Penning ionization electron spectroscopy of anisole, thioanisole, and selenoanisole by collision with He*(23S): Conjugation effects and conformational stability

Abstract

The electronic structures of chalcogenoanisole C6H5XCH3 (X = O, S, and Se) have been determined by Penning ionization electron spectroscopy experiments with density functional theory (DFT), multi-configuration molecular orbital, and natural bond orbital (NBO) calculations. Ionization energies and electron distributions outside molecular surfaces were calculated by outer valence Green's functions (OVGF) and exterior electron density (EED) calculations, respectively. The PIES spectra and calculations allow characterizations of conformational potential with respect to the Cring-X bond. It has been found that selenoanisole is in the vertical from. The σ-π interaction is calculated to become stronger on going X = O → S → Se.