What is... aromaticity: a critique of the concept of aromaticity-can it really be defined?

Chem Commun (Camb). 2009 Apr 21:(15):1939-47. doi: 10.1039/b816811c. Epub 2009 Feb 9.

Abstract

Aromaticity has been a basic concept in chemistry for many years, yet it is poorly understood. This Feature Article introduces some questions regarding the concept, describes major paradigms in the field, and emphasizes the contradictions and paradoxes between these paradigms, and between different measures of aromaticity.