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Updated: Jul 12, 2026

Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Non-centrosymmetric racemates: space-group frequencies and conformational similarities between crystallographically
1Department of Chemistry, University of Oslo, PO Box 1033, Blindern, N-0315 Oslo, Norway. bjornda@kjemi.uio.no
Abstract:
DL-Allylglycine (DL-2-amino-4-pentenoic acid, C5H9NO2) yields crystals with Pca2(1) symmetry and two crystallographically independent yet pseudo-inversion-related enantiomers. The distribution among the common space groups of other crystalline racemates with more than one molecule in the asymmetric unit has been established. The conformational similarities between crystallographically independent enantiomers in 114 non-centrosymmetric racemates were quantified using the r.m.s. deviation for a molecular superposition. The analysis shows that in the majority of crystals the conformations of the crystallographically independent molecules are very similar with mean r.m.s. deviation = 0.190 A. In almost 80% of the structures the mean r.m.s. deviations is in the interval 0-0.2 A. It is estimated that racemates constitute 23% of the centrosymmetric organic structures in the Cambridge Structural Database.
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