Elimination of HBr from CH3Br by Cu+ and Au+: A DFT study

Li, Tao Hong; Wang, Chuanming; Liu, Xiang Yi; Xie, Xiao Guang

doi:10.1016/j.cclet.2008.04.039

Cited by 7 publications

(6 citation statements)

References 5 publications

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“…Agreement between our calculated Au + –BrCH 3 binding energy of 213.4 kJ/mol and that reported in this earlier study is within 2 kJ/mol. Likewise, our relative energetics for the rearrangement of IM4 to IM6 agree with those reported by Li et al within ±4 kJ/mol, and bond lengths agree within 0.08 Å . As noted above, Brown et al report bond strengths calculated by using coupled-cluster methods for AuBr + and AuI + , which agree well with those predicted by our calculations .…”

Section: Resultssupporting

confidence: 91%

“…All structures (Figure ) associated with these reaction surfaces were determined by using the DFT techniques described above, and key bond lengths and angles have been included. Li et al used a similar level of theory to model the Au + /CH 3 Br system, including intermediates IM4 [Br–Au–CH 3 ] + and IM6 [Au–Br–CH 3 ] + shown in Figures and . Agreement between our calculated Au + –BrCH 3 binding energy of 213.4 kJ/mol and that reported in this earlier study is within 2 kJ/mol.…”

Section: Resultssupporting

confidence: 80%

“…For our purposes, it is also illustrative to include the energetics for the related processes arising from Au + ( 1 S) with CH 3 Br and CH 3 I (upper right asymptotes) since and 4. 20 Agreement between our calculated Au + −BrCH 3 binding energy of 213.4 kJ/mol and that reported in this earlier study is within 2 kJ/mol. Likewise, our relative energetics for the rearrangement of IM4 to IM6 agree with those reported by Li et al within ±4 kJ/mol, and bond lengths agree within 0.08 Å.…”

Section: ■ Experimental Sectionsupporting

confidence: 86%

“…More specifically, the charge state of the gold atoms occupying active sites has not been fully determined, although evidence of both cationic and anionic gold centers has been reported. ,− In certain cases, gold exhibits catalytically relevant activity in the gas phase as exemplified by the oxidation of CO by ionic gold oxide clusters. − Beyond these specific examples, gas phase studies can offer insights into intrinsic reaction parameters associated with individual catalytic steps by providing a glimpse into molecular processes without the complicating influence of a solvent. This is exemplified by numerous experimental and theoretical studies that have examined the ability of gas-phase gold cations to activate sigma bonds. − …”

Section: Introductionmentioning

confidence: 99%

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Near-Thermal Reactions of Au⁺(¹S,³D) and AuX⁺ with CH₃X (X = Br, I): A Combined Experimental and Computational Analysis

et al. 2021

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Reactions of Au + ( 1 S, 3 D) and AuX + with CH 3 X (X = I and Br) were performed in the gas phase by utilizing a selectedion drift cell reactor. These experiments were done at room temperature as well as reduced temperature (∼200 K) at a total pressure of 3.5 Torr in helium. Rate coefficients, product sequencing, and branching fractions were obtained for all reactions to evaluate reaction efficiencies and higher-order processes. Reactions of both Au + states proceed with moderate efficiencies as compared to the average dipole orientation model with these neutral substrates. Results from this work revealed that, dependent on the reacting partner, Au + ( 1 S) exhibits, among others, halogen abstraction, HX elimination, and association. By comparison, Au + ( 3 D) participates primarily in charge transfer and halogen abstraction. Dependent on the halogen ligand, AuX + ions induce several processes, including association, charge transfer, halogen loss, and halogen substitution. AuI + reacting with CH 3 Br resulted in association exclusively, whereas the AuI + /CH 3 I and AuBr + /CH 3 Br systems exhibited halogen loss as the dominant process. By contrast, all possible bimolecular pathways occurred in the reaction of AuBr + with CH 3 I. Observed products indicate that displacement of bromine by iodine on gold is favored in ionic products, consistent with the thermochemical preference for formation of the Au + −I bond. All AuX + reactions proceed at maximum efficiency. Potential energy surfaces calculated at the B3LYP/def2-TZVPP level of theory for the AuX + reactions are in good agreement with the available thermochemistry for these species and with previously calculated structures and energetics. Experimental and computational results are consistent with a mechanism for the AuX + /CH 3 Y systems where bimolecular products occur either via direct loss of the halogen originally on Au or via a common intermediate resulting from methyl migration in which the Au center is three-coordinate.

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 80%

Section: ■ Experimental Sectionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

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Near-Thermal Reactions of Au⁺(¹S,³D) and AuX⁺ with CH₃X (X = Br, I): A Combined Experimental and Computational Analysis

et al. 2021

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“…HAI JUN ZHU 1,2 , WEI XIAN CHENG 1 , YI LEI CHEN 1 , HUAI CAO 1 , XIAO GAUNG XIE 3 and TAO HONG LI 4,* Based on the theoretical results of this work and our previous study, comparisons can be made. D-alanine has two conformations like D-phenylalanine due to the C-C bond rotation: the C=O and -NH2 groups are in the same side or different sides of the C-C bond.…”

Section: Theoretical Investigation Of the Gas Phase Cu + -Activated Fmentioning

confidence: 90%

Theoretical Investigation of the Gas Phase Cu+-Activated Fragmentation of D-Alanine

Zhu¹,

Cheng²,

Chen³

et al. 2013

Asian J. Chem.

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The gas phase Cu +-activated fragmentation of D-alanine was theoretically investigated at B3LYP and MP2 levels. The experimentally observed products can be rationalized by the mechanism as: Cu + +D-alanine → η 2 (NH2, C=O) complex → Cα-COOH bond insertion → O=C-OH bond insertion → H migration from-NH2 to-OH → [CH3CHNH-(H2O)Cu(CO)] +. Dissociations of the final intermediate in different forms produce the products corresponding to loss of H2O, CO and H2O + CO, respectively. Another product channel leading to elimination of HCOOH was also identified but it is energetically less favourable than the first one. By comparing the Cu + + alanine reaction with previously studied Cu + + phenylalanine reaction, it was concluded that different α-amino acids may share common reaction mechanisms for the same product channels. Different side chains change the reactivity but do not change the mechanisms significantly.

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A comparative theoretical study of the reactivities of the Al⁺ and Cu⁺ ions toward methylamine and dimethylamine

Liu

Zhang

et al. 2009

Int J of Quantum Chemistry

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A very recent laser ablation-molecular beam experiment shows that an Al ϩ ion can react with a single methylamine (MA, CH 3 NH 2 ) or dimethylamine (DMA, (CH 3 ) 2 NH) molecule to form a 1:1 ion-molecule complex Al ϩ [CH 3 NH 2 ] or Al ϩ [(CH 3 ) 2 NH)], whereas a dehydrogenated complex ion Cu ϩ [CH 3 N] or Cu ϩ [C 2 H 5 N] is detected, respectively, in the similar reaction for a Cu ϩ ion. Here, we show a comparative density functional theory study for the reactivities of the Al ϩ and Cu ϩ ions toward MA and DMA to reveal the intrinsic mechanism. It is found that the interactions of the Al ϩ ion with MA and DMA are mostly electrostatic, leading to the direct ion-molecule complexes, Al ϩ ONH 2 CH 3 and Al ϩ ONH(CH 3 ) 2 , in contrast to the non-negligible covalent character in the corresponding Cu ϩ -containing complexes, Cu ϩ ONH 2 CH 3 and Cu ϩ ONH(CH 3 ) 2 . The general dehydrogenation mechanism for MA and DMA promoted by the Cu ϩ ion has been shown, and the preponderant structures contributing to the mass spectra of the product ions Cu ϩ [CH 3 N] and Cu ϩ [C 2 H 5 N] are rationalized as Cu ϩ ONHCH 2 and Cu ϩ ON(CH 2 )(CH 3 ). The presumed dehydrogenation reactions are also discussed for the Al ϩ -containing systems. However, the involved barriers are found to be too high to be overcome at low energy conditions. These results have rationalized all the experimental observations well. FIGURE 5. Calculated minimum energy paths for forming the dehydrogenation products ions Al ϩ (C 2 H 5 N) andCu ϩ (C 2 H 5 N). Numbers refer to the relative stability (in kJ/mol) with respect to the separated reactants calculated at the B3LYP/6-311ϩG(d,p) level.

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Elimination of HBr from CH3Br by Cu+ and Au+: A DFT study

Cited by 7 publications

References 5 publications

Near-Thermal Reactions of Au⁺(¹S,³D) and AuX⁺ with CH₃X (X = Br, I): A Combined Experimental and Computational Analysis

Near-Thermal Reactions of Au⁺(¹S,³D) and AuX⁺ with CH₃X (X = Br, I): A Combined Experimental and Computational Analysis

Theoretical Investigation of the Gas Phase Cu+-Activated Fragmentation of D-Alanine

A comparative theoretical study of the reactivities of the Al⁺ and Cu⁺ ions toward methylamine and dimethylamine

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Elimination of HBr from CH3Br by Cu+ and Au+: A DFT study

Cited by 7 publications

References 5 publications

Near-Thermal Reactions of Au+(1S,3D) and AuX+ with CH3X (X = Br, I): A Combined Experimental and Computational Analysis

Near-Thermal Reactions of Au+(1S,3D) and AuX+ with CH3X (X = Br, I): A Combined Experimental and Computational Analysis

Theoretical Investigation of the Gas Phase Cu+-Activated Fragmentation of D-Alanine

A comparative theoretical study of the reactivities of the Al+ and Cu+ ions toward methylamine and dimethylamine

Contact Info

Product

Resources

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Near-Thermal Reactions of Au⁺(¹S,³D) and AuX⁺ with CH₃X (X = Br, I): A Combined Experimental and Computational Analysis

Near-Thermal Reactions of Au⁺(¹S,³D) and AuX⁺ with CH₃X (X = Br, I): A Combined Experimental and Computational Analysis

A comparative theoretical study of the reactivities of the Al⁺ and Cu⁺ ions toward methylamine and dimethylamine