Berlin 2001 – wissenschaftliches Programm
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MO: Molekülphysik
MO 3: Reactive and Energy Transfer Processes
MO 3.3: Vortrag
Montag, 2. April 2001, 16:15–16:30, H1058
Gas Phase Protonation of Aromatic Molecules — •Nicola Solca and Otto Dopfer — Institute for Physical Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
Protonated aromatic molecules AH+ are very important species in chemistry and biochemistry. For instance, arenium ions appear as reactive intermediates in electrophilic aromatic substitution reactions (σ-complexes) and their stability often determine the kinetic and thermodynamic properties of the reaction [1]. In this contribution, we present the first spectroscopic information on the gas-phase protonation of aniline, phenol and p-fluorophenol. For this purpose, mid-infrared photodissociation (IRPD) spectra of protonated phenol, p-fluorophenol and aniline complexed with neutral ligands L (L=Ar, N2) are analyzed in the region of the X-H stretch fundamentals (X=C,N,O). The ligand L is considered as a No-dqmessengerNo-dq or No-dqspyNo-dq, which only slightly perturbs the stability of the bare monomer. The effects of complexation identify the protonation site and provide also information on the intermolecular potential and microsolvation of the bare ion.
[1] R. Holman, T.Eary, E. Whittle and M. L. Gross, J. Chem. Soc., Prekin Trans. 2, 10, 2187 (1998).