The activation of C-H bonds in C1-C3 alkanes by zirconium(III,IV) and titanium(III,IV) hydrides immobilized on the surface of SiO2: a density functional theory study

Ustynyuk, L. Yu.; Aleshkin, I. A.; Suleimanov, Yury V.; Besedin, D. V.; Ustynyuk, Yu. A.; Лунин, В. В.

doi:10.1134/s0036024407050184

Cited by 7 publications

(5 citation statements)

References 14 publications

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“…The tantalum atom is covalently bonded to two vicinal oxygen surface atoms leading to a non-constrained 6-membered ring [{(l-O)[(HO) 2 SiO] 2 }Ta(NH)(NH 2 )], 2 q, whose notation will be simplified to [(-SiO) 2 Ta(NH)(NH 2 )]. This model is very similar or equal to those used in previous studies for modeling silica-supported transition metal hydrides [63][64][65][66][67][68]. The reliability of the representation of 2T (Si 2 O 7 H 4 )Ta has been verified by comparing the structures and energetics of all minima obtained with the cluster model with those obtained with the periodic calculations, using (C (100) ) as model for silica.…”

Section: Dft Calculationsmentioning

confidence: 93%

H/D Exchange on Silica-Grafted Tantalum(V) Imido Amido [(≡SiO)2Ta(V)(NH)(NH2)] Synthesized from Either Ammonia or Dinitrogen: IR and DFT Evidence for Heterolytic Splitting of D2

et al. 2009

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The silica-grafted Ta (V) imido amido complex [(:SiO) 2 Ta(NH)(NH 2 )], 2, obtained from the reaction of either ammonia or dinitrogen plus hydrogen with the silicagrafted hydrides [(:SiO) 2 Ta (III) H], 1a, and [(:SiO) 2-Ta (V) H 3 ], 1b, undergoes H/D exchange with D 2 . In situ IR spectroscopy shows that the fully labelled compound [(:SiO) 2 Ta(ND)(ND 2 )], 2-d, can be obtained by moderate heating (60°C, 3 h) under D 2 atmosphere (550 torr, 300 eq. with respect to Ta), and that the exchange is reversible. The observed stretching and bending frequencies of 2-d are in agreement with the expected isotopic shift upon H/D replacement with respect to literature values reported for 2 and have been corroborated by the independent synthesis of 2-d by reaction of deuterated 1a and 1b with N 2 and D 2 . Density functional theory (DFT) calculations, performed using a periodic or a cluster model, explored the structures and energetics of all minima involved in the reaction with H 2 and showed that among the explored pathways the energetically preferred mechanisms for H 2 reaction with [{(l-O)[(HO) 2 SiO] 2 }Ta (V) (NH) (NH 2 )], 2q, is the heterolytic cleavage of either the imido Ta=N or the amido Ta-N bonds, to yield respectively [{(l-O)[(HO) 2 SiO] 2 }TaH(NH 2 ) 2 ], 3q (DE = -9.5 kcal mol -1 and DG 298K = ?2.6 kcal mol -1 with respect to 2q) and [{(l-O)[(HO) 2 SiO] 2 }Ta(NH) (NH 3 )], 4q (DE = -6.0 kcal mol -1 and DG 298K = ?7.9 kcal mol -1 with respect to 2q). All activation barriers are moderate (between 17.7 and 30.2 kcal mol -1 ) in agreement with the observed mild heating conditions necessary for the reaction to occur.

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Section: Dft Calculationsmentioning

confidence: 93%

H/D Exchange on Silica-Grafted Tantalum(V) Imido Amido [(≡SiO)2Ta(V)(NH)(NH2)] Synthesized from Either Ammonia or Dinitrogen: IR and DFT Evidence for Heterolytic Splitting of D2

et al. 2009

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“…They are very hydridic, reacting rapidly and quantitatively at room temperature with water, alcohols, alkyl halides, ,, oxidants like O 2 and N 2 O, ligands, and even hydrocarbons (Scheme ). ,,,,,− Unsaturated substrates also react with metal hydrides. For example, the reaction of Zr–H with acetone was used as early evidence of the hydride character of these hydrides .…”

Section: Supported Metal Hydrides Prepared Via Surface Organometallic...mentioning

confidence: 99%

Isolated Surface Hydrides: Formation, Structure, and Reactivity

et al. 2016

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Surface hydrides are ubiquitous in catalysis. However, their structures and properties are not as well-understood as those of their molecular counterparts, which have been extensively studied for the past 70 years. Hydrides isolated on surfaces have been characterized as stable entities on oxide surfaces or in zeolites. They have also been proposed as reaction intermediates in numerous catalytic processes (hydrogenation, hydrogenolysis, etc.). They have also been prepared via surface organometallic chemistry. In this review, we describe their key structural features and spectroscopic signatures. We discuss their reactivity and stability and also point out unexplored areas.

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“…[430,436] Thedepolymerization of polyethylene under H 2 has also been reported for Zr (Scheme 32 c). [437,438] 7. [437,438] 7.…”

Section: Supported Metal Hydrides As Catalyst Precursorsmentioning

confidence: 99%

“…The depolymerization of polyethylene under H 2 has also been reported for Zr (Scheme c) . In the case of Ti, a significant number of Ti III −H sites are formed that are proposed to be very active in the polymerization of ethylene …”

Section: Alkene Polymerizationmentioning

confidence: 99%

Bridging the Gap between Industrial and Well‐Defined Supported Catalysts

et al. 2018

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Many industrial catalysts contain isolated metal sites on the surface of oxide supports. Although such catalysts have been used in a broad range of processes for more than 40 years, there is often a very limited understanding about the structure of the catalytically active sites. This Review discusses how surface organometallic chemistry (SOMC) engineers surface sites with well-defined structures and provides insight into the nature of the active sites of industrial catalysts; the Review focuses in particular on olefin production and conversion processes.

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The activation of C-H bonds in C1-C3 alkanes by zirconium(III,IV) and titanium(III,IV) hydrides immobilized on the surface of SiO2: a density functional theory study

Cited by 7 publications

References 14 publications

H/D Exchange on Silica-Grafted Tantalum(V) Imido Amido [(≡SiO)2Ta(V)(NH)(NH2)] Synthesized from Either Ammonia or Dinitrogen: IR and DFT Evidence for Heterolytic Splitting of D2

H/D Exchange on Silica-Grafted Tantalum(V) Imido Amido [(≡SiO)2Ta(V)(NH)(NH2)] Synthesized from Either Ammonia or Dinitrogen: IR and DFT Evidence for Heterolytic Splitting of D2

Isolated Surface Hydrides: Formation, Structure, and Reactivity

Bridging the Gap between Industrial and Well‐Defined Supported Catalysts

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