Through-bond interactions in the lone-pair ionization of p-benzoquinone

Abstract The photoelectron spectrum of p -benzoquinone for the most loosely bound electrons is calculated using the CASSCF and related methods with localization of the hole state. The results are in satisfactory agreement with the experiments and support a through-bond interaction model for the splitting of the lone-pair ionization energies where the two major contributions have different signs and tend to cancel.