Tertiary cation IV undergoes nucleophilic attack by the arene via TS-IV to give Wheland intermediate V. Deprotonation of Wheland intermediate V by base B1 via TS-V is disfavoured compared to deprotonation via contact ion pair VII (adduct of PF 6 - and V) and TS-VII. The choice of the counterion is crucial for controlling the deprotonation kinetics. The conformational space was explored using CREST 49 and low energy conformers were further refined with wB97XD/def2-TZVP(IEFPCM(CH 2 Cl 2 )). For transition states selected distances are given in angstrom.
