F or O, Which One Is the Better Hydrogen Bond (Is It?) Acceptor in C–H···X–C (X– = F–, O═) Interactions?

Three sets of statistical analyses have been performed to evaluate whether C–F or C═O is the better C–H hydrogen bond acceptor and to understand the nature and preferred geometry of the C–H···F–C interactions. The first analysis uses Hirshfeld surface of the molecules, which shows that C═O is a better hydrogen bond acceptor than C–F, though C–H···F–C interactions also play an important role in crystal packing. The second analysis compares the population densities of C–H···F–C interactions at different H···F distances and at different C–H···F or C–F···H angles. This analysis shows the directional nature of this interaction. The third analysis shows which combinations of the C–H···F and C–F···H angles are preferred by the C–H···F–C interactions.