The He(I) and X-ray photoelectron spectra of some substituted benzalmalonitrile compounds

The He(I) photoelectron spectra of some substituted benzalmalonitriles are discussed in terms of inductive and resonance effects. It has been observed that the radical cation ground state is mainly localized on the phenyl moiety of the molecules and involves all the molecule when strong resonance interaction is present, especially in the case of para- and meta-nitrobenzalmalonitrile. The presence of a shake-up structure in the N1s energy region of the XPS of these compounds confirms the presence of such strong resonance interactions. Semi-empirical quantum mechanical calculations using the MINDO/3 method yield eigenvalues which, within the Koopmans' approximation, correlate well with the experimental ionization energies. © 1989. © 2014 Elsevier B.V., All rights reserved.