Photoinitiation of the anionic condensation reaction in 2-chloroacrylonitrile via the charge-transfer bands of the Cl−·(2-chloroacrylonitrile)1,2 clusters

The ion-molecule complexes Cl−·(2-chloroacrylonitrile)n, n = 1, 2 were used to study electron-induced reactions of solvent molecules initiated by a charge-transfer transition of the cluster. Photoexcitation of the Cl−·2-chloroacrylonitrile complex produces the radical anion of 2-chloroacrylonitrile (CAN), with expulsion of the Cl atom. Excitation of Cl−·(CAN)2 yielded photofragments that indicate the occurrence of an addition reaction of the CAN− radical to the second CAN molecule, where Cl is again ejected. This photochemistry corresponds to the chain propagation step in the polymerization of (CAN)n− clusters, and is sufficiently exothermic to sequentially eliminate HCl units.