scholarly journals The activity of indenylidene derivatives in olefin metathesis catalysts

2018 ◽  
Vol 14 ◽  
pp. 2956-2963 ◽  
Author(s):  
Maria Voccia ◽  
Steven P Nolan ◽  
Luigi Cavallo ◽  
Albert Poater
Keyword(s):  
Olefin Metathesis ◽  
Density Functional ◽  
Bond Orders ◽  
Metathesis Reaction ◽  
Functional Theory ◽  
New Family ◽  
Sterically Demanding ◽  
Electronic Parameters ◽  
Metathesis Catalysts ◽  
Dissociation Step

The first turnover event of an olefin metathesis reaction using a new family of homogenous Ru-based catalysts bearing modified indenylidene ligands has been investigated, using methoxyethylene as a substrate. The study is carried out by means of density functional theory (DFT). The indenylidene ligands are decorated with ortho-methyl and isopropyl groups at both ortho positions of their phenyl ring. DFT results highlight the more sterically demanding indenylidenes have to undergo a more exothermic first phosphine dissociation step. Overall, the study emphasises advantages of increased steric hindrance in promoting the phosphine release, and the relative stability of the corresponding metallacycle over classical ylidene ligands. Mayer bond orders and steric maps provide structural reasons for these effects, whereas NICS aromaticity and conceptual DFT confirm that the electronic parameters do not play a significant role.

scholarly journals MOF Encapsulation of Ru Olefin Metathesis Catalysts to Block Catalyst Decomposition

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 687
Author(s):  
Gerard Pareras ◽  
Davide Tiana ◽  
Albert Poater
Keyword(s):  
Olefin Metathesis ◽  
Density Functional ◽  
Metal Organic Framework ◽  
Functional Theory ◽  
Ammonium N ◽  
Metathesis Catalyst ◽  
Metal Organic ◽  
Non Covalent Interactions ◽  
Metathesis Catalysts

In the present work, a catalyst variation of the second-generation Hoveyda–Grubbs catalyst, particularly the ammonium-tagged Ru-alkylidene metathesis catalyst AquaMetTM, is under study, not simply to increase the efficiency in olefin metathesis but also the solubility in polar solvents. Moreover, this ionic catalyst was combined with the metal organic framework (MOF) (Cr)MIL-101-SO3−(Na·15-crown-5)+. We started from the experimental results by Grela et al., who increased the performance when the ruthenium catalyst was confined inside the cavities of the MOF, achieving non-covalent interactions between both moieties. Here, using density functional theory (DFT) calculations, the role of the ammonium N-heterocyclic carbene (NHC) tagged and the confinement effects are checked. The kinetics are used to compare reaction profiles, whereas SambVca steric maps and NCI plots are used to characterize the role of the MOF structurally and electronically.

Two-dimensional metal-organic frameworks Mo3(C2O)12 as promising single-atom catalysts for selective nitrogen-to-ammonia

2022 ◽  
Author(s):  
Zhen Feng ◽  
Zelin Yang ◽  
Xiaowen Meng ◽  
Fachuang Li ◽  
Zhanyong Guo ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Metal Organic Frameworks ◽  
Density Functional Theory Calculations ◽  
Reduction Reaction ◽  
Single Atom ◽  
Two Dimensional ◽  
Functional Theory ◽  
New Family ◽  
Metal Organic

The development of single-atom catalysts (SACs) for electrocatalytic nitrogen reduction reaction (NRR) remains a great challenge. Using density functional theory calculations, we design a new family of two-dimensional metal-organic frameworks...

Structural, elastic, electronic and thermoelectric properties of XPN2 (X = Li, Na): First-principles study

2019 ◽  
Vol 33 (21) ◽  
pp. 1950234
Author(s):  
T. Ghellab ◽  
H. Baaziz ◽  
Z. Charifi ◽  
K. Bouferrache ◽  
Ş Uğur ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Three Dimensional ◽  
Lattice Parameter ◽  
Full Potential ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Electronic Parameters ◽  
Linearized Augmented Plane Wave

Based on the density functional theory (DFT) implemented by the wien2k code which uses the full potential linearized augmented plane wave plus local orbitals (APW + lo) method, we have been able to study different physical properties of X[Formula: see text]PN2 (X = Li, Na) chalcopyrite such as structural, electronic, elastic and thermoelectric properties. According to our calculations, we have found that our structural and electronic parameters, such as the lattice parameter, energy bandgap, the tetragonal ratio, the displacement of the anions, are in very good agreement with the previous experimental and theoretical results. Based on the Voigt–Reuss–Hill approximations, we were able to compute the elastic constants: the compressibility, Young’s and the shear’s moduli, the average velocity of the elastic waves, the Debye temperature and the Poisson’s coefficient of the chalcopyrite LiPN2 and NaPN2. The elastic anisotropy is estimated and further illustrated by the three-dimensional (3D) direction of Young’s and Bulk’s moduli. Finally, using the semi-classical Boltzmann theory implemented in the BolzTraP code, we calculated the transport properties such as the Seebeck coefficient, the thermal electrical conductivity and the figure of merit of these materials.

scholarly journals In tandem or alone: a remarkably selective transfer hydrogenation of alkenes catalyzed by ruthenium olefin metathesis catalysts

2015 ◽  
Vol 13 (9) ◽  
pp. 2684-2688 ◽  
Author(s):  
Grzegorz Krzysztof Zieliński ◽  
Cezary Samojłowicz ◽  
Tomasz Wdowik ◽  
Karol Grela
Keyword(s):  
Olefin Metathesis ◽  
Transfer Hydrogenation ◽  
Selective Transfer ◽  
Metathesis Reaction ◽  
Metathesis Catalyst ◽  
Selective System ◽  
Metathesis Catalysts

A remarkably selective system for transfer hydrogenation of alkenes, composed of Grubbs’ ruthenium metathesis catalyst and HCOONa/HCOOH, is presented. This system can also be formed directly after a metathesis reaction to effect hydrogenation in a single-pot.

Searching for a new family of high energy explosives by introducing N atoms, N-oxides, and NO2 into a cage adamantane

2016 ◽  
Vol 94 (8) ◽  
pp. 667-673 ◽  
Author(s):  
Dong Xiang ◽  
Hao Chen ◽  
Weihua Zhu ◽  
Heming Xiao
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Design Strategy ◽  
High Energy ◽  
Impact Sensitivity ◽  
Lower Sensitivity ◽  
Detonation Properties ◽  
Potential Candidate ◽  
Functional Theory ◽  
New Family

A design strategy that including N atoms, N-oxides, and nitro groups into a cage azaadamantane at the same time was used to design 10 polyazaoxyadamantanes (PAOAs) and eight polynitroazaoxyadamantanes (PNTAOAs). First, four stable azaadamantanes were built by replacing the tertiary C atoms of an adamantane with N atoms. Then, 10 PAOAs were designed by introducing one to four N-oxides into the four azaadamantanes. After that, eight PNTAOAs were formed when the H atoms of four N-oxide-substituted azaadamantanes were replaced with different numbers of nitro groups. Finally, their heats of formation, densities, detonation properties, and impact sensitivity were estimated by using density functional theory. Among the eight PNTAOAs, seven compounds had better detonation performances than CL-20, the outstanding, novel, high-energy, and relatively insensitive cage explosive. Two compounds had higher detonation performance and lower sensitivity than CL-20 and HMX, suggesting that their overall performances are outstanding and they may be considered as the potential candidate of high-energy explosives.

Mechanistic Study of ROS-photogeneration by Pterin

Pteridines ◽  
2011 ◽  
Vol 22 (1) ◽  
pp. 73-76 ◽  
Author(s):  
Hong-Fang Ji ◽  
Liang Shen
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Transfer Reaction ◽  
Direct Electron Transfer ◽  
Density Functional Theory Calculations ◽  
Electron Transfer Reaction ◽  
Mechanistic Study ◽  
Functional Theory ◽  
Direct Energy ◽  
Electronic Parameters

Abstract Pterins are widespread in biological systems and possess photosensitizing activities. In the present study, the photosensitization mechanism of acid form of pterin (PTA) and basic form of pterin (PTB) is investigated by means of density functional theory calculations. The reactive oxygen species-photogenerating pathways of the lowest triplet excited (T1) state PTA and PTB are proposed as follows. Through direct energy transfer, both T1 state PTA and PTB can photogenerate 1O2. Two possible O2 .−-generating pathways are proposed according to the electronic parameters of PTA and PTB: i) direct electron transfer from T1 state PTA and PTB to 3O2 and the electron transfer reaction is more favorable energetically for PTB in comparison with PTA; and ii) electron transfer from anion radical of PTA and PTB to 3O2.

scholarly journals Preparation of Ruthenium Olefin Metathesis Catalysts Immobilized on MOF, SBA-15, and 13X for Probing Heterogeneous Boomerang Effect

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 438 ◽  
Author(s):  
Artur Chołuj ◽  
Wojciech Nogaś ◽  
Michał Patrzałek ◽  
Paweł Krzesiński ◽  
Michał J. Chmielewski ◽  
...  
Keyword(s):  
Olefin Metathesis ◽  
Metal Organic Framework ◽  
Chemical Production ◽  
Metathesis Reaction ◽  
Solid Supports ◽  
13X Zeolite ◽  
Boomerang Effect ◽  
Metal Organic ◽  
Metathesis Catalysts ◽  
First Time

Promoted by homogeneous Ru-benzylidene complexes, the olefin metathesis reaction is a powerful methodology for C-C double bonds formation that can find a number of applications in green chemical production. A set of heterogeneous olefin metathesis pre-catalysts composed of ammonium-tagged Ru-benzylidene complexes 4 (commercial FixCat™ catalyst) and 6 (in-house made) immobilized on solid supports such as 13X zeolite, metal-organic framework (MOF), and SBA-15 silica were obtained and tested in catalysis. These hybrid materials were doped with various amounts of ammonium-tagged styrene derivative 5—a precursor of a spare benzylidene ligand—in order to enhance pre-catalyst regeneration via the so-called release-return “boomerang effect”. Although this effect was for the first time observed inside the solid support, we discovered that non-doped systems gave better results in terms of the resulting turnover number (TON) values, and the most productive were hybrid catalysts composed of 4@MOF, 4@SBA-15, and 6@SBA-15.

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