Mechanistic insight into the selective trans-1,4-polymerization of butadiene by terpyridine–iron(II) complexes — A computational study

2009 ◽  
Vol 87 (10) ◽  
pp. 1392-1405 ◽  
Author(s):  
Sven Tobisch
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Dft Method ◽  
Chain Growth ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Insertion Mechanism ◽  
Trans Regulation ◽  
Insight Into

The density functional theory (DFT) method has been employed to unravel mechanistic intricacies of the 1,4-polymerization of 1,3-butadiene mediated by the [(η3-RC3H4)FeII(C15H11N3)(η2-C4H6)]+ terpyridine–iron(II) active catalyst species. The π-allyl-insertion mechanism is operative for chain growth, whilst the alternative σ-allyl-insertion mechanism has been explicitly demonstrated as being inoperable. This study elucidates the mechanism of cis–trans regulation and unveils the factors that govern the observed high trans-1,4 stereoselectivity, in particular, the discriminative role of allylic isomerization. An atactic trans-1,4-polydiene is expected from polymerization of a terminally monosubstituted butadiene, the experimental results of which have not been reported thus far.

Synthesis of [Re2Cl4(O)2(µ-O)(3,5-lut)4] and investigation of its structure via X-ray and spectroscopic measurements and DFT calculations

2014 ◽  
Vol 68 (5) ◽  
Author(s):  
Sławomir Michalik ◽  
Jan Małecki ◽  
Natalia Młynarczyk
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Computational Study ◽  
Dft Method ◽  
Time Dependent ◽  
Electronic Transitions ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
The Density Functional Theory

AbstractA combined experimental and computational study of the dinuclear rhenium(V) complex containing (ReO)2(µ-O) core is presented in this article. The solid-state [Re2Cl4(O)2(µ-O)(3,5-lut)4] (3,5-lut = 3,5-dimethylpyridine) complex was characterised structurally (by single crystal X-ray diffraction) and spectroscopically (by IR, NMR, UV-VIS). The electronic structure was examined using the density functional theory (DFT) method. The spin-allowed electronic transitions were calculated using the time-dependent DFT method, and the UV-VIS spectrum was discussed.

scholarly journals Application of β-Phosphorylated Nitroethenes in [3+2] Cycloaddition Reactions Involving Benzonitrile N-Oxide in the Light of a DFT Computational Study

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 26-37
Author(s):  
Karolina Zawadzińska ◽  
Karolina Kula
Keyword(s):  
Density Functional ◽  
Reaction Path ◽  
Computational Study ◽  
Cyano Group ◽  
Cycloaddition Reactions ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Reaction Channels ◽  
One Step ◽  
Step Mechanism

The regiochemistry of [3+2] cycloaddition (32CA) processes between benzonitrile N-oxide 1 and β-phosphorylated analogues of nitroethenes 2a–c has been studied using the Density Functional Theory (DFT) at the M062X/6-31+G(d) theory level. The obtained results of reactivity indices show that benzonitrile N-oxide 1 can be classified both as a moderate electrophile and moderate nucleophile, while β-phosphorylated analogues of nitroethenes 2a–c can be classified as strong electrophiles and marginal nucleophiles. Moreover, the analysis of CDFT shows that for [3+2] cycloadditions with the participation of β-phosphorylatednitroethene 2a and β-phosphorylated α-cyanonitroethene 2b, the more favored reaction path forms 4-nitro-substituted Δ2-isoxazolines 3a–b, while for a reaction with β-phosphorylated β-cyanonitroethene 2c, the more favored path forms 5-nitro-substituted Δ2-isoxazoline 4c. This is due to the presence of a cyano group in the alkene. The CDFT study correlates well with the analysis of the kinetic description of the considered reaction channels. Moreover, DFT calculations have proven the clearly polar nature of all analyzed [3+2] cycloaddition reactions according to the polar one-step mechanism.

First principles analysis of oxygen vacancy formation and migration in Sr2BMoO6 (B = Mg, Co, Ni)

RSC Advances ◽  
2016 ◽  
Vol 6 (38) ◽  
pp. 31968-31975 ◽  
Author(s):  
Shuai Zhao ◽  
Liguo Gao ◽  
Chunfeng Lan ◽  
Shyam S. Pandey ◽  
Shuzi Hayase ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Oxygen Vacancy ◽  
First Principles ◽  
Density Functional ◽  
Dft Method ◽  
Double Perovskites ◽  
Functional Theory ◽  
Oxygen Vacancy Formation ◽  
The Density Functional Theory ◽  
And Migration

In this work, we present a detailed first-principles investigation on the stoichiometric and oxygen-deficient structures of double perovskites, Sr2BMoO6 (B = Mg, Co and Ni), using the density functional theory (DFT) method.

scholarly journals Vibrational Study and Force Field of the Citric Acid Dimer Based on the SQM Methodology

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Laura Cecilia Bichara ◽  
Hernán Enrique Lanús ◽  
Evelina Gloria Ferrer ◽  
Mónica Beatriz Gramajo ◽  
Silvia Antonia Brandán
Keyword(s):  
Citric Acid ◽  
Force Field ◽  
Density Functional ◽  
Solid Phase ◽  
Dft Method ◽  
Electronic Charge ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Atoms In Molecules Theory ◽  
Best Fit

We have carried out a structural and vibrational theoretical study for the citric acid dimer. The Density Functional Theory (DFT) method with the B3LYP/6-31G∗ and B3LYP/6-311++ methods have been used to study its structure and vibrational properties. Then, in order to get a good assignment of the IR and Raman spectra in solid phase of dimer, the best fit possible between the calculated and recorded frequencies was carry out and the force fields were scaled using the Scaled Quantum Mechanic Force Field (SQMFF) methodology. An assignment of the observed spectral features is proposed. A band of medium intensity at 1242  together with a group of weak bands, previously not assigned to the monomer, was in this case assigned to the dimer. Furthermore, the analysis of the Natural Bond Orbitals (NBOs) and the topological properties of electronic charge density by employing Bader's Atoms in Molecules theory (AIM) for the dimer were carried out to study the charge transference interactions of the compound.

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

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

<p>We investigate the mechanism of direct CO<sub>2</sub> hydrogenation to methanol on Pd (111), (100) and (110) surfaces using density functional theory (DFT), providing insight into the reactivity of CO<sub>2</sub> on Pd-based catalysts. The initial chemisorption of CO<sub>2</sub>, forming a partially charged CO<sub>2</sub><sup>δ-</sup>, 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 CO<sub>2</sub><sup>δ-</sup><sub> </sub>on the Pd (111) surface to a negative charge that accumulates on the surface Pd atoms interacting directly with the CO<sub>2</sub><sup>δ-</sup><sub> </sub>adsorbate. For the reaction of the adsorbed species on the Pd surface, HCOOH hydrogenation to H<sub>2</sub>COOH 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.<br></p>

scholarly journals Chloroquine drug and Graphene complex for treatment of COVID-19

2020 ◽  
Author(s):  
Saeedeh Mohammadi ◽  
Mohammad Esmailpour ◽  
Mina Mohammadi
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Energy Gap ◽  
Dft Method ◽  
Complex State ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Structural And Electrical Properties ◽  
Suitable Structure ◽  
Drug Complex

Abstract This paper is a new step in helping the treatment of coronavirus by improving the performance of chloroquine drug. For this purpose, we propose a complex of chloroquine drug with graphene nanoribbon (GNR) scheme. We compute the structural and electrical properties and absorption of chloroquine (C18H26ClN3) and GNR complex using the density functional theory (DFT) method. By creating a drug and GNR complex, the density of states of electrons increases and the energy gap decreases compared to the chloroquine. Also, using absorption calculations and spectrums such as infrared and UV-Vis spectra, we showed that GNR is a suitable structure for creating chloroquine drug complex. Our results show that the dipole moment, global softness and electrophilicity for the drug complex increases compared to the non-complex state. Our calculations can be useful for increasing performance and reducing the side effects of chloroquine, and thus can be effective in treating coronavirus.

scholarly journals Computational study on the mechanism of metal-free photochemical borylation of aryl halides

2021 ◽  
Author(s):  
Chenhao Tu ◽  
Nana Ma ◽  
Qingli Xu ◽  
Wenyue Guo ◽  
Lanxin Zhou ◽  
...  
Keyword(s):  
Density Functional ◽  
Uv Light ◽  
Computational Study ◽  
Halogen Bond ◽  
Bond Cleavage ◽  
Aryl Halides ◽  
Homolytic Cleavage ◽  
Functional Theory ◽  
Aryl Radicals

C-radical borylation is an significant approach for the construction of carbon−boron bond. Photochemical borylation of aryl halides successfully applied this strategy. However, precise mechanisms, such as the generation of aryl radicals and the role of base additive(TMDAM) and water, remain controversy in these reactions. In this study, photochemical borylation of aryl halides has been researched by density functional theory (DFT) calculations. Indeed, the homolytic cleavage of the C−X bond under irradiation with UV-light is a key step for generation of aryl radicals. Nevertheless, the generation of aryl radicals may also undergo the process of single electron transfer and the heterolytic carbon-halogen bond cleavage sequence, and the latter is favorable during the reaction.

Modeling of Atomistic Processes in Semiconductors: from Defect Signatures to a Hierarchy of Annealing Mechanisms

2006 ◽  
Vol 978 ◽  
Author(s):  
Michel Bockstedte
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
The Self ◽  
Functional Theory ◽  
Dopant Activation ◽  
Defect Centers ◽  
The Density Functional Theory ◽  
Modeling And Experiments ◽  
Microscopic Origin

AbstractThe modeling of atomistic processes in semiconductors based on the density functional theory is outlined. The role of intrinsic defects in the self and dopant diffusion, as well as in the dopant activation is investigated for the case of silicon carbide. A hierarchy of annealing mechanisms for vacancies and interstitials is proposed. The identification of the microscopic origin of experimental defect centers by calculated defect signatures establishes a link between theoretical modeling and experiments.

Mechanistic Insight into Construction of Axially Chiral Biaryls via Palladium/Chiral Norbornene Cooperative Catalysis: a DFT-Based Computational Study

2021 ◽  
Author(s):  
Xuexiang Ma ◽  
Aili Feng ◽  
Chengbu Liu ◽  
Dongju Zhang
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Computational Study ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Cooperative Catalysis ◽  
Mechanistic Insight ◽  
Aryl Bromides ◽  
Axially Chiral ◽  
Insight Into

Density functional theory calculations were performed on a prototype of three-component reactions involving aryl iodides, 2,6-substituted aryl bromides, and acrylates to understand the construction of axially chiral biaryls through the...

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

2021 ◽  
Vol 43 (1) ◽  
pp. 25-25
Author(s):  
Said Abdelqadar Said Said Abdelqadar Said ◽  
Omar A Shareef and Abdulkhalik S Alkazzaz Omar A Shareef and Abdulkhalik S Alkazzaz
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Ring Closure ◽  
Basis Set ◽  
Functional Theory ◽  
Rate Determining Step ◽  
The Density Functional Theory ◽  
Electronic And Structural Properties ◽  
Maximum Hardness Principle

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

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