Through-space and Through-bond Interactions as Mirrored in Photoelectron Spectra

Abstract

Useful and transparent orbital models for rationalizing intramolecular interactions between identical functional groups are discussed in some detail. A seminal idea of Hoffmann, Imamura and Hehre to dissect interactions between molecular fragments into through-bond and through-space is found to possess a high interpretive power. A simple perturbational approach employing semilocalized molecular orbitals suffices for most purposes if information at the qualitative level is desired. Quantitative theoretical data are conveniently produced by the method of Heilbronner and Schmelzer. It is gratifying and intellectually pleasing that theoretical results are in good agreement with PES observations. Thus one can say that orbital models represent a useful means for treating and understanding long-range interactions within molecules themselves. They give a theoretical framework to the empirical knowledge which relates properties of molecular systems to the features of their constituent fragments.