title: Structural isomerization of the gas-phase 2-norbornyl cation revealed with infrared spectroscopy and computational chemistry.
abstract: In an attempt to produce the 2-norbornyl cation (2NB(+)) in the gas phase, protonation of norbornene was accomplished in a pulsed discharge ion source coupled with a supersonic molecular beam. The C7H11(+) cation was size-selected in a time-of-flight mass spectrometer and investigated with infrared laser photodissociation spectroscopy using the method of "tagging" with argon. The resulting vibrational spectrum, containing sharp bands in the C-H stretching and fingerprint regions, was compared to that predicted by computational chemistry. However, the measured spectrum did not match that of 2NB(+), prompting a detailed computational study of other possible isomers of C7H11(+). This study finds five isomers more stable than 2NB(+). The spectrum obtained corresponds to the 1,3-dimethylcyclopentenyl cation, the global minimum-energy structure for C7H11(+), which is produced through an unanticipated ring-opening rearrangement path.
authors.affiliation: Department of Chemistry, University of Georgia, Athens, GA 30602 (USA) http://maduncan.myweb.uga.edu.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Mosley
authors.forename: Justin W
authors.initials: JW
authors.lastname: Young
authors.forename: Jay
authors.initials: J
authors.lastname: Agarwal
authors.forename: Henry F
authors.initials: HF
authors.lastname: Schaefer
authors.forename: Paul v R
authors.initials: Pv
authors.lastname: Schleyer
authors.forename: Michael A
authors.initials: MA
authors.lastname: Duncan
keywords: carbocations; computational chemistry; ion spectroscopy; mass spectrometry