Competition between stacking and hydrogen bonding: Theoretical study of the phenol⋯Ar cation and neutral complex and comparison to experiment

Experimental results obtained previously for vdW-bonded and H-bonded phenol⋯argon (PhOH⋯Ar) complexes in their S0 and D 0 states are combined with ab initio quantum-chemical theoretical results. Such a combination allows us to present a "complete" description of the geometry, relative energies, interaction energies and enthalpies of PhOH⋯Ar complexes. Based on a minimum-energy-path study, the transition structures and barrier heights related to transitions between stable conformers are also presented. For the presented structures, the agreement between the theoretical interaction enthalpy at 0 K with experimentally obtained values is very good. On the other hand, for numerical harmonic-frequency calculations we find a very poor performance for the neutral PhOH⋯Ar complex and complete failure for the studied complexes in their cationic form. © the Owner Societies.