THEORETICAL STUDY OF IONIZATION POTENTIALS OF N-HETEROCYCLIC COMPOUNDS

Abstract

The ability to predict the redox properties is an important tool for study electron transfer processes occurring in the gas-phase (atmospheric chemistry) or in the condensed phase (electrochemistry, biochemistry). MPWB1K/6-31+G(d) and MPWB1K/tzvp theoretical models were found to provide reasonable accuracy of the prediction of ionization potentials for mono- and polycyclic azacompounds. The root mean square errors of the methods are 0.19 and 0.20, respectively. While the mean absolute deviation for both methods is the same and equals to 0.15 eV . These theoretical models were applied to predict ionization potentials for compounds not evaluated experimentally. Influence of substitutes and a number of nitrogen atoms on value of ionization potential was analyzed. Methyl-, and phenyl- groups, and fused benzo cycle decrease ionization potentials of N -heterocycles. Increase of amount of nitrogen atoms in five-membered cycles leads to significant enlargement of ionization potentials.