Intermolecular C⋅⋅⋅H–Cl Bonding in Methane, Ethane, and Propane Complexes with Hydrogen Chloride

Abstract

Quantum chemical calculations of binary complexes of methane, ethane, and propane with hydrogen chloride, having an intermolecular С⋅⋅⋅H−Cl bond, were performed by the MP2/aug-cc-pVTZ method. It was shown that the binding of an alkane with an HCl molecule is possible at different mutual orientations of the monomers; the properties of the resulting complexes are similar to those of molecular systems with a typical hydrogen bond. Elongation of the covalent H−Cl bond upon complexation is observed with a frequency shift of the corresponding IR band of the stretching vibrations to the long-wave region and a chemical shift on the bridging hydrogen atom characteristic of H-bonded complexes. The analysis of the nature of the intermolecular bond included decomposition of the binding energy into components, as well as NBO analysis and a study of electron density topology using the AIM method of Bader’s theory. The potential curves of intermolecular interaction and maps of electron density shift upon complexation from monomers were plotted.