title: Characterization of a closed-shell fluorine-fluorine bonding interaction in aromatic compounds on the basis of the electron density.
abstract: A bond path linking two saturated fluorine atoms is found to be ubiquitous in crowded difluorinated aromatic compounds. The bond path is shown to persist for a range of internuclear distances (2.3-2.8 A) and a range of relative orientations of the two C-F internuclear axes. The F. . .F bonding is shown to exhibit all the hallmarks of a closed-shell weak interaction. The presence of such a bond path can impart as much as 14 kcal/mol of local stabilization to the molecule in which it exists, a stabilization that can be offset or even overwhelmed by destabilization of other regions in the molecule. Several other weak closed-shell interactions were also found and characterized including F. . .C, F. . .O, and C. . .C interactions, hydrogen bonding, dihydrogen bonding, and hydrogen-hydrogen bonding. This study represents another example of the usefulness and richness of the bond path concept and of the theory of atoms in molecules in general.
authors.affiliation: Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J3.
authors.forename: Chérif F
authors.initials: CF
authors.lastname: Matta
authors.forename: Norberto
authors.initials: N
authors.lastname: Castillo
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Boyd