Potential energy surfaces of fluorobenzene radical anions

Ab initio ROHF/6‐31+G* and MP2/6‐31+G*//ROHF/6‐31+G* calculations were used to consider fluorination's effect on potential energy surfaces (PESs) of benzene radical anion's (RAs). The Hartree–Fock PESs of symmetrically fluorinated radical anions were found to be pseudorotation surfaces. Unlike the benzene anion PES, pseudorotation surfaces include nonplanar structures. A Möbius band may represent the pseudorotation scheme of C6H stationary structures. Cutting the band out, we may obtain a pseudorotation scheme peculiar to C6F . This way of PES scheme building is also applicable to partially fluorinated RAs. A complicated structure of fluorinated anions' PES results from the avoided crossing of π states closed in energy together with the presence of a low‐lying vibronically active excited σ state. The number of stationary structures involved in pseudorotation varies in the series of anions, and may be changed at a higher level of calculations.