A Direct Dynamics Trajectory Study of F^₋ + CH₃OOH Reactive Collisions Reveals a Major Non-IRC Reaction Path

Journal Article · Sat Jul 21 04:00:00 EDT 2007 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja0717360· OSTI ID:917575

Lopez, Jose G; Vayner, Grigoriy; Lourderaj, Upakarasamy; Addepalli, Srirangam V; Kato, Shuji; De Jong, Wibe A; Windus, Theresa L; Hase, William L

A direct dynamics simulation at the B3LYP/6-311+G(d,p) level of theory was used to study the reaction dynamics of F^₋ + CH₃OOH collisions. The results of 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 E_CO2 mechanism in which F^₋ attacks the CH₃₋ group, abstracting a proton. Concertedly, a carbon-oxygen double bond is formed and OH^₋ eliminated. Somewhat surprisingly this is not the reaction path, predicted by the intrinsic reaction coordinate (IRC), following F^₋ attack of the CH₃₋ group. The IRC leads to a deep potential energy minimum for the CH₂(OH)₂ · · · F^₋ complex which dissociates to F^₋+ CH₂(OH)₂. None of the direct dynamics trajectories followed the IRC, leading to this minimum and product channel. This channel has an exothermicity of ₋60 kcal/mol, much lower than the ₋27 kcal/mol exothermicity for the observed channel. Other channels not observed and which have lower exothermicities are F^₋+CO+H₂+H₂O (₋43 kcal/mol) and F^₋ + CH₂O + H₂O (₋51 kcal/mol). Formation of a CH₃OOH· · ·F^₋ complex, with randomization of its internal energy, is important. This complex dissociates via the E_CO2 mechanism forming HF + CH₂O + OH₋. Trajectories which form HF + CH₃OO^₋ are non-statistical events and, for the 4 ps direct dynamics simulation, are not mediated by a CH₃OOH· · · F^₋ complex. Dissociation of this complex to form HF + CH₃OO^₋ may occur on longer time scales.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 917575
• Report Number(s): PNNL-SA-53765; 3566; KP1303000
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 32 Vol. 129; ISSN JACSAT; ISSN 0002-7863
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CHEMICAL REACTION KINETICS
DISSOCIATION
DOUBLE BONDS
Environmental Molecular Sciences Laboratory
FLUORINE
PEROXIDES
POTENTIAL ENERGY
REACTION INTERMEDIATES
SIMULATION