Substituent effects on the electronic structure of some styryl methyl sulphones studied by ultraviolet photoelectron spectroscopy

Abstract

A gas-phase u.v. photoelectron spectroscopic study is reported on some para-substituted styryl methylsulphones in which the para-substituent varies in electronegativity and conjugating ability. The main purpose was to observe the substituent effect on electronic structure. The spectral analysis and the trends in ionization energies relative to the highest MOs show that the substituent has both short- and long- range effects, influencing even the orbitals of the –SO₂Me group. Satisfactory linear relationships were found between the spectral data for the three highest MOs and the Hammett σ_p values, the wavenumbers of the SO₂ stretching vibrations, and the ¹³C n.m.r. shifts for C-1 of the styryl group.