Electronic or steric effects: Detailed DFT investigations of titanium amino based Kaminsky type olefin catalysts

2018 ◽  
Author(s):  
Jörg Saßmannshausen
Keyword(s):  
Density Functional Theory ◽  
Strong Correlation ◽  
Density Functional ◽  
Steric Effects ◽  
Aryl Group ◽  
Functional Theory

We report detailed Density Functional Theory (DFT) investigations of a series of structurally similar titanium (IV) chelating σ-aryl catalysts. Particular attention was paid to the electronic charges of the Ti, C ipso of the substituted aryl group and the benzylic CH<sub>2</sub> and C<i><sub>ipso</sub></i> atoms. The Bader and NBO derived charges were compared with the recently reported polymerisation results by Chan. We found a strong correlation between the relative energies of one of the computed isomers and the activity of the catalyst. Neither NBO nor Bader charges could be convincingly correlated to the observed activity.

Electronic or steric effects: Detailed DFT investigations of titanium amino based Kaminsky type olefin catalysts

2018 ◽  
Author(s):  
Jörg Saßmannshausen
Keyword(s):  
Density Functional Theory ◽  
Strong Correlation ◽  
Density Functional ◽  
Steric Effects ◽  
Aryl Group ◽  
Functional Theory

We report detailed Density Functional Theory (DFT) investigations of a series of structurally similar titanium (IV) chelating σ-aryl catalysts. Particular attention was paid to the electronic charges of the Ti, C ipso of the substituted aryl group and the benzylic CH<sub>2</sub> and C<i><sub>ipso</sub></i> atoms. The Bader and NBO derived charges were compared with the recently reported polymerisation results by Chan. We found a strong correlation between the relative energies of one of the computed isomers and the activity of the catalyst. Neither NBO nor Bader charges could be convincingly correlated to the observed activity.

scholarly journals Substituent effects in the decarboxylation reactions of coordinated arylcarboxylates in dinuclear copper complexes, [(napy)Cu2(O2CC6H4X)]+

2017 ◽  
Vol 23 (6) ◽  
pp. 351-358 ◽  
Author(s):  
Qiuyan Jin ◽  
Jiaye Li ◽  
Alireza Ariafard ◽  
Allan J Canty ◽  
Richard AJ O’Hair
Keyword(s):  
Density Functional Theory ◽  
Transition State ◽  
Density Functional ◽  
Copper Complexes ◽  
Substituent Effects ◽  
Density Functional Theory Calculations ◽  
Molecular Formula ◽  
Binuclear Complexes ◽  
Aryl Group ◽  
Functional Theory

A combination of gas-phase ion trap mass spectrometry experiments and density functional theory (DFT) calculations have been used to examine the role of substituents on the decarboxylation of 25 different coordinated aromatic carboxylates in binuclear complexes, [(napy)Cu2(O2CC6H4X)]+, where napy is the ligand 1,8-naphthyridine (molecular formula, C8H6N2) and X = H and the ortho ( o), meta ( m) and para ( p) isomers of F, Br, CN, NO2, CF3, OAc, Me and MeO. Two competing unimolecular reaction pathways were found: decarboxylation to give the organometallic cation [(napy)Cu2(C6H4X)]+ or loss of the neutral copper benzoate to yield [(napy)Cu]+. The substituents on the aryl group influence the branching ratios of these product channels, but decarboxylation is always the dominant pathway. Density functional theory calculations reveal that decarboxylation proceeds via two transition states. The first enables a change in the coordination mode of the coordinated benzoate in [(napy)Cu2(O2CC6H4X)]+ from the thermodynamically favoured O, O-bridged form to the O-bound form, which is the reactive conformation for the second transition state which involves extrusion of CO2 with concomitant formation of the CO2 coordinated organometallic cation, [(napy)Cu2(C6H4X)(CO2)]+, which then loses CO2 in the final step to yield [(napy)Cu2(C6H4X)]+. In all cases the barrier is highest for the second transition state. The o-substituted benzoates show a lower activation energy than the m-substituted ones, while the p-substituted ones have the highest energy, which is consistent with the experimentally determined normalised collision energy required to induce fragmentation of [(napy)Cu2(O2CC6H4X)]+.

Strong correlation in density functional theory: general discussion

2020 ◽  
Vol 224 ◽  
pp. 373-381
Author(s):  
Emmanuel Fromager ◽  
Nikitas Gidopoulos ◽  
Paola Gori-Giorgi ◽  
Trygve Helgaker ◽  
Pierre-François Loos ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Strong Correlation ◽  
Density Functional ◽  
Functional Theory

Fully Nonlocal Functionals Along the Adiabatic Connection of Density Functional Theory

2019 ◽  
Author(s):  
Stefan Vuckovic
Keyword(s):  
Density Functional Theory ◽  
Strong Correlation ◽  
Density Functional ◽  
Correlation Energy ◽  
Electronic Effects ◽  
Functional Theory ◽  
Strongly Interacting ◽  
Kinetic Component ◽  
Exact Exchange ◽  
New Framework

Inspired by the exact form of the strongly interacting limit of density functional theory, Vuckovic and Gori Giorgi have recently proposed [J. Phys. Chem. Lett. 2017, 8, 2799] the multiple radii functional (MRF), a new framework for the construction of exchange-correlation (xc) energy approximations able to describe strong correlation electronic effects. To facilitate the construction of improved approximations based on the MRF functional, in the present work we use reverse engineering strategies to reveal the forms of the MRF functional which reproduce the exact xc functional for small atoms. We also develop a procedure that allows the MRF functional to be built on the top of exact exchange. Using the adiabatic connection representation of the xc functional, we also investigate routes for the construction of the correlation functional by combining information from the physical, weakly and strongly interacting regimes. We highlight the advantages of this approach over previous adiabatic connection-based approaches for the treatment of strong correlation and discuss how it can be used for recovering the presently missing kinetic component of the correlation energy in the MRF framework.<br> <pre><br></pre>

Effect of carbon content and electronic strong correlation on the mechanical and thermodynamic properties of ytterbium carbides

RSC Advances ◽  
2015 ◽  
Vol 5 (125) ◽  
pp. 103082-103090 ◽  
Author(s):  
Wei Dong ◽  
Chao Zhang ◽  
Hong Jiang ◽  
Yue-Hua Su ◽  
Zhen-Hong Dai
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Properties ◽  
Ab Initio ◽  
Carbon Content ◽  
Strong Correlation ◽  
Density Functional ◽  
Functional Theory

The mechanical and thermodynamic properties of four ytterbium carbides with increasing carbon content have been examined usingab initiocalculations based on density functional theory.

Insights into disilylation and distannation: sequence influence and ligand/steric effects on Pd-catalyzed difunctionalization of carbenes

2018 ◽  
Vol 47 (6) ◽  
pp. 1819-1826 ◽  
Author(s):  
Xiaoyu Yue ◽  
Chunhui Shan ◽  
Xiaotian Qi ◽  
Xiaoling Luo ◽  
Lei Zhu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Dft Calculation ◽  
Steric Effects ◽  
Functional Theory

Density functional theory (DFT) calculation has been used to reveal the mechanism of Pd-catalyzed disilylation of carbene, which is a pathway to construct disilylmethane derivatives.

The Structure of Two 1-(Nitrophenyl)-Δ2-pyrazolines: a Crystallographic and Theoretical Study

2004 ◽  
Vol 57 (11) ◽  
pp. 1103 ◽  
Author(s):  
Glenn P. A. Yap ◽  
Ibon Alkorta ◽  
Nadine Jagerovic ◽  
José Elguero
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Gas Phase ◽  
Density Functional ◽  
Theoretical Study ◽  
Chemical Shifts ◽  
Molecular Structures ◽  
Steric Effects ◽  
Functional Theory ◽  
Crystal And Molecular Structures

The crystal and molecular structures of two nitrophenylpyrazolines have been determined. The geometries have been used as starting geometries for density functional theory (DFT) calculations. The differences in conformation between both molecules and between the solid state and gas phase are explained in terms of steric effects. An attractive intramolecular N···N interaction between the nitro group and the pyrazoline N2 nitrogens has been found. Absolute shieldings have been calculated (GIAO) and compared with experimental 1H and 13C chemical shifts.

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