Quasiclassical Trajectory Calculations of the Rate Constant of the OH + HBr → Br + H<sub>2</sub>O Reaction Using a Full-Dimensional Ab Initio Potential Energy Surface Over the Temperature Range 5 to 500 K

Oliveira-Filho, Antonio G. S. de; Ornellas, Fernando R.; Bowman, Joel M.

doi:10.1021/jz5000325

Cited by 37 publications

(55 citation statements)

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“…The existence of such complexes has also been reported in other ab initio studies [10][11][12][13]. Interestingly, the F⋯H 2 O complex has been shown to aid the F + H 2 O reaction by guiding the trajectories to the transition state, resulting in a significant enhancement of the reactivity, particularly at low collision energies [14].…”

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confidence: 61%

Hemibond complexes between H2S and free radicals (F, Cl, Br, and OH)

Alday

Johnson

et al. 2014

Theor Chem Acc

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as F [4][5][6][7][8] and Cl [9] and found that there often exists a pre-reaction complex between the two reactants. The existence of such complexes has also been reported in other ab initio studies [10][11][12][13]. Interestingly, the F⋯H 2 O complex has been shown to aid the F + H 2 O reaction by guiding the trajectories to the transition state, resulting in a significant enhancement of the reactivity, particularly at low collision energies [14]. More interestingly, it was demonstrated that such complexes are not van der Waals or electrostatic in nature, but due to covalent interactions based on a twocenter three-electron bond [15].Such a two-center three-electron bond was first discussed by Pauling [16]. Due to the fact that one electron is in the antibonding orbital, such a covalent bond is usually quite weak with a relatively long bond length and hence called a hemibond [17]. Hemibond bonding has been found in many branches of chemistry [18], particularly between molecules with lone pairs of electrons and a free radical with an unpaired electron [19-31]. As mentioned above, such hemibond complexes are not only of a fundamental interest, but might also play an important role in molecule-radical reactions. Like oxygen-containing molecules, sulfur compounds may also provide lone electron pairs on S, thus allowing the formation of hemibonds with free radicals. In the literature, however, most such complexes investigated before are charged [17,19,21,22,[24][25][26], which complicates the bonding with electrostatic interactions. To further understand the sulfur-containing hemibond complexes, we report here an extensive highlevel ab initio and density functional theory (DFT) study of the complexes formed by H 2 S and several free radicals. The major aim is to understand the similarities and differences between the H 2 O⋯X and H 2 S⋯X complexes with X = F, Cl, Br, and OH by examining the structural, energetic, and electronic aspects of these interesting systems. AbstractThe interaction of hydrogen sulfide (H 2 S) with F, Cl, Br, and OH is investigated using ab initio methods to identify the two-center three-electron hemibond responsible for their complexation. The binding energies are found to be stronger than those in the analogous water complexes, but follow the same trend of increasing strength: F > Cl > Br > OH. The radicals are located nearly perpendicular to the H 2 S plane forming an angle of about 90°. Analysis of molecular orbitals and natural bond orbitals are carried out to understand the energetics, structures, and bonding characteristics of these hemibonded complexes.

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confidence: 61%

Hemibond complexes between H2S and free radicals (F, Cl, Br, and OH)

Alday

Johnson

et al. 2014

Theor Chem Acc

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“…Recently, quantum chemical calculations of an accurate global potential energy surface 8 and extensive classical trajectory simulations 9 reproduced the behavior, while a review 10 pointed out at existing evidence from molecular beam scattering experiments with oriented reactants 11,12 of the key role of stereodynamics, establishing the ground for a mechanistic interpretation.…”

Section: Table Of Contents (Toc)mentioning

confidence: 99%

Stereodynamical Origin of Anti-Arrhenius Kinetics: Negative Activation Energy and Roaming for a Four-Atom Reaction

Coutinho

Silva

Oliveira

et al. 2015

J. Phys. Chem. Lett.

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The OH + HBr → H2O + Br reaction, prototypical of halogen-atom liberating processes relevant to mechanisms for atmospheric ozone destruction, attracted frequent attention of experimental chemical kinetics: the nature of the unusual reactivity drop from low to high temperatures eluded a variety of theoretical efforts, ranking this one among the most studied four-atom reactions. Here, inspired by oriented molecular-beams experiments, we develop a first-principles stereodynamical approach. Thermalized sets of trajectories, evolving on a multidimensional potential energy surface quantum mechanically generated on-the-fly, provide a map of most visited regions at each temperature. Visualizations of rearrangements of bonds along trajectories and of the role of specific angles of reactants' mutual approach elucidate the mechanistic change from the low kinetic energy regime (where incident reactants reorient to find the propitious alignment leading to reaction) to high temperature (where speed hinders adjustment of directionality and roaming delays reactivity).

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“…The results show that ICSs almost stick together in regard to the translation energy, and the ICSs decrease as the translational energy increases. The reaction path of the PES24 we used here has a vdW minimum at the entrance channel with a structure of the O-end of OH linked to HBr, HOHBr. This means the favorite route of this reaction is the two reactants enter the entrance vdW minimum to form HOHBr, then scale the transition state to make the reaction occur.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, Bowman’s group24 has developed a high-quality, full dimensional PES for the HBr + OH system based on 26,000 high-level ab initio energies. There is a van der Waals (vdW) well in the entrance channel, as well as in the product channel respectively, and a negative energy saddle-point barrier on the PES.…”

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confidence: 99%

“…Thus, in this paper, we carry out the first, full-dimensional, quantum dynamics time-dependent, wave-packet study on the PES developed by Bowman’s group. Our purpose of the present work is to (1) calculate the thermal rate constants over the temperature range of 5–500 K and compare our six degrees of freedom (6DOF) results with experiments2345678910111213 and the QCT results24, see the relationship of the rate constants with the temperature; (2) investigate the energy efficiency of the translational, vibrational, and rotational energy on a negative-energy barrier.…”

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confidence: 99%

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Quantum dynamics study of energy requirement on reactivity for the HBr + OH reaction with a negative-energy barrier

Wang

2017

Sci Rep

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A time-dependent, quantum reaction dynamics approach in full dimensional, six degrees of freedom was carried out to study the energy requirement on reactivity for the HBr + OH reaction with an early, negative energy barrier. The calculation shows both the HBr and OH vibrational excitations enhance the reactivity. However, even this reaction has a negative energy barrier, the calculation shows not all forms of energy are equally effective in promoting the reactivity. On the basis of equal amount of total energy, the vibrational energies of both the HBr and OH are more effective in enhancing the reactivity than the translational energy, whereas the rotational excitations of both the HBr and OH hinder the reactivity. The rate constants were also calculated for the temperature range between 5 to 500 K. The quantal rate constants have a better slope agreement with the experimental data than quasi-classical trajectory results.

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Quasiclassical Trajectory Calculations of the Rate Constant of the OH + HBr → Br + H₂O Reaction Using a Full-Dimensional Ab Initio Potential Energy Surface Over the Temperature Range 5 to 500 K

Cited by 37 publications

References 80 publications

Hemibond complexes between H2S and free radicals (F, Cl, Br, and OH)

Hemibond complexes between H2S and free radicals (F, Cl, Br, and OH)

Stereodynamical Origin of Anti-Arrhenius Kinetics: Negative Activation Energy and Roaming for a Four-Atom Reaction

Quantum dynamics study of energy requirement on reactivity for the HBr + OH reaction with a negative-energy barrier

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Quasiclassical Trajectory Calculations of the Rate Constant of the OH + HBr → Br + H2O Reaction Using a Full-Dimensional Ab Initio Potential Energy Surface Over the Temperature Range 5 to 500 K

Cited by 37 publications

References 80 publications

Hemibond complexes between H2S and free radicals (F, Cl, Br, and OH)

Hemibond complexes between H2S and free radicals (F, Cl, Br, and OH)

Stereodynamical Origin of Anti-Arrhenius Kinetics: Negative Activation Energy and Roaming for a Four-Atom Reaction

Quantum dynamics study of energy requirement on reactivity for the HBr + OH reaction with a negative-energy barrier

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Quasiclassical Trajectory Calculations of the Rate Constant of the OH + HBr → Br + H₂O Reaction Using a Full-Dimensional Ab Initio Potential Energy Surface Over the Temperature Range 5 to 500 K