Klaus‐Dieter Schleinitz

Electronic and molecular structure of some substituted azomethines: a gas-phase u.v. photoelectron spectroscopic investigation

Abstract Four azomethinic molecules, three of which present a seven-member ring with two carbon atoms shared with an aromatic system, have been studied by gas-phase u.v. photoelectron spectroscopy with the aim of correlating their electronic and molecular structure. The analysis of the experimental findings, supported by quantum-mechanical calculation (EHT and HAM/3) on model molecules, showed that no appreciable interactions occur between the systems of the aromatic and of the seven-member ring, and that the electronic structure of these molecules depends critically on the geometry. The comparison with smaller parent molecules pointed out that the formation of the seven-member ring induces drastic changes in the electronic structure of the valence levels.

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

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 σp values, the wavenumbers of the SO2 stretching vibrations, and the 13C n.m.r. shifts for C-1 of the styryl group.