Aromaticity descriptors based on electron delocalization

Abstract Aromaticity is a fundamental concept that contributes to the understanding of chemical reactions as well as to the design of new chemical compounds. Nowadays, aromatic molecules include a large diversity of compounds, making its characterization a complicated process. With the aid of quantum chemistry tools, we can measure energetic, geometric, magnetic, or electronic manifestations of aromaticity using an assorted collection of indices available in the literature. In this chapter, we will focus on the aromaticity measures that are based on electron delocalization, showing their performance in a small set of molecules. Our results reveal, in accordance with previous works, that multicenter index and Iring are the most reliable electronic indices despite they cannot be used in large rings. For the latter, we propose the use of AVmin electronic index.