Electron attachment to the van der Waals complexes of azabenzene-(CO2)(n) results in the formation of covalent bonds between the nitrogen atoms of azabenzene and the carbon atom of CO2. The newly formed C-N bonds establish an extended pi-orbital network over the entire moieties of the complex and thus greatly stabilize the anion, yielding a very large value of vertical detachment energy for the excess electron. The rare "associative" nature of electron attachment was found to be generally occurring in all azabenzene series, only subject to steric hindrance against the formation of the covalent C-N bond.