Reactivity of haloethanes with hydroxyl radicals: Effects of basis set and correlation energy on reaction energetics

Sekušak, Sanja; Sabljić, Aleksandar

doi:10.1002/(sici)1096-987x(19970715)18:9<1190::aid-jcc7>3.0.co;2-m

Cited by 10 publications

(20 citation statements)

References 54 publications

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“…Thus, the annihilation of the spin contamination from the unrestricted wave functions seems to be mandatory for calculation of both reaction enthalpies and barrier heights. This result is in agreement with results of previous investigations of radical reactions. ,,, …”

Section: Resultssupporting

confidence: 93%

“…Gaussian-2 theory fails to describe the investigated reactions as a consequence of the inferior results obtained by the MP2, MP4, and QCISD(T) methods in combination with small basis sets such as 6-311G(d,p) and 6-311+G(d,p) that are used within the G2 scheme. Therefore, the G2 method is not suitable for the prediction of energetics of OH addition to ethene and halogenated analogues, in contrast to the very good results obtained for abstraction reactions . The best results are obtained using the MP2 method with large basis sets, such as 6-311+G(3df,2p), 6-311++G(3df,2pd), aug-cc-pVDZ, and aug-cc-pVTZ, which are in agreement with measured reactivity.…”

Section: Resultsmentioning

confidence: 77%

See 1 more Smart Citation

Reactivity and Regioselectivity of Hydroxyl Radical Addition to Halogenated Ethenes

1998

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The reactions of hydroxyl radical with ethene, fluoroethene, and chloroethene have been studied by quantum chemical methods. Reactants, prereaction complexes, transition-state structures, and products were optimized and vibrational frequencies were calculated at the UMP2/6-311+G(2d,p) level. Transition-state structures are significantly different from the prereaction complexes formed on the reactant side of the MEP. The convergence of barrier heights and reaction enthalpies has been systematically investigated with respect to the size and quality of basis set and the treatment of correlation energy. The best agreement with experimental results is found at the MP2/aug-cc-pVTZ level of theory. Regioselectivity is discussed in terms of two properties of the radical and the investigated alkenes. The first factor is the relative spin density in the 3ππ* state of the alkene. The second factor is the relative strengths of the product C−O bond, i.e., relative stability of the corresponding radical product. In the case of fluoroethene these two effects oppose each other and regioselectivity is negligible. In the case of chloroethene spin density is the dominant factor and the addition of OH radicals to the unsubstituted carbon atom is preferred.

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Section: Resultssupporting

confidence: 93%

Section: Resultsmentioning

confidence: 77%

Reactivity and Regioselectivity of Hydroxyl Radical Addition to Halogenated Ethenes

1998

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“…The BSSE corrected barrier height is found to be widely off from the corresponding experimental value. Similar observation was made earlier by Sekusak and Sabljic for the reaction between haloethanes and OH radical 7 Basis Set Superposition Error (in kcal/mol) Calculated by the Counterpoise Method for Barrier Heights of Hydrogen Abstraction Reactions between Dichloroethane and OH Radical a TSMP2QCISD(T) α-TS1 4.67 4.75 β-TS2 4.82 4.91 β-TS3 4.63 4.70 T-TS4 4.58 4.75 T-TS5 5.47 5.63 G-TS6 5.43 5.60 G-TS7 4.55 4.64 a Calculations were performed with the 6-311G(d,p) basis set. …”

Section: Resultssupporting

confidence: 72%

“…Scheiner and co-workers analyzed this problem for the proton transfer reaction . Very recently, Sekusak and Sabljic evaluated the effect of BSSE on the calculated activation energies for the hydrogen abstraction reactions between haloethanes and OH radical . They observed that the uncorrected results were always more close to the experiment than the BSSE corrected results and advised that one should use BSSE uncorrected results obtained from a reasonably large basis set.…”

Section: Methodsmentioning

confidence: 99%

An ab Initio Investigation of the Reactions of 1,1- and 1,2-Dichloroethane with Hydroxyl Radical

1999

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The hydrogen abstraction reactions by OH radical from 1,1-dichloroethane and 1,2-dichloroethane have been investigated by ab initio molecular orbital theory. Optimized geometries and harmonic vibrational frequencies have been calculated for all reactants, transition structures, and products at the (U)HF/6-311G(d,p) and (U)MP2=full/6-311G(d,p) levels of theory. Single point QCISD(T)/6-311G(d,p)//(U)MP2=full/6-311G(d,p) calculations have also been carried out for the inclusion of higher order electron correlation. Three distinct transition structures have been located for the H3C−CHCl2 + OH reaction (one for α-abstraction and two for β-abstraction). Four transition structures have been located for the reaction ClH2C-CH2Cl + OH. The calculated barrier heights, reaction enthalpies, and change in entropy are found to be in good agreement with available experimental values. In addition, the rate constants calculated by using the transition state theory are found to be in good agreement with the experimental results. Non-Arrhenius behavior of the rate constants arises from the tunneling effects and availability of multiple reaction channels.

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“…84 For reactive surfaces, we use results from calculations without counterpoise corrections because they can sometimes worsen results in such situations. 85 In this work, single-point energy calculations are often preceded by geometry optimizations, allowing secondary geometrical parameters to relax in response to those explicitly varied. As an example, an optimization using restricted second-order Møller-Plesset perturbation theory (RMP2) with the AVDZ basis set and followed by an RCCSD(T) singlepoint energy calculation using the AVTZ basis set is designated by the abbreviation MP2/AVDZ//RCCSD(T)/AVTZ.…”

Section: The Interaction Energy Of Two Monomers a And B Is Defined Asmentioning

confidence: 99%

Reactions between cold methyl halide molecules and alkali-metal atoms

Lutz

Hutson

2014

The Journal of Chemical Physics

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We investigate the potential energy surfaces and activation energies for reactions between methyl halide molecules CH 3 X (X = F, Cl, Br, I) and alkali-metal atoms A (A = Li, Na, K, Rb) using high-level ab initio calculations. We examine the anisotropy of each intermolecular potential energy surface (PES) and the mechanism and energetics of the only available exothermic reaction pathway, CH 3 X + A → CH 3 + AX. The region of the transition state is explored using two-dimensional PES cuts and estimates of the activation energies are inferred. Nearly all combinations of methyl halide and alkali-metal atom have positive barrier heights, indicating that reactions at low temperatures will be slow.

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Reactivity of haloethanes with hydroxyl radicals: Effects of basis set and correlation energy on reaction energetics

Cited by 10 publications

References 54 publications

Reactivity and Regioselectivity of Hydroxyl Radical Addition to Halogenated Ethenes

Reactivity and Regioselectivity of Hydroxyl Radical Addition to Halogenated Ethenes

An ab Initio Investigation of the Reactions of 1,1- and 1,2-Dichloroethane with Hydroxyl Radical

Reactions between cold methyl halide molecules and alkali-metal atoms

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