Revisiting the Hückel’s rule: Where Comes the Aromaticity and Antiaromaticity

The twin property of aromaticity and antiaromaticity is one of the most important and well-known concepts in chemical structure and bonding, but it is also an over-a-century enigma as the necessary and sufficient conditions of aromaticity and antiaromaticity has not been fully understood yet, and the relationships between stability and aromaticity are still under debate. Here we present a theory that allows easy understanding, analyses, determinations and predictions for every possible type of aromaticity. Based on this theory, we conclude that the magnetic aromaticity and antiaromaticity are only properties derived from the magnetic perturbation of molecular orbitals suitable to generate angular momentums, and there are no cause-and-effect relationships between magnetic aromaticity and stability. Till then, the twin property of aromaticity and antiaromaticity could be deciphered uniformly by one theory.