Infrared spectra and structures of aniline+–furan and aniline+–phenol: Preference between π-type and σ-type hydrogen-bonded structures

Infrared photodissociation spectra of aniline+–M (M = thiophene, furan and phenol) are measured in the 2700–3700 cm–1 region and analyzed by density functional theory calculations. Only a structure with a π-type hydrogen bond is found for aniline+–thiophene. Two structural isomers are identified for aniline+–furan and aniline+–phenol, which have either a π-type or a σ-type hydrogen bond, where an amino proton of aniline+ interacts with the π-electrons or the oxygen atom of the neutral molecules, respectively. The isomer with a σ-type hydrogen bond is more stable for aniline+–phenol, while less stable for aniline+–furan. __________________ * Corresponding author. Fax: +81-92-642-2607. E-mail address: [email protected] (K. Ohashi).