The Impact of Secondary Coordination Sphere Nucleophiles on Methane Activation: A Computational Study

10.26434/chemrxiv.9899576.v1 ◽

2019 ◽

Author(s):

Mary E. Anderson ◽

Thomas Cundari

Keyword(s):

Active Sites ◽

Density Functional ◽

Bond Activation ◽

Computational Study ◽

Solvent Polarity ◽

Active Hydrogen ◽

Functional Theory ◽

Activation Barriers ◽

Secondary Coordination Sphere ◽

The Impact

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px 'Helvetica Neue'} Density functional theory and ab initio calculations indicate that nucleophiles can significantly reduce enthalpic barriers to methane C–H bond activation. Different pieces of evidence point to an electrostatic origin for the nucleophile effect such as the sensitivity of the C–H activation barriers to the external nucleophile and to continuum solvent polarity. The data further imply a transition state with significant charge build-up on the active hydrogen of the hydrocarbon substrate. From the present modeling studies, one may propose proteins with hydrophobic active sites, available nucleophiles, and hydrogen bond donors as attractive targets for the engineering of novel methane functionalizing enzymes.

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A Computational Study of Direct CO2 Hydrogenation to Methanol on Pd Catalysts

10.26434/chemrxiv.14423600 ◽

2021 ◽

Author(s):

Igor Kowalec ◽

Lara Kabalan ◽

Richard Catlow ◽

Andrew Logsdail

Keyword(s):

Density Functional ◽

Negative Charge ◽

Computational Study ◽

Adsorbed Species ◽

Pd Catalysts ◽

Functional Theory ◽

Activation Barriers ◽

Rate Determining Step ◽

Adsorption Energies ◽

Insight Into

We investigate the mechanism of direct CO2 hydrogenation to methanol on Pd (111), (100) and (110) surfaces using density functional theory (DFT), providing insight into the reactivity of CO2 on Pd-based catalysts. The initial chemisorption of CO2, forming a partially charged CO2δ-, is weakly endothermic on a Pd (111) surface, with an adsorption energy of 0.06 eV, and slightly exothermic on Pd (100) and (110) surfaces, with adsorption energies of -0.13 and -0.23 eV, respectively. Based on Mulliken analysis, we attribute the low stability of CO2δ- on the Pd (111) surface to a negative charge that accumulates on the surface Pd atoms interacting directly with the CO2δ- adsorbate. For the reaction of the adsorbed species on the Pd surface, HCOOH hydrogenation to H2COOH is predicted to be the rate determining step of the conversion to methanol in all cases, with activation barriers of 1.35, 1.26, and 0.92 eV on Pd (111), (100) and (110) surfaces, respectively.

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Computational Study of Methane C–H Activation by Main Group and Mixed Main Group–Transition Metal Complexes

Molecules ◽

10.3390/molecules25122794 ◽

2020 ◽

Vol 25 (12) ◽

pp. 2794

Author(s):

Carly C. Carter ◽

Thomas R. Cundari

Keyword(s):

Transition Metal Complexes ◽

Active Site ◽

Density Functional ◽

Computational Study ◽

Divalent Metal ◽

Main Group ◽

Free Energies ◽

Functional Theory ◽

Activation Barriers ◽

Experimental Values

In the present density functional theory (DFT) research, nine different molecules, each with different combinations of A (triel) and E (divalent metal) elements, were reacted to effect methane C–H activation. The compounds modeled herein incorporated the triels A = B, Al, or Ga and the divalent metals E = Be, Mg, or Zn. The results show that changes in the divalent metal have a much bigger impact on the thermodynamics and methane activation barriers than changes in the triels. The activating molecules that contained beryllium were most likely to have the potential for activating methane, as their free energies of reaction and free energy barriers were close to reasonable experimental values (i.e., ΔG close to thermoneutral, ΔG‡ ~30 kcal/mol). In contrast, the molecules that contained larger elements such as Zn and Ga had much higher ΔG‡. The addition of various substituents to the A–E complexes did not seem to affect thermodynamics but had some effect on the kinetics when substituted closer to the active site.

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Computational Study of Mechanism and Thermodynamics of Ni/IPr-Catalyzed Amidation of Esters

Molecules ◽

10.3390/molecules23102681 ◽

2018 ◽

Vol 23 (10) ◽

pp. 2681 ◽

Cited By ~ 6

Author(s):

Chong-Lei Ji ◽

Pei-Pei Xie ◽

Xin Hong

Keyword(s):

Density Functional ◽

Bond Activation ◽

Computational Study ◽

Coupling Mechanism ◽

Nickel Catalysis ◽

Functional Theory ◽

Reaction Thermodynamics ◽

Powerful Approach ◽

Related Reaction ◽

Shed Light

Nickel catalysis has shown remarkable potential in amide C–N bond activation and functionalization. Particularly for the transformation between ester and amide, nickel catalysis has realized both the forward (ester to amide) and reverse (amide to ester) reactions, allowing a powerful approach for the ester and amide synthesis. Based on density functional theory (DFT) calculations, we explored the mechanism and thermodynamics of Ni/IPr-catalyzed amidation with both aromatic and aliphatic esters. The reaction follows the general cross-coupling mechanism, involving sequential oxidative addition, proton transfer, and reductive elimination. The calculations indicated the reversible nature of amidation, which highlights the importance of reaction thermodynamics in related reaction designs. To shed light on the control of thermodynamics, we also investigated the thermodynamic free energy changes of amidation with a series of esters and amides.

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Theoretical Study on the Lewis Acidity of the Pristine AlF3 and Cl-Doped α-AlF3 Surfaces

Catalysts ◽

10.3390/catal11050565 ◽

2021 ◽

Vol 11 (5) ◽

pp. 565

Author(s):

Christian Becker ◽

Thomas Braun ◽

Beate Paulus

Keyword(s):

Active Sites ◽

Density Functional ◽

Bond Activation ◽

Lewis Acidity ◽

Dft Methods ◽

Functional Theory ◽

Heterogenous Catalysis ◽

Adsorption Structure ◽

Metal Fluorides ◽

Principle Density Functional Theory

In the past two decades, metal fluorides have gained importance in the field of heterogenous catalysis of bond activation reaction, e.g., hydrofluorination. One of the most investigated metal fluorides is AlF3. Together with its chlorine-doped analogon aluminiumchlorofluoride (AlClxF3−x, x = 0.05–0.3; abbreviated ACF), it has attracted much attention due to its application in catalysis. Various surface models for α-AlF3 and their chlorinated analogues (as representatives of amorphous ACF) are investigated with respect to their Lewis acidity of the active centres. First-principle density functional theory (DFT) methods with dispersion correction are used to determine the adsorption structure and energy of the probe molecules CO and NH3. The corresponding vibrational frequency shift agrees well with the measured values. With this insight we predict the local structure of the active sites and can clarify the importance of secondary interactions to the local anionic surrounding of the catalytic site.

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A Computational Study of Direct CO2 Hydrogenation to Methanol on Pd Catalysts

10.26434/chemrxiv.14423600.v2 ◽

2021 ◽

Author(s):

Igor Kowalec ◽

Lara Kabalan ◽

Richard Catlow ◽

Andrew Logsdail

Keyword(s):

Density Functional ◽

Negative Charge ◽

Computational Study ◽

Adsorbed Species ◽

Pd Catalysts ◽

Functional Theory ◽

Activation Barriers ◽

Rate Determining Step ◽

Adsorption Energies ◽

Insight Into

We investigate the mechanism of direct CO2 hydrogenation to methanol on Pd (111), (100) and (110) surfaces using density functional theory (DFT), providing insight into the reactivity of CO2 on Pd-based catalysts. The initial chemisorption of CO2, forming a partially charged CO2δ-, is weakly endothermic on a Pd (111) surface, with an adsorption energy of 0.06 eV, and slightly exothermic on Pd (100) and (110) surfaces, with adsorption energies of -0.13 and -0.23 eV, respectively. Based on Mulliken analysis, we attribute the low stability of CO2δ- on the Pd (111) surface to a negative charge that accumulates on the surface Pd atoms interacting directly with the CO2δ- adsorbate. For the reaction of the adsorbed species on the Pd surface, HCOOH hydrogenation to H2COOH is predicted to be the rate determining step of the conversion to methanol in all cases, with activation barriers of 1.35, 1.26, and 0.92 eV on Pd (111), (100) and (110) surfaces, respectively.

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The luminescent [Mo6X8(NCS)6]2− (X=Cl, Br, I) clusters?: A computational study based on time-dependent density functional theory including spin–orbit and solvent-polarity effects

Chemical Physics Letters ◽

10.1016/j.cplett.2008.02.037 ◽

2008 ◽

Vol 455 (1-3) ◽

pp. 38-41 ◽

Cited By ~ 24

Author(s):

Rodrigo Ramirez-Tagle ◽

Ramiro Arratia-Pérez

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Computational Study ◽

Solvent Polarity ◽

Time Dependent ◽

Spin Orbit ◽

Functional Theory ◽

Polarity Effects ◽

Dependent Density

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Exploring the peri-, chemo-, and regioselectivity of addition of technetium metal oxides of the type TcO3L (L = Cl–, O–, OCH3, CH3) to substituted ketenes: a DFT computational study

Canadian Journal of Chemistry ◽

10.1139/cjc-2015-0295 ◽

2016 ◽

Vol 94 (5) ◽

pp. 523-532

Author(s):

Issahaku Ahmed ◽

Richard Tia ◽

Evans Adei

Keyword(s):

Density Functional Theory ◽

Oxidation State ◽

Density Functional ◽

Computational Study ◽

Density Functional Theory Calculations ◽

High Activation ◽

Functional Theory ◽

Activation Barriers ◽

Lower Activation ◽

Zwitterionic Intermediate

The addition of TcO3L (L = Cl, O–, OCH3, CH3) to substituted ketenes along various addition pathways was studied with density functional theory calculations to explore the peri-, chemo-, and regioselectivity of the reactions. In the reactions of TcO3L with dimethyl ketene, the results show that for L = O– and CH3, [1 + 1] addition to form a triplet zwitterionic intermediate is the preferred first step; for L = Cl, the [3 + 2]C=C addition across the O–Tc–Cl bond is the preferred first step and for L = OCH3 the [3 + 2]C=C addition across the O–Tc–OCH3 bond is the preferred first step. In the reactions of TcO3Cl with substituted ketenes, [1 + 1] addition to form a triplet zwitterionic intermediate is the preferred first step for X = Ph, CN, and Cl; the [3 + 2]C=C addition across the O–Tc–O bond of the complex is the preferred first step for X = H, while the [3 + 2]C=C addition across the O–Tc–CH3 bond is the preferred first step. Reactions involving a change in the oxidation state of metal have high activation barriers, while reactions that do not involve a change in oxidation state have low activation barriers. Reactions of ketenes with TcO3L complexes have lower activation barriers for the preferred addition pathways than those of the ReO3L complexes reported in the literature. Thus, the TcO3L complexes may be better catalysts for the activation of the C=C bonds of substituted ketenes than the reported ReO3L complexes.

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A Computational Study of Direct CO2 Hydrogenation to Methanol on Pd Catalysts

10.26434/chemrxiv.14423600.v1 ◽

2021 ◽

Author(s):

Igor Kowalec ◽

Lara Kabalan ◽

Richard Catlow ◽

Andrew Logsdail

Keyword(s):

Density Functional ◽

Negative Charge ◽

Computational Study ◽

Adsorbed Species ◽

Pd Catalysts ◽

Functional Theory ◽

Activation Barriers ◽

Rate Determining Step ◽

Adsorption Energies ◽

Insight Into

We investigate the mechanism of direct CO2 hydrogenation to methanol on Pd (111), (100) and (110) surfaces using density functional theory (DFT), providing insight into the reactivity of CO2 on Pd-based catalysts. The initial chemisorption of CO2, forming a partially charged CO2δ-, is weakly endothermic on a Pd (111) surface, with an adsorption energy of 0.06 eV, and slightly exothermic on Pd (100) and (110) surfaces, with adsorption energies of -0.13 and -0.23 eV, respectively. Based on Mulliken analysis, we attribute the low stability of CO2δ- on the Pd (111) surface to a negative charge that accumulates on the surface Pd atoms interacting directly with the CO2δ- adsorbate. For the reaction of the adsorbed species on the Pd surface, HCOOH hydrogenation to H2COOH is predicted to be the rate determining step of the conversion to methanol in all cases, with activation barriers of 1.35, 1.26, and 0.92 eV on Pd (111), (100) and (110) surfaces, respectively.

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Computational Study of the Electron Spectra of Vapor-Phase Indole and Four Azaindoles

Molecules ◽

10.3390/molecules26071947 ◽

2021 ◽

Vol 26 (7) ◽

pp. 1947

Author(s):

Delano P. Chong

Keyword(s):

Density Functional Theory ◽

Vapor Phase ◽

Density Functional ◽

Computational Study ◽

Geometry Optimization ◽

The Other ◽

Functional Theory ◽

Electron Spectra

After geometry optimization, the electron spectra of indole and four azaindoles are calculated by density functional theory. Available experimental photoemission and excitation data for indole and 7-azaindole are used to compare with the theoretical values. The results for the other azaindoles are presented as predictions to help the interpretation of experimental spectra when they become available.

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