engleski

Aromatic Stability of Heterocyclic Conjugated Systems

The graph-theoretical approach for calculation of the aromatic stability of conjugated polycyclic hydrocarbons is extended here to polycyclic systems having a single heteroatom. Advantages of this algebraic approach, which yields expressions for the molecular resonance energies, are discussed.In particular, the relative stabilities of positional isomers have been predicted for many derivatives of benzenoid conjugated systems in which a carbon atom is replaced by a heteroatom.The basis for the analysis is conjugated circuits (circuits defined within individual Kekulé valence structures) and their enumeration.The results are illustrated on azabenzenoid systems (N-arenes), but the nonnumerical conclusions are valid for a broader class of heterocyclic compounds.

Graph theory ; aromatic stability ; heterocycles ; conjugated circuits

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