Potential energy surface as a key to understanding the structure and properties of short-living radical ions of cyclic organic molecules

Abstract

The review proposed summarizes the results of investigations on the adiabatic potential energy surfaces (PESes) for the radical ions of some derivatives of highly symmetric organic molecules such as benzene and cyclohexane. The results obtained show that the main feature of the PESes of highly symmetric Jahn-Teller ions, namely conical intersection, may persist for their low-symmetric derivatives. Hence, their PESes have a pseudorotational shape resulting from the intersection avoidance. A distinctive feature of radical anions of fluorine containing aromatic compounds is the planar structure disturbance due to the vibronic coupling of the ground π and low-lying excited σ states. The data on the PES structure including the positions and relative energies of its extrema, curvature in their vicinity, and stationary point interrelations provide the foundation for understanding the spectral properties and reactivity of radical ionic species. Examples of applying the PES study results to experimental data interpretation are given.