The Role of Benzonitrile Chlorination Explored by Dissociative Electron Attachment

The dissociative electron attachment process to ortho- and para-chlorobenzonitrile was investigated in the 0-12 eV energy range with a crossed-beam time-of-flight mass spectrometer, supported by quantum chemical scattering calculations. The major dissociation channel corresponds to Cl^- formation, accompanied by [M─Cl]^-, CN^-, [M─CN]^-, and minor fragments. A key distinction between the two isomers is the observation of a parent anion at near-zero energy in the ortho-chlorobenzonitrile, whereas it is absent in the para-chlorobenzonitrile. Calculations on the basis of the Schwinger Multichannel method reproduce the main resonant features and provide a consistent representation of the electron attachment pathways. The results highlight how dipole-bound states and orbital coupling shape fragmentation dynamics, with implications for halogenated nitrile chemistry in astrophysical environments.