Analysis of intramolecular hydrogen bonding in terms of the topological properties of the charge density. The protonated fluoroacetones

A new method for the analysis of intramolecular hydrogen bonding is proposed and applied to the equilibrium structures of the protonated fluoroacetones. The method, based on a theory of molecular structure due to Bader, uses the topological properties of the charge density to elucidate the types of interactions within a molecule of interest. The calculations show a strong basis set dependence. In particular, the STO-3G optimized geometries exhibit intramolecular hydrogen bonding between a fluorine substituent and the carbonyl proton, whereas some calculations with geometries optimized at the 4-31G and 6-31G* levels indicate a direct bonding interaction between the fluorine and oxygen atoms. Two types of catastrophe point, namely conflict and bifurcation, are possible in protonated monofluoroacetone. Only the latter was located in the present calculations.