Electron structures of azoloisoindoles with a nodal nitrogen atom. 1. Derivatives of isoindolobenzimidazole and imidazo- and pyrazoloisoindoles

11H-isoindolo[2,1-a]benzimidazoles (Review)

“…In the spectra of the compounds having an isoindole ortho-quinonoid structure there is a long-wave absorption band for compound 52a, for example, at λ max 414 nm (log ε 3.22) [64].…”

“…On the basis of analysis of the localized molecular orbitals of 5-methyl-5H-isoindolo[2,1-a]-benzimidazole 52a it was shown that its electronic structure can be represented in the form of three weakly interacting parts: The isoindole fragment, the electron pair of the nitrogen attached to the methyl group, and the benzene ring [64]. Thus, this compound can be considered to a first approximation an analog of 1,2-disubstituted isoindoles (10π-electron systems).…”