Supramolecular Perspective of Coordination Effects on Fluorine Interactions
Marija M. Petković Benazzouz, Aleksandra Rakić, Nemanja Trišović, Božidarka Zarić, Goran V. Janjić
Abstract
Coordination effects have been considered through the most common interactions in the crystal structures of fluoro compounds (C–H/F and F/F interactions). The supramolecular profile of these effects is based on quantum-chemical calculations for the assessment of the interaction strength and electrostatic potential maps, which provide a qualitative insight into the examined effect. Coordination of aliphatic fluorides leads to an increase of the negative potential of the F atoms, and, hence, an increase in the hydrogen-bonding acceptor ability (strengthening of C–H/F interactions) and a weakening of the F/F interactions, due to an increase in repulsive interactions between the F atoms. There is no significant change in the potential of the F atoms due to coordination of C6-aromatic fluorides, as in the case of aliphatic ones. This results in slight changes in the strengths of the C–H/F and F/F interactions (coupled with parallel interaction at large offsets, PILO), in a noticeable enhancement of stacking interactions, as well as in a significant enhancement of interactions involving the π-system (F/π and C–H/π interactions). It has also been shown that a decrease in the charge of the metal ions leads to a decrease in the negative potential of the F atom and also that the nature of the metal ion has a significant influence on the value of the potential of the F atoms.