Activation of Molecular Hydrogen over a Binuclear Complex with Rh2S2Core:  DFT Calculations and NMR Mechanistic Studies

2004 ◽  
Vol 126 (38) ◽  
pp. 11954-11965 ◽  
Author(s):  
Andrea Ienco ◽  
Maria José Calhorda ◽  
Joachim Reinhold ◽  
Francesca Reineri ◽  
Claudio Bianchini ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Molecular Hydrogen ◽  
Binuclear Complex ◽  
Mechanistic Studies

scholarly journals C-H Functionalization Reactions of Unprotected N-Heterocycles by Gold Catalyzed Carbene Transfer

2020 ◽  
Author(s):  
Sripati Jana ◽  
Claire Empel ◽  
Chao Pei ◽  
Polina Aseeva ◽  
Thanh Vinh Nguyen ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Functional Groups ◽  
Gold Catalyst ◽  
Protecting Groups ◽  
Transfer Reactions ◽  
Mechanistic Studies ◽  
Economic Strategies ◽  
Carbene Transfer ◽  
Functionalization Reaction

<p>The C-H functionalization reaction of N-heterocycles with unprotected N-H group is one of the most step-economic strategies to introduce functional groups without the need of installation and removal of protecting groups. Despite recent significant advances in C-H functionalization chemistry, this strategy remains unsatisfactorily developed. In this report, we disclose a simple and straightforward protocol to allow for the selective C-H functionalization of unprotected double benzannellated N-heterocycles via gold catalyzed carbene transfer reactions (29 examples, up to 86% yield). The scope of the reaction can also be expanded to the corresponding protected heterocycles (37 examples, up to 98% yield), further demonstrating the generality of this method. Mechanistic studies by DFT calculations underpin the importance of the gold catalyst and reveal that the selectivity of this reaction is driven by trace amounts of water present in the reaction mixture.</p>

Mechanistic studies of base-catalysed lignin depolymerisation in dimethyl carbonate

2018 ◽  
Vol 20 (1) ◽  
pp. 170-182 ◽  
Author(s):  
Saumya Dabral ◽  
Julien Engel ◽  
Jakob Mottweiler ◽  
Stephanie S. M. Spoehrle ◽  
Ciaran W. Lahive ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Lignin Degradation ◽  
Dimethyl Carbonate ◽  
Analytical Techniques ◽  
Mechanistic Studies

Various analytical techniques and DFT calculations have been applied in studying base-catalysed lignin degradation in dimethyl carbonate.

Multi-scale theoretical investigation of molecular hydrogen adsorption over graphene: coronene as a case study

RSC Advances ◽  
2014 ◽  
Vol 4 (97) ◽  
pp. 54447-54453 ◽  
Author(s):  
Md Bin Yeamin ◽  
N. Faginas-Lago ◽  
M. Albertí ◽  
I. G. Cuesta ◽  
J. Sánchez-Marín ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Dft Calculations ◽  
Modeling And Simulation ◽  
Molecular Dynamics Simulations ◽  
Multiscale Modeling ◽  
Molecular Hydrogen ◽  
Hydrogen Adsorption ◽  
Multi Scale ◽  
Dynamics Simulations

Multiscale modeling and simulation (MMS) combining B97-D/TZV2P DFT calculations and molecular dynamics simulations are performed to investigate the adsorption of hydrogen over coronene as a model of graphene.

scholarly journals Manganese-Catalyzed Ammonia Oxidation into Dinitrogen

2020 ◽  
Author(s):  
Hiroki Toda ◽  
Kazunari Nakajima ◽  
Ken Sakata ◽  
Yoshiaki Nishibayashi
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Density Functional ◽  
Ammonia Oxidation ◽  
Nucleophilic Attack ◽  
Mechanistic Studies ◽  
Oxidative Conversion ◽  
Functional Theory ◽  
Metal Catalyzed ◽  
Nitrogen Bond

Base metal-catalyzed oxidative conversion of ammonia into dinitrogen is a promising process to utilize ammonia as an energy carrier. In this study, we report the manganese-catalyzed ammonia oxidation under chemical and electrochemical conditions. Mechanistic studies including density functional theory (DFT) calculations suggest that a nucleophilic attack of ammonia on manganese nitrogenous complexes occurs to form a nitrogen–nitrogen bond leading to dinitrogen.<br>

scholarly journals Bimetallic Cooperativity with a 2-Phosphinoimidazole-Derived Pd(II) Dimer Enables Naphthalene Synthesis via dimeric Pd(III) Catalysis

2020 ◽  
Author(s):  
Chloe C. Ence ◽  
S. Hadi Nazari ◽  
Mariur Rodriguez Moreno ◽  
Manase F. Matu ◽  
Samantha G. Kulka ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Dft Calculations ◽  
Oxidation State ◽  
Methyl Ketone ◽  
Methyl Ketones ◽  
Mechanistic Studies ◽  
High Oxidation State ◽  
Pd Catalysts ◽  
Silver Triflate ◽  
High Oxidation

We report the synthesis of bimetallic Pd(I) and Pd(II) complexes scaffolded on bidentate 2-phosphinoimidazole ligands. These complexes display unique catalytic activity and enable the expeditious formation of 1,3-disubstituted naphthalenes via an unprecedented coupling of aryl iodides and methyl ketones in the presence of silver triflate. Excellent substrate scope for naphthalene formation is also demonstrated. Mechanistic studies suggest that the transformation proceeds via Pd-catalyzed arylation of a methyl ketone, followed by cyclization with a second equivalent of ketone. Importantly, this ketone arylation processes occurs under oxidizing conditions, suggesting involvement of higher oxidation state dimeric Pd catalysts. Based on experiments and DFT calculations, we propose a mechanism involving high oxidation state Pd(III) bimetallic catalysis. These new bimetallic complexes possess reactivity that is not seen with monometallic Pd catalysts and we confirm the importance of the palladium catalyst for both arylation and cyclization for naphthalene formation.

scholarly journals Ligand-Controlled Regiodivergence in Nickel-Catalyzed Hydroarylation and Hydroalkenylation of Alkenyl Carboxylic Acids

2020 ◽  
Author(s):  
Zi-Qi Li ◽  
Yue Fu ◽  
Ruohan Deng ◽  
Van Tran ◽  
Yang Gao ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Transition State ◽  
Carboxylic Acids ◽  
Alkyl Group ◽  
Steric Effects ◽  
High Yield ◽  
Mechanistic Studies ◽  
Ligand Environment ◽  
Ligand Free ◽  
Electronic And Steric Effects

<div>A nickel-catalyzed regiodivergent hydroarylation and hydroalkenylation of unactivated alkenyl carboxylic acids is reported, whereby the ligand environment around the metal center dictates the regiochemical outcome. Markovnikov hydrofunctionalization products are obtained under mild ligand-free conditions, with up to 99% yield and >20:1 selectivity. Alternatively, anti-Markovnikov products can be accessed with a novel 4,4-disubstituted Pyrox ligand in excellent yield and >20:1 selectivity. Both electronic and steric effects on the ligand contribute to the high yield and selectivity. Mechanistic studies suggest a change in the turnover-limiting and selectivity-determining step induced by the optimal ligand. DFT calculations reveal that in the anti-Markovnikov pathway, repulsion between the ligand and the alkyl group is minimized (by virtue of it being 1° versus 2°) in the rate- and regioselectivity-determining transmetalation transition state. <br></div>

scholarly journals Stabilization of two conformers via intra- or inter-molecular hydrogen bonds in a dinuclear vanadium(v) complex with a pendant Schiff base: theoretical insight

RSC Advances ◽  
2019 ◽  
Vol 9 (60) ◽  
pp. 35165-35175 ◽  
Author(s):  
Snehasish Thakur ◽  
Michael G. B. Drew ◽  
Antonio Franconetti ◽  
Antonio Frontera ◽  
Shouvik Chattopadhyay
Keyword(s):  
Density Functional Theory ◽  
Schiff Base ◽  
Hydrogen Bonds ◽  
Dft Calculations ◽  
Molecular Hydrogen ◽  
Density Functional ◽  
Functional Theory ◽  
Theoretical Insight ◽  
Hydrogen Bonded

Two different hydrogen bonded conformers coexist in a synthesized dinuclear oxovanadium(v) Schiff base. Density functional theory (DFT) calculations were utilized to calculate the energies involved in two different conformers.

scholarly journals Rethinking Basic Concepts - Hydrogenation of Alkenes Catalyzed by Bench-Stable Alkyl Mn(I) Complexes

2019 ◽  
Author(s):  
Stefan Weber ◽  
Berthold Stöger ◽  
Luis F. Veiros ◽  
Karl Kirchner
Keyword(s):  
Dft Calculations ◽  
Molecular Hydrogen ◽  
Precious Metal ◽  
Hydrogen Pressure ◽  
Environmentally Benign ◽  
Metal Catalyst ◽  
Catalyst Loading ◽  
Migratory Insertion ◽  
Earth Abundant ◽  
Basic Concepts

An efficient additive-free manganese-catalyzed hydrogenation of alkenes to alkanes with molecular hydrogen is described. This reaction is environmentally benign and atom economic, implementing an inexpensive, earth abundant non-precious metal catalyst. The most efficient pre-catalyst is the bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dippe)(CO)3(CH2CH2CH3)]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn-alkyl bond to yield an acyl intermediate which undergoes rapid hydrogenolysis to form the active 16e Mn(I) hydride catalyst [Mn(dippe)(CO)2(H)]. A range of mono- and disubstituted alkenes were efficiently converted into alkanes in good to excellent yields. The hydrogenation of 1-alkenes and 1,1-disubstituted alkenes proceeds at 25 oC, while 1,2-disubstituted alkenes require a reaction temperature of 60oC. In all cases, a catalyst loading of 2 mol % and a hydrogen pressure of 50 bar was applied. A mechanism based on DFT calculations is presented.<br>

scholarly journals Ligand-Controlled Regiodivergence in Nickel-Catalyzed Hydroarylation and Hydroalkenylation of Alkenyl Carboxylic Acids

2020 ◽  
Author(s):  
Zi-Qi Li ◽  
Yue Fu ◽  
Ruohan Deng ◽  
Van Tran ◽  
Yang Gao ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Transition State ◽  
Carboxylic Acids ◽  
Alkyl Group ◽  
Steric Effects ◽  
High Yield ◽  
Mechanistic Studies ◽  
Ligand Environment ◽  
Ligand Free ◽  
Electronic And Steric Effects

<div>A nickel-catalyzed regiodivergent hydroarylation and hydroalkenylation of unactivated alkenyl carboxylic acids is reported, whereby the ligand environment around the metal center dictates the regiochemical outcome. Markovnikov hydrofunctionalization products are obtained under mild ligand-free conditions, with up to 99% yield and >20:1 selectivity. Alternatively, anti-Markovnikov products can be accessed with a novel 4,4-disubstituted Pyrox ligand in excellent yield and >20:1 selectivity. Both electronic and steric effects on the ligand contribute to the high yield and selectivity. Mechanistic studies suggest a change in the turnover-limiting and selectivity-determining step induced by the optimal ligand. DFT calculations reveal that in the anti-Markovnikov pathway, repulsion between the ligand and the alkyl group is minimized (by virtue of it being 1° versus 2°) in the rate- and regioselectivity-determining transmetalation transition state. <br></div>

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