scholarly journals MNDO and DFT Computational Study on the Mechanism of the Oxidation of 1,2-Diphenylhydrazine by Iodine

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Gideon A. Shallangwa ◽  
Adamu Uzairu ◽  
Victor O. Ajibola ◽  
Hamza Abba
Keyword(s):  
Reaction Mechanisms ◽  
Density Functional ◽  
Computational Study ◽  
The Other ◽  
Complex Mechanism ◽  
Functional Theory ◽  
One Step ◽  
The One ◽  
Activated Complex ◽  
Step Mechanism

The reaction mechanisms of the oxidation of 1,2-diphenylhydrazine by iodine have been examined using semiempirical and density functional theory methods, the oxidation proceeded via two independent pathways that can be separately monitored. One pathway involved the chain multistep mechanism. The other pathway occurred via a one-step mechanism in which a “cyclic” activated complex was formed which on disproportionation gave the products. The one-step “cyclic” activated complex mechanism proceeds more rapidly than the chain multistep mechanism. The results were explained by analyses based on computational energetics of the optimised reactants, intermediates, transition states, and products of the reaction of iodine with 1,2-diphenylhydrazine.

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.

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

Molecules ◽  
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.

Mechanism and regioselectivity of 1,3-dipolar cycloaddition reactions of bicyclic monoterpenes with aryl and heteroaryl nitrile oxides: a DFT study

2015 ◽  
Vol 93 (7) ◽  
pp. 749-753 ◽  
Author(s):  
Hossein Eshghi ◽  
Amir Khojastehnezhad ◽  
Farid Moeinpour ◽  
Mehdi Bakavoli
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Energy Surface ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Functional Theory ◽  
Nitrile Oxides ◽  
Reactivity Indices ◽  
One Step ◽  
Step Mechanism

The reactivity and regioselectivity of 1,3-dipolar cycloaddition reactions of aryl and heteroaryl nitrile oxides (1a–1c) with bicyclic monoterpenes (R)-(+)-a-pinene (2a) and (S)-(–)-b-pinene (2b) have been investigated by using density functional theory based on reactivity indices and activation energy calculations at the B3LYP/6-31G(d) level of theory in the gas phase. The potential energy surface analyses for both reactions are in agreement with the experimental observations. Moreover, our calculations on the geometries, bond orders, and global electron density transfers at the transition state structures shows that these 1,3- dipolar cycloaddition reactions occur via an asynchronous one-step mechanism.

scholarly journals [3 + 2] versus [2 + 2] Addition: A Density Functional Theory Study on the Mechanistic Aspects of Transition Metal-Assisted Formation of 1,2-Dinitrosoalkanes

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Ernest Opoku ◽  
Richard Tia ◽  
Evans Adei
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Basis Set ◽  
Functional Theory ◽  
Activation Barriers ◽  
One Step ◽  
The One ◽  
Electron Donating Groups ◽  
Very High ◽  
Addition Pathway

The pathways for the transition metal-assisted formation of 1,2-dinitrosoalkane complexes of cobalt and its congeners, have been studied using DFT/M06 with theLACVP*basis set. The activation barriers for the one-step [3 + 2] addition pathway for the formation of 1,2-dinitrosoalkanes, proposed by Bergman and Becker, are generally low compared to the activation barriers for the [2 + 2] addition to form an intermediate, which is the first of the two-step pathway proposed by Rappé and Upton, which are very high. The barriers of the rearrangement of the Rappé intermediates to the final products by reductive elimination involving the second metal-nitrogenπ-bond are also very high. The reactions of the Co complexes have lower activation barriers than Rh and Ir complexes. The barriers of the reactions involving olefins with electron-donating groups are generally lower compared to the reactions of the parent (unsubstituted) ethylene while the activation barriers for reactions of olefins with electron-withdrawing groups are generally higher compared to the parent (unsubstituted) ethylene. The one-step [3 + 2] pathway remains the most favoured irrespective of the metal centre or the nature of the olefin. The mechanism of the reaction is therefore settled in favour of the [3 + 2] addition pathway.

scholarly journals A computational study of the competing reaction mechanisms of the photo-catalytic reduction of CO2 on anatase(101)

2016 ◽  
Vol 18 (36) ◽  
pp. 25010-25021 ◽  
Author(s):  
Chung Man Ip ◽  
Alessandro Troisi
Keyword(s):  
Carbon Dioxide ◽  
Density Functional Theory ◽  
Reaction Mechanisms ◽  
Density Functional ◽  
Catalytic Reduction ◽  
Computational Study ◽  
Density Functional Theory Calculations ◽  
Reaction Pathways ◽  
Functional Theory ◽  
Reduction Of Co2

Three reaction pathways for the photocatalytic reduction of carbon dioxide to methane are investigated with density functional theory calculations.

scholarly journals Understanding the Molecular Mechanism of the Rearrangement of Internal Nitronic Ester into Nitronorbornene in Light of the MEDT Study

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 462 ◽  
Author(s):  
Agnieszka Kącka-Zych
Keyword(s):  
Density Functional ◽  
Functional Theory ◽  
Molecular Electron ◽  
Bet Analysis ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Step Mechanism ◽  
Nitronic Ester ◽  
Computational Level

The characterization of the structure of nitronic esters and their rearrangement into nitronorbornene reactions has been analyzed within the Molecular Electron Density Theory (MEDT) using Density Functional Theory (DFT) calculations at the B3LYP/6-31G(d) computational level. Quantum-chemical calculations indicate that this rearrangement takes place according to a one-step mechanism. The sequential bonding changes received from the Bonding Evolution Theory (BET) analysis of the rearrangement of internal nitronic ester to nitronorbornene allowed us to distinguish seven different phases. This fact clearly contradicts the formerly-proposed concerted pericyclic mechanism.

Phenanthro[9,10-a]corannulene by one-step annulative π-extension of corannulene

2017 ◽  
Vol 95 (3) ◽  
pp. 329-333 ◽  
Author(s):  
Kenta Kato ◽  
Yasutomo Segawa ◽  
Kenichiro Itami
Keyword(s):  
Crystal Structure ◽  
Density Functional ◽  
Photophysical Properties ◽  
Coupling Reaction ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
X Ray ◽  
Palladium Catalyzed ◽  
One Step ◽  
The One

The one-step π-extension of corannulene was achieved using a palladium-catalyzed C–H coupling reaction. The X-ray crystal structure and photophysical properties of the thus formed phenanthro[9,10-a]corannulene (1) were investigated, and the structural properties of 1 were examined by density functional theory calculations. In contrast to dibenzo[g,p]chrysene, the most stable structure of 1 was a butterfly-shaped structure, resulting from the bowl-shaped distortion of the corannulene moiety.

scholarly journals Theoretical Studies on the Reactions of Aryl and Hetaryl Thioketones with Nitrilimines

2021 ◽  
Author(s):  
George Baffour Pipim ◽  
Ernest Opoku
Keyword(s):  
Density Functional ◽  
Biologically Active ◽  
Functional Theory ◽  
Atomic Spin ◽  
One Step ◽  
Synthetic Routes ◽  
The One ◽  
Total Agreement ◽  
Ethylene Derivative ◽  
Spin Densities

<p>Many synthetic routes to constructing biologically-active heterocyclic compounds are made feasible through the (3 + 2) cycloaddition 32CA reactions. Due to a large number of possible combinations of several heteroatoms from either the three-atom components (TACs) or the ethylene derivatives, the potential of the 32CA reactions in heterocyclic syntheses is versatile. Herein, the 32CA of thiophene-2-carbothialdehyde derivatives and <i>C</i>,<i>N</i>-disubstituted nitrilimines have been studied through density functional theory (DFT) calculations at the B3LYP/6-311G(d,p) level of theory. In the present study, one-step (3 + 2) and two-step (4 + 3) mechanisms of the addition of the TAC and ethylene derivative have been investigated. In all reactions considered, the one-step (3 + 2) cycloaddition is preferred over the two-step (4 + 3) cycloaddition. The TAC chemoselectively adds across the thiocarbonyl group present in the ethylene derivative in a (3 + 2) fashion to form the corresponding cycloadduct. Analysis of the electrophilic ( and nucleophilic ( Parr functions at the various reaction centers in the ethylene derivative show that the TAC adds across the atomic centers with the largest Mulliken atomic spin densities, which is in total agreement with the experimental observation. The selectivities observed in the title reaction are kinetically controlled.</p>

Dynamics Induced by Femtosecond Laser and Photovoltaic Phenomena Studied by Using Time-Dependent First Principles Method

2012 ◽  
Vol 1455 ◽  
Author(s):  
Yoshiyuki Miyamoto
Keyword(s):  
Femtosecond Laser ◽  
First Principles ◽  
Density Functional ◽  
The Other ◽  
Time Dependent ◽  
Ion Dynamics ◽  
Functional Theory ◽  
Photovoltaic Materials ◽  
The One ◽  
Dependent Density

ABSTRACTIn this work, the first-principles computational scheme of electron-ion dynamics based on the time-dependent density functional theory is presented as a tool to study dynamical phenomena induced by light. Two applications of computations for photo-induced phenomena are shown. The one is structural change induced by intense and short laser shot with a purpose to simulate experiments using the femtosecond laser. The other is photo-excitation and subsequent carrier splitting into electrons and holes, which is a key process needed in photovoltaic materials.

scholarly journals Insights Into The Origin of Selectivity For [2+2] Cycloaddition Step Reaction Involved In The Mechanism of Enantioselective Reduction of Ketones With Borane Catalyzed By A B-Methoxy Oxazaborolidine Catalyst Derived From (–)-β-Pinene. A DFT And Combined Topological ELF, NCI And QTAIM Study

2021 ◽  
Author(s):  
Hichem Sadrik Kettouche
Keyword(s):  
Density Functional ◽  
Topological Analysis ◽  
Density Functional Theory Method ◽  
Theoretical Studies ◽  
Functional Theory ◽  
Enantioselective Reduction ◽  
The Density Functional Theory ◽  
One Step ◽  
Step Mechanism ◽  
Reduction Of Ketones

Abstract Theoretical studies on [2+2] cycloaddition step involved in the Enantioselective Reduction of ketones with borane catalyzed by a B-MethoxyOxazaborolidine Catalyst Derived from Pinene has been performed by means of the Density Functional Theory method (DFT) at MPWB1K /6-31G (d,p). The formation of the M5a(S) complexes via transition state TSa(S) was the more favorable pathway among other [2+2]cycloaddition competing steps. The explanation of the formation of O-B and N-B through two-stage one-step mechanism was allowed by means of the electron localization function (ELF) topological analysis. NCI and QTAIM analysis of the two computed transition states TSa(S) and TSa(R) indicate that the difference between both in term of stability comes mainly from the orientation of the methanediyl group inside the pinene skeleton, which implies that CH-H…O interaction found at TSa(S) is the great factor that makes it more stable than TSa(R).

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