Effect of the Substituents on the Nature and Strength of Lone-Pair-Carbonyl Interactions in Acyl Halides

We have performed a combined structural and theoretical analysis of lone-pair-carbonyl interactions in several families of acyl halides (R-CO-X). CSD searches have allowed us to establish the geometrical preferences for such short contacts. The study of the molecular electrostatic potential (MEP) of several molecules along with an energy decomposition analysis (EDA) disclosed the nature of the interaction and the factors that affect its strength. To further understand lone-pair-carbonyl contacts, we have systematically analyzed, by means of DFT calculations, the effect of the lone pair as well as of the halogen atom (X) and the substituent attached to the carbonyl group (R). Interaction energies up to 3 kcal/mol suggest that these interactions can be exploited in crystal design and supramolecular chemistry.