scholarly journals A Theoretical Study on Pd-catalyzed, Friedel-Crafts Intermolecular Acylation: Does Generated In Situ Aroyl Triflate Act as A Reactive Electrophile to Functionalize C–H Bond of Arenes?

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 141
Author(s):  
Rong Chang ◽  
Ye Tian ◽  
Niu Li ◽  
Jin Bai ◽  
Huimin Yan ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Theoretical Study ◽  
Reductive Elimination ◽  
Pd Catalysts ◽  
Bond Functionalization ◽  
Rate Determining Step ◽  
Co Insertion ◽  
Experimental Findings ◽  
Key Steps

The mechanism of Pd-catalyzed, Friedel-Crafts intermolecular acylation of arenes to ketones was comprehensively investigated by using DFT calculations. The calculated results revealed that this transformation was composed of several key steps: C–I bond oxidative addition, CO insertion, reductive elimination and C–H bond functionalization. Of these steps, the last was found to be the rate–determining step, and it occurred much more easily with strongly electrophilic aroyl triflate compared to other resultant counterparts. In addition, our calculation provides a rationale for experimental findings that simple Pd salts exhibit superior catalytic abilities compared to phosphine-ligated Pd catalysts.

scholarly journals Theoretical study on the mechanism of iridium-catalyzed γ-functionalization of primary alkyl C–H bonds

2016 ◽  
Vol 94 (12) ◽  
pp. 1028-1037 ◽  
Author(s):  
Zhe Li ◽  
Miaoren Xia ◽  
Russell J. Boyd
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Experimental Observation ◽  
Density Functional ◽  
Theoretical Study ◽  
Reductive Elimination ◽  
Catalytic Cycle ◽  
Catalyst Precursor ◽  
Functional Theory ◽  
Initial Formation

The mechanism of the iridium-catalyzed functionalization of a primary C–H bond at the γ position of an alcohol 5 is investigated by density functional theory (DFT) calculations. A new IrIII–IrV mechanism is found to be more feasible than the previously reported IrI–IrIII mechanism. 10 In the IrIII–IrV mechanism, the reaction begins with the initial formation of (Me4phen)IrIII(H)[Si(OR)Et2]2 from the catalyst precursor, [Ir(cod)OMe]2 (cod = 1,5-cyclooctadiene). The catalytic cycle includes five steps: (1) the insertion of norbornene into the Ir–H bond to produce (Me4phen)IrIII(norbornyl)[Si(OR)Et2]2 (R = –CH(C2H5)C3H7); (2) the Si–H oxidative addition of HSi(OR)Et2 to form (Me4phen)IrVH(norbornyl)[Si(OR)Et2]3; (3) the reductive elimination of norbornane to furnish (Me4phen)IrIII[Si(OR)Et2]3; (4) the intramolecular C–H activation of the primary C–H bond at the γ position; and (5) the Si–C reductive elimination to produce the final product and regenerate the catalyst. The highest barrier in the IrIII–IrV mechanism is 7.3 kcal/mol lower than that of the IrI–IrIII mechanism. In addition, the regioselectivity of the C–H activation predicted by this new IrIII–IrV mechanism is consistent with experimental observation.

A DFT STUDY ON CO INSERTION AND C–C REDUCTIVE ELIMINATION INVOLVED IN THE CARBONYLATION OF METALLACYCLIC ZIRCONACENES

2011 ◽  
Vol 10 (01) ◽  
pp. 9-17
Author(s):  
MIN SUN ◽  
NING ZHENG ◽  
LINGJUN LIU ◽  
PING LI ◽  
SIWEI BI
Keyword(s):  
Dft Calculations ◽  
Reductive Elimination ◽  
Dft Study ◽  
B3lyp Level ◽  
Co Insertion

CO insertion and C–C reductive elimination involved in the carbonylation of the metallacyclic zirconocene complex, 1,1-bis(η5-cyclopentadienyl)-1-zirconaindan (R), have been theoretically studied with the aid of DFT calculations at the B3LYP level. It is found that the C(sp3)-C(sp2) reductive elimination is preferred over C(sp2)-C(sp2) , and importantly, this preference for C–C reductive elimination directs the CO insertion into the Zr-C(sp2) bond rather than the Zr-C(sp3) bond, even though the CO insertion into the former bond is kinectically less favorable than into the latter bond, a result related to that the CO insertion is found to be reversible.

Relative stabilities of M/NHC complexes (M = Ni, Pd, Pt) against R–NHC, X–NHC and X–X couplings in M(0)/M(ii) and M(ii)/M(iv) catalytic cycles: a theoretical study

2019 ◽  
Vol 48 (45) ◽  
pp. 17052-17062 ◽  
Author(s):  
Alexander V. Astakhov ◽  
Safarmurod B. Soliev ◽  
Evgeniy G. Gordeev ◽  
Victor M. Chernyshev ◽  
Valentine P. Ananikov
Keyword(s):  
Dft Calculations ◽  
Relative Stability ◽  
Theoretical Study ◽  
Reductive Elimination ◽  
Catalyst Stability ◽  
Relative Stabilities ◽  
Elimination Reactions ◽  
Catalytic Cycles

DFT calculations reveal relative stability of MII/NHC and MIV/NHC complexes of nickel, palladium and platinum against the R–NHC coupling and various reductive elimination reactions that influence catalyst stability/decomposition.

Probing enantioselectivity in rhodium-catalyzed Si–C bond cleavage to construct silicon-stereocenters: a theoretical study

2019 ◽  
Vol 9 (3) ◽  
pp. 646-651 ◽  
Author(s):  
Zhaoyuan Yu ◽  
Tao Zhang ◽  
Ruopeng Bai ◽  
Yu Lan
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Density Functional ◽  
Theoretical Study ◽  
Bond Cleavage ◽  
Oxidative Addition ◽  
Reductive Elimination ◽  
Functional Theory ◽  
Elimination Process

Density functional theory (DFT) calculations indicate that favorable oxidative addition/reductive elimination process from arylrhodium complex determines the enantioselectivity.

Density Functional Theoretical Study on the Mechanism of Alcoholysis of Acylpalladium(II) Complexes

2017 ◽  
Vol 42 (1) ◽  
pp. 52-61 ◽  
Author(s):  
Hamed Chegini ◽  
Ali Morsali ◽  
Mohammad Reza Bozorgmehr ◽  
S. Ali Beyramabadi
Keyword(s):  
Carbon Monoxide ◽  
Carbon Atom ◽  
Solvent Effects ◽  
Energy Barrier ◽  
Density Functional ◽  
Theoretical Study ◽  
Experimental Studies ◽  
Reductive Elimination ◽  
Rate Determining Step ◽  
Insertion Mechanism

The mechanism of alcoholysis of acylpalladium(II) complexes relevant to the alternating copolymerisation of ethene and carbon monoxide has been investigated theoretically in detail. The solvolysis of acylpalladium(II) complexes is an important step in palladium-catalysed reactions. Based on experimental studies, two mechanisms have been proposed for this process, which consist of a concerted reductive elimination and an insertion mechanism (reductive elimination via a Meisenheimer intermediate). Both mechanisms include deprotonating of an acylpalladium(II) complex and according to our calculations, any mechanism involving this step, has an energy barrier higher than that of the rate-determining step. We propose a new mechanism for the insertion in which proton transfer to Pd is simultaneous with an inner-sphere attack of the alkoxide ligand (OCH3) at the carbon atom of the palladium-bound carbonyl group (new Meisenheimer intermediate). Considering solvent effects, the activation energies of the two mechanisms and other contingent mechanisms were calculated and compared with each other and the experimental results.

DFT modelling of a diphosphane − N-heterocyclic carbene–Rh(i) pincer complex rearrangement: a computational evaluation of the electronic effects in C–P bond activation

2018 ◽  
Vol 47 (8) ◽  
pp. 2662-2669 ◽  
Author(s):  
H.-L. Qin ◽  
J. Leng ◽  
W. Zhang ◽  
E. A. B. Kantchev
Keyword(s):  
Dft Calculations ◽  
Bond Activation ◽  
Oxidative Addition ◽  
Reductive Elimination ◽  
Electronic Effects ◽  
Complex Rearrangement ◽  
Rate Determining Step ◽  
Computational Evaluation ◽  
Pincer Complex ◽  
Dft Modelling

DFT calculations confirmed that the rearrangement of a PCP-Rh-H pincer to a CCP-Rh-phosphane pincer occured by C–P oxidative addition (ΔG‡ = 29.5 kcal mol−1, rate-determining step), followed by P–H reductive elimination (ΔG‡ = 4.8 kcal mol−1).

Reversible Oxidative-Addition and Reductive-Elimination of Thiophene from a Titanium Complex and Its Thermally-Induced Hydrodesulfurization Chemistry

2019 ◽  
Author(s):  
Alejandra Gomez-Torres ◽  
J. Rolando Aguilar-Calderón ◽  
Carlos Saucedo ◽  
Aldo Jordan ◽  
Alejandro J. Metta-Magaña ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Ring Opening ◽  
Thiophene Ring ◽  
Oxidative Addition ◽  
Reductive Elimination ◽  
Thermally Induced ◽  
Titanium Complex

<p>The masked Ti(II) synthon (<sup>Ket</sup>guan)(<i>η</i><sup>6</sup>-Im<sup>Dipp</sup>N)Ti (<b>1</b>) oxidatively adds across thiophene to give ring-opened (<sup>Ket</sup>guan)(Im<sup>Dipp</sup>N)Ti[<i>κ</i><sup>2</sup>-<i>S</i>(CH)<sub>3</sub><i>C</i>H] (<b>2</b>). Complex <b>2</b> is photosensitive, and upon exposure to light, reductively eliminates thiophene to regenerate <b>1</b> – a rare example of early-metal mediated oxidative-addition/reductive-elimination chemistry. DFT calculations indicate strong titanium π-backdonation to the thiophene π*-orbitals leads to the observed thiophene ring opening across titanium, while a proposed photoinduced LMCT promotes the reverse thiophene elimination from <b>2</b>. Finally, pressurizing solutions of <b>2 </b>with H<sub>2</sub> (150 psi) at 80 °C leads to the hydrodesulfurization of thiophene to give the Ti(IV) sulfide (<sup>Ket</sup>guan)(Im<sup>Dipp</sup>N)Ti(S) (<b>3</b>) and butane. </p>

Pt-Pd Nanoalloy for the Unprecedented Activation of Carbon-Fluorine Bond at Low Temperature

2019 ◽  
Author(s):  
Raghu Nath Dhital ◽  
keigo nomura ◽  
Yoshinori Sato ◽  
Setsiri Haesuwannakij ◽  
Masahiro Ehara ◽  
...  
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Dft Calculations ◽  
Bond Activation ◽  
Mild Conditions ◽  
Selective Transformation ◽  
Rate Determining Step ◽  
Highly Active ◽  
Harsh Conditions ◽  
Reaction Profile

Carbon-Fluorine (C-F) bonds are considered the most inert organic functionality and their selective transformation under mild conditions remains challenging. Herein, we report a highly active Pt-Pd nanoalloy as a robust catalyst for the transformation of C-F bonds into C-H bonds at low temperature, a reaction that often required harsh conditions. The alloying of Pt with Pd is crucial to activate C-F bond. The reaction profile kinetics revealed that the major source of hydrogen in the defluorinated product is the alcoholic proton of 2-propanol, and the rate-determining step is the reduction of the metal upon transfer of the <i>beta</i>-H from 2-propanol. DFT calculations elucidated that the key step is the selective oxidative addition of the O-H bond of 2-propanol to a Pd center prior to C-F bond activation at a Pt site, which crucially reduces the activation energy of the C-F bond. Therefore, both Pt and Pd work independently but synergistically to promote the overall reaction

Physicochemical properties of geopolymer composites with DFT calculations of in-situ reduction of graphene oxide

2021 ◽  
Author(s):  
Amun Amri ◽  
Ahmad Ainun Najib ◽  
Monita Olivia ◽  
Mohammednoor Altarawneh ◽  
Aman Syam ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Dft Calculations ◽  
Physicochemical Properties ◽  
In Situ Reduction ◽  
Geopolymer Composites
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