Imidazolidin-2-one: pseudosymmetry and twinning

Abstract

The title compound, C3H6N2O, crystallizes with imposed twofold symmetry in the space groupI41/a. The five-membered ring displays a half-chair conformation. N—H...O hydrogen bonds connect the molecules to formR22(8) rings and thence ribbons parallel to theaandbaxes. These intersectviaO2H2rings involving longer H...O contacts. The crystal was merohedrally twinned. Preliminary indications of the higher symmetry space groupI41/amd, which would require the ring to be planar, proved to be incorrect. A previous brief report of the structure inFdd2 is also probably incorrect.