d) After finding the transition state, we obtained the reaction path with the intrinsic reaction coordinate (IRC) analysis78-79. With the IRC, the analysis starts at a transitions state and slides down the hill towards the adjacent local minimum at either side of the transition state. The IRC analysis gives full information about the pathway as well as the height of the barrier in the reaction80. For all three cations, the isomerization reaction is found to be endothermic and compounds iii and compounds iv are found as the stationary points for the reactants and products, respectively. Thus, the isomerization with proton transfer as the reaction coordinate remains the preferred pathway from compound iii to compound iv for all three cations. Table S3.2 reports the barrier height for all three cations. No noticeable difference is found for the three cations in terms of activation energy. This is in striking contrast with our electrochemical results and challenges the idea of isomerization as a rate-determining step. Table S3.2. Activation energy for proton transfer in the isomerization step Cation G* MM 46.11 n-Pr n-Pr 46.066 i-Pr i-Pr 46.098
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