Ab Initio Molecular Dynamics Simulation Study on the Stereo Reactions between Atomic Oxygen Anion and Methane

Abstract

Ion–molecule reaction between atomic oxygen anion (O−) and methane (CH4) has been systematically investigated employing the on-the-fly ab initio molecular dynamics simulations. Besides the major H-abstraction process as the exothermic reaction studied widely, an endothermic pathway to produce OCH3− and H is also observed in this study. Three typical O− attack modes with reference to the pyramid structure of CH4 fixed in space have been considered. It was found that the internal motions of the radical products are significantly dependent on the O− attack modes. As for the reaction between O− and the thermally vibrating CH4, the major pathway to produce OH− and CH3 is preferred by the direct H-abstraction and the minor pathway to produce H and OCH3− is the roaming reaction via the transient negative ion [HO-CH3]−.

Imaging the Ion–Molecule Reaction Dynamics of O– + CD4

“…Their findings concluded that this reaction proceeds predominantly via a direct mechanism. This is supported by the recent on-the-fly molecular dynamics simulations, which found predominantly direct dynamics at collision energies above 1.5 eV …”

“…This is supported by the recent on-thefly molecular dynamics simulations, which found predominantly direct dynamics at collision energies above 1.5 eV. 24 Here, we present experimental reactive scattering data for reaction 1 using a velocity map imaging (VMI) spectrometer in combination with the crossed-beam technique. We obtained experimental energy-and angle-dependent differential scattering cross sections for the OD − product anion in the energy range of 0.2−1.5 eV relative collision energy.…”

“…This is in very good agreement with the on-the-fly molecular dynamics simulations, which predict direct dynamics and predominantly sideways scattering at this energy. 24 We have quantified the contribution of forward, backward, and sideways scattering by an angle-dependent integration of the scattering images at each collision energy (see the Supporting Information for details). Specifically, we have divided the cross sections into sectors of −1 ≤ cos θ < −1/3 for backscattered products, −1/3 ≤ cos θ < 1/3 for sideways scattering and 1/3 ≤ cos θ ≤ 1 for forward scattered products.…”

Computational Studies of Coinage Metal Anion M− + CH3X (X = F, Cl, Br, I) Reactions in Gas Phase

“…The nucleophilicity of gold is important in oxidative reactions, the Au − anion is more nucleophilic than Au(0), Au(I), and Au(III) species, and thus reactions of atomic Au − anions with hydrocarbons in the gas phase were studied [ 14 , 19 ]. The study of gas-phase ion-molecule reactions provides mechanistic insights into the bond-breaking and -making steps that are often obscured under condensed-phase environments, which are complicated by solvents, counterions, and ligands [ 14 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. Although gas-phase obtained information cannot replace that of the condensed phase, understanding the intrinsic unit makes it more feasible to improve chemical reactions or catalysts from a bottom-up approach [ 20 , 22 , 26 , 30 , 31 ].…”

Reactions of Microorganisms with Atomic Oxygen Radical Anions: Damage of Cells and Irreversible Inactivation

“…At the same time, Ois also considered as a radical because it has an unpaired electron in its outermost orbit. It was found that atomic Ohad extremely high oxidation and reactivity towards the hydrocarbons' small molecules [23][24][25][26]. Moreover, Omay be one of the most reactive oxygen species and therefore has various potential applications, such as a one-step synthesis of phenol from benzene [27], the reduction of NO [28], and the dissociation and oxidation of bio-oil [29,30].…”