Structures of piperazine, piperidine and morpholine

A Parkin, I D H Oswald, S Parsons

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71 Citations (Scopus)

Abstract

The crystal structures of piperazine, piperidine and morpholine have been determined at 150 K. All three structures are characterized by the formation of NH...N hydrogen-bonded chains. In piperazine these are linked to form sheets, but the chains are shifted so that the molecules interleave. In morpholine there are in addition weak CH...O interactions. Topological analyses show that these three structures are closely related to that of cyclohexane-II, which can be described in terms of a pseudo-cubic close-packed array of molecules in a familiar ABC layered arrangement. While the positions of the molecules within each layer are similar, hydrogen bonding occurs between the ABC layers and in order to accommodate this the molecules are rotated relative to those in cyclohexane-II. Piperidine and morpholine also adopt layered structures, with hydrogen-bonding or CH...O interactions between the layers. In these cases, however, the layering more resembles a hexagonal close-packed arrangement.

Original languageEnglish
Pages (from-to)219-227
Number of pages9
JournalActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials
Volume60
Issue numberPart 2
DOIs
Publication statusPublished - Apr 2004

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Keywords

  • crystal-structures
  • temperature
  • pressure
  • database
  • packings

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