Crystal structure of malonamide

Abstract

Crystals of malonamide, CH₂(CONH₂)₂, are monoclinic, space group P2₁/c, a= 13·07, b= 9·45, c= 8·04 Å, β= 73·0°, Z= 8 (two molecules in the asymmetric unit). The structure was determined with Mo-K_α diffractometer data by the symbolic addition procedure, and refined by least-squares methods, to R 0·05 for 941 observed reflexions. Hydrogen atom positions were determined.

The two symmetry-unrelated molecules have different orientations in the crystal, but have similar conformations and dimensions. The amide groups are rotated out of the central CCC plane, one group in each molecule by about 65°, and the other group by 40°. The mean bond distances, after applying rotational oscillation corrections, are C–C 1·507, C–N 1·334, C–O 1·253 Å(σ 0·004 Å); there are no significant deviations from these mean values. The molecules are held together by a system of eight N–H ⋯ O hydrogen bonds (2·89–3·14 Å) involving all the amino-hydrogen atoms, with each oxygen atom acting as an acceptor in two hydrogen bonds.