Effect of cycles on total π-electron energy of alternant conjugated hydrocarbons
Mathematical properties of the function eƒ(G, C), the effect of a cycle on total π-electron energy of a conjugated molecule, are analysed. The main results of the paper are summarized in propositions (1)–(7). The conditions under which the Hückel rule holds are discussed and an approximate formula for total π-electron energy is derived, which is an additive function of the eƒ(G, C). Several rules are obtained for the sign of ef(G, C).