A model study on the mechanism and kinetics for reactions of the hydrated electron with H3O+ and NH4+ ions

Abstract

Mechanism and kinetics of the reactions of the hydrated electron (e(aq)(-)) with H3O+ and NH4+ cations were determined using quantum chemical computations with both density functional theory (B3LYP) and wavefunction (MP2 and CCSD(T)) methods and the 6-311 + + G(3df,2p) basis set, in conjunction with a PCM method for treating structures in solution. Although both reactions occur with a hydrogen atom transfer, their mechanisms differ from each other by kinetic results. While the reaction of e(aq)(-) and H3O+ in solution is diffusion-controlled, NH4+ reacts with e(aq)(-) via a transition structure with H-tunneling. The predicted rate constants agree well with available experimental results.