Abstract
The effects of the interaction of various heteroatoms (and heteroatomic fragments) with carbon π-electron systems in covalent organoelemental compounds are discussed in the review in terms of molecular orbital theory. Particular attention is devoted to the analysis of the structure of the molecular orbitals, determined from photoelectron spectroscopic data and quantum-chemical calculations within the framework of the simple Hückel molecular orbital method parametrised on their basis. It is shown that the parameters characterising the mixing of the orbitals in model compounds can be used to obtain the molecular-orbital characteristics and to interpret the spectroscopic properties and reactivities of complex heteroaromatic compounds.
The bibliography includes 222 references.