Crystal Structure Determination of 5,6-Dibromoacenaphthene from X-ray Powder Diffraction Data

The new crystal structure of 5,6-dibromoacenaphthene has been successfully determined from X-ray powder diffraction data with monoclinic crystals, P21/n, a = 7.88(1) Å, b = 11.64(1) Å, c = 11.62(1) Å, β =107.09(9)°, V = 1019.9(1) Å and Z = 4. Individual reflection intensities were extracted by means of Le Bail’s method. The molecular structure of 1 was solved by direct methods and refined using the combination of least-squares and Rietveld methods. The final Rietveld refinement converged to the value of Rp = 0.114, Rwp = 0.155, Bragg-Rf = 5.28 for 8532 data points and 933 extracted reflections collected in the 2° < 2θ < 95° range. The molecules have an interplanar π-π interaction between the acenaphthene planes with the average distance of 3.57(9) Å. Moreover, the molecular dimer-pairwise packing diagram has an unexpected straight stacking, as opposed to the usual lateral stacking normally occured in 5,6-dihaloacenaphthene.