title: Imino tautomers of gas-phase guanine from mid-infrared laser spectroscopy.
abstract: We reinvestigated the assignment of the three major guanine conformers detected via resonance enhanced two-photon ionization (R2PI) in supersonic expansions and present IR/UV double resonance spectra in the spectral region between 1500 and 1800 cm(-1). Comparison with B3LYP/TZVPP and RI-MP2/cc-pVQZ calculations shows that both conformers B and C are 7H-keto tautomers with an imine group in the 2-position. They differ only in the local conformation of the imine group but are otherwise identical. Conformer A is an amino-enol form with the OH group in the trans position.
authors.affiliation: Institut für Physikalische Chemie, Heinrich-Heine Universität Düsseldorf, 40225 Düsseldorf, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Seefeld
authors.forename: Robert
authors.initials: R
authors.lastname: Brause
authors.forename: Thomas
authors.initials: T
authors.lastname: Häber
authors.forename: Karl
authors.initials: K
authors.lastname: Kleinermanns