Lone-pair delocalization Subject

Although less than a decade old, the bulk of the experimental information now available on the subject of heteroannulene chemistry is sufficiently advanced to permit meaningful generalizations concerning the basic requirements for the development of lone-pair-induced ir delocalization. 

The first step of the analysis consists in the diagonalization of the matrix that represents the hole (eqn (10)) in appropriate basis (usually canonical orbitals). This primary diagonalization yields the set of eigenvalues and eigenfunctions that are, in the second step subjected to the isopycnic transformation. Its aim is to transform the primary eigenvectors, that are usually delocalized over the nearest neighborhood of the reference basin, into the set of more localized functions whose resemblance with localized orbitals often allows the association with classical concepts of bonds, lone pairs etc., in terms of which chemists are used to classify the molecular structures. 

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