Molecular orbital calculations of the substituent effect on intermolecular CH/π interaction in C2H3X-C6H6 complexes (X=H, F, Cl, Br, and OH)

The effect of a substituent group in dimeric complexes of benzene with ethylene and its four derivatives on the intermolecular CH/π interaction was studied theoretically. The hydrogen-bonding nature of the CH/π interaction is confirmed by the bond critical point analysis within the atoms-in-molecules (AIM) theory. It has been found that the CH · · · π access angle depends on the exchange repulsion and the induction effect from the substituent group. The effect of the CT interaction by the substituent group is energetically insignificant. However, the charge density can be varied by substitution, and this contribution cannot be ignored.