Theoretical study on the intramolecular hydrogen bond in chloro-substituted N,N-dimethylaminomethylphenols. I. Structural effects

Ab initio and density functional calculations are applied to study the influence of an increasing number of chlorine substituents on the properties of the intramolecular hydrogen bond in substituted Mannich bases. It is shown, that not only the acidity of the proton donor, which depends on the number of chlorine atoms at the aromatic ring, but also steric interactions modify the geometry of the hydrogen bond. Specific interactions of O–Cl· · ·H–O hydrogen-bonding in some derivatives are estimated by calculations on related chlorophenols. q 2003 Elsevier B.V. All rights reserved