CHARACTERIZATION OF THE 2-CHLOROACRYLONITRILE NEGATIVE-ION USING PHOTOELECTRON AND PHOTOFRAGMENTATION SPECTROSCOPIES

We describe the spectroscopic characterization of the anions produced by low-energy electron attachment to neutral clusters of 2-chloroacryl onitrile (CAN). The photoelectron spectrum of the CAN(-) anion is mark edly similar to that of the ion-molecule complex, Cl-.CAN, implying th at the excess charge in CAN(-) is localized on the chlorine atom. Ab i nitio calculations support this inference, indicating that upon electr on attachment CAN(-) rearranges to a novel distonic ion-radical comple x, Cl-.H2C=CCN. The photoabsorption spectrum of the anion is consisten t with a charge transfer transition to an excited state, Cl.[H2C=CCN]( -). This chromophore dominates the photofragmentation chemistry of CA N(-), with the dominant photofragments at all wavelengths being Cl- (p resumably formed by reverse charge transfer relaxation of the excited state) and [H2C=CCN](-). The propensity of neutral clusters of CAN to polymerize upon electron attachment is readily explicable in view of t he proposed ion-radical structure of CAN(-).