Ethene trimerization at CrI/CrIII — A density functional theory (DFT) study

2009 ◽  
Vol 87 (7) ◽  
pp. 832-837 ◽  
Author(s):  
Peter H.M. Budzelaar
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Reductive Elimination ◽  
Dft Methods ◽  
Functional Theory ◽  
Chromium Catalyst ◽  
Kinetic Isotope ◽  
Additional Stabilization ◽  
Bound Chloride

Catalytic ethene trimerization at a chromium(I) indolate-AlR2Cl centre has been studied by density functional theory (DFT) methods. The reaction is found to follow the standard metallacycle mechanism. At most stages of the reaction, coordination of Cr to the pyrrole ring of the indolate is preferred. In all 13-e intermediates, coordination of the Al-bound chloride to Cr provides additional stabilization: the chloride behaves as a hemilabile ligand. Benzene is found to compete with ethene for coordination to CrI. The final hexene-forming step involves direct Cβ → Cα′ hydrogen transfer; reductive elimination from a possible (hydride)(hexenyl) intermediate is more difficult. The kinetic isotope effect calculated for the direct hydrogen transfer (4.1) agrees well with the experimental value for a bis(phosphino)amide chromium catalyst. Side products obtained in such systems (methylenecyclopentane, methylcyclopentane) can plausibly be explained through routes not involving any (hydride)(alkyl) reductive elimination. Our results indicate that a CrI/CrIII trimerization cycle is possible for some chromium trimerization catalysts, and also suggest that direct hydrogen transfer is most likely a general feature of trimerization at Cr centres.

scholarly journals Analysis of the structural and electronic properties of 1-(5-Hydroxymethyl - 4 –[ 5 – (5-oxo-5-piperidin-1-yl-penta- 1,3dienyl)-benzo[1,3]dioxol-2-yl] -tetrahydro-furan-2-yl)-5- methyl-1H-pyrimidine-2,4dione molecule

2018 ◽  
Vol 33 (1) ◽  
pp. 71
Author(s):  
Ali Hashem Essa ◽  
A. F. Jalbout
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Ground State ◽  
Density Functional ◽  
Molecular Orbital Calculations ◽  
Active Molecule ◽  
Dft Methods ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Semi Empirical

The structural and electronic properties of 1-(5-Hydroxymethyl - 4 –[ 5 – (5-oxo-5-piperidin- 1 -yl-penta- 1,3 -dienyl)-benzo [1,3] dioxol- 2 -yl]- tetrahydro -furan-2 -yl)-5-methy l-1Hpyrimidine-2,4dione (AHE) molecule have been investigated theoretically by performing density functional theory (DFT), and semi empirical molecular orbital calculations. The geometry of the molecule is optimized at the level of Austin Model 1 (AM1), and the electronic properties and relative energies of the molecules have been calculated by density functional theory in the ground state. The resultant dipole moment of the AHE molecule is about 2.6 and 2.3 Debyes by AM1 and DFT methods respectively, This property of AHE makes it an active molecule with its environment, that is AHE molecule may interacts with its environment strongly in solution.

Hexaethyl-2,4-dicarba-nido-hexaborane(8), Deprotonation and Complexation Studied by NMR Spectroscopy and Density Functional Theory (DFT) Calculations

2004 ◽  
Vol 59 (6) ◽  
pp. 685-691 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Hans-Jörg Schanz
Keyword(s):  
Density Functional Theory ◽  
Nmr Spectroscopy ◽  
Density Functional ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Analogous Reaction ◽  
Sandwich Complex ◽  
Dft Methods ◽  
Functional Theory ◽  
Nmr Data

Deprotonation of hexaethyl-2,4-dicarba-nido-borane(8) 2 leads first to the hexaethyl-2,4-dicarbanido- borate(1−) 3, and further deprotonation, using BuLi/KOtBu, gives the hexaethyl-2,4-dicarbanido- hexaborate(2−) 4. The reaction of 3 with FeCl2 affords the commo-ferracarborane [Fe(Et6-2,4- C2B4H)2] 5, and the analogous reaction of 4 leads to the anionic sandwich complex [Fe(Et6-2,4- C2B4)2]2− 6 which can be protonated to give 5. The complex 5 contains two hydrido ligands, each bridging the iron and two boron atoms. Reactions were monitored and the products were characterised by 11B NMR spectroscopy in solution. The geometries of the carboranes, the borates (all unsubstituted and permethyl-substituted) and the iron complexes (all unsubstituted) were optimised by DFT methods [B3LYP/6-311+G(d,p) or B3LYP/6-31+G(d)], and the relevant NMR data [chemical shifts δ11B, δ13C, δ57Fe, and coupling constants 1J(13C,1H), 1J(11B,1H), 1J(57Fe,1H), 1J(57Fe,11B)] were calculated at the same level of theory.

Binuclear O2 activation and hydrogen transfer mechanism for aerobic oxidation of alcohols

2020 ◽  
Vol 10 (7) ◽  
pp. 2183-2192
Author(s):  
Zhiyun Hu ◽  
Hongyu Ge ◽  
Xinzheng Yang
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Aerobic Oxidation ◽  
Density Functional Theory Calculations ◽  
Transfer Mechanism ◽  
Functional Theory ◽  
O2 Activation ◽  
Oxidation Of Alcohols

Density functional theory calculations reveal a binuclear O2 activation and hydrogen transfer mechanism with spin-crossovers for aerobic oxidation of alcohols.

THEORETICAL STUDIES ON THE REACTION MECHANISM OF HNCS WITH CH2CH RADICAL

2007 ◽  
Vol 06 (01) ◽  
pp. 1-12 ◽  
Author(s):  
JIAN-HUA XU ◽  
LAI-CAI LI ◽  
YAN ZHENG ◽  
JUN-LING LIU ◽  
XIN WANG
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanism ◽  
Reaction Mechanisms ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Main Product ◽  
Reaction Pathways ◽  
Theoretical Studies ◽  
Functional Theory ◽  
Ch Radical

The reaction mechanisms of HNCS with CH 2 CH radical have been investigated by density functional theory (DFT). The geometries and harmonic frequencies of the reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311++G(d,p) level. The results show that the reaction is very complicated. Nine possible reaction pathways were identified. The results show that the most feasible reaction channel is the hydrogen-transfer pathway CH 2 CH + HNCS → IMA1 → TSA1 → CH 2 CHH + NCS . The pathway VIC C-S addition channel ( CH 2 CH + HNCS → TSD5 → IMD4 → TSD9 → CH 2 CHS + CNH ) can also occur easily. Ethene and radical NCS is the main product of the studied reaction, and product P8 ( CH 2 CHS and CNH ) may also be observed. Compared with our previous study on the reaction HNCS + CH 2 CH , the present reaction is easier to proceed.

Comparative DFT study for molecular geometries and spectra of methyl pheophorbides-a: test of M06-2X and two other functionals

2010 ◽  
Vol 14 (07) ◽  
pp. 592-604 ◽  
Author(s):  
Do Sung Huh ◽  
Sang Joon Choe
Keyword(s):  
Density Functional Theory ◽  
Standard Deviation ◽  
Density Functional ◽  
Visible Spectrum ◽  
Mean Value ◽  
Time Dependent ◽  
Dft Methods ◽  
Functional Theory ◽  
Td Dft ◽  
The Mean

The recent interest in the application of density functional theory (DFT) has prompted us to test several functions in molecular geometries of methyl pheophorbides-a (MPa), an important starting material in photodynamic therapy (PDT). In this study, we report on tests for three popular DFT methods: M06-2X, B3LYP, and LSDA. Based on the standard deviation and the mean value, and by using the difference between optimized calculated value and experimental value in geometries, we drew the following conclusions: M06-2X/6-311+G(d,p) attained the smallest standard deviation of difference among the tested DFT methods in terms of bond length, whereas the standard deviation of bond angle in LSDA/6-311+G(d,p) was the smallest. In terms of absolute value, the mean value of LSDA/6-311+G(d,p) calculation was larger than that of M06-2X/6-311+G(d,p). We found that M06-2X/6-311+G(d,p) gave the best performance for MPa in the molecular geometries. The UV-visible spectrum was calculated with time-dependent density-functional theory (TD-DFT). Time-dependent M06-2X/6-311+G(d,p) gave the best performance for MPa in CH2Cl2 solution. In general, TD-DFT calculations in CH2Cl2 solution were more red-shifted compared with those in the solid state.

Theoretical study of the non linear optical properties of alkali metal (Li, Na, K) doped aluminum nitride nanocages

RSC Advances ◽  
2016 ◽  
Vol 6 (96) ◽  
pp. 94228-94235 ◽  
Author(s):  
Maria Maria ◽  
Javed Iqbal ◽  
Khurshid Ayub
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Alkali Metal ◽  
Aluminum Nitride ◽  
Density Functional ◽  
Theoretical Study ◽  
Dft Methods ◽  
Functional Theory ◽  
Non Linear ◽  
Linear Optical Properties

The effect of alkali metal (Li, Na, and K) doping in aluminum nitride (Al12N12) nanocages is studied through density functional theory (DFT) methods.

ENERGETICS AND STRUCTURAL INSIGHTS OF MOLECULAR CONDUCTORS USING DENSITY FUNCTIONAL THEORY METHODS: 1,3-DITHIOLE-2-THIONE, 1,3-DITHIOLE-2-ONE, 1,3-DIOXOLE-2-ONE, AND 1,3-DIOXOLE-2-THIONE

2009 ◽  
Vol 08 (06) ◽  
pp. 1185-1195 ◽  
Author(s):  
R. L. PRASAD ◽  
A. KUSHWAHA ◽  
RAJENDRA PRASAD ◽  
S. JAISWAL ◽  
R. A. YADAV
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Energy Requirement ◽  
Radical Cations ◽  
Geometrical Parameters ◽  
Dft Methods ◽  
Molecular Conductors ◽  
Relaxation Energy ◽  
Functional Theory ◽  
Hartree Fock

Computations were carried out employing the restricted Hartree–Fock (RHF) and density functional theory (DFT) methods to investigate the geometries and energies for the 1,3-dithiole-2-thione (DTT), 1,3-dithiole-2-one (DTO), 1,3-dioxole-2-thione (DOT), and 1,3-dioxole-2-one (DOO) molecules and their radical cations. The geometrical parameters of all the four molecules suggest a finite extent of extended conjugation across the molecules. The radical cations of the DTT and DOT molecules exhibit increased extent of conjugation compared to their neutral analogues. However, on going from the neutral DOO and DTO molecules to their radical cations, the extent of conjugation across the ions decreases and two unsaturated sites become isolated from each other. Requirement of the relaxation energy for the formation of radical cation is much lower for the DTT and DOT molecules compared to that for the DOO and DTO molecules. Smaller relaxation energy requirement favors minimal resistance to charge transport along the molecular stacking. Therefore, it is speculated that the DTT and DOT molecules are better molecular conductors as compared to the DOO and DTO molecules.

Simultaneous CO2 and SO2 capture by using ionic liquids: a theoretical approach

2017 ◽  
Vol 19 (7) ◽  
pp. 5411-5422 ◽  
Author(s):  
Gregorio García ◽  
Mert Atilhan ◽  
Santiago Aparicio
Keyword(s):  
Density Functional Theory ◽  
Ionic Liquids ◽  
Theoretical Approach ◽  
Density Functional ◽  
Dft Methods ◽  
Functional Theory ◽  
Acidic Gases ◽  
So2 Capture ◽  
Mechanism Of Interaction

Density functional theory (DFT) methods were used to analyze the mechanism of interaction between acidic gases and ionic liquids based on the 1-ethyl-3-methylimidazolium cation coupled with five different anions.

scholarly journals DFT and TD-DFT Study of Structure and Properties of Semiconductive Hybrid Networks Formed by Bismuth Halides and Different Polycyclic Aromatic Ligands

2011 ◽  
Vol 8 (s1) ◽  
pp. S195-S202
Author(s):  
Y. Belhocine ◽  
M. Bencharif
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Density Functional ◽  
Relativistic Effects ◽  
Spectroscopic Properties ◽  
Basis Set ◽  
Dft Methods ◽  
Functional Theory ◽  
Td Dft ◽  
Polycyclic Aromatic

The structure and spectroscopic properties of polycyclic aromatic ligands of 2,3,6,7,10,11-hexakis (alkylthio) triphenylene (alkyl: methyl, ethyl, and isopropyl; corresponding to the abbreviations of the molecules: HMTT, HETT and HiPTT) were studied using density functional theory (DFT) and time dependent density functional theory (TD-DFT) methods with triple-zeta valence polarization (TZVP) basis set. It was shown that the type of functional theory used, Becke-Perdew (BP) and Leeuwen-Baerends (LB94) implemented in Amsterdam Density functional (ADF) program package, does not have essential influence on the geometry of studied compounds in both ground and excited states. However, significant differences were obtained for the band gap values with relativistic effects of the zero order regular approximation scalar corrections (ZORA) and LB94 functional seems to reproduce better the experimental optical band gap of these systems.

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