The C₆H₅F⁺, σ-C₆H₄F₂⁺, m-C₆H₄F₂⁺, p-C₆H₄F₂⁺, 1,2,3-C₆H₃F₃⁺, 1,2,4-C₆H₂F₄⁺, 1,3,5-C₆H₄F₂⁺, 1,2,3,4-C₆H₂F₄⁺, 1,2,3,5-C₆H₂F₄⁺, 1,2,4,5-C₆H₂F₄⁺, C₆HF₅⁺ and C₆F₆⁺ cations were studied by using the DFT B3LYP method in conjunction with the 6 311G (d,p) and 6 311+G (d,p) basis sets.The ground state geometries of these cations were predicted.The 1,3,5-C₆H₃F₃⁺ and C₆F₆⁺ ions are the Jahn Teller active species, and they are predicted to have C_2v and D_2h structures, in contrast with the D_3h and D_6h structures of their parent molecules, respectively.Differences in geometry between the cations and their parent molecules were examined.Natural population analysis calculations for these cations indicate that the positive charge resides mainly at the C atom(s) connecting with the F atom(s) and at the H atoms.The B3LYP calculations with the 6-311+G (d,p) basis predict vertical and adiabatic ionization potential values of the fluorinated benzene molecules in good agreement with the experimental values.

Key words: fluorinated benzene cation, geometry, ionization potential, B3L YP