On the empirical correlation schemes for ionization energies in ring compounds

Abstract

HeI photoelectron spectra of various five- and six-membered ring compounds with either a sulfur heteroatom or a sulfone group, and/or double bond(s), both unsubstituted and methyl-substituted, have been measured. In the case of five-membered rings, the values of the low energy ionization potentials can be reproduced within 0.1eV through a simple empirical correlation scheme and a set of transferable parameters. The same approach does not work for six-membered ring compounds where substantial and non-uniform deviation from planarity complicates the scheme. The results also show that conjugative interaction of the sulfone group with the double bond in these compounds is very weak.