Gas-Phase Benzene–Methanol Dimer Configurations: Geometries, Relative Stabilities, and Interaction Energies

The benzene···methanol dimer is one of the simplest systems that manifests an O–H···π nonbonded interaction. This interaction can be found in numerous systems, ranging from small-molecule clusters to biological systems, for example, phenyl-containing ligands bound within a protein’s binding pocket. Herein, four gas-phase configurations are examined using quantum mechanics, which have O–H···π, CH3···π and Bz–H···O interactions. Geometry optimization and frequency calculations were performed up to the MP2/aug-cc-pVQZ theory level, with electronic energies obtained up to the CCSD(T)/complete basis set (CBS) limit. Considering the electronic energy (ΔEel), the O–H···π configuration is the most stable, with a CCSD(T)/CBS (counterpoise corrected) interaction energy of −4.09 kcal mol–1, while the other three configurations ranged from −2.00 to −2.60 kcal mol–1. Using scaled harmonic frequencies, the temperature influence was investigated by computing Gibbs relative and interaction free energies over a 10–800 K temperature range.