Photoelectron spectroscopic studies of the electronic structure of some silatranes

Abstract

Ultraviolet photoelectron spectra of 17 substituted silatranes (silatrane = 2,8,9-trioxa-5-aza-1-silabicyclo[3.3.3]undecane), measured for gas-phase samples at convenient temperatures, are presented. The spectra are interpreted using both valence-electron molecular orbital calculations and a composite-molecule model. The first ionization band is, in most cases, assigned to the nitrogen lone-pair electrons which comprise the Siâ†�N dative bond. This assignment is verified by the observed sensitivity of the location of this band towards substitution at the silicon atom. The σ_SiN ionization energies also correlate with the N 1s binding energies measured for these compounds.