F...HO intramolecular hydrogen bond forming five-membered rings hardly appears in monocyclic organofluorine compounds

Abstract

This paper emphasizes that fluorine atoms in organic molecules need special geometric requirements to experience intramolecular hydrogen bonds (H-bonds). Calculations at the B3LYP/aug-cc-pVDZ theoretical level and using the quantum theory of atoms in molecules applied over a series of monocyclic compounds, which have similar C[double bond, length as m-dash]C(F)–C(OH)[double bond, length as m-dash]C fragments, predict that the F⋯HO intramolecular H-bond does not exist when forming five-membered rings. Indeed, it is shown that the geometric restrictions imposed by the rigid rings are the main reasons in preventing fluorine participating in such a F⋯HO intramolecular H-bond.