Intermolecular Dissociation Energies of 1-Naphthol Complexes with Ethene and Chloroethenes

The stimulated-emission-pumping/resonant 2-photon ionization (SEP-R2PI) method was used to determine the intermolecular ground-state dissociation energies, D0(S0) of jet-cooled complexes of 1- naphthol (1NpOH) with ethene, trans-1,2-dichloroethene, trichloroethene and tetrachloroethene. UV/UV holeburning measurements revealed a single isomer for the ethene and tetrachloroethene complexes, two isomers (A, B) for the trans-1,2-dichloroethene and four for the trichloroethene complex. The D0(S0) of 1-naphtholethene was measured to be 13.370.29 kJ/mol, those of 1NpOHtrans-1,2-dichloroethene are 21.990.10 kJ/mol for isomer A and 21.940.07 kJ/mol for isomer B. That of 1-naphtholtrichloroethene (isomer A) is 25.680.24 kJ/mol, and that of 1- naphtholtetrachloroethene is 26.700.39 kJ/mol. Calculations of the same complexes were carried out with the dispersion-corrected density functional methods B97-D3, B3LYP-D3 and B97xD. The ethene complex is predicted to have an Edge geometry, with the naphthol -OH group forming a hydrogen bond to the ethene C=C double bond. The polychloroethene complexes are predicted to have Face structures, with the admolecule adsorbed onto the naphthalene aromatic ring. All three DFT-D methods predict minimum-energy structures with the plane of the chloroethene tilted away from the plane of the naphthalene moiety.