Single Solvent Molecules Induce Dual Nucleophiles in Gas-Phase Ion-Molecule Nucleophilic Substitution Reactions.

Direct dynamics simulation of singly hydrated peroxide ion reacting with CHCl reveals a new product channel that forms CHOH + Cl + HOOH, besides the traditional channel that forms CHOOH + Cl + HO. This finding shows that singly hydrated peroxide ion behaves as a dual nucleophile through proton transfer between HOO(HO) and HO(HOOH). Trajectory analysis attributes the occurrence of the thermodynamically and kinetically unfavored HO-induced pathway to the entrance channel dynamics, where extensive proton transfer occurs within the deep well of the prereaction complex. This study represents the first example of a single solvent molecule altering the nucleophile in a gas-phase ion-molecule nucleophilic substitution reaction, in addition to reducing the reactivity and affecting the dynamics, signifying the importance of dynamical effects of solvent molecules.