(vii) The overall activation barrier to the first redox process is determined by the following formula: ΔG ‡ t = ΔG1 + ΔG2 + ΔG ‡ 1 (Table ). As discussed above, ΔG1 is mainly independent from the nature of the X-ligand and thus only ΔG2 and ΔG ‡ 1 contribute to the ease of the dearomatization process. A strong coordinating X-ligand makes both transformations 21_X  22_X (hypervalent twist) and 22_X  TS22-23_X (redox step) unfavorable, and as a result such a ligand is not appropriate for the phenol oxidation.