Fig. 1. Reaction between benzene and 1 SO₃ in gas phase, CCl₃F, and CH₃NO₂. PMF of 1D MTD with error bars representing the standard deviation. Numbers above the curves indicate free energy ΔF (kJ mol^–1) of the σ-complex at CN_CS = 0.6 relative to the reactant state. Structures refer to the gas phase curve.