Topological analysis of the electron localisation function (ELF) applied to the electronic structure of oxaziridine: the nature of N-O bond

Abstract

Topological analysis of the electron localisation function (ELF), natural bond orbital and Wiberg bond index calculations have been applied to study the electronic structure of the oxaziridine molecule with a special focus on the nitrogen-oxygen bond. The calculations have been performed at the DFT(B3LYP, CAM-B3LYP, ωB97XD, M06-L, M06-2X) and post-Hartree-Fock (CCSD(T) and CASSCF) computational levels with applied aug-cc-pVTZ basis set. Nature of N-O bonding has been characterised by two resonance forms, N+O− and N−O+, owing to a very small population (< 0.60e) of the bonding basin V(N,O), localised in the ELF field for the N-O region. The importance of electron correlation effects for the description of the N-O bonding has been observed in the CASSCF calculations. The orbital description (Wiberg, NBO) differs from topological characterisation, indicating a single N-O bond.