Potential energy surface and dissociative cleavage of chlorobenzene radical anion

Potential energy surface (PES) of the short-lived PhCl− radical anion has been studied by ROHF/6-31+G∗ and MP2/6-31+G∗//ROHF/6-31+G∗ calculations. The PES peculiarities were found to result from two reasons: (a) the quasi-degeneracy of PhCl− π states; (b) the presence of a low-lying repulsive σ term. The anion meta-stable 2Π state has been located, and transition state for C–Cl cleavage has been found revealing an asymmetrical non-planar structure. Possible mechanisms of halobenzene anions dissociative cleavage are discussed, with the PhCl− as a model.