Theoretical study of intermolecular interactions in benzopyrans substituted with polyhaloalkyl groups

Halogen bonds have been found to occur in organic, inorganic, and biological systems, these bonds can be defined as a short C-X---O-Y interaction, where the X---O distance is less than or equal to the sums of the respective van der Waals radius, and have recently attracted much attention in medical chemistry, chemical biology and supramolecular chemistry. A study of the solid-state intermolecular interactions of twenty-nine benzopyrans substituted with polyhaloalkyl groups was carried out by quantum chemical calculations using the Mercury and WinGX computer programs. Molecular structures were obtained from crystallographic information files (CIF) of the CCDC database. C-H---O, C-H---X, C-X---O and C-X---X type contacts, characterized as unconventional hydrogen bonds, were identified and calculated. The criteria used for distances and angles were d(D---A) < R(D) + R(A) + 0.50 and d(H---A) < R(H) + R(A) - 0.12°, D-H---A > 100.0°, where D is the donor atom, A is the acceptor atom, R is the Van der Waals radius and d is the interatomic distance. In addition, Etter's notation was used to describe sets of hydrogen bonds in organic crystals, detailing the intermolecular contacts and periodic arrangements of the crystal packing. It was corroborated that certain positions of halogen atoms and their interactions play an important role in stabilizing the crystal lattice.