Photoelectron spectra and electronic structure of nitrogen analogues of boron β-diketonates

The electronic structure of the valence levels of seven nitrogen-containing boron complexes was investigated using methods of ultraviolet photoelectron spectroscopy and density functional theory. The ionization energies of pi- and sigma-levels were obtained from photoelectron spectra. The electronic structure of nitrogen-containing compounds was compared with the electronic structure of beta-diketonates. It was shown the influence of various substituents on carbon and nitrogen atoms of six-membered ring on the electronic structure of complexes. The changes in the electronic structure after the substitution of atoms in condensed cycles have been identified. In order to compare the experimental vertical ionization energies IEi with Kohn-Sham orbital energies epsilon(i) we used the analogue of Koopmans theorem and average amendment to the orbital energy of the electrons ((delta) over bar (i)). For 26 electronic levels of seven studied complexes, the calculated values are in good accordance with experimental energy intervals between electron levels. (C) 2016 Elsevier B.V. All rights reserved.