The Isomerization Equilibrium between Cis and Trans Chloride Ruthenium Olefin Metathesis Catalysts from Quantum Mechanics Calculations

Benítez, Diego; Goddard, William A.

doi:10.1021/ja051796a

Cited by 96 publications

(68 citation statements)

References 21 publications

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“…Particularly, the phosphine-phosphonium ylide is, in principle, sterically more demanding than most of the NHCs, including the typical SIMes (1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene) NHC ligand of the complex B. This could lead to a preference for the cis attack in phosphine-phosphonium ylide-based complexes, in agreement with statements by Goddard and Grubbs [49].…”

Section: Resultssupporting

confidence: 88%

Olefin Metathesis with Ru-Based Catalysts Exchanging the Typical N-Heterocyclic Carbenes by a Phosphine–Phosphonium Ylide

2017

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Density functional theory (DFT) calculations have been used to describe the first turnover of an olefin metathesis reaction calling for a new in silico family of homogenous Ru-based catalysts bearing a phosphine-phosphonium ylide ligand, with ethylene as a substrate. Equal to conventional Ru-based catalysts bearing an N-heterocyclic carbene (NHC) ligand, the activation of these congeners occurs through a dissociative mechanism, with a more exothermic first phosphine dissociation step. In spite of a stronger electron-donating ability of a phosphonium ylide C-ligand with respect to a diaminocarbene analogue, upper energy barriers were calculated to be on average ca. 5 kcal/mol higher than those of Ru-NHC standards. Overall, the study also highlights advantages of bidentate ligands over classical monodentate NHC and phosphine ligands, with a particular preference for the cis attack of the olefin. The new generation of catalysts is constituted by cationic complexes potentially soluble in water, to be compared with the typical neutral Ru-NHC ones.

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Section: Resultssupporting

confidence: 88%

Olefin Metathesis with Ru-Based Catalysts Exchanging the Typical N-Heterocyclic Carbenes by a Phosphine–Phosphonium Ylide

2017

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“…This isomerization is postulated to occur via a decoordination of the nitrogen-atom of chelating carbene ligand. 15,21 As the accessibility of such 14 electron intermediates should cause polymerization to some extend, it is even more remarkable that no polymerization occurred. To retrieve more information about the isomerization process, the isomerization kinetics were studied by adding 5 equiv.…”

Section: Resultsmentioning

confidence: 99%

Ruthenium quinoline and quinoxaline complexes: Thermally triggered initiators for ring opening metathesis polymerization

Gstrein

Burtscher

Szadkowska

et al. 2007

J. Polym. Sci. A Polym. Chem.

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“…[38][39][40][41][42][43][44] This functional also provides a good description of the PES of transition metal-containing molecules. [45][46][47][48][49][50][51][52][53][54][55] It is important to have a consistent QM method for building a training set, so we have chosen to use the B3LYP functional to build and expand the force field to describe systems such as hydrocarbons, metals, and metal oxides.…”

Section: Quantum Mechanical Calculationsmentioning

confidence: 99%

ReaxFF Reactive Force Field for Molecular Dynamics Simulations of Hydrocarbon Oxidation

2008

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To investigate the initial chemical events associated with high-temperature gas-phase oxidation of hydrocarbons, we have expanded the ReaxFF reactive force field training set to include additional transition states and chemical reactivity of systems relevant to these reactions and optimized the force field parameters against a quantum mechanics (QM)-based training set. To validate the ReaxFF potential obtained after parameter optimization, we performed a range of NVT-MD simulations on various hydrocarbon/O 2 systems. From simulations on methane/O 2 , o-xylene/O 2 , propene/O 2 , and benzene/O 2 mixtures, we found that ReaxFF obtains the correct reactivity trend (propene > o-xylene > methane > benzene), following the trend in the C-H bond strength in these hydrocarbons. We also tracked in detail the reactions during a complete oxidation of isolated methane, propene, and o-xylene to a CO/CO 2 /H 2 O mixture and found that the pathways predicted by ReaxFF are in agreement with chemical intuition and our QM results. We observed that the predominant initiation reaction for oxidation of methane, propene, and o-xylene under fuel lean conditions involved hydrogen abstraction of the methyl hydrogen by molecular oxygen forming hydroperoxyl and hydrocarbon radical species. While under fuel rich conditions with a mixture of these hydrocarbons, we observed different chemistry compared with the oxidation of isolated hydrocarbons including a change in the type of initiation reactions, which involved both decomposition of the hydrocarbon or attack by other radicals in the system. Since ReaxFF is capable of simulating complicated reaction pathways without any preconditioning, we believe that atomistic modeling with ReaxFF provides a useful method for determining the initial events of oxidation of hydrocarbons under extreme conditions and can enhance existing combustion models.

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The Isomerization Equilibrium between Cis and Trans Chloride Ruthenium Olefin Metathesis Catalysts from Quantum Mechanics Calculations

Cited by 96 publications

References 21 publications

Olefin Metathesis with Ru-Based Catalysts Exchanging the Typical N-Heterocyclic Carbenes by a Phosphine–Phosphonium Ylide

Olefin Metathesis with Ru-Based Catalysts Exchanging the Typical N-Heterocyclic Carbenes by a Phosphine–Phosphonium Ylide

Ruthenium quinoline and quinoxaline complexes: Thermally triggered initiators for ring opening metathesis polymerization

ReaxFF Reactive Force Field for Molecular Dynamics Simulations of Hydrocarbon Oxidation

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