Electron affinity of 1,3,5,7-cyclooctatetraene determined by the kinetic method

• Published in: Journal of the American Society for Mass Spectrometry 1998, Vol.9 (11), p.1141-1145
• Main Authors: Denault, Jeff W., Chen, Guodong, Cooks, R.Graham
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; Mass spectrometry; Organic chemistry; Reactivity and mechanisms
• ISSN: 1044-0305; 1879-1123
• DOI: 10.1016/S1044-0305(98)00092-0

The kinetic method is used to determine the electron affinity (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 −1 K −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.