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Title: Theoretical study of the fragmentation pathways of norbornane in its doubly ionized ground state
Authors: KNIPPENBERG, Stefan
FRANCOIS, Jean-Pierre
DELEUZE, Michael
Issue Date: 2007
Citation: JOURNAL OF PHYSICAL CHEMISTRY A, 111(42). p. 10834-10848
Abstract: The potential energy surface of norbornane in its dicationic singlet ground state has been investigated in detail using density functional theory along with the nonlocal hybrid and gradient-corrected Becke three-parameter Lee-Yang-Parr functional (B3LYP) and the cc-pVDZ basis set. For the sake of more quantitative insight into the chemical reactions induced by double ionization of norbornane, this study was supplemented by a calculation of basic thermodynamic state functions coupled to a focal point analysis of energy differences obtained using correlation treatments and basis sets of improving quality, enabling an extrapolation of these energy differences at the CCSD(T) level in the limit of an asymptotically complete (cc-pV infinity Z) basis set. Our results demonstrate the likelihood of an ultrafast intramolecular rearrangement of the saturated hydrocarbon cage after a sudden removal of two electrons into a kinetically metastable five-membered cyclic C5H8+-CH+-CH3 intermediate, prior to a Coulomb explosion into C5H7+=CH2 and CH3+ fragments, which might explain a tremendous rise of electron-impact (e, 2e) ionization cross sections at electron binding energies around the double-ionization threshold. The first step is straightforward and strongly exothermic (Delta H-298 = -114.0 kcal mol(-1)). The second step is also exothermic (Delta H-298 = -10.2 kcal mol(-1)) but requires an activation enthalpy (Delta H-298(dagger)) of 39.7 kcal/mol. The various factors governing the structure of this intermediate, such as electrostatic interactions, inductive effects, cyclic strains, and methylenic hyperconjugation interactions, are discussed in detail.
Notes: Hasselt Univ, Dept SBG, B-3590 Diepenbeek, Belgium.Deleuze, MS, Hasselt Univ, Dept SBG, Agoralaan,Gebouw D, B-3590 Diepenbeek, Belgium.michael.deleuze@uhasselt.be
URI: http://hdl.handle.net/1942/7843
DOI: 10.1021/jp074207r
ISI #: 000251947900051
ISSN: 1089-5639
Category: A1
Type: Journal Contribution
Validation: ecoom, 2009
Appears in Collections: Research publications

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