scholarly journals Computational Design of SCS Nickel Pincer Complexes for the Asymmetric Transfer Hydrogenation of 1-Acetonaphthone

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 101 ◽  
Author(s):  
Bing Qiu ◽  
Wan Wang ◽  
Xinzheng Yang
Keyword(s):  
Density Functional ◽  
Enantiomeric Excess ◽  
Density Functional Theory Calculations ◽  
Computational Design ◽  
Transfer Hydrogenation ◽  
Pincer Complexes ◽  
Free Energy Barrier ◽  
Asymmetric Transfer Hydrogenation ◽  
Functional Theory ◽  
Prochiral Ketones

Inspired by the active site structures of lactate racemase and recently reported sulphur–carbon–sulphur (SCS) nickel pincer complexes, a series of scorpion-like SCS nickel pincer complexes with an imidazole tail and asymmetric claws was proposed and examined computationally as potential catalysts for the asymmetric transfer hydrogenation of 1-acetonaphthone. Density functional theory calculations reveal a proton-coupled hydride transfer mechanism for the dehydrogenation of (R)-(+)-1-phenyl-ethanol and the hydrogenation of 1-acetonaphthone to produce (R)-(+)-1-(2-naphthyl)ethanol and (S)-(−)-1-(2-naphthyl)ethanol. Among all proposed Ni complexes, 1Ph is the most active one with a rather low free energy barrier of 24 kcal/mol and high enantioselectivity of near 99% enantiomeric excess (ee) for the hydrogenation of prochiral ketones to chiral alcohols.

Mechanistic insights into asymmetric transfer hydrogenation of pyruvic acid catalysed by chiral osmium complexes with formic acid assisted proton transfer

2019 ◽  
Vol 55 (65) ◽  
pp. 9633-9636 ◽  
Author(s):  
Wan Wang ◽  
Xinzheng Yang
Keyword(s):  
Density Functional Theory ◽  
Formic Acid ◽  
Pyruvic Acid ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Transfer Hydrogenation ◽  
Asymmetric Transfer Hydrogenation ◽  
Functional Theory ◽  
Osmium Complexes ◽  
Acid Catalyzed

Density functional theory calculations reveal a proton-coupled hydride transfer mechanism with the participation of formic acid for asymmetric transfer hydrogenation of pyruvic acid catalyzed by chiral Os complexes.

scholarly journals Mechanistic Insights into Selective Hydrogenation of C=C Bonds Catalyzed by CCC Cobalt Pincer Complexes: A DFT Study

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 168
Author(s):  
Zheng Zuo ◽  
Xinzheng Yang
Keyword(s):  
Energy Barrier ◽  
Density Functional ◽  
Pincer Complexes ◽  
Free Energy Barrier ◽  
Electronic Effects ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Hydrogenation Reactions ◽  
Catalytic Cycles ◽  
Hydrogenation Selectivity

The mechanistic insights into hydrogenations of hex-5-en-2-one, isoprene, and 4-vinylcyclohex-1-ene catalyzed by pincer (MesCCC)Co (Mes = bis(mesityl-benzimidazol-2-ylidene)phenyl) complexes are computationally investigated by using the density functional theory. Different from a previously proposed mechanism with a cobalt dihydrogen complex (MesCCC)Co-H2 as the catalyst, we found that its less stable dihydride isomer, (MesCCC)Co(H)2, is the real catalyst in those catalytic cycles. The generations of final products with H2 cleavages for the formations of C−H bonds are the turnover-limiting steps in all three hydrogenation reactions. We found that the hydrogenation selectivity of different C=C bonds in the same compound is dominated by the steric effects, while the hydrogenation selectivity of C=C and C=O bonds in the same compound could be primarily influenced by the electronic effects. In addition, the observed inhabition of the hydrogenation reactions by excessive addition of PPh3 could be explained by a 15.8 kcal/mol free energy barrier for the dissociation of PPh3 from the precatalyst.

scholarly journals Syntheses, characterization, density functional theory calculations, and activity of tridentate SNS zinc pincer complexes

2011 ◽  
Vol 376 (1) ◽  
pp. 515-524 ◽  
Author(s):  
John R. Miecznikowski ◽  
Wayne Lo ◽  
Matthew A. Lynn ◽  
Brianne E. O’Loughlin ◽  
Amanda P. DiMarzio ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Pincer Complexes ◽  
Functional Theory

A Phosphine-Free Mn(I)-NNS Catalyst For Asymmetric Transfer Hydrogenation of Acetophenone: A Theoretical Prediction

2021 ◽  
Author(s):  
Yaqi Zhao ◽  
Lin Zhang ◽  
Min Pu ◽  
Ming Lei
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanism ◽  
Theoretical Prediction ◽  
Density Functional ◽  
Dft Method ◽  
Transfer Hydrogenation ◽  
Asymmetric Transfer Hydrogenation ◽  
Functional Theory ◽  
Hydrogen Activation

A density functional theory (DFT) method was employed to investigate the reaction mechanism of hydrogen activation and asymmetric transfer hydrogenation (ATH) of acetophenone catalyzed by well-defined phosphine-free Mn(I)-NNS complex. The...

scholarly journals Computational Prediction of Chiral Iron Complexes for Asymmetric Transfer Hydrogenation of Pyruvic Acid to Lactic Acid

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1892
Author(s):  
Wan Wang ◽  
Xinzheng Yang
Keyword(s):  
Free Energy ◽  
Formic Acid ◽  
Pyruvic Acid ◽  
Energy Barrier ◽  
Density Functional ◽  
Iron Complexes ◽  
Computational Prediction ◽  
Transfer Hydrogenation ◽  
Free Energy Barrier ◽  
Asymmetric Transfer Hydrogenation

Density functional theory calculations reveal a formic acid-assisted proton transfer mechanism for asymmetric transfer hydrogenation of pyruvic acid catalyzed by a chiral Fe complex, FeH[(R,R)-BESNCH(Ph)CH(Ph)NH2](η6-p-cymene), with formic acid as the hydrogen provider. The rate-determining step is the hydride transfer from formate anion to Fe for the formation and dissociation of CO2 with a total free energy barrier of 28.0 kcal mol−1. A series of new bifunctional iron complexes with η6-p-cymene replaced by different arene and sulfonyl groups were built and computationally screened as potential catalysts. Among the proposed complexes, we found 1g with η6-p-cymene replaced by 4-isopropyl biphenyl had the lowest free energy barrier of 26.2 kcal mol−1 and excellent chiral selectivity of 98.5% ee.

Computational design of double transition metal MXenes with intrinsic magnetic properties

2022 ◽  
Author(s):  
Yinggan Zhang ◽  
Zhou Cui ◽  
Baisheng Sa ◽  
Naihua Miao ◽  
Jian Zhou ◽  
...  
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Structural Diversity ◽  
Computational Design ◽  
Metal Carbides ◽  
Functional Theory ◽  
Transition Metal Carbides ◽  
Spin Polarized ◽  
Double Transition

Two-dimensional transition metal carbides (MXenes) have a great potential to achieve intrinsic magnetism due to their available chemical and structural diversity. In this work, by spin-polarized density functional theory calculations,...

THE REACTION MECHANISMS OF ALDEHYDES AND NITROSTYRENE CATALYZED BY A CHIRAL SILYLATED PYRROLIDINE CATALYST

2013 ◽  
Vol 12 (03) ◽  
pp. 1350004
Author(s):  
LI-HUA GAN ◽  
JIN ZHOU ◽  
XIAO GUO
Keyword(s):  
Density Functional ◽  
Michael Reaction ◽  
Enantiomeric Excess ◽  
Density Functional Theory Calculations ◽  
Reaction Pathways ◽  
Functional Theory ◽  
Substituent Group ◽  
Excess Value ◽  
Asymmetric Michael Reaction ◽  
Good Agreement

The asymmetric Michael reaction of aldehydes and nitrostyrene catalyzed by a new (S)-tertbutyl-diphenyl-silyl-pyrrolidine catalyst has been investigated by using density functional theory calculations. The Re face of the enamine is effectively shielded, because of the bulky 2-substituent group on the pyrrolidine ring. For acetaldehyde, there are two different conformers of enamines. Based on the two conformers of enamines, four different reaction pathways have been considered. The calculated enantiomeric excess value is 80.27% in favor of the (R)-configuration product. For propanal, eight different reaction pathways have been considered and the eight corresponding transition states have been located. The calculated enantiomeric excess value is 98.96% in favor of the (2S, 3R)-configuration product. These calculated results are in good agreement with the experimental observations. In addition, the calculations also show that both the used solvent and the enamines play important roles in determining the stereochemical outcome of the product.

On the Linear Geometry of Lanthanide Hydroxide (Ln—OH, Ln=La-Lu)

2019 ◽  
Author(s):  
Hassan Harb ◽  
Lee Thompson ◽  
Hrant Hratchian
Keyword(s):  
Triple Bond ◽  
Density Functional ◽  
Valence Electron ◽  
Density Functional Theory Calculations ◽  
Electron Configuration ◽  
Functional Theory ◽  
Key Species ◽  
Pi Orbitals ◽  
Lanthanide Hydroxide ◽  
Linear Geometry

Lanthanide hydroxides are key species in a variety of catalytic processes and in the preparation of corresponding oxides. This work explores the fundamental structure and bonding of the simplest lanthanide hydroxide, LnOH (Ln=La-Lu), using density functional theory calculations. Interestingly, the calculations predict that all structures of this series will be linear. Furthermore, these results indicate a valence electron configuration featuring an occupied sigma orbital and two occupied pi orbitals for all LnOH compounds, suggesting that the lanthanide-hydroxide bond is best characterized as a covalent triple bond.

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