Fig. 5. Optimized structures of (a) aniline-deprotonation transition states and (b) proton-shifted intermediates with L1 and L3. Relative free energies in kcal mol⁻¹ referenced to 1D′ and 3D′, respectively, are given in parentheses and key distances are given in Å. The molecular components responsible for steric repulsion are coloured in dark blue.