The Influence of Substituents on Double‐Bond Localization, e.g. in s‐Indacene

In a molecule with conjugated π bonds, which substituents favor localized double bonds? Heuristic rules to answer this question qualitatively have been derived in the framework of the Hückel model. Only the maximum eigenvalue of the unperturbed system is required along with the atomic orbital coefficients of the HOMO and LUMO and their energies.