Resonant two-photon ionization spectra of van der Waals complexes p, m, o-C6H4F2⋯NH3(ND3)

Abstract

Effect of solvent on molecular conformation: Microwave spectra and structures of 2-aminoethanol van der Waals complexesInvestigation of the Ne-NH 3 van der Waals complex: Rotational spectrum and ab initio calculationsWe have studied the resonant two-photon ionization ͑R2PI͒ spectra of three van der Waals ͑vdW͒ complexes p, m, o-C 6 H 4 F 2¯N H 3 ͑ND 3 ͒ through the S 1 ←S 0 transition with mass selectivity. The stretching frequencies of the three vdW complexes were found to be quite close ͑86 cm Ϫ1 ͒. From the photodissociation mechanism and the relationship between anharmonicity of the stretching vibration and the dissociation energy, we estimated the dissociation energies of all the three vdW complexes in the S 0 and S 1 states. A quantum ab initio calculation on p-C 6 H 4 F 2¯N H 3 at the MP2/6-31G** level gave the following geometry: The N atom of NH 3 is located on the symmetry axis ͑Z-axis͒ and 3.53 Å above the benzene ring; the C 3 axis of NH 3 is at an angle of 52.5°with the Z-axis of p-C 6 H 4 F 2 with one of the hydrogen atoms pointing towards the benzene ring; the rotation of NH 3 around the Z-axis is nearly free. The calculated bond dissociation energies and the expectation of internal rotation are consistent with our experimental results.

Molecular Clusters of π-Systems: Theoretical Studies of Structures, Spectra, and Origin of Interaction Energies

“…1 More details on the features of this hydrogen bond can be obtained from the review of Hobza in this issue. The interaction of o-, m-, and p-difluorobenzene with ammonia has been the focus of an experimental investigation by Hu et al 196 Their study also includes some theoretical calculations carried out at the MP2/ 6-31G** level.…”