Activation Energy and NBO Interaction Approaches to Torquoselectivity and its Dependence on the Conformational Profile of the Substituent

The torquoselectivity of ring opening of 3-fluoromethylcyclobutenes, 2-fluoromethyl-3-oxetenes and perfluoro-3-methyl-cyclobutene have been studied at the MP2/cc-pVTZ level of theory and the results analysed by using the activation energy approach and also the NBO interactions of the breaking ring bond with the substituent bond. The outward or inward opening that has lower activation energy in the activation energy approach or larger interaction in the NBO approach constitutes the preferred mode. The CHF₂ and CH₂F substituents on cyclobutene and oxetene can adopt three distinct conformations with respect to the cleaving ring bond. It has been discovered that each conformer exhibits a distinct level of torquoselectivity and some higher lying conformer may even significantly contribute to the overall selectivity. The conformational profile of the substituent, therefore, is recommended for taking into consideration in any serious treatment of the subject. The experimental selectivity, if otherwise, is likely to be a consequence of secondary reactions such as the reaction equilibration, which honours the relative thermodynamic stabilities of the ring opened products.

Differential Activation Energy and NBO Interaction Approaches to Torquoselectivity and Its Dependence on the Conformational Profile of the Substituent

The torquoselectivity of ring opening of 3-CF₃-cyclobutene, 3-CHF₂-cyclobutene, 3-CH₂F-cyclobutene, 3-CF₃-oxetene and perfluoro-3-CH₃-cyclobutene have been studied at the MP2/cc-pVTZ level of theory and the results analysed by using the differential activation energy approach and also differential NBO interactions of the breaking ring bond with the substituent bonds. The outward or inward ring opening that has lower activation energy in the differential activation energy approach or larger interaction in the differential NBO interaction approach constitutes the preferred mode. The predictions from the two approaches are largely found to be contradicting each other, specifically when the substituent is electron-deficient. The CHF₂ and CH₂F substituents on cyclobutene and oxetene can adopt three distinct conformations with respect to the cleaving ring bond. It has been discovered that each conformer exhibits a distinct level of torquoselectivity and some may even contribute to the overall selectivity substantially. The conformational profile of the substituent, therefore, is recommended to be taken into account in any serious treatment of the subject. The experimental torquoselectivity, if otherwise, is a likely consequence of secondary reactions, specifically equilibration through reaction reversal while honouring the relative thermodynamic stabilities of the ring opened products.

Differential Activation Energy and NBO Interaction Approaches to Torquoselectivity and Its Dependence on the Conformational Profile of the Substituent

The torquoselectivity of ring opening of 3-CF₃-cyclobutene, 3-CHF₂-cyclobutene, 3-CH₂F-cyclobutene, 3-CF₃-oxetene and perfluoro-3-CH₃-cyclobutene have been studied at the MP2/cc-pVTZ level of theory and the results analysed by using the differential activation energy approach and also differential NBO interactions of the breaking ring bond with the substituent bonds. The outward or inward ring opening that has lower activation energy in the differential activation energy approach or larger interaction in the differential NBO interaction approach constitutes the preferred mode. The predictions from the two approaches are largely found to be contradicting each other, specifically when the substituent is electron-deficient. The CHF₂ and CH₂F substituents on cyclobutene and oxetene can adopt three distinct conformations with respect to the cleaving ring bond. It has been discovered that each conformer exhibits a distinct level of torquoselectivity and some may even contribute to the overall selectivity substantially. The conformational profile of the substituent, therefore, is recommended to be taken into account in any serious treatment of the subject. The experimental torquoselectivity, if otherwise, is a likely consequence of secondary reactions, specifically equilibration through reaction reversal while honouring the relative thermodynamic stabilities of the ring opened products.

Differential Activation Energy and NBO Interaction Approaches to Torquoselectivity and Its Dependence on the Conformational Profile of the Substituent

The torquoselectivity of ring opening of 3-CF₃-cyclobutene, 3-CHF₂-cyclobutene, 3-CH₂F-cyclobutene, 3-CF₃-oxetene and perfluoro-3-CH₃-cyclobutene have been studied at the MP2/cc-pVTZ level of theory and the results analysed by using the differential activation energy approach and also differential NBO interactions of the breaking ring bond with the substituent bonds. The outward or inward ring opening that has lower activation energy in the differential activation energy approach or larger interaction in the differential NBO interaction approach constitutes the preferred mode. The predictions from the two approaches are largely found to be contradicting each other, specifically when the substituent is electron-deficient. The CHF₂ and CH₂F substituents on cyclobutene and oxetene can adopt three distinct conformations with respect to the cleaving ring bond. It has been discovered that each conformer exhibits a distinct level of torquoselectivity and some may even contribute to the overall selectivity substantially. The conformational profile of the substituent, therefore, is recommended to be taken into account in any serious treatment of the subject. The experimental torquoselectivity, if otherwise, is a likely consequence of secondary reactions, specifically equilibration through reaction reversal while honouring the relative thermodynamic stabilities of the ring opened products.

Electrical Conduction Characteristic of a 2D MXene Device with Cu/Cr2C/TiN Structure Based on Density Functional Theory

The electronic structure and the corresponding electrical conductive behavior of the Cu/Cr2C/TiN stack were assessed according to a newly developed first-principle model based on density functional theory. Using an additional Cr2C layer provides the metal-like characteristic of the Cu/Cr2C/TiN stack with much larger electrical conduction coefficients (i.e., mobility, diffusivity, and electrical conductivity) than the conventional Ag/Ti3C2/Pt stack due to the lower activation energy. This device is therefore capable of offering faster switching speeds, lower programming voltage, and better stability and durability than the memristor device with conventional Ti3C2 MXene.

The influence of ceria on Cu/TiO2 catalysts to produce abundant oxygen vacancies and induce highly efficient CO oxidation

Ce and Cu species deposited on TiO2 can apparently provide a higher turnover frequency rate and lower activation energy than the Cu/TiO2 catalyst and the Ce and Cu species on SiO2 catalysts.

Hydrolytic dehydrogenation of NH3BH3 catalyzed by ruthenium nanoparticles supported on magnesium–aluminum layered double-hydroxides

Ru/MgAl-LDHs catalyst was successfully prepared, which exhibited higher catalytic activity and lower activation energy toward the hydrolysis of ammonia borane for hydrogen production.

Symmetry-Adapted Perturbation Theory Decomposition of the Reaction Force: Insights into Substituent Effects Involved in Hemiacetal Formation Mechanisms

<div>The decomposition of the reaction force based on symmetry-adapted perturbation theory (SAPT) has been proposed. This approach was used to investigate the subtituent effects along the reaction coordinate pathway for the hemiacetal formation mechanism between methanol and substituted aldehydes of the form CX₃CHO (X = H, F, Cl, and Br), providing a quantitative evaluation of the reaction-driving and reaction-retarding force components. Our results highlight the importance of more favorable electrostatic and induction effects in the reactions involving halogenated aldehydes that leads to lower activation energy barriers. These substituent effects are further elucidated by applying the functional-group partition of symmetry-adapted</div><div>perturbation theory (F-SAPT). The results show that the reaction is largely driven by favorable direct non-covalent interactions between the CX₃ group on the aldehyde and the OH group on methanol.</div>

Symmetry-Adapted Perturbation Theory Decomposition of the Reaction Force: Insights into Substituent Effects Involved in Hemiacetal Formation Mechanisms

<div>The decomposition of the reaction force based on symmetry-adapted perturbation theory (SAPT) has been proposed. This approach was used to investigate the subtituent effects along the reaction coordinate pathway for the hemiacetal formation mechanism between methanol and substituted aldehydes of the form CX₃CHO (X = H, F, Cl, and Br), providing a quantitative evaluation of the reaction-driving and reaction-retarding force components. Our results highlight the importance of more favorable electrostatic and induction effects in the reactions involving halogenated aldehydes that leads to lower activation energy barriers. These substituent effects are further elucidated by applying the functional-group partition of symmetry-adapted</div><div>perturbation theory (F-SAPT). The results show that the reaction is largely driven by favorable direct non-covalent interactions between the CX₃ group on the aldehyde and the OH group on methanol.</div>