Hydrogen atom transfer in alkane thiol-gold cluster complexes: A density functional theory study

Although it has been reported that some radical reactions are possibly promoted by external ions, the origin of this phenomenon is unclear. In this work, several hydrogen atom transfer (HAT) reactions in the presence of anions were studied by density functional theory (DFT) calculations, electronic structure analysis and other methods, and it is concluded that both the electrostatic interaction and polarization of the transition state (TS) by the electric field generated by anions play a fundamental role in the TS stabilization effect, whereas the “charge shift bonding” that was previously presumed to be a major contributor is ruled out. Although the stabilization toward TSs in terms of electronic energy (and thus enthalpy) is significant, it should be noted that the effect is almost completely cancelled by entropy and solvation, and further cancelled by the formation of stable resting states. Thus there is still a long way for this effect to be used in actual catalysis.

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The “Decisive” Role for Secondary Coordination Sphere Nucleophiles on Hydrogen Atom Transfer (HAT) Reactions: Does It Exist and What Is Its Origin?

10.26434/chemrxiv.11994582 ◽

2020 ◽

Author(s):

Yumiao Ma ◽

Yishan Li

Keyword(s):

Hydrogen Atom ◽

Density Functional ◽

Decisive Role ◽

Electronic Energy ◽

Hydrogen Atom Transfer ◽

Atom Transfer ◽

Major Contributor ◽

Functional Theory ◽

Secondary Coordination Sphere ◽

Stabilization Effect

Although it has been reported that some radical reactions are possibly promoted by external ions, the origin of this phenomenon is unclear. In this work, several hydrogen atom transfer (HAT) reactions in the presence of anions were studied by density functional theory (DFT) calculations, electronic structure analysis and other methods, and it is concluded that both the electrostatic interaction and polarization of the transition state (TS) by the electric field generated by anions play a fundamental role in the TS stabilization effect, whereas the “charge shift bonding” that was previously presumed to be a major contributor is ruled out. Although the stabilization toward TSs in terms of electronic energy (and thus enthalpy) is significant, it should be noted that the effect is almost completely cancelled by entropy and solvation, and further cancelled by the formation of stable resting states. Thus there is still a long way for this effect to be used in actual catalysis.

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The “Decisive” Role for Secondary Coordination Sphere Nucleophiles on Hydrogen Atom Transfer (HAT) Reactions: Does It Exist and What Is Its Origin?

10.26434/chemrxiv.11994582.v1 ◽

2020 ◽

Author(s):

Yumiao Ma ◽

Yishan Li

Keyword(s):

Hydrogen Atom ◽

Density Functional ◽

Decisive Role ◽

Electronic Energy ◽

Hydrogen Atom Transfer ◽

Atom Transfer ◽

Major Contributor ◽

Functional Theory ◽

Secondary Coordination Sphere ◽

Stabilization Effect

Although it has been reported that some radical reactions are possibly promoted by external ions, the origin of this phenomenon is unclear. In this work, several hydrogen atom transfer (HAT) reactions in the presence of anions were studied by density functional theory (DFT) calculations, electronic structure analysis and other methods, and it is concluded that both the electrostatic interaction and polarization of the transition state (TS) by the electric field generated by anions play a fundamental role in the TS stabilization effect, whereas the “charge shift bonding” that was previously presumed to be a major contributor is ruled out. Although the stabilization toward TSs in terms of electronic energy (and thus enthalpy) is significant, it should be noted that the effect is almost completely cancelled by entropy and solvation, and further cancelled by the formation of stable resting states. Thus there is still a long way for this effect to be used in actual catalysis.

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MClx (M = Hg, Au, Ru; x = 2, 3) catalyzed hydrochlorination of acetylene — A density functional theory study

Canadian Journal of Chemistry ◽

10.1139/cjc-2012-0308 ◽

2013 ◽

Vol 91 (2) ◽

pp. 120-125 ◽

Cited By ~ 41

Author(s):

Mingyuan Zhu ◽

Lihua Kang ◽

Yan Su ◽

Shanzheng Zhang ◽

Bin Dai

Keyword(s):

Density Functional Theory ◽

Dft Calculations ◽

Chlorine Atom ◽

Density Functional ◽

Activation Barrier ◽

Stable Complex ◽

Atom Transfer ◽

Density Functional Theory Study ◽

Functional Theory ◽

Complex Species

Density functional theory (DFT) calculations were used to study the mechanism for the hydrochlorination of acetylene catalyzed by MClx (M = Hg, Au, Ru; x = 2, 3). For the three catalysts, the reaction occurs via a one-shift chlorine atom transfer, which avoids the formation of highly stable complex species. The adsorbed HCl acts as a chlorine donor, while the C2H2 favors the chlorine abstraction. The calculated real activation barrier decreases in the order: HgCl2 > AuCl3 > RuCl3, which suggests that the RuCl3 would be a good candidate catalyst for the hydrochlorination of acetylene.

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