Ab Initio Study of the Conformational and Geometrical Isomerism in Heteroallyl and Heteropropenyl Systems

Кобычев, В. Б.; Larionova, E. Yu.; Klyba, N. S.

doi:10.1023/b:jory.0000029810.09191.93

Cited by 5 publications

(3 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…c See Figure S1 is more stable than TC, and in group II the GSk and GSk′ forms are more stable than GC (see Figure 1). These results follow the general trend exhibited by heteroallyl compounds, as discussed in detail by Kobychev et al 33 For 3-hydroxyprop-1ene, 3-methoxyprop-1-ene and formoxime allyl ether, which are molecules exhibiting the O-CH 2 CHdCH 2 moiety common to ABID, the energy differences between the cis and skew conformers were found to range from 0.42 to 3.01 kJ mol -1 , 33,34 which compare nicely with the energy differences between the cis and skew conformers in ABID: ∆E TC-TSk ) 1.97 kJ mol -1 ; ∆E GC-GSk ) 4.02 kJ mol -1 ; ∆E GC-GSk′ ) 2.20 kJ mol -1 (see Figure 1). 3C).…”

Section: Resultssupporting

confidence: 90%

Conformational Space of the Pseudosaccharin Allyl Ether 3-(Allyloxy)-1,2-benzisothiazole 1,1-Dioxide in Gas Phase and in Rare Gas Matrices

et al. 2008

View full text Add to dashboard Cite

In this work, the conformational space of the pseudosaccharyl ether 3-(allyloxy)-1,2-benzisothiazole 1,1-dioxide (ABID) has been studied by means of infrared spectroscopy and density functional theory (DFT) calculations. Five different low energy conformers (TSk, TC, GSk, GSk' and GC, with relative energies of 0.00, 1.97, 2.00, 3.82 and 6.02 kJ mol(-1), respectively) were found on the DFT(B3LYP)/6-311++G(3df,3pd) potential energy surface of the molecule, all of them differing in the conformation of the allyl substituent. According to the calculations, in the gaseous phase all conformers are significantly populated (TSk:TC:GSk:GSk':GC = 47%:16%:18%:12%:7%, at 350 K). In the cryogenic matrices, however, only the TSk and TC conformers exist due to isomerization from the higher energy gauche forms to the most stable trans isomers during deposition of the matrix (conformational cooling). The observed conformational cooling is in consonance with the low calculated energy barriers for the GSk --> TSk, GSk' --> TSk and GC --> TC isomerization processes. Results from annealing experiments in krypton matrix doubtlessly show that in this matrix the order of stability of the TSk and TC conformers is reversed, with the more planar TC form becoming the most stable conformer.

show abstract

Section: Resultssupporting

confidence: 90%

Conformational Space of the Pseudosaccharin Allyl Ether 3-(Allyloxy)-1,2-benzisothiazole 1,1-Dioxide in Gas Phase and in Rare Gas Matrices

et al. 2008

View full text Add to dashboard Cite

show abstract

“…Following the general trend exhibited by heteroallyl compounds, as discussed in detail by Kobychev et al [29], the two skew conformers (Sk and Sk 0 ) were predicted to be more stable than the cis (C) form. The most stable conformer was found to be Sk, with the zero point corrected relative energies of the Sk 0 and C conformers being ca.…”

Section: Geometries and Energiesmentioning

confidence: 73%

Conformational and structural analysis of 2-allyl-1,2-benzisothiazol-3(2H)-one 1,1-dioxide as probed by matrix-isolation spectroscopy and quantum chemical calculations

Gómez‐Zavaglia

Kaczor

Coelho

et al. 2009

Journal of Molecular Structure

View full text Add to dashboard Cite

a b s t r a c t 2-Allyl-1,2-benzisothiazol-3(2H)-one 1,1-dioxide (ABIOD) has been studied by matrix-isolation infrared spectroscopy and quantum chemical calculations. A conformational search on the B3LYP/6-311++G(3df,3pd) potential energy surface of the molecule demonstrated the existence of three conformers, Sk, Sk 0 and C, with similar energies, differing in the orientation of the allyl group. The calculations predicted the Sk form as the most stable in the gaseous phase, whereas the Sk 0 and C conformers have calculated relative energies of ca. 0.6 and 0.8-3.0 kJ mol À1 , respectively (depending on the level of theory). In agreement with the relatively large (>6 kJ mol À1 ) calculated barriers for conformational interconversion, the three conformers could be efficiently trapped in an argon matrix at 10 K, the experimental infrared spectrum of the as-deposited matrix fitting well the simulated spectrum built from the calculated spectra for individual conformers scaled by their predicted populations at the temperature of the vapour of the compound prior to matrix deposition. Upon annealing the matrix at 24 K, however, both Sk and Sk 0 conformers were found to convert to the more polar C conformer, indicating that this latter form becomes the most stable ABIOD conformer in the argon matrix.

show abstract

“…Though there have been prior computational studies of molecules featuring E/Z equilibria, most studies have focused on one or two functional groups using Hartree−Fock (HF), B3LYP-based density functional, or second-order Møller−Plesset (MP2) theory. – Some classic studies include those of Wiberg and co-workers on formic acid, acetic acid, methyl formate, and methyl acetate ,,,, The need for quantum mechanical investigations in this area is enhanced by the fact that experimental studies of E/Z equilibria are often challenging owing to a very small population of the higher energy conformer.…”

Section: Introductionmentioning

confidence: 99%

E/Z Energetics for Molecular Modeling and Design

Terhorst

Jorgensen

2010

J. Chem. Theory Comput.

View full text Add to dashboard Cite

Thermochemical data have been obtained from G3B3 quantum mechanical calculations for 18 prototypical organic molecules, which exhibit E/Z conformational equilibria. The results are fundamentally important for molecular design including evaluation of structures from protein-ligand docking. For the 18 E/Z pairs, relative energies, enthalpies, free energies, and dipole moments are reported; the E – Z free-energy differences at 298 K range from +8.2 kcal/mol for 1,3-dimethyl carbamate to −6.4 kcal/mol for acetone oxime. A combination of steric and electronic effects can rationalize the variations. Free energies of hydration were also estimated using the GB/SA continuum solvent model. These results indicate that differential hydration is unlikely to qualitatively change the preferred direction of the E/Z equilibria, though further study with free-energy methods using explicit solvent is desirable.

show abstract

Ab Initio Study of the Conformational and Geometrical Isomerism in Heteroallyl and Heteropropenyl Systems

Cited by 5 publications

References 12 publications

Conformational Space of the Pseudosaccharin Allyl Ether 3-(Allyloxy)-1,2-benzisothiazole 1,1-Dioxide in Gas Phase and in Rare Gas Matrices

Conformational Space of the Pseudosaccharin Allyl Ether 3-(Allyloxy)-1,2-benzisothiazole 1,1-Dioxide in Gas Phase and in Rare Gas Matrices

Conformational and structural analysis of 2-allyl-1,2-benzisothiazol-3(2H)-one 1,1-dioxide as probed by matrix-isolation spectroscopy and quantum chemical calculations

E/Z Energetics for Molecular Modeling and Design

Contact Info

Product

Resources

About