Computational modeling of the catalyzed and uncatalyzed dealkylation reactions of phosphonium chloride 10 was performed with continuum solvation in a low dielectric (PCM, toluene, 𝜖=2.38) to mimic the experimental reaction conditions (Fig. ). In the absence of catalyst, the phosphonium chloride 10 is found to rest as a tight ion pair with a cage-like structure in which the chloride anion engages in multiple stabilizing interactions with the cation. All of the stabilizing H-bonding interactions and a significant portion of the Coulombic attraction present in the ground state must be sacrificed to attain the linear geometry mandated by the SN2 mechanism as in TS uncat . In considering this geometric reorganization, the concerted pathway for dealkylation can be partitioned conceptually into an ion-pair reorganization phase followed by an ion-pair collapse phase. These two phases can be demarcated by a non-stationary state 10' located on the computed intrinsic reaction coordinate, wherein the chloride ion is positioned along the SN2 trajectory but formation of the C-O bond has yet to commence. By this analysis, >75% of the overall electronic activation barrier results from reorganization of the chloride anion in the first phase (10a  10'), whereas the ion-pair collapse phase corresponding to the covalent bond-breaking and forming events contributes <25% (ca. 4 kcal/mol) to the overall barrier.