A New Model of Aromaticity of Benzenoid Hydrocarbons——Symmetric Coupling Circuits

It is assumed that the weight of each Kekule structure for a benzenoid hydrocarbon is directly proportional to the number of Kekule benzene rings, that is, basic conjugated circuits, contained in the said Kekule structure——the assumption of diect proportion by weight. In the light of the computational results of spin-coupled valence bond method a new model of aromaticity of benzenoid hydrocarbons-the symmetric coupling circuit (SCC) model-is proposed; and this model involves concept SCC, SCC structure, and SCC method. From the SCC method has been derived the general equation for the calculation of the resonance energies of benzenoid hydrocarbons. The calculated values approximated highly to the experimental values, and the results are satisfactory.