The Jahn–Teller distortion in the X 2 E″ state of sym-C 6 Cl 3 F+3 as determined from laser-induced fluorescence studies

Both gas-phase and matrix laser-induced fluorescence studies of sym-C6CL3F3+ provide detailed information on the energy-level structure of the Jahn–Teller perturbed e′ vibrations in the ground electronic state. These experimental results are analysed in terms of a multi-mode Jahn–Teller theory to yield distortion constants, unperturbed oscillator frequencies, stabilization energies and distorted geometries. These results are combined with similar results for the symmetrical ions C6F3H3+, C6Cl3H3+ and C6F6+ to reach some general conclusions about the quantitative nature of the Jahn–Teller distortion of benzenoid cations.