Imino tautomers of gas-phase guanine from mid-infrared laser spectroscopy.
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.
Seefeld
Kai
K
Institut für Physikalische Chemie, Heinrich-Heine Universität Düsseldorf, 40225 Düsseldorf, Germany.
Brause
Robert
R
Häber
Thomas
T
Kleinermanns
Karl
K