scholarly journals On the variation of the belt and chiral screw and spring conformations of substituted regioregular HT undecathiophenes

RSC Advances ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 2116-2122 ◽  
Author(s):  
Jan Cz. Dobrowolski ◽  
Małgorzata E. Jamróz
Keyword(s):  
Electron Delocalization ◽  
The Stability

The stability and characteristics of shape and π-electron delocalization of a belt- and two chiral screw- and spring-conformers of HT regioregular substituted undecathiophenes was calculated.

Carbo-[3]oxocarbon and its isomers: evaluation of the stability and of the electron delocalization

2008 ◽  
Vol 10 (24) ◽  
pp. 3578 ◽  
Author(s):  
Mickaël Gicquel ◽  
Jean-Louis Heully ◽  
Christine Lepetit ◽  
Remi Chauvin
Keyword(s):  
Electron Delocalization ◽  
The Stability

The search for formal electrostatic effects on molecular conformation and crystal packing: crystal structure of 2,2′′-disubstituted (HversusPPh2) 1,1′-(1,2-phenylene)bis(3-methyl-1H-imidazol-3-ium) bis(trifluoromethanesulfonate)

2016 ◽  
Vol 72 (3) ◽  
pp. 198-202
Author(s):  
Carine Duhayon ◽  
Yves Canac ◽  
Laurent Dubrulle ◽  
Carine Maaliki ◽  
Remi Chauvin
Keyword(s):  
Crystal Structure ◽  
Electrostatic Interactions ◽  
Molecular Conformation ◽  
Crystal Packing ◽  
Relative Orientation ◽  
Electron Delocalization ◽  
Electrostatic Effects ◽  
Conformational Freedom ◽  
The Stability ◽  
Bond Character

Electrostatic interactions between localized integral charges make the stability and structure of highly charged small and rigid organics intriguing. Can σ/π-electron delocalization compensate reduced conformational freedom by lowering the repulsion between identical charges? The crystal structure of the title salt, C14H16N42+·2CF3SO3−, (2), is described and compared with that of the 2,2′′-bis(diphenylphosphanyl) derivative, (4). The conformations of the dications and their interactions with neighbouring trifluoromethanesulfonate anions are first analyzed from the standpoint of formal electrostatic effects. Neither cation exhibits any geometrical strain induced by the intrinsic repulsion between the positive charges. In contrast, the relative orientation of the imidazolium rings [i.e. antifor (2) andsynfor (4)] is controlled by different configurations of the interactions with the closest trifluoromethanesulfonate anions. The long-range arrangement is also found to be specific: beyond the formal electrostatic packing, C—H...O and C—H...F contacts have no definite `hydrogen-bond' character but allow the delineation of layers, which are either pleated or flat in the packing of (2) or (4), respectively.

scholarly journals Tautomerisation of thymine acts against the Hückel 4N + 2 rule. The effect of metal ions and H-bond complexations on the electronic structure of thymine

2014 ◽  
Vol 12 (33) ◽  
pp. 6476-6483 ◽  
Author(s):  
Olga A. Stasyuk ◽  
Halina Szatylowicz ◽  
Tadeusz M. Krygowski
Keyword(s):  
Electronic Structure ◽  
Metal Ions ◽  
Electron Delocalization ◽  
The Stability

Not necessarily the π-electron delocalization is responsible for the stability of thymine tautomers.

A Computational Study of the Conformational Behavior of 2,5-Dimethyl- 1,4-dithiane-2,5-diol and Analogous S and Se: DFT and NBO Study

2020 ◽  
Vol 17 (10) ◽  
pp. 749-759
Author(s):  
Elmira Danaie ◽  
Shiva Masoudi ◽  
Nasrin Masnabadi
Keyword(s):  
Thermodynamic Parameters ◽  
Computational Study ◽  
Structural Parameters ◽  
Nbo Analysis ◽  
Electron Delocalization ◽  
Stereoelectronic Effects ◽  
Conformational Properties ◽  
Molecular Reactivity ◽  
Stabilization Energies ◽  
The Stability

Conformational behaviors of 2,5-dimethyl-1,4-dithiane-2,5-diol (compound 1), 2,5- dimethyl-1,4-dithiane-2,5-dithiol (compound 2) and 2,5-dimethyl-1,4-dithiane-2,5-diselenol (compound 3) were investigated by the B3LYP/6-311+G **, the M06-2X/aug-ccpvdz levels of theory and natural bond orbital NBO analysis. The structures and the structural parameters of the mentioned molecules were optimized by the B3LYP and the M06-2X methods. We assessed the roles and contributions of the effective factors in the conformational properties of the mentioned compounds by means of the B3LYP and M06-2X levels of theory and the NBO interpretations. The stereoelectronic effects of the mentioned molecules were studied using the NBO analysis. The results showed that the stereoelectronic effects were in favor of the (ax,ax) conformers (the most stable conformations), from compound 1 to compound 3; therefore, these effects have impacts on the conformational properties of compounds 1-3, and stabilization energies associated with LP2X→ σ*S1-C2 electron delocalization, where [X= O, S, and Se], for 1-ax, ax conformer has the greatest value between all of the other conformers. Therefore, according to the calculated thermodynamic parameters, the stability of the 1-ax, ax compound was justified by the presence of LP2X→σ*S1-C2 electron delocalization. A molecular orbital explanation was conducted to investigate the correlations between the linear combinations of natural bond orbitals in the HOMOs, LUMOs and the molecular reactivity parameters. There is a direct relationship between the stereoelectronic effects, molecular reactivity and thermodynamic parameters of compounds 1 to 3 as the harder ax, ax conformations with the greater stereoelectronic effects and ΔG(eq-ax) values are more stable than their corresponding eq, eq conformers. Besides frontier molecular orbitals (FMOs), mapped molecular electrostatic potential (MEP) surfaces of conformations of compounds 1 to 3 were investigated.

scholarly journals The influence of electron delocalization upon the stability and structure of potential N-heterocyclic carbene precursors with 1,3-diaryl-imidazolidine-4,5-dione skeletons

2010 ◽  
Vol 34 (7) ◽  
pp. 1295 ◽  
Author(s):  
Matthew G. Hobbs ◽  
Taryn D. Forster ◽  
Javier Borau-Garcia ◽  
Chrissy J. Knapp ◽  
Heikki M. Tuononen ◽  
...  
Keyword(s):  
Electron Delocalization ◽  
The Stability

scholarly journals Steric effects vs electron delocalization: a new look into stability of diastereomers, conformers and constitutional Isomers

2021 ◽  
Author(s):  
Sopanant Datta ◽  
Taweetham Limpanuparb
Keyword(s):  
Quantum Chemical ◽  
Electron Delocalization ◽  
Steric Effects ◽  
Quantum Mechanical ◽  
Quantum Chemical Investigation ◽  
Mechanical Methods ◽  
Qualitative Models ◽  
The Stability ◽  
Stable Forms ◽  
Meta Isomer

A quantum chemical investigation of the stability of compounds with identical formulas was carried out on 23 classes of compounds made of C, N, P, O, S atoms as core structures and halogens H, F, Cl, Br, I as substituents. All possible structures were generated and investigated by quantum mechanical methods. The prevalence of formula in which its <i>Z</i> configuration, <i>gauche</i> conformation and meta isomer are the most stable forms is calculated and discussed. Quantitative and qualitative models to explain the stability of the 23 classes of halogenated compounds were also proposed.<br>

scholarly journals Steric effects vs. electron delocalization: a new look into stability of diastereomers, conformers and constitutional Isomers

2021 ◽  
Author(s):  
Sopanant Datta ◽  
Taweetham Limpanuparb
Keyword(s):  
Quantum Chemical ◽  
Chemical Investigation ◽  
Electron Delocalization ◽  
Steric Effects ◽  
Quantum Mechanical ◽  
Stable Form ◽  
Quantum Chemical Investigation ◽  
Mechanical Methods ◽  
Qualitative Models ◽  
The Stability

<div> <p>A quantum chemical investigation of the stability of compounds with identical formulas was carried out on 23 classes of compounds made of C, N, P, O, S atoms as core structures and halogens H, F, Cl, Br, I as substituents. All possible structures were generated and investigated by quantum mechanical methods. The prevalence of a formula in which its <i>Z</i> configuration, <i>gauche</i> conformation or <i>meta</i> isomer is the most stable form is calculated and discussed. Quantitative and qualitative models to explain the stability of 23 classes of halogenated compounds were also proposed.</p></div>

scholarly journals Steric effects vs electron delocalization: a new look into stability of diastereomers, conformers and constitutional Isomers

2021 ◽  
Author(s):  
Sopanant Datta ◽  
Taweetham Limpanuparb
Keyword(s):  
Quantum Chemical ◽  
Electron Delocalization ◽  
Steric Effects ◽  
Quantum Mechanical ◽  
Quantum Chemical Investigation ◽  
Mechanical Methods ◽  
Qualitative Models ◽  
The Stability ◽  
Stable Forms ◽  
Meta Isomer

A quantum chemical investigation of the stability of compounds with identical formulas was carried out on 23 classes of compounds made of C, N, P, O, S atoms as core structures and halogens H, F, Cl, Br, I as substituents. All possible structures were generated and investigated by quantum mechanical methods. The prevalence of formula in which its <i>Z</i> configuration, <i>gauche</i> conformation and meta isomer are the most stable forms is calculated and discussed. Quantitative and qualitative models to explain the stability of the 23 classes of halogenated compounds were also proposed.<br>

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