of good quality ( = 0.069). This example illustrates that while using Ag α radiation (λ = 0.56083 Å), scatterers heavier than Cl should be present in a chiral crystal in order to determine confidently the absolute structure of the crystal.
标题化合物CHNO·CHCl是羟胺在具有已知绝对构型的手性试剂上进行双氮杂迈克尔加成反应的产物。该对映体纯的化合物以氯仿溶剂化物形式结晶，空间群为1，在室温下用Ag α射线收集衍射数据。Flack参数精修至 = -0.01 (16)；然而，Flack和Watkin 2图清楚地表明，Friedel对映体之间的差异（图的 分量）并未携带任何关于Cl原子共振散射的可靠信息，而是主要受随机误差和系统误差的影响。使用1941个非中心Friedel对计算得到的 因子为 = 0.995。另一方面，图的2分量与Friedel对的平均强度相关，表明数据质量良好（ = 0.069）。这个例子说明，在使用Ag α射线（λ = 0.56083 Å）时，手性晶体中应存在比Cl重的散射体，以便可靠地确定晶体的绝对结构。
