Structural Characteristics of Intramolecular Hydrogen Bonding in Benzene Derivatives

Abstract

In this Account, the intramolecular hydrogen bonding (HB) properties of various proton acceptor groups (BX(n): C=N, NO(2), C=O, P=O, F, CF(3)) with OH and NH(2) (AH) in benzene derivatives are assessed on the basis of gas electron diffraction, spectroscopic, and quantum chemical results. The most important properties are the HB energy, the characteristic geometrical changes in the interacting groups (lengthening of the A-H and B-X, shortening of the C-A and C-B bonds) and in the benzene ring, and the vibrational properties of the AH groups. These properties are characteristic of the particular HB interaction (in particular of the AH and BX(n) pair in single and multiple hydrogen-bonded systems); however, they cannot be related directly to the computed HB energies.