Use of intensity quotients and differences in absolute structure refinement

Abstract

Differences and quotients can be defined using Friedel pairs of reflections and applied in refinement to enable absolute structure to be determined precisely even for light atom crystal structures.

Design, synthesis and antitrypanosomal activities of 2,6-disubstituted-4,5,7-trifluorobenzothiophenes

“…Computational studies to predict oral druglikeness demonstrated no compound within this study violated more than one of the parameters constituting Lipinski's rule of 5 and all fall within acceptable limits of rotational bond count and polar surface area [21,22,23,24]. The structure of compound 5bb was confirmed by single crystal X-ray diffraction analysis, with the molecular structure shown in Figure 1 [25,26,27]. (Table 1) were screened in a phenotypic assay against Trypanosoma brucei rhodesiense (STIB 900) and cytotoxicities determined against MCF7 cells [28].…”

The crystal structure of 3-((1R,2S)-1-methylpyrrolidin-1-ium-2-yl)pyridin-1-ium tetrachloridocobaltate(II) monohydrate, C10H18Cl4CoN2O

“…Their U iso values were set to 1.2Ueq of the parent atoms. The absolute structure was established by refinement of the Flack parameter (−0.009(11) from 1458 selected quotients) using Parsons' method [5]. The classical refinement of the Flack parameter gave a similar result (−0.012(23)) [3].…”

“…The bond lengths and angles within these moieties are in the expected ranges. As discussed recently [5], the protonation at the nitrogen atom of the pyrrolidinylium moiety leads to a second chiral center at N2 …”

Crystal structures of (N-methyl-N-phenylamino)(N-methyl-N-phenylcarbamoyl)sulfide and the corresponding disulfane

“…Hydrogen atoms were included at calculated positions [C-H(aromatic) = 0.95 Å or C-H(methyl) = 0.98 Å ] and treated as riding, with U iso H = 1.2U eq C(aromatic) or 1.5U eq C(methyl). With (I), although of no importance in this achiral molecule, the Flack absolute structure factor (Parsons et al, 2013) was determined as 0.05 (3) for 1450 Friedel pairs. Crystal packing of (II).…”