Syntheses, crystal structures, Hirshfeld surface analyses and crystal voids of...

The asymmetric units of the compounds, C₈H₅BrCl₂O (I), and C₉H₈Br₂O (II), contain two and one crystallographically independent mol-ecules, respectively. In compound (I), the planar rings are oriented at a dihedral angle of 13.23 (8)°. In crystals of both compounds, inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into infinite chains along the b-axis direction. In crystal of (I), there are π-π inter-actions between the centroids of the parallel rings with centroid-to-centroid distances of 3.5974 (14), 3.6178 (16) and 3.9387 (16) Å while neither π-π nor C-H⋯ π(ring) inter-actions are present in (II). The Hirshfeld surface analyses of the crystal structures indicate that the most important contributions for the crystal packings are from H⋯Cl/Cl⋯H (27.5%), H⋯O/O⋯H (15.0%), H⋯Br/Br⋯H (10.2%) and H⋯H (9.0%) for (I) and H⋯Br/Br⋯H (36.1%), H⋯H (22.2%), H⋯O/O⋯H (14.1%) and H⋯C/C⋯H (13.9%) for (II). Hydrogen bonding and van der Waals inter-actions are the dominant inter-actions in the crystal packings. The volumes of the crystal voids and the percentages of free spaces in the unit cells were calculated to 111.55 ų and 12.27% for (I) and 63.37 Å and 6.69% for (II), showing that no large cavities are present in either structure.