The use of dispersion-corrected DFT calculations to prevent an incorrect structure determination from powder data: the case of acetolone, C11H11N3O3

Abstract

AbstractThe 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 thecheckCIFprocedure. 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 improvedR-values. This structure was confirmed by dispersion-corrected DFT calculations. The compound crystallises inP-1 with two molecules per unit cell. The molecules are connected by a 2-dimensional hydrogen bond network.