The effect of steric repulsion on the torsional potential of n-butane: a theoretical study

Stojanović, Milovan; Aleksić, Jovana; Baranac‐Stojanović, Marija

doi:10.1016/j.tet.2015.06.002

Cited by 9 publications

(6 citation statements)

References 42 publications

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“…This profile coincides what is usually meant by ''steric'' repulsion, and it is in stark contrast to the preceding results described for ethane. Our results in Table 2 do not comport with a recent localized MO decomposition analysis of n-butane conformers [48] that assigned a decrease in ''steric'' repulsion for A ? G.…”

Section: Struct Chemcontrasting

confidence: 98%

The response electron–electron repulsion energy and energy component analysis in CC/MBPT methods

Salter

Wierzbicki

2016

Struct Chem

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Molecular properties are computed as responses to perturbations (energy derivatives) in coupled-cluster (CC)/many-body perturbation theory (MBPT) models. Here, the CC/MBPT energy derivative with respect to a general two-electron (2-e) perturbation is assembled from gradient theory for 2-e property evaluation, including the electron repulsion energy. The correlation energy (DE) is shown to be the sum of response kinetic (DT), electronnuclear attraction (DV), and electron repulsion (DV ee ) energies. Thus, evaluation of total V ee for energy component analysis is simple: For total energy (E), total 1-e responses T and V, and nuclear-nuclear repulsion energy (V NN ), V ee = E -V NN -T -V is the true 2-e response value. Component energy analysis is illustrated in an assessment of steric repulsion in ethane's rotational barrier. Earlier SCF-based results (Bader et al. in J Am Chem Soc 112:6530, 1990) are corroborated: The higher-energy eclipsed geometry is favored versus staggered in the two repulsion energies (V NN and V ee ), while decisively disfavored in electron-nuclear attraction energy (V). Our best quality calculations (CCSD/cc-pVQZ) attain practical Virial Theorem compliance (i.e., agreement among the kinetic energy, potential energy, and total energy representations) in assigning 2.70 ± 0.06 to the barrier height; -195.80 kcal/mol is assigned to the drop in ''steric'' repulsion upon going to the eclipsed geometry. Steric repulsion is not responsible for any fraction of the *3 kcal/mol barrier.

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Section: Struct Chemcontrasting

confidence: 98%

The response electron–electron repulsion energy and energy component analysis in CC/MBPT methods

Salter

Wierzbicki

2016

Struct Chem

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“…The EDA was performed at the UB3LYP/6‐311+G(d,p) level with the Gamess program package . The analysis of the interaction energy between two or more radical fragments that constitute a molecule has been applied before to study the torsional potential of ethane,, butane and group 13‐elements (B–Tl); the fluorine gauche effect and the azido gauche effect; the distortion to the trans ‐bent geometry in heavier ethylene homologues; the isomerization energy of heterocyclic and polycyclic compounds; the strength of conjugation and hyperconjugation; and the nature of covalent bonds…”

Section: Computational Detailsmentioning

confidence: 99%

4π‐Electron B–N Monocycles: Stability and (Anti)aromaticity

Baranac‐Stojanović¹

2017

Eur J Org Chem

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This is a theoretical (DFT) study of the impact of electronic structural changes, induced by B–N/C–C isosterism, on two basic properties of 4π‐electron antiaromatic system, that is, stability and antiaromaticity. The main driving force for the nonplanarity of B2N2 rings is electrostatic energy, and that for a ring with one B–N unit is the relief of Pauli repulsion. The charge‐separation instability, inherent for a 1,3‐B,N relationship, turns the ground state of the BCNC system to an aromatic triplet, which is less stable than the isomeric BNCC system, mostly because of larger Pauli interactions. The alternating BNBN connectivity is favoured primarily by orbital interaction energy and, secondarily, by better electrostatic attraction. The C–C → B–N substitution weakens the antiaromatic character, except that for a 1,3‐B,N relationship, which results in increased antiaromaticity in the closed‐shell state relative to that of cyclobutadiene.q

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“…Such an analysis of the interaction energy between two or more radical fragments constituting a molecule has been applied to study the torsional potential of ethane, , butane, and group 13 elements (E = B–Tl), conformational preferences in 1,2-difluoroethane, 1-chloro-2-fluoroethane, (protonated) 2-haloethanol, and 2-haloethylamine (X = F, Cl), distortion to the trans-bent geometry in heavier ethylene homologues, the isomerization energy of heterocyclic and polycyclic compounds, the strength of conjugation and hyperconjugation, and the nature of covalent bonds …”

Section: Resultsmentioning

confidence: 99%

Origin of Fluorine/Sulfur Gauche Effect of β-Fluorinated Thiol, Sulfoxide, Sulfone, and Thionium Ion

2015

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The well-known gauche preference in FCCX systems, where X is an electronegative element from Period 2, is widely exploited in synthetic, medicinal, and material chemistry. It is rationalized on the basis of σ(C-H) → σ*(C-F) hyperconjugation and electrostatic interactions. The recent report (Thiehoff, C.; et al. Chem. Sci. 2015, 6, 3565) showed that the fluorine gauche effect can extend to Period 3 elements, such as sulfur. The aim of the present work is to disclose factors governing conformational behavior of FCCS containing systems. We examine conformational preferences in seven classes of compounds by ab initio and DFT calculations and rationalize the results by quantitatively decomposing the anti/gauche isomerization energy into contributions from electrostatic, orbital, dispersion, and Pauli interactions, and energy spent on structural changes. The results show that the fluorine/sulfur gauche effect is primarily electrostatic (63-75%), while all orbital interactions contribute 22-41% to stabilizing interactions. Stereoelectronic effects, involved in orbital interactions, also play a role in gauche conformer stabilization.

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The effect of steric repulsion on the torsional potential of n-butane: a theoretical study

Cited by 9 publications

References 42 publications

The response electron–electron repulsion energy and energy component analysis in CC/MBPT methods

The response electron–electron repulsion energy and energy component analysis in CC/MBPT methods

4π‐Electron B–N Monocycles: Stability and (Anti)aromaticity

Origin of Fluorine/Sulfur Gauche Effect of β-Fluorinated Thiol, Sulfoxide, Sulfone, and Thionium Ion

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