The far infrared spectrum, ab initio calculations and conformational energy differences of 1-butene

Bell, Stephen; Drew, Barry R.; Guirgis, Gamil A.; Durig, J. R.

doi:10.1016/s0022-2860(00)00572-x

Cited by 49 publications

(46 citation statements)

References 18 publications

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“…This rather small difference could be due to in part to a slightly larger value for the liquid from the small association in the condensed phase. For several methyl rotors attached to a carbon atom we have found that MP2(full)/6-31G(d) predicted barriers are in good agreement with the experimentally determined values [37][38][39][40][41].…”

Section: Barriers To Internal and Asymmetric Rotationssupporting

confidence: 79%

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Conformational stability, r0 structural parameters, barriers to internal rotation, vibrational spectra and ab initio calculations of c-C3H5SiH2CH3

Durig

Panikar

Guirgis

et al. 2009

Journal of Molecular Structure

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Section: Barriers To Internal and Asymmetric Rotationssupporting

confidence: 79%

“…Potential function governing the internal rotation of the CH 3 SiH 2 moiety from the gauche to the cis form for methylsilylcyclopropane. [41], values without uncertainties are not independent parameters. b Ref.…”

Section: Discussionmentioning

confidence: 99%

Conformational stability, r0 structural parameters, barriers to internal rotation, vibrational spectra and ab initio calculations of c-C3H5SiH2CH3

Durig

Panikar

Guirgis

et al. 2009

Journal of Molecular Structure

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“…This rather small difference could be due to, in part, to a slightly larger value for the liquid from the small association in the condensed phase. For several methyl rotors attached to a carbon atom we have found that the MP2(full)/6-31G(d) predicted barriers are usually in good agreement with the experimentally determined values [26][27][28][29][30].…”

Section: Barriers To Internal and Asymmetric Rotationssupporting

confidence: 73%

Conformational stability, r0 structural parameters, barriers to internal rotation, vibrational assignments and ab initio calculations of c-C3H5GeH2CH3

Durig

Panikar

Guirgis

et al. 2010

Journal of Molecular Structure

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a b s t r a c tThe infrared spectra (3100-40 cm À1 ) of gaseous and amorphous solid and Raman spectra (3200-20 cm À1 ) of the liquid at various temperatures for methylgermylcyclopropane, c-C 3 H 5 GeH 2 CH 3 , have been obtained. Additionally, variable temperature (À55 to À100°C) studies of the infrared spectra of the sample dissolved in xenon have been recorded. From these spectral data, two conformers have been identified with one the cis (syn) form where the methyl group is over the three-membered ring and the other the gauche form. By utilizing six conformer pairs of the vibrational bands the enthalpy difference of the sample dissolved in xenon has been determined to be 43 ± 11 cm À1 (0.51 ± 0.13 kJ mol À1 ) with the gauche form the more stable conformer. It is estimated that there is approximately 30 ± 3% of the cis form present at ambient temperature. It was not possible to achieve crystallization of the compound by annealing it, and both conformers were present at all temperatures. The Ge-H distances of 1.531 and 1.533 Å for the gauche conformer have been determined from their stretching frequencies. By utilizing the microwave rotational constants of the gauche conformer for five isotopomers ( 70 Ge, 72 Ge, 73 Ge, 74 Ge, 76 Ge) combined with the structural parameters predicted from the MP2(full)/6-311+G(d,p) calculations, the adjusted r 0 structural parameters have been obtained. The heavy atom distances (Å) are: (GeC 2 ) = 1.925(5); (C 2 C 4 ) = 1.517(3); (C 2 C 5 ) = 1.519(3); (C 4 C 5 ) = 1.502(3); (GeC 6 ) = 1.947(5) and the angles (°) are: \CGeC = 110.6(5); \GeC 2 C 4 = 120.1(5); \GeC 2 C 5 = 119.2(5). For the cis form very small differences of 0.003 and 0.001 Å from those of the gauche form are predicted for the GeC bonds whereas the other distances are predicted to be the same or differ at the most by 0.002 Å. A complete vibrational assignment is given for both the conformers. To support the vibrational assignments, normal coordinate calculations with scaled force constants from MP2(full)/6-31G(d) calculations were carried out to predict the fundamental vibrational frequencies, infrared intensities, Raman activities, depolarization values and infrared band contours. Barriers to internal rotation have been predicted. The results are discussed and compared to the corresponding properties of some similar molecules.

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“…It was also reported that the vibrational band ascribed to the nearly planar conformer disappeared under crystallization indicating a non-planar form to be the most stable one. In subsequent infrared studies [2][3][4] the opposite was found: of the two conformers, cis and gauche, the former one is the most stable form in the liquid as well as in the gas phase. The gauche-cis enthalpy difference was determined to be 77 cm −1 in liquid [2], 26 cm −1 in gas phase [2], 73 cm −1 in gas phase [3], 73 cm −1 in krypton [4] and 64 cm −1 in xenon [4].…”

Section: Introductionmentioning

confidence: 99%

The conformational stability of gaseous 1-butene studied by femtosecond nonlinear spectroscopy and ab initio calculations

Kunitski

Knippenberg

Dreuw

et al. 2011

Vibrational Spectroscopy

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The far infrared spectrum, ab initio calculations and conformational energy differences of 1-butene

Cited by 49 publications

References 18 publications

Conformational stability, r0 structural parameters, barriers to internal rotation, vibrational spectra and ab initio calculations of c-C3H5SiH2CH3

Conformational stability, r0 structural parameters, barriers to internal rotation, vibrational spectra and ab initio calculations of c-C3H5SiH2CH3

Conformational stability, r0 structural parameters, barriers to internal rotation, vibrational assignments and ab initio calculations of c-C3H5GeH2CH3

The conformational stability of gaseous 1-butene studied by femtosecond nonlinear spectroscopy and ab initio calculations

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