An estimation of strength of intramolecular hydrogen bonds - ab initio and AIM studies

Intramolecular H-bonds existing for derivatives of malonaldehyde have been studied by using the MP2/6-311 + + G(**) level of theory. The nature of these interactions, known as resonance assisted hydrogen bonds, has been discussed. The topological properties of the electron density distributions for O-(HO)-O-... intramolecular bridges have been analyzed in terms of the Bader theory of atoms in molecules (AIM). The results of calculations show that the e-parameter describing the degree of pi -electron delocalization within the O=C-C=C-O-H keto-enol group correlates with the strength of the H-bond. Correlations between the H-bond strength and topological parameters have been also studied. (C) 2001 Elsevier Science B.V. All rights reserved.