PHOTOELECTRON-SPECTRA AND MOLECULAR-PROPERTIES .148. 1ST VERTICAL IONIZATION ENERGIES OF BETA-TRIMETHYL-SUBSTITUTED ETHERS RO-CH(3-N)[SI(CH3)3]N

The first vertical ionization energies of dialkylethers are lowered up to 3 eV (!) by beta-trimethylsilyl substituents and, therefore, further confirm the powerful electron donor effect of -CH3-n[Si(CH3)3]n and -Si[Si(CH3)3]3 groups. The gas-phase photoelectron spectra are assigned based on geometry-optimized MNDO calculations and the substituent effects are discussed in terms of conformationally dependent hyperconjugative second order perturbations.