3-chloro-1-butene: gas-phase molecular structure and conformations as determined by electron diffraction and by molecular mechanics and ab initio calculations

Schei, S.H.

doi:10.1016/0022-2860(84)87228-2

Cited by 14 publications

(6 citation statements)

References 31 publications

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“…However, it differs from these earlier studies in the stability of the other two conformers. It is clearly shown by both the ab initio calculations and the measurements in liquid xenon that the ME conformer is the second most stable form, which is at variance with the electron diffraction result, 3 where it was concluded that the CIE form is the second most stable rotamer. In addition, definite evidence was found in the vibrational spectrum for the existence of the third conformer (CIE), which was not the conclusion in the previous vibrational investigation.…”

Section: Discussionsupporting

confidence: 49%

“…In theoretical studies, 3,4 the conformer with the methyl group eclipsing the double bond (ME) and the ClE conformation were calculated to have only 1.0-1.3 kcal mol 1 (350 to 455 cm 1 ) higher energy than the HE form. With such an energy difference, the two high-energy conformers (ME and ClE) should be present in detectable amounts at ambient temperature.…”

Section: Introductionmentioning

confidence: 99%

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Raman and infrared spectra, conformational stability, normal coordinate analysis andab initio calculations of 3-chloro-1-butene

Lee

Feng

Hur

et al. 2000

J. Raman Spectrosc.

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The Raman and infrared spectra (3300-30 cm −1 ) of gaseous and solid 3-chloro-1-butene, H 2 C CHCCl (CH 3 )H, were recorded. Additionally, the Raman spectrum (3300-30 cm −1 ) of the liquid was recorded. All three conformers were observed in the fluid phases and the conformer with the hydrogen atom eclipsing the double bond (HE form) was identified as the most predominant. From variable-temperature measurements in liquified xenon, the enthalpy differences between the HE form and the two less stable conformers, i.e. the methyl group eclipsing the double bond (ME form) and the chlorine atom eclipsing the double bond (ClE form), were determined to be 75 ± 8 cm −1 (214 ± 23 cal mol −1 ) and 197 ± 37 cm −1 (563 ± 106 cal mol −1 ), respectively. Nearly complete vibrational assignments are proposed for all three conformers, which are consistent with the predicted wavenumbers utilizing the force constants from ab initio MP2/6-31G(d) calculations. Both the infrared intensities and the Raman activities and depolarization values were obtained from the ab initio calculations. Complete equilibrium geometries were determined by ab initio calculations employing the 6-31G(d) and 6-311YYG(d,p) basis sets with full electron correlation by the Möller-Plesset (MP2) perturbation method to second order. The structural parameters obtained with the larger basis set are comparable to those obtained from a previously reported electron diffraction study. The results are discussed and the theoretical values are compared with the experimental values when appropriate.

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Section: Discussionsupporting

confidence: 49%

Section: Introductionmentioning

confidence: 99%

Raman and infrared spectra, conformational stability, normal coordinate analysis andab initio calculations of 3-chloro-1-butene

Lee

Feng

Hur

et al. 2000

J. Raman Spectrosc.

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“…Earlier ab initio calculations found the same conformers. 12,13 The lowest energy form has the hydrogen at the chiral center eclipsed with the double bond, and the other two rotamers have significantly higher energies. It has been studied both by infrared spectroscopy and electron diffraction.…”

Section: -Chloro-1-butene (1)mentioning

confidence: 99%

Conformational Effects on Optical Rotation. 3-Substituted 1-Butenes

2003

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A calculation of the optical rotation of (R)-(-)-3-chloro-1-butene found a remarkably large dependence on the C=C-C-C torsional angle. At tau = 0 degrees, [alpha](D) = +244 degrees, whereas at tau = 180 degrees, [alpha](D) = -526 degrees. The effect of conformation on the optical rotation was confirmed by a study of the temperature dependence of the rotation. An analysis of the data gave the difference in free energy between the low- and high-energy conformers as 1315 cal/mol and gave the optical rotation of the low-energy conformer and the average of the rotations of the higher energy forms. Although a large effect was found, the observed rotations are a factor of 2.6 smaller than the calculated values, independent of both conformation and wavelength from 589 to 365 nm. The effect of replacing Cl with F, CN, and CCH was examined theoretically. The effects of substituents are remarkably small despite large changes in the calculated electronic transition energies.

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“…4 The structural parameters obtained from the BLYP/6-31G(d), BLYP/6-31G(d,3p) and B3LYP/6-31G(d) calculations are not significantly different from those experimentally obtained by electron diffraction (see Table 6). 13 At the B3LYP/6-31G(d) level, the C-C and C-Cl bond lengths are about 0.6 and 1.8% shorter, respectively, than those at the BLYP/6-31G(d,3p) and closer to those of electron diffraction. The C-H bond lengths at the BLYP/6- By utilizing combining density functional calculations with the BLYP/6-31G(d,3p) and B3LYP/6-31G(d) basis sets, we have found an excellent agreement between the calculated vibrational frequencies and those obtained experimentally for the 3-chloro-1-butene.…”

Section: Resultsmentioning

confidence: 99%

An Application of Combining DFT Methods to Calculate the Vibrational Frequencies of All Three Conformers of 3-Chloro-1-butene

Lee¹

2005

Journal of the Korean Chemical Society

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3-chloro-1-butene: gas-phase molecular structure and conformations as determined by electron diffraction and by molecular mechanics and ab initio calculations

Cited by 14 publications

References 31 publications

Raman and infrared spectra, conformational stability, normal coordinate analysis andab initio calculations of 3-chloro-1-butene

Raman and infrared spectra, conformational stability, normal coordinate analysis andab initio calculations of 3-chloro-1-butene

Conformational Effects on Optical Rotation. 3-Substituted 1-Butenes

An Application of Combining DFT Methods to Calculate the Vibrational Frequencies of All Three Conformers of 3-Chloro-1-butene

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