Theoretical Investigations of Proton-bound Cluster Ions
Several proton-bound cluster ions have been studied by means of coupled cluster calculations with large basis sets. Among these are complexes of a krypton or xenon atom with the cations HCO+, HN2+ and HNCH+. Various spectroscopic properties have been calculated in all cases. Effects of vibrational anharmonicity are particularly pronounced for the intramolecular stretching vibrations of Kr···HN2+ and Xe···HN2+. The proton stretching vibration of (N2)H+(N2) is predicted around 800 cm−1, with a large transition dipole moment of 1.15 D. Both (N2)H+(N2) and (HCN)H+(NCH) have linear centrosymmetric equilibrium structures. Those of (OC)H+(CO) and (HCC−)H+(CCH−) are asymmetric with barrier heights to the centrosymmetric saddle points of 382 and 2323 cm−1, respectively. The dissociation energy of the anionic complex Cl−···HCCH is calculated to be Do = 3665 cm−1, 650 cm−1 larger than the corresponding value for Br−···HCCH. The complex between a fluoride ion and acetylene is more strongly bound and shows strongly anharmonic behaviour, similar to the bihalides FHF− or ClHCl−. Strong Fermi resonance interaction is predicted between ν3 (∽proton stretch) and 2ν4 (first overtone of intermolecular stretch).
Dutoi, A. D.,
Theoretical Investigations of Proton-bound Cluster Ions.
Faraday Discussions, 118, 433–453.