Quantum-chemical investigation of some oligomeric heteroaromatic compounds

The results of calculations by the Pariser-Parr-Pople method and the expanded Hückel method of oligomeric compounds and fragments from which aromatic polyimide macromolecules are constructed are presented and discussed. In connection with the controversial character of the problem of the structures of the intermediates in the destruction of polyimides and the use, in this case, of the concept of imide-isoimide rearrangement, the relative advantageousness of the tautomeric forms of imides is evaluated, the participation of the imide ring in one or another form in conjugation is discussed, the spectral differences in the forms are established, etc. The strength characteristics of the bonds in polyimides were estimated in connection with the possibility of homolytic and hydrolytic cleavage of polyimides at these bonds.See 1] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.8, pp. 1048–1056, August, 1972.