Vibrational frequency-shifts of H2O caused by complex formation with a molecular cation: a density functional study

Citation
H. Tachikawa et al., Vibrational frequency-shifts of H2O caused by complex formation with a molecular cation: a density functional study, PHYS CHEM P, 3(15), 2001, pp. 3052-3056
Citations number
24
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
ISSN journal
14639076 → ACNP
Volume
3
Issue
15
Year of publication
2001
Pages
3052 - 3056
Database
ISI
SICI code
1463-9076(2001)3:15<3052:VFOHCB>2.0.ZU;2-E
Abstract
Structure and vibrational frequencies of the benzene-water complex cation [ BzH(2)O](+) have been calculated by means of density functional theory (B3L YP calculation). A planar structure with a C-s symmetry, in which all heavy atoms are located on a molecular plane, was obtained as the most stable fo rm of the [BzH(2)O](+) cation. Hydrogen atoms of the water molecule are loc ated above and below the molecular plane. From the present calculations, it was predicted that vibrational frequencies of symmetric and asymmetric O-H stretching modes of H2O (nu (1) and nu (3) modes, respectively) are red-sh ifted from those of a free H2O by the formation of a complex, whereas the H -O-H bending mode (nu (2) mode) is blue-shifted. Infrared intensities of th e three modes of H2O were significantly increased by the complex formation. Similar features were obtained for the ethylene-H2O complex cation [C2H4-H 2O](+). The origin of the frequency-shifts is discussed on the basis of the oretical results. The hydrogen-hyperfine coupling constants of the complex cations were also predicted theoretically.