TuP-17
AN EXPERIMENTAL AND THEORETICAL STUDY OF THE CYCLOALKANE IONIZATION ENERGIES
John C. Traeger and Barbara. M. Kompé
School of Chemistry, La Trobe University, Bundoora, Victoria 3083
In a recent study, Holmes and Lossing [1] found that, unlike other homologous series of organic compounds, the adiabatic ionization energies for the cycloalkanes were independent of size. However, their experimental value for the ionization energy of cyclopentane was significantly lower than all previous studies [2].
We have investigated the effect of size on the adiabatic ionization energies for the C3-C8 cycloalkanes both experimentally, using photoionization mass spectrometry, and theoretically, using ab initio molecular orbital calculations. In each case the ionization energy for cyclopentane is higher than any other homolog. Rather than this value being anomalously high, the observed trend can be explained in terms of the cyclopropane and cyclobutane ionization energies being lower than expected due to destabilizing effects associated with their smaller ring size.
1. Holmes, J. L.; Lossing, F. P. Org. Mass Spectrom. 1991, 26, 537-541.
2. Lias, S. G.; Bartmess, J. E.; Liebman, J. F.; Holmes, J. L.; Levin, R. D.; Mallard, W. G. J. Phys. Chem. Ref. Data 1988, 17 Suppl. 1.