Anhydrous 1-methyl­imidazolidin-2-one

The title compound, C₄H₈N₂O, crystallizes from the vapor phase in sheets supported by a one-dimensional hydrogen-bonded network. The mol­ecular unit shows planar ureido -NCH₃ groups, but the slight out-of-plane hydrogen-bond geometry may be indicative of some pyramidalization of the ureido -NH groups.