The electronic structure of conjugated systems I. General theory

Abstract This paper develops the general theory of conjugated systems by the method of molecular orbitals. The electron densities and bond orders appear as first-order derivatives of the energy of the mobile electrons with respect to the energy integrals in the secular equations; and various other relations are established which confirm the appropriateness of the definitions. A set of new quantities are introduced and discussed for the first time, namely, the mutual polarizability of two atoms or two bonds or an atom and a bond, and it is shown that they are important in determining the effect of structural changes on chemical reactivity, and also in calculating force constants and interaction terms for the vibration of bonds. Formulae are derived for the calculation of the total energy, electron densities, bond orders and mutual polarizabilities, and the relation of these quantities to other physical and chemical properties is briefly discussed.