The He(I) and He(II) photoelectron spectra of silylated nitrogen and oxygen compounds were recorded in order to study their electronic structure and geometry. The X-ray crystal structure of N-trimethylsilyl O-tert-butyl carbamate is given. Ab initio Hartree-Fock calculations were also carried out to obtain theoretical geometries of the compounds and to help the assignments of their photoelectron spectra by means of Koopmans' theorem. Our results show that the planar/pyramidal spatial arrangements around nitrogen in the investigated compounds can be rationalised by the negative hyperconjugative effect of silyl group(s), by electrostatic effects and by the lone-pair repulsion of the neighbouring nitrogen and oxygen atoms. The considerable distortions in geometry cause only small variations in the electronic structure, and there are relatively small energy differences (about 15-20 kJ mol-1) between the planar and the pyramidal conformers. These conclusions can also be applied for silylated oxygen compounds.
- Ultraviolet photoelectron spectroscopy
- X-ray diffraction
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry
- Materials Chemistry