Attila Kovács, Andrea Szabó, István Hargittai

Structural Characteristics of Intramolecular Hydrogen Bonding in Benzene Derivatives.

Accounts of Chemical Research, 35 (2002) 887-894

In this review the intramolecular hydrogen bonding (HB) properties of various proton acceptor groups (BX_n : C=N, NO₂, C=O, P=O, F, CF₃) with OH and NH₂ (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; 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. Much better agreement wasobserved between the lengthening of the A–H bond and the shift of the OH stretching (n_OH) and OH torsional (t_OH) frequencies.