| Abstrakt: |
The kinetic method is used to determine the electron inity (EA) of 1,3,5,7-cyclooctatetraene (COT), a compound that undergoes a significant structural change upon electron attachment. Collision-induced dissociation of anionic clusters of COT with a set of reference compounds (Ref), [COT·Ref]-·, at various collision energies, allowed deconvolution of the relative enthalpies and entropies of the competitive reactions. The adiabatic EA of COT is determined to be 0.58±0.10 eV, in good agreement with the value, 0.58±0.04 eV, of Wentworth and Ristau (J. Phys. Chem.1969,73, 2126) determined by thermal electron detachment as well as the more recent value, 0.55±0.02 eV, of Kato et al. (J. Am. Chem. Soc.1997,119, 7863) determined by equilibrium electron transfer with molecular oxygen. A large entropy difference, 25.6±10.0 e.u. (J mol-1K-1), is observed between the two dissociation channels. This entropy difference corresponds to a negative 14.7±13.0 e.u. change for the dissociation of the dimer to give COT-·and the neutral reference compound and a positive 10.9±8.4 e.u. entropy change for the dissociation of the dimer to give Ref-·and neutral COT. |
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