Non-conventional intramolecular and intermolecular interactions have been investigated employing glycine (VIIp), (NH3HCl)-H-..., (NH3HO)-H-... and (PH3H2O)-H-... as model systems. Geometries and harmonic frequencies were determined at a correlated ab initio level, which shows a elongating of the Cl-H or O-H bond of the proton donor and a red-shifting of the corresponding Cl-H or O-H bond stretching frequency. NBO analysis indicates there is a significant charge transfer from the proton acceptor to the proton donor. However, this type of interaction cannot be called hydrogen bond according to a comparative analysis of electron density topology in the four systems. (c) 2005 Elsevier B.V. All rights reserved.