Effect of “Reducible” Titania Promotion on the Mechanism of H-Migration in Pd/SiO2 Clusters

Asatryan, Rubik; Ruckenstein, Eli

doi:10.1007/s10562-015-1642-0

Cited by 4 publications

(2 citation statements)

References 140 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“… 56 Its performance has been extensively studied for various properties and systems, including cases in the same problem domain as the work presented here. 15 , 36 , 51 , 57 – 59 , 64 For instance, the barrier height of the iconic BPR rearrangement in Fe(CO) 5 was computed by Harris et al at the BP86 GGA level to be 2.1 kcal mol –1 , 36 which is in remarkably good agreement to the experimental activation energy of 1.6 ± 0.3 kcal mol –1 obtained via temperature-dependent two-dimensional infrared spectroscopy. 36 While no experimental data is available for the geometries of the HFe˙(CO) 4 isomers to benchmark the employed geometry optimization approach, it is known that DFT successfully predicts the geometries of the precursor H 2 Fe(CO) 4 ( ref.…”

Section: Methods and Computational Detailssupporting

confidence: 72%

Revisiting the polytopal rearrangements in penta-coordinate d⁷-metallocomplexes: modified Berry pseudorotation, octahedral switch, and butterfly isomerization

2017

Self Cite

View full text Add to dashboard Cite

show abstract

Section: Methods and Computational Detailssupporting

confidence: 72%

Revisiting the polytopal rearrangements in penta-coordinate d⁷-metallocomplexes: modified Berry pseudorotation, octahedral switch, and butterfly isomerization

2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…These include single point calculations on the stationary points obtained at UB97-D3 level using the coupled cluster theory with singles, doubles, and perturbative triples amplitudes (CCSD(T) . The latter is considered the “gold standard” of computational quantum chemistry, , largely employed to verify and improve results for open-shell systems and reactions (see, e.g., refs , , , and ). For further comparisons, we employed MP2 wave function method .…”

Section: Methods and Computational Detailsmentioning

confidence: 99%

Roaming-like Mechanism for Dehydration of Diol Radicals

et al. 2018

Self Cite

View full text Add to dashboard Cite

Diol radicals (DRs) are important intermediates in biocatalysis, atmospheric chemistry, and biomass combustion. They are particularly generated from photolysis of halogenated diols and addition of hydroxyl radical to a double bond of unsaturated alcohols, such as lignols. The energized DRs further isomerize/decompose to form products, including water. Aqueous-phase dehydration in radiolytic and biomimetic systems typically occurs at low temperatures, with or without catalysis, whereas the gas-phase dehydration is usually considered energetically unfavorable. In the present study, we propose a new low-energy, roaming-like mechanism based on a detailed dispersion-corrected DFT and ab initio level analysis of the gas-phase dehydration of DRs obtained from the combination of OH radicals with allyl alcohol (AA, CH2CHCH2OH)the simplest relevant model of the unsaturated alcohols. The roaming pathways involve a nearly dissociated OH-group, which subsequently abstracts an H atom of the remaining fragment to form water and [C3H5O] radical via a transition state (TS) with energy close to the C–O bond fission asymptote. Two types of roaming-like first-order saddle points (SP) are identified for unimolecular dehydration of 1,2- and 1,3-DR radical adducts involving either both hydroxyl groups of diol radicals to generate an oxygen-centered radical, or β-OH group and a skeletal α-hydrogen atom of the 1,2-DR to form a resonantly stabilized hydroxyallyl radical. Two higher energy conventional (tight) transition states, along with the pathways to 1,2-OH-migration, as well as direct H-abstraction, are also identified and analyzed. Most of the traditional density functional theory methods that have been successfully employed in the literature to locate so-far-known roaming SPs were also able to identify the new mechanism, in accord with dispersion-corrected double hybrid B2PLYP-D3(BJ) and mPW2PLYPD methods involving MP2-correlation corrections. However, the MP2 method itself failed to locate any of them, which seems to be typical for MP2 method for loose TS structures, confirmed here for a flat region of PES connecting direct and roaming saddle points. However, MP2 method correctly locates an identical roaming SP for a larger p-coumaryl alcohol model involving hydroxyphenyl substituent at Cγ atom of AA. Two types of interfragmental interactions are identified that stabilize the roaming SPs: (a) H-bonding of the leaving OH radical either with the H atom of the remaining OH group, or with π-cloud of the double bond; (b) direct interaction of π-electrons with the lone-pair electrons of the heteroatom in the leaving OH group through the TS-ring. The alternative TSs are qualitatively characterized by “collinearity” angle of the OH radical attack on the O–H/C–H bonds of the substrate in abstraction-like O–H–O geometry, attributed to the improved orbital overlaps. The proposed mechanism presents broader implications to signify, particularly, a larger role in atmospheric and combustion processes, especially biomass pyrolysis.

show abstract

Ce-doped SBA-15 supported Pd catalyst for efficient hydrogenation of 2-ethyl-anthraquinone

Zhang

Liu

et al. 2023

Applied Surface Science

View full text Add to dashboard Cite

Effect of “Reducible” Titania Promotion on the Mechanism of H-Migration in Pd/SiO2 Clusters

Cited by 4 publications

References 140 publications

Revisiting the polytopal rearrangements in penta-coordinate d⁷-metallocomplexes: modified Berry pseudorotation, octahedral switch, and butterfly isomerization

Revisiting the polytopal rearrangements in penta-coordinate d⁷-metallocomplexes: modified Berry pseudorotation, octahedral switch, and butterfly isomerization

Roaming-like Mechanism for Dehydration of Diol Radicals

Ce-doped SBA-15 supported Pd catalyst for efficient hydrogenation of 2-ethyl-anthraquinone

Contact Info

Product

Resources

About

Effect of “Reducible” Titania Promotion on the Mechanism of H-Migration in Pd/SiO2 Clusters

Cited by 4 publications

References 140 publications

Revisiting the polytopal rearrangements in penta-coordinate d7-metallocomplexes: modified Berry pseudorotation, octahedral switch, and butterfly isomerization

Revisiting the polytopal rearrangements in penta-coordinate d7-metallocomplexes: modified Berry pseudorotation, octahedral switch, and butterfly isomerization

Roaming-like Mechanism for Dehydration of Diol Radicals

Ce-doped SBA-15 supported Pd catalyst for efficient hydrogenation of 2-ethyl-anthraquinone

Contact Info

Product

Resources

About

Revisiting the polytopal rearrangements in penta-coordinate d⁷-metallocomplexes: modified Berry pseudorotation, octahedral switch, and butterfly isomerization

Revisiting the polytopal rearrangements in penta-coordinate d⁷-metallocomplexes: modified Berry pseudorotation, octahedral switch, and butterfly isomerization