The photoelectron spectra of some 1-halogenobicycloalkanes

Abstract

The He^I photoelectron spectra of the 1-bromo- and 1-iodo-substituted bicyclo[2.2.2]octane, bicyclo-[2.2.1]heptane, and bicyclo[2.1.1]hexane have been measured. Comparisons are made with the spectra of the corresponding alkanes, and assignments are derived with the assistance of He^II measurements and ab initio molecular orbital calculations based on a valence-electron model-potential method. The low-ionization-energy region of the spectra reveals interesting variations in the competition of spin–orbit coupling and conjugative effects which operate for ionizations involving the halogen lone-pair orbitals.