The electron density vs. NICS scan: a new approach to assess aromaticity in molecules with different ring sizes

Abstract

The influence of electron density on the magnitude of non-nuclear magnetic shielding, NICS, is studied in detail by scanning the electron density vs. NICS_zz (the out-of-plane component of NICS). This study sheds new light on the role of electron density on the magnitude of NICS. Scanning the electron density vs. NICS_zz not only helps to discriminate the electronic ring currents operative in aromatic, nonaromatic and antiaromatic species, but also yields a measure to compare the strength of diatropic/paratropic currents in molecules with different ring sizes or different number of π electrons without relying on the methods of σ–π separation.