Density Functional Theory Calculations of the Transition States for Hydrogen Exchange and Dehydrogenation of Methane by a Broensted Zeolitic Proton

1994 ◽  
Vol 98 (49) ◽  
pp. 12938-12944 ◽  
Author(s):  
S. R. Blaszkowski ◽  
A. P. J. Jansen ◽  
M. A. C. Nascimento ◽  
R. A. van Santen
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Hydrogen Exchange ◽  
Transition States ◽  
Density Functional Theory Calculations ◽  
Functional Theory

scholarly journals A density functional theory study on the mechanism of the allylpalladium-catalyzed dehydrogenation of aldehydes and cyclic ketones

2021 ◽  
Vol 46 ◽  
pp. 146867832110206
Author(s):  
Anan Haj Ichia Arisha
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Transition States ◽  
Density Functional Theory Calculations ◽  
Carbonyl Complex ◽  
Cyclic Ketones ◽  
Complex Catalyst ◽  
Functional Theory ◽  
Hydride Elimination

The results of density functional theory calculations at the APFD/SDD level are detailed herein in order to study the main steps in the α,β-dehydrogenation of aldehydes and cyclic ketones in the presence of an allylpalladium complex catalyst. The mechanism is believed to proceed via an allylpalladium enolate complex (A) in equilibrium with the carbon-bonded complex (B), followed by β-hydride elimination to yield the allylpalladium hydride coordinated to the α,β-unsaturated carbonyl (complex C). The optimized structures and detailed energy profiles of these intermediates and their corresponding transition states are presented herein. The results indicate that the intermediates and their transition states are more stable in THF solution than in the gas phase. In detail, the energy barriers for the two steps are found to be 25.22 and 11.13 kcal/mol, respectively, in THF, and 29.93 and 9.77 kcal/mol, respectively, in the gas phase.

scholarly journals Structures and reaction rates of the gaseous oxidation of SO<sub>2</sub> by an O<sub>3</sub><sup>−</sup>(H<sub>2</sub>O)<sub>0-5</sub> cluster – a density functional theory investigation

2012 ◽  
Vol 12 (8) ◽  
pp. 3639-3652 ◽  
Author(s):  
N. Bork ◽  
T. Kurtén ◽  
M. B. Enghoff ◽  
J. O. P. Pedersen ◽  
K. V. Mikkelsen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Atmospheric Chemistry ◽  
Density Functional ◽  
Transition States ◽  
Density Functional Theory Calculations ◽  
Reaction Rates ◽  
Water Molecules ◽  
Functional Theory ◽  
High Entropy ◽  
Collision Complexes

Abstract. Based on density functional theory calculations we present a study of the gaseous oxidation of SO2 to SO3 by an anionic O3−(H2O)n cluster, n = 0–5. The configurations of the most relevant reactants, transition states, and products are discussed and compared to previous findings. Two different classes of transition states have been identified. One class is characterised by strong networks of hydrogen bonds, very similar to the reactant complexes. The other class is characterised by sparser structures of hydration water and is stabilised by high entropy. At temperatures relevant for atmospheric chemistry, the most energetically favourable class of transition states vary with the number of water molecules attached. A kinetic model is utilised, taking into account the most likely outcomes of the initial SO2 O3−(H2O)n collision complexes. This model shows that the reaction takes place at collision rates regardless of the number of water molecules involved. A lifetime analysis of the collision complexes supports this conclusion. Hereafter, the thermodynamics of water and O2 condensation and evaporation from the product SO3−O2(H2O)n cluster is considered and the final products are predicted to be O2SO3− and O2SO3−(H2O)1. The low degree of hydration is rationalised through a charge analysis of the relevant complexes. Finally, the thermodynamics of a few relevant reactions of the O2SO3− and O2SO3−(H2O)1 complexes are considered.

Density functional theory calculations of Rh-β-diketonato complexes

2015 ◽  
Vol 44 (4) ◽  
pp. 1503-1515 ◽  
Author(s):  
J. Conradie
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Transition States ◽  
Density Functional Theory Calculations ◽  
Functional Theory

Density functional theory results on the geometry, energies and charges of selected Rh-β-diketonato reactants, products and transition states.

scholarly journals Structures and reaction rates of the gaseous oxidation of SO<sub>2</sub> by an O<sub>3</sub><sup>−</sup>(H<sub>2</sub>O)<sub>0–5</sub> cluster – a density functional theory investigation

2011 ◽  
Vol 11 (11) ◽  
pp. 29647-29679 ◽  
Author(s):  
N. Bork ◽  
T. Kurtén ◽  
M. B. Enghoff ◽  
J. O. P. Pedersen ◽  
K. V. Mikkelsen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Atmospheric Chemistry ◽  
Density Functional ◽  
Transition States ◽  
Density Functional Theory Calculations ◽  
Reaction Rates ◽  
Water Molecules ◽  
Functional Theory ◽  
High Entropy ◽  
Collision Complexes

Abstract. Based on density functional theory calculations we present a study of the gaseous oxidation of SO2 to SO3 by an anionic O3−(H2On cluster, n=0–5. The configurations of the most relevant reactants, transition states, and products are discussed and compared to previous findings. Two different classes of transition states have been identified. One class is characterized by strong networks of hydrogen bonds, very similar to the reactant complexes. The other class is characterized by loose structures of hydration water and is stabilized by high entropy. At temperatures relevant for atmospheric chemistry, the most energetically favorable class of transition states vary with the number of water molecules attached. A kinetic model is utilized, taking into account the most likely outcomes of the initial SO2O3−(H2O)n collision complexes. This model shows that the reaction takes place at collision rates regardless of the number of water molecules involved. A lifetime analysis of the collision complexes supports this conclusion. Hereafter, the thermodynamics of water and O2 condensation and evaporation from the product SO3−O2(H2O)n cluster is considered and the final products are predicted to be O2SO3− and O2SO3−(H2O)1. The low degree of hydration is rationalized through a charge analysis of the relevant complexes. Finally, the thermodynamics of a few relevant reactions of the O2SO3− and O2SO3−(H2O)1 complexes are considered.

Is a Non-Transition Element Nitride Ferromagnet Ever Achievable? Indication of the N-N Pairing Instability

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1525-1531 ◽  
Author(s):  
Wojciech Grochala
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Transition Element ◽  
Density Functional Theory Calculations ◽  
Functional Theory

The enthalpy of four polymorphs of CaN has been scrutinized at 0 and 100 GPa using density functional theory calculations. It is shown that structures of diamagnetic calcium diazenide (Ca2N2) are preferred over the cubic ferromagnetic polymorph (CaN) postulated before, both at 0 and 100 GPa.

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