Can QTAIM topological parameters be a measure of hydrogen bonding strength?

Abstract

The block-localized wave function (BLW) method, which is the simplest variant of ab initio valence bond (VB) theory, together with the quantum theory of atoms in molecules (QTAIM) approach, have been used to probe the intramolecular hydrogen bonding interactions in a series of representative systems of resonance-assisted hydrogen bonds (RAHBs). RAHB is characteristic of the cooperativity between the π-electron delocalization and hydrogen bonding interactions and is identified in many biological systems. While the deactivation of the π resonance in these RAHB systems by the use of the BLW method is expected to considerably weaken the hydrogen bonding strength, little change on the topological properties of electron densities at hydrogen bond critical points (HBCPs) is observed. This raises a question of whether the QTAIM topological parameters can be an effective measure of hydrogen bond strength. © 2012 American Chemical Society.