A direct dynamics trajectory study of F- + CH3OOH reactive collisions reveals a major non-IRC reaction path

José G. López, Grigoriy Vayner, Upakarasamy Lourderaj, Srirangam V. Addepalli, Shuji Kato, Wibe A. DeJong, Theresa L. Windus, William L. Hase

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119 Scopus citations

Abstract

A direct dynamics simulation at the B3LYP/6-311+G(d,p) level of theory was used to study the F- + CH3OOH reaction dynamics. The simulations are in excellent agreement with a previous experimental study (J. Am. Chem. Soc. 2002, 124, 3196). Two product channels, HF + CH2O + OH- and HF + CH3OO-, are observed. The former dominates and occurs via an ECO2 mechanism in which F- attacks the CH3-group, abstracting a proton. Concertedly, a carbon-oxygen double bond is formed and OH- is eliminated. Somewhat surprisingly this is not the reaction path, predicted by the intrinsic reaction coordinate (IRC), which leads to a deep potential energy minimum for the CH 2(OH)2⋯F- complex followed by dissociation to HF + CH2(OH)O-. None of the direct dynamics trajectories followed this path, which has an energy release of -63 kcal/mol and is considerably more exothermic than the ECO2 path whose energy release is -27 kcal/mol. Other product channels not observed, and which have a lower energy than that for the ECO2 path, are F- + CO + H2 + H2O (-43 kcal/mol), F- + CH 2O + H2O (-51 kcal/mol), and F- + CH 2(OH)2 (-60 kcal/mol). Formation of the CH 3OOH⋯F- complex, with randomization of its internal energy, is important, and this complex dissociates via the ECO2 mechanism. Trajectories which form HF + CH3OO- are nonstatistical events and, for the 4 ps direct dynamics simulation, are not mediated by the CH3OOH⋯F- complex. Dissociation of this complex to form HF + CH3OO- may occur on longer time scales.

Original languageEnglish
Pages (from-to)9976-9985
Number of pages10
JournalJournal of the American Chemical Society
Volume129
Issue number32
DOIs
StatePublished - Aug 15 2007

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