scholarly journals Toward Thermodynamically Stable Triplet Carbenes

2019 ◽  
Author(s):  
Yumiao Ma
Keyword(s):  
Free Energy ◽  
Dft Calculations ◽  
Gibbs Free Energy ◽  
Electronic Structures ◽  
Sharp Contrast ◽  
Fine Tuning ◽  
Experimental Development ◽  
Triplet Carbenes ◽  
Singlet Carbenes

<p>In sharp contrast to the widely studied and applied stable singlet carbenes, only several kinetically persistent triplet carbenes have been studied, and thermodynamically stable triplet carbenes are much less developed. With the Gibbs free energy of C-H bond insertion into methane as a probe, DFT calculations were employed to examine a variety of candidate molecules for stable triplet carbenes. Guided by these calculations, some molecules with significant stability against C-H insertion were designed by fine tuning of geometry and electronic structures. These compounds might be potential candidates for experimental development of stable triplet carbenes.</p>

scholarly journals Toward Thermodynamically Stable Triplet Carbenes

2019 ◽  
Author(s):  
Yumiao Ma
Keyword(s):  
Free Energy ◽  
Dft Calculations ◽  
Gibbs Free Energy ◽  
Electronic Structures ◽  
Sharp Contrast ◽  
Fine Tuning ◽  
Experimental Development ◽  
Triplet Carbenes ◽  
Singlet Carbenes

<p>In sharp contrast to the widely studied and applied stable singlet carbenes, only several kinetically persistent triplet carbenes have been studied, and thermodynamically stable triplet carbenes are much less developed. With the Gibbs free energy of C-H bond insertion into methane as a probe, DFT calculations were employed to examine a variety of candidate molecules for stable triplet carbenes. Guided by these calculations, some molecules with significant stability against C-H insertion were designed by fine tuning of geometry and electronic structures. These compounds might be potential candidates for experimental development of stable triplet carbenes.</p>

scholarly journals A Study effect of Substituents X on Methylenecyclopentane and 1- Methylcyclopentene System

2018 ◽  
Vol 1 (1) ◽  
pp. 38-44
Author(s):  
Ghassab Al-Mazaideh
Keyword(s):  
Free Energy ◽  
Dft Calculations ◽  
Gibbs Free Energy ◽  
Free Energy Calculations ◽  
Relative Stabilities ◽  
Energy Calculations ◽  
Effect Of Substituents ◽  
Orbital Energies ◽  
The Stability ◽  
Homo Lumo

In this study, the geometry optimizations, orbital energies (HOMO-LUMO) and relative stabilities of methylene cyclopentane and 1-methylcyclopentene were investigated by DFT calculations. 1-methylcyclopentene was found to be more stable than methylene cyclopentane isomer with enthalpy value H=18.518 kJ/mol. Also, the effect of substituents X (F, OH, CH3, NH2, CN, NO2, CHO and CF3) also studied on the relative stabilities of these two tautomers. The results showed that the stability of both isomers is increased by all substitutes. Gibbs free energy calculations have been used to find the effect of substituents X on the system.

Chemical equilibrium and chemical kinetics

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
Free Energy ◽  
Equilibrium Constant ◽  
Gibbs Free Energy ◽  
Chemical Kinetics ◽  
Chemical Equilibrium ◽  
First Principles ◽  
Effect Of Temperature ◽  
Total System ◽  
Free Energies

Building on the previous chapter, this chapter examines gas phase chemical equilibrium, and the equilibrium constant. This chapter takes a rigorous, yet very clear, ‘first principles’ approach, expressing the total Gibbs free energy of a reaction mixture at any time as the sum of the instantaneous Gibbs free energies of each component, as expressed in terms of the extent-of-reaction. The equilibrium reaction mixture is then defined as the point at which the total system Gibbs free energy is a minimum, from which concepts such as the equilibrium constant emerge. The chapter also explores the temperature dependence of equilibrium, this being one example of Le Chatelier’s principle. Finally, the chapter links thermodynamics to chemical kinetics by showing how the equilibrium constant is the ratio of the forward and backward rate constants. We also introduce the Arrhenius equation, closing with a discussion of the overall effect of temperature on chemical equilibrium.

Extended Gibbs Free Energy and Laplace Pressure of Ordered Hexagonal Close-Packed Spherical Particles: A Wettability Study

Langmuir ◽  
2021 ◽  
Author(s):  
Amir Bayat ◽  
Mahdi Ebrahimi ◽  
Saeed Rahemi Ardekani ◽  
Esmaiel Saievar Iranizad ◽  
Alireza Zaker Moshfegh
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Laplace Pressure ◽  
Spherical Particles ◽  
Hexagonal Close Packed

scholarly journals First-Principles Study of Mechanical and Thermodynamic Properties of Binary and Ternary CoX (X = W and Mo) Intermetallic Compounds

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1404
Author(s):  
Yunfei Yang ◽  
Changhao Wang ◽  
Junhao Sun ◽  
Shilei Li ◽  
Wei Liu ◽  
...  
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Density Functional ◽  
Vibrational Entropy ◽  
Functional Theory ◽  
Lattice Constants ◽  
The Density Functional Theory ◽  
Ductile Behavior ◽  
Pseudo Potential

In this study, the structural, elastic, and thermodynamic properties of DO19 and L12 structured Co3X (X = W, Mo or both W and Mo) and μ structured Co7X6 were investigated using the density functional theory implemented in the pseudo-potential plane wave. The obtained lattice constants were observed to be in good agreement with the available experimental data. With respect to the calculated mechanical properties and Poisson’s ratio, the DO19-Co3X, L12-Co3X, and μ-Co7X6 compounds were noted to be mechanically stable and possessed an optimal ductile behavior; however, L12-Co3X exhibited higher strength and brittleness than DO19-Co3X. Moreover, the quasi-harmonic Debye–Grüneisen approach was confirmed to be valid in describing the temperature-dependent thermodynamic properties of the Co3X and Co7X6 compounds, including heat capacity, vibrational entropy, and Gibbs free energy. Based on the calculated Gibbs free energy of DO19-Co3X and L12-Co7X6, the phase transformation temperatures for DO19-Co3X to L12-Co7X6 were determined and obtained values were noted to match well with the experiment results.

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