The cover shows the bimolecular substitution (SN2) reaction of CH3F + OH– in an aqueous solution along its reaction pathway. The purple curve represents the free energy reaction pathway in a water solution. Structures of the reactant complex, transition state, and product complex in water are shown along the reaction pathway from left to right. The transition state is the highest point on the curve. On page 445, Jie Chen et al. present a system containing 1418 water molecules in the solution environment.