Theoretical Examination of the S–C–P Anomeric Effect

Juaristi, Eusebio; Notario, Rafael

doi:10.1021/jo5029425

Cited by 21 publications

(8 citation statements)

References 67 publications

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“…As a first approach, the NBO method, which is considered by some researchers as the ideal method to study these types of interactions, was used . Although NBO has been successful in several studies, this approach failed in previous analysis of the role of the lone pairs in the oxygen atom in the Perlin effect . The energy profile for these data, as well as its corresponding fitting equation, is shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

Charge transfer and electron localization as the origin of the anomeric effect in theO─C─Osegment of dimethoxymethane and spiroketals

Buschbeck-Alvarado

Hernández‐Fernández

Hernández‐Trujillo

et al. 2017

J of Physical Organic Chem

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Every day, more evidence accumulates, leading to the conclusion that the stereoelectronic model through the nO → σ*C─O interaction is of minor relevance or even inoperative to explain conformational preference in the specific O─C─O segment. In the present study, dimethoxymethane (DMM) and some model spiroketals were chosen to develop a reliable and easy to apply methodology that is simple to interpret by experimental chemists. The general conformation observed in these molecules, present in many biologically active natural products, is the gauche‐gauche (g,g) in DMM and bis‐diaxial in spiroketals. To study this conformational preference, this paper presents a new approach, where general trends for the atomic and molecular energetic components, as well as localization and delocalization indices, and their bonded (Δb) and nonbonded (Δnb) electronic contributions are analyzed. In addition, group contributions to the electron localization and polarization are also defined, agreeing with the conformational preference. It is clear that electronic localization/delocalization is capable of reproducing experimental observations, showing an adequate correlation of this property to the cos θ term in the context of Pople's analysis. It is proposed that electron delocalization between electronegative atoms or total delocalization between nonbonded atoms is not the major contributors to the axial conformational preference observed in spiroketals. Conformational preference shows defined trends in terms of group delocalization in DMM and ring localization and charge transfer between groups in spiroketals. This way, electronic delocalization can be used to evaluate the anomeric effect, using just a few parameters, which makes the method broadly functional.

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Section: Resultsmentioning

confidence: 99%

Charge transfer and electron localization as the origin of the anomeric effect in theO─C─Osegment of dimethoxymethane and spiroketals

Buschbeck-Alvarado

Hernández‐Fernández

Hernández‐Trujillo

et al. 2017

J of Physical Organic Chem

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“…The differences between the hyperconjugative generalized anomeric effect ( HCGAE ) values in the anti - and gauche -conformations are used to calculate the total hyperconjugative generalized anomeric effect ( HCGAE total ): , …”

Section: Resultsmentioning

confidence: 99%

“…The anomeric effect , which is emerging as a central player in carbohydrate chemistry (as the most dominant conformation-controlling factor), could be defined as the preference of an electronegative substituent to be axially oriented on the chair-type cyclohexane derivatives rather than equatorially oriented, which is in opposition to the steric effect that normally leads to a preference for the equatorial conformation. − This concept has now been generalized to open-chain (or acyclic) nonplanar compounds as the preference of a gauche -conformation over an anti -conformation for a R–X–C–Y moiety in which the X atom possesses one or more nonbonded lone electron pairs (O, S, N, ...) whereas the Y atom donates an electronegative group (F, Cl, −CC–H, −CC–R, −CN, ...). ,, The efficiency of the negative hyperconjugative interactions associated with the LPX → σ* C–Y electron delocalization depends on the orientations of the R and Y groups around the X–C bond.…”

Section: Introductionmentioning

confidence: 99%

Exploring the Origin of the Generalized Anomeric Effects in the Acyclic Nonplanar Systems

et al. 2017

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Contrary to the published conclusions in the literature concerning the origin of the generalized anomeric relationships in open-chain nonplanar systems, its origin has remained an open question. In order to explore the origin of the generalized anomeric relationships in open-chain nonplanar systems, we assessed the roles and contributions of the effective factors on the conformational properties of methyl propargyl ether (1), methyl propargyl sulfide (2), and methyl propargyl selenide (3) by means of the G3MP2, CCSD(T), MP2, LC-ωPBE, and B3LYP methods and natural bond orbital (NBO) interpretations. We examined the contributions of the hyperconjugative interactions on the conformational preferences of compounds 1-3 by the deletions of the orbitals overlapping from the Fock matrices of the gauche- and anti-conformations. The trend observed for energy changes in the Fock matrices justify the variations of the gauche-conformations preferences going from compound 1 to compound 3, revealing that the hyperconjugative interactions are solely responsible for the generalized anomeric relationships in compounds 1-3. Accordingly, the conclusions published in the literature concerning the origin of the generalized anomeric effect in the acyclic nonplanar compounds should be revised by these findings. The Pauli exchange type repulsions (PETR) are in favors of the gauche-conformations and the variations of the PETR differences between the gauche- and anti-conformations of compounds 1-3 correlate well with their gauche-conformations preferences, revealing that the generalized anomeric relationships in compounds 1-3 have also the Pauli exchange-type repulsions origin. The resemblance between the preorthogonal natural bond orbitals (that are involved in the hyperconjugative interactions) and their corresponding molecular orbitals have been investigated.

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“…1a. Briefly, phenylphosphinic acid (C 6 H 5 -PO 3 H 2 ) is gradually carbonized to form an active carbon matrix, which chemically reacts with Na 2 SO 4 to produce Na 2 S, in which S 2− can be captured by the available active sites on the carbon matrix, along with the synergistic effect of S-C-P [20,21], leading to the formation of covalent sulfurized-carbon. With the optimized conditions (Table S1 and Fig.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

The bond evolution mechanism of covalent sulfurized carbon during electrochemical sodium storage process

Zhang

Zou

et al. 2019

Sci. China Mater.

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The excellent energy storage performance of covalent sulfur-carbon material has gradually attracted great interest. However, in the electrochemical sodium storage process, the bond evolution mechanism remains an elusive topic. Herein, we develop a one-step annealing strategy to achieve a high covalent sulfur-carbon bridged hybrid (HCSC) utilizing phenylphosphinic acid as the carbon-source/catalyst and sodium sulfate as the sulfur-precursor/salt template, in which the sulfur mainly exists in the forms of C-S-C and C-S-S-C. Notably, most of the bridge bonds are electrochemically cleaved when the cycling voltage is lower than 0.6 V versus Na/Na + , leading to the appearance of two visible redox peaks in the following cyclic voltammogram (CV) tests. The in-situ and ex-situ characterizations demonstrate that S 2− is formed in the reduction process and the carbon skeleton is concomitantly and irreversibly isomerized. Thus, the cleaved sulfur and isomerized carbon could jointly contribute to the sodium storage in 0.01-3.0 V. In a Na-S battery system, the activated HCSC in cut off voltage window of 0.6-2.8 V achieves a high reversible capacity (770 mA h g −1 at 300 mA g −1). This insight reveals the charge storage mechanism of sulfur-carbon bridged hybrid and provides an improved enlightenment on the interfacial chemistry of electrode materials.

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Theoretical Examination of the S–C–P Anomeric Effect

Cited by 21 publications

References 67 publications

Charge transfer and electron localization as the origin of the anomeric effect in theO─C─Osegment of dimethoxymethane and spiroketals

Charge transfer and electron localization as the origin of the anomeric effect in theO─C─Osegment of dimethoxymethane and spiroketals

Exploring the Origin of the Generalized Anomeric Effects in the Acyclic Nonplanar Systems

The bond evolution mechanism of covalent sulfurized carbon during electrochemical sodium storage process

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