Comparative analysis of the electronic structure of positional isomers: Indole-isoindole

On the basis of an analysis of the canonical and localized molecular orbitals of indole and isoindole, calculated in the SCF and CNDO/2 approximations, as well as an x-ray crystallographic investigation of 2-methyl-isoindole, a comparison of the electronic structure of the positional isomers was made. The 10-electronic system of isoindole is more integral than for indole: isoindole is a single 10-electronic system with an appreciable localization of the bonds in the carbocyclic portion of the bicycle; the electronic structure of indole can be represented in a first approximation as the aggregate of three weakly interacting -subsystems: the benzene ring, the double bond between the - and -carbon atoms, and the free electron pair of the nitrogen atom.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1497–1503, November, 1984.