Article

# A Theoretical Study of the H-Abstraction Reactions from HOI by Moist Air Radiolytic Products (H, OH, and O (3P)) and Iodine Atoms (2P3/2)

Université Catholique de Louvain, Bâtiment Lavoisier, Place L. Pasteur 1, B-1348 Louvain-la-Neuve, Belgium.

The Journal of Physical Chemistry A (Impact Factor: 2.69). 05/2011; 115(24):6664. DOI: 10.1021/jp202760u ### Full-text

Florent Louis, Oct 09, 2015 Available from: Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

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**ABSTRACT:**Ab initio electronic structure calculations at the coupled cluster level with a correction for the triples extrapolated to the complete basis set limit have been made for the estimation of the thermochemical properties of Cs2, CsH, CsO, Cs2O, CsX, and Cs2X2 (X = OH, Cl, Br, and I). The standard enthalpies of formation and standard molar entropies at 298 K, and the temperature dependence of the heat capacities at constant pressure were evaluated. The calculated thermochemical properties are in good agreement with their literature counterparts. For Cs2, CsH, CsOH, Cs2(OH)2, CsCl, Cs2Cl2, CsBr, CsI, and Cs2I2, the calculated DfH°298K values are within chemical accuracy of the most recent experimental values. Based on the excellent agreement observed between our calculated DfH°298K values and their literature counterparts, the standard enthalpies of formation at 298 K are estimated to be the following: DfH° 298K (CsO) = 17.0 kJ mol-1 and DfH°298K (Cs2Br2) = -575.4 kJ mol-1.Journal of Nuclear Materials 11/2011; 420(1-3):452. DOI:10.1016/j.jnucmat.2011.10.034 · 1.87 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**The rate constants of the H-abstraction reactions from CH(3)Cl and CH(3)Br molecules by ClO and BrO radicals have been estimated over the temperature range of 300-2500 K using four different levels of theory. Calculations of optimized geometrical parameters and vibrational frequencies are performed using B3LYP and MP2 methods combined with the cc-pVTZ basis set. Single-point energy calculations have been carried out with the highly correlated ab initio coupled cluster method in the space of single, double, and triple (perturbatively) electron excitations CCSD(T) using the cc-pVTZ and cc-pVQZ basis sets. Canonical transition-state theory combined with an Eckart tunneling correction has been used to predict the rate constants as a function of temperature. In order to choose the appropriate levels of theory with chlorine- and bromine-containing species, the reference reaction Cl ((2)P(3/2)) + CH(3)Cl → HCl + CH(2)Cl (R(ref)) was first theoretically studied because its kinetic parameters are well-established from numerous experiments, evaluation data, and theoretical studies. The kinetic parameters of the reaction R(ref) have been determined accurately using the CCSD(T)/cc-pVQZ//MP2/cc-pVTZ level of theory. This level of theory has been used for the rate constant estimation of the reactions ClO + CH(3)Cl (R(1)), ClO + CH(3)Br (R(2)), BrO + CH(3)Cl (R(3)), and BrO + CH(3)Br (R(4)). Six-parameter Arrhenius expressions have been obtained by fitting to the computed rate constants of these four reactions (including cis and trans pathways) over the temperature range of 300-2500 K.The Journal of Physical Chemistry A 04/2012; 116(17):4396-408. DOI:10.1021/jp301557c · 2.69 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**The rate constants of the H- and I-abstraction reactions from CH3I molecules by I (2P3/2) atom and IO radical have been estimated over the range 600–2500 K using three levels of theory. Calculations of optimized geometrical parameters and vibrational frequencies have been performed using MP2 method combined with the cc-pVTZ basis set. Single-point energy calculations have been carried out with the highly-correlated ab initio coupled cluster method in the space of single, double, and triple (perturbatively) electron excitations CCSD(T) using the cc-pVTZ and cc-pVQZ basis sets. The CCSD(T) calculated potential energies were extrapolated to estimate the complete basis limit (CBS). Canonical transition-state theory combined with an Eckart tunneling correction and a hindered rotor treatment has been used to predict the rate constants as a function of temperature. In order to choose the appropriate levels of theory with iodine-containing species, the reference pathway CH3I + I (2P3/2) → CH3 + I2 was theoretically studied because its kinetic parameters have been established from numerous experimental and evaluation studies. The rate constants of the reference pathway calculated at the CCSD(T)/cc-pVQZ//MP2/cc-pVTZ level of theory are in good agreement with the literature counterparts. This level of theory has been used to calculate the rate constant of the pathways CH3I + I (2P3/2) → CH2I + HI, CH3I + IO → CH2I + HOI (cis and trans), CH3I + IO → CH2I + HIO, CH3I + IO → CH3 + IOI, and CH3I + IO → CH3 + IIO. For the seven pathways, three-parameter Arrhenius expressions have been obtained by fitting to the calculated rate constants over the range 600–2500 K. For the reaction CH3I + I (2P3/2), the pathway CH3I + I (2P3/2) → CH3 + I2 is the fastest one over the range 600–2500 K. For the reaction CH3I + IO, the cis pathway CH3I + IO → CH2I + HOI is the fastest one over the range 600–2500 K.Computational and Theoretical Chemistry 05/2013; 1012:72–83. DOI:10.1016/j.comptc.2013.02.013 · 1.55 Impact Factor