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 CH2(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- + CH2O + H2O (-51 kcal/mol), and F- + CH2(OH)2 (-60 kcal/mol). Formation of the CH3OOH...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.

Two competitive reaction mechanisms for the gas-phase chemical transformation of singlet chlorocarbene into chloromethanol in the presence of one and two water molecules are examined in detail. An analysis of bond orders and bond order derivatives as well as of properties of bond critical points in the electron densities along the intrinsic reaction coordinates (IRCs for intermediates → transition state (TS) → products) suggests that, from the perspective of bond breaking/formation, both reactions should be considered to be highly nonsynchronous, concerted processes. Both transition states are early, resembling the intermediates, yielding rate constants whose magnitudes are mostly influenced by structural changes and to a lesser degree by bond breaking/formation. For the case of one water molecule, most of the energy in the reactants region of the IRC is used for structural changes, while the transition state region encompasses the majority of electron activity, except for the formation of the C-O bond, which extends well into the products region. In the case of two water molecules, very little electron flux and comparatively less work required for structural changes is noticed in the reactants region, leading to an earlier transition state and therefore to a smaller activation energy and to a larger rate constant. This, together with evidence gathered from other sources, allows us to provide plausible explanations for the observed difference in rate constants.