Intermolecular dissociation energies of dispersively bound complexes of aromatics with noble gases and nitrogen

We measured accurate intermolecular dissociation energies D₀ of the supersonic jet-cooled complexes of 1-naphthol (1NpOH) with the noble gases Ne, Ar, Kr, and Xe and with N₂, using the stimulated-emission pumping resonant two-photon ionization method. The ground-state values D₀(S₀) for the 1NpOH·S complexes with S= Ar, Kr, Xe, and N₂ were bracketed to be within ±3.5%; they are 5.67 ± 0.05 kJ/mol for S = Ar, 7.34 ± 0.07 kJ/mol for S = Kr, 10.8 ± 0.28 kJ/mol for S = Xe, 6.67 ± 0.08 kJ/mol for isomer 1 of the 1NpOH·N₂ complex, and 6.62 ± 0.22 kJ/mol for the corresponding isomer 2. For S = Ne, the upper limit is D₀ < 3.36 kJ/mol. The dissociation energies increase by 1%-5% upon S₀ → S₁ excitation of the complexes. Three dispersion-corrected density functional theory (DFT-D) methods (B97-D3, B3LYP-D3, and ωB97X-D) predict that the most stable form of these complexes involves dispersive binding to the naphthalene "face." A more weakly bound edge isomer is predicted in which the S moiety is H-bonded to the OH group of 1NpOH; however, no edge isomers were observed experimentally. The B97-D3 calculated dissociation energies D₀(S₀) of the face complexes with Ar, Kr, and N₂ agree with the experimental values within <5%, but the D₀(S₀) for Xe is 12% too low. The B3LYP-D3 and ωB97X-D calculated D₀(S₀) values exhibit larger deviations to both larger and smaller dissociation energies. For comparison to 1-naphthol, we calculated the D₀(S₀) of the carbazole complexes with S = Ne, Ar, Kr, Xe, and N₂ using the same DFT-D methods. The respective experimental values have been previously determined to be within <2%. Again, the B97-D3 results are in the best overall agreement with experiment.