Simple Electron Counting Rules

Abstract

The nonobservable nature of aromaticity precludes an unambiguous quantitative definition of this property. Despite the imprecise character of aromaticity, there is a number of very simple electron counting rules that are followed by a large number of organic and inorganic aromatic compounds. Hückel's, Baird's, Wade–Mingos', and Hirsch's rules are among the most celebrated simple rules of aromaticity. In this chapter, these rules, together with other less-known counting rules of aromaticity, are discussed.