On the structure of 4-amino-(Z)-5-(4′-hydroxy-(E)-but-2′enylidene)-1,5-dihydro-2H-imidazol-2-one·H2O in the crystalline state

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The structure of 4-amino-(Z)-5-(4′-hydroxy-(E)-but-2′-enlydinene)-1,5-dihydro-2H-imidazol-2-one monohydrate has been established by X-ray crystallography from diffractometer data: C7H9N3O2·H2O (Mr-185.18) crystallizes in the orthorhombic, space group P212121 with a-4.591 (1) Å, b=9.952 (3) Å, c-19.271 (3) Å, V-880.6 (6) Å3, Z-4, Dc-1.40 g cm-3 and μ(CuKα)=9.0 cm-1. The structure has been solved by direct methods and refined to R=0.037 for 777 observed reflections. While substantiating the molecular geometry inferred from NMR spectra, the X-ray analysis revealed that, in contrast to the preponderance of the 4-imino tautomer (IIb) in solution, in the crystalline state only the 4-amino form (IIa) is present. In solution, the 4-amino tautomer is terminated by the short intramolecular =CH⋯H(NH)- close contact of 2.14 Å repulsing hte contact amino proton to N(3), whereas in crystalline state the hydrogen-bond network developed between the molecules with the assitance of the solvent (water) molecule seems to account for its stability. Among others, the N(1)-H⋯N(3) intermolecular hydrogen bond hardly tolerates a simultaneously protonated N(3) atom required by tautomer IIb.

Original languageEnglish
Pages (from-to)257-263
Number of pages7
JournalJournal of Molecular Structure
Issue numberC
Publication statusPublished - Oct 15 1990

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry
  • Inorganic Chemistry

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