Further Evidence on the Importance of Fluorous–Fluorous Interactions in Supramolecular Chemistry: A Combined Structural and Computational Study

The solid-state structures of CF₃(CF₂)₅CH₂CO₂H and a fluorous triazole are reported, both of which display a wide variety and large number of noncovalent interactions in their packing. The solid-state structure of CF₃(CF₂)₅CH₂CO₂H is stabilized by multiple F···F contacts but only one C–H···F–C interaction, as well as O–H···O and C–H···O hydrogen bonds. In contrast to other reported structures, the torsion angles in the fluorous chain are close to 180°, which means that the fluorine atoms are eclipsed. A DFT study of the interactions in both compounds show that F···F interactions, along with stacking and C–H···F and C–H···O contacts, are individually weakly energetically stabilizing, but collectively, they can give rise to interaction energies of up to 13 kcal mol^–1. A topological approach to the interactions using atoms-in-molecules (AIM) theory reveals that there are bond critical points between the C–F···F–C interactions as well as C–F···H–C interactions that are not recognized when using only the van der Waals distances.