An Electron Momentum Spectroscopy Study on Molecules Having Two Equivalent Functional Groups

Abstract

Investigation of functional groups, which give characteristic chemical properties to molecules, has been one of the most important theme in chemistry. Molecules having two equivalent functional groups have particularly attracted interests of many researchers. For the understanding of intramolecular interactions between the identical functional groups, Hoffmann et al. 1,2 have proposed the concept of through-space (TS) and through-bond (TB) interactions. TS interaction originates from the direct overlap between the semi-localized orbitals of the two functional groups, and places their symmetric linear combination (+) below the anti-symmetric one (-). In contrast, TB interaction, which occurs with participation of intervening bonds, may force the orbital ordering to be the reverse. These TS and TB interactions are usually competitive, and hence the orbital ordering depends on the molecule in question.