title: Cryogenic neon matrix-isolation FTIR spectroscopy of evaporated ionic liquids: geometrical structure of cation-anion 1:1 pair in the gas phase.
abstract: Low-temperature infrared spectra of thermally evaporated ionic liquids, 1-ethyl- and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and bis(trifluoromethanesulfonyl)amide have been measured in a cryogenic Ne matrix. The experimental IR spectrum of bis(trifluoromethanesulfonyl)amide can be reproduced theoretically by not B3LYP/6-31G* but MP2/6-31G* calculation, which suggests that the vibrational analysis for ionic liquids composed of bis(trifluoromethanesulfonyl)imide anion would be more successfully performed using the MP2 calculation. By comparison of the matrix-isolation spectra of the ionic liquids with the MP2 calculation, their geometrical structures in the gas phase are determined to be of C(2-position)-H(+)...N(-) interaction structure, which corresponds to the geometry of the energetically second-lowest ion-pair structure. The present study may provide a valuable clue to understand a vaporization mechanism of ionic liquid.
authors.affiliation: Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 H57 Ohokayama, Meguro-ku, Tokyo 152-8551, Japan. akai.n.ab@m.titech.ac.jp
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Akai
authors.forename: David
authors.initials: D
authors.lastname: Parazs
authors.forename: Akio
authors.initials: A
authors.lastname: Kawai
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Shibuya
mesh_terms: D000838:Anions / Q000737:chemistry; D002412:Cations / Q000737:chemistry; D003198:Computer Simulation; D005740:Gases / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D017550:Spectroscopy, Fourier Transform Infrared; D013449:Sulfonamides / Q000737:chemistry*; D013696:Temperature
chemical_list: C419324:1-butyl-3-methylimidazolium tetrafluoroborate; C517865:1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide; D000838:Anions; D002412:Cations; D005740:Gases; D007093:Imidazoles; D052578:Ionic Liquids; D013449:Sulfonamides