The crystal structure of acetolone (5-(acetoacetylamino)benzimidazolone, C11H11N3O3), was determined from X-ray powder data. Despite strong preferred orientation effects, the structure could be solved with real-space methods and refined by the Rietveld method using restraints. The resulting structure gave a good Rietveld fit with reasonable confidence values; the structure looked chemically sensible and passed all tests including a CSD check and the checkCIF procedure. But dispersion-corrected density functional theory (DFT) calculations revealed that this structure was actually wrong, and further work showed that the terminal acetyl group had to be rotated by 180°. The correct crystal structure led to a better Rietveld refinement with improved R-values. This structure was confirmed by dispersion-corrected DFT calculations. The compound crystallises in P-1 with two molecules per unit cell. The molecules are connected by a 2-dimensional hydrogen bond network.
Zeitschrift für Kristallographie – Crystalline Materials offers a place for researchers to present results of their crystallographic studies. The journal includes theoretical as well as experimental research. It publishes Original Papers, Letters and Review Articles in manifold areas of crystallography.