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pπ-Conjugation in Aromatic Compounds of Group V and VI Elements

The results of experimental and theoretical studies of intramolecular electronic interactions in aromatic compounds of group V and VI elements have been reviewed. The principal characteristics of their electronic structure, their geometry, and their electron-donor properties have been discussed. The possibilities provided by various methods (UV spectroscopy, NMR, PES, thermochemistry) for detecting and estimating the degree of combination of the unshared pair of electrons of the heteroatom with the π-electron system of the aromatic fragment have been analysed in detail. Quantitative estimates of the energy of pπ-conjugation have been given. The bibliography contains 240 references.