Vibrational overtone induced elimination reactions within hydrogen-bonded molecular clusters: the dynamics of water catalyzed reactions in CH2FOH·(H2O)n

Abstract

The dynamics of the light initiated OH-overtone induced elimination reactions CH₂FOH·(H₂O)_n + hν → HF + CH₂O + n(H₂O), n = 1–3, are studied using classical trajectory simulations where the ab initio potential energy surface is computed “on-the-fly”. Hydrogen bonding to the water is found to lower the barrier to reaction by over 20 kcal mol⁻¹ and modifies the mechanism to a concerted multiple H-atom transfer process. The reaction process is found to occur on a rapid timescale, <100 fs, and involves the hydronium ion as an intermediate. An essential aspect of dynamics is the successful competition of reaction with energy dissipation through water evaporation from the cluster.