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Title: Direct Dynamics Simulation of Dissociation of the [CH3--I--OH]- Ion-Molecule Complex

Abstract

Direct dynamics simulations were used to study dissociation of the [CH3--I--OH]- complex ion, which was observed in a previous study of the OH- + CH3I gas phase reaction (J. Phys. Chem. A 2013, 117, 7162). Restricted B97-1 simulations were performed to study dissociation at 65, 75 and 100 kcal/mol and the [CH3--I--OH]- ion dissociated exponentially, in accord with RRKM theory. For these energies the major dissociation products are CH3I + OH-, CH2I- + H2O, and CH3OH + I-. Unrestricted B97-1 and restricted and unrestricted CAM-B3LYP simulations were also performed at 100 kcal/mol to compare with the restricted B97-1 results. The {CH3I + OH-}:{CH2I- + H2O}:{CH3OH + I-} product ratio is 0.72 : 0.15 : 0.13, 0.81 : 0.05 : 0.14, 0.71 : 0.19 : 0.10 , and 0.83 : 0.13 : 0.04 for the restricted B97-1, unrestricted B97-1, restricted CAM-B3LYP, and unrestricted CAM-B3LYP simulations, respectively. Other product channels found are CH2 + I- + H2O, CH2 + I-(H2O), CH4 + IO-, CH3 - + IOH, and CH3 + IOH-. The CH3 - + IOH singlet products are only given by the restricted B97-1 simulation and the lower energy CH3 + IOH- doublet products are only formed by the unrestricted B97-1more » simulation. Also studied were the direct and indirect atomic-level mechanisms for forming CH3I + OH-, CH2I- + H2O, and CH3OH + I-. The majority of CH3I + OH- were formed through a direct mechanism. For both CH2I- + H2O and CH3OH + I-, the direct mechanism is overall more important than the indirect mechanisms, with the round-about like mechanism the most important indirect mechanism at high excitation energies. Mechanism comparisons between the B97-1 and CAM-B3LYP simulations showed that formation of the CH3OH---I- complex is favored for the B97-1 simulations, while formation of the HO----HCH2I complex is favored for the CAM-B3LYP simulations. The unrestricted simulations give a higher percentage of indirect mechanisms than the restricted simulations. The possible role of the self-interaction error in the simulations is also discussed. The work presented here gives a detailed picture of the [CH3--I--OH]- dissociation dynamics, and is very important for unraveling the role of [CH3--I--OH]- in the dynamics of the OH-(H2O)n=1,2 + CH3I reactions.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1184972
Report Number(s):
PNNL-SA-106956
48614; KP1704020
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry A, 119(5):817-825
Country of Publication:
United States
Language:
English
Subject:
Ion; molecule; simulations; gas phase; Environmental Molecular Sciences Laboratory

Citation Formats

Xie, Jing, McClellan, Miranda, Sun, Rui, Kohale, Swapnil C., Govind, Niranjan, and Hase, William L. Direct Dynamics Simulation of Dissociation of the [CH3--I--OH]- Ion-Molecule Complex. United States: N. p., 2015. Web. doi:10.1021/jp511898y.
Xie, Jing, McClellan, Miranda, Sun, Rui, Kohale, Swapnil C., Govind, Niranjan, & Hase, William L. Direct Dynamics Simulation of Dissociation of the [CH3--I--OH]- Ion-Molecule Complex. United States. doi:10.1021/jp511898y.
Xie, Jing, McClellan, Miranda, Sun, Rui, Kohale, Swapnil C., Govind, Niranjan, and Hase, William L. Thu . "Direct Dynamics Simulation of Dissociation of the [CH3--I--OH]- Ion-Molecule Complex". United States. doi:10.1021/jp511898y.
@article{osti_1184972,
title = {Direct Dynamics Simulation of Dissociation of the [CH3--I--OH]- Ion-Molecule Complex},
author = {Xie, Jing and McClellan, Miranda and Sun, Rui and Kohale, Swapnil C. and Govind, Niranjan and Hase, William L.},
abstractNote = {Direct dynamics simulations were used to study dissociation of the [CH3--I--OH]- complex ion, which was observed in a previous study of the OH- + CH3I gas phase reaction (J. Phys. Chem. A 2013, 117, 7162). Restricted B97-1 simulations were performed to study dissociation at 65, 75 and 100 kcal/mol and the [CH3--I--OH]- ion dissociated exponentially, in accord with RRKM theory. For these energies the major dissociation products are CH3I + OH-, CH2I- + H2O, and CH3OH + I-. Unrestricted B97-1 and restricted and unrestricted CAM-B3LYP simulations were also performed at 100 kcal/mol to compare with the restricted B97-1 results. The {CH3I + OH-}:{CH2I- + H2O}:{CH3OH + I-} product ratio is 0.72 : 0.15 : 0.13, 0.81 : 0.05 : 0.14, 0.71 : 0.19 : 0.10 , and 0.83 : 0.13 : 0.04 for the restricted B97-1, unrestricted B97-1, restricted CAM-B3LYP, and unrestricted CAM-B3LYP simulations, respectively. Other product channels found are CH2 + I- + H2O, CH2 + I-(H2O), CH4 + IO-, CH3 - + IOH, and CH3 + IOH-. The CH3 - + IOH singlet products are only given by the restricted B97-1 simulation and the lower energy CH3 + IOH- doublet products are only formed by the unrestricted B97-1 simulation. Also studied were the direct and indirect atomic-level mechanisms for forming CH3I + OH-, CH2I- + H2O, and CH3OH + I-. The majority of CH3I + OH- were formed through a direct mechanism. For both CH2I- + H2O and CH3OH + I-, the direct mechanism is overall more important than the indirect mechanisms, with the round-about like mechanism the most important indirect mechanism at high excitation energies. Mechanism comparisons between the B97-1 and CAM-B3LYP simulations showed that formation of the CH3OH---I- complex is favored for the B97-1 simulations, while formation of the HO----HCH2I complex is favored for the CAM-B3LYP simulations. The unrestricted simulations give a higher percentage of indirect mechanisms than the restricted simulations. The possible role of the self-interaction error in the simulations is also discussed. The work presented here gives a detailed picture of the [CH3--I--OH]- dissociation dynamics, and is very important for unraveling the role of [CH3--I--OH]- in the dynamics of the OH-(H2O)n=1,2 + CH3I reactions.},
doi = {10.1021/jp511898y},
journal = {Journal of Physical Chemistry A, 119(5):817-825},
number = ,
volume = ,
place = {United States},
year = {Thu Feb 05 00:00:00 EST 2015},
month = {Thu Feb 05 00:00:00 EST 2015}
}