An unusually short inter-molecular N-H?N hydrogen bond in crystals of the hemi-hydro-chloride salt of 1-exo-acetamido-pyrrolizidine.

ABSTRACT: The title compound [systematic name: (1R*, 8S)-2-acetamidoocta-hydro-pyrrol-izin-4-ium chloride-N-[(1R, 8S)-hexa-hydro-1H-pyrrolizin-2-yl)acetamide (1/1)], 2(C9H16N2O)·HCl or C9H17N2O+·Cl-·C9H16N2O, arose as an unexpected product when 1-exo-acetamido-pyrrolizidine (AcAP; C9H16N2O) was dissolved in CHCl3. Within the AcAP pyrrolizidine group, the unsubstituted five-membered ring is disordered over two orientations in a 0.897?(5):0.103?(5) ratio. Two AcAP mol-ecules related by a crystallographic twofold axis link to H+ and Cl- ions lying on the rotation axis, thereby forming N-H?N and N-H?Cl?H-N hydrogen bonds. The first of these has an unusually short N?N separation of 2.616?(2)?Å: refinement of different models against the present data set could not distinguish between a symmetrical hydrogen bond (H atom lying on the twofold axis and equidistant from the N atoms) or static or dynamic disorder models (i.e. N-H?N + N?H-N). Computational studies suggest that the disorder model is slightly more stable, but the energy difference is very small.

SUBMITTER: Bhardwaj M 

PROVIDER: S-EPMC6944077 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature