On the use of NICS criterion to evaluate aromaticity in heteroaromatics involving III and IV row main group elements

Abstract

Ab initio (HF and MP2) and hybrid density functional theory (B3LYP) calculations were performed on a series of skeletally mono- and di-substituted benzenes with substituents from the II to IV row of the periodic table. The aromaticity in this class of compounds is evaluated based on the nucleus independent chemical shift (NICS) values. Routine classification of 6π-electronic benzenoid systems as aromatic molecules solely based on NICS criterion is questioned in heteroatomics with III and IV row substituents based on the calculated NICS values. However, the NICS criterion is found to be satisfactory in those compounds involving substituents from II row.