Aromaticity and substitution effect of the mono-boron-nitrogen-replaced analogues of cyclo[18]carbon

Abstract

The geometrical structures and relative stability of 9 monocyclic BNC₁₆, which are analogues of cyclo[18]carbon, were investigated at ωB97X-D/def2-TZVP level, the electron delocalization was considered by the localized orbital locator purely contributed by π electrons (LOL-π) analysis and the interaction region indicator (IRI) analysis, and the π bonding electrons distributed on each atom were quantified. The nucleophilic and electrophilic sites were predicted by the orbital-weighted dual descriptor. The pronounced aromaticity and the high delocalization of π electrons were demonstrated by the iso-chemical shielding surface (ICSS), and were further confirmed by their large I_ring indices and the AV1245 values.