Ab initio study of the molecular structure and photoelectron spectra of caged monoamines and diamines

Abstract

Complete geometry optimization of 1, k + 2-diaza- and 1-aza-bicyclo[ k. k. k]alkanes ( k = 1, 2, 3, and 4) was carried out at the SCF/6-31G ∗ level of theory. The equilibrium structures range from out,out, to in,out and in,in conformations, controlled by a delicate balance between nitrogen pyramidalization, valence angles, torsion angles and transannular H···H non-bonded effects. The outer valence ionization potentials of these caged amines were investigated at the ab initio level using the outer valence Green function approach. The theoretical results give an overall, consistent reproduction of the main features in the photo-electron spectra, in particular of the n bands. A comparative analysis of the relative effects of the through-bond and through-space interactions on the nitrogen lone pair energies is also reported.