Rotational isomerism—XIII

Abraham, Raymond J.; Siverns, T. M.

doi:10.1016/0040-4020(72)80016-4

Cited by 75 publications

(32 citation statements)

References 19 publications

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“…Previous spectroscopic investigations of the furfural molecule (C 4 H 3 OCHO) have dealt mainly with infrared and Raman spectra [9][10][11]. These investigations have enabled the determination of relative stabilities of the cisand trans-conformations of furfural in the gas phase (see Fig.…”

Section: Introductionmentioning

confidence: 99%

Microwave spectrum and structure of furfural

Motiyenko

Alekseev

Dyubko

et al. 2006

Journal of Molecular Spectroscopy

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Section: Introductionmentioning

confidence: 99%

Microwave spectrum and structure of furfural

Motiyenko

Alekseev

Dyubko

et al. 2006

Journal of Molecular Spectroscopy

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“…9 3FA, as well as its structural isomer 2-furaldehyde (2FA; also known as furfural), have been the subject of many experimental and theoretical studies in the 1970s and 1980s. [10][11][12][13][14][15][16][17][18][19][20] 3FA and 2FA have been found to exist in the gas phase, nematic and isotropic solutions, and neat liquid state, as a mixture of two planar conformers differing by rotation of the aldehyde group around the exocyclic C-C bond (cis and trans with respect to the ring oxygen atom; see Scheme 1). [21][22][23][24][25][26][27][28] For 2FA, the trans conformer was found to be the lowest energy form, with gas phase reported values for ∆E (cis-trans) ranging from 3.10 to 8.79 kJ mol -1 , [18][19][20][21][22][23][24][25][26][27] which implies a minimum expected population of the conformational ground state of 2FA at room temperature (RT) of ca.…”

Section: Introductionmentioning

confidence: 99%

Photoisomerization and Photochemistry of Matrix-Isolated 3-Furaldehyde

2010

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3-Furaldehyde (3FA) was isolated in an argon matrix at 12 K and studied using FTIR spectroscopy and quantum chemistry. The molecule has two conformers, with trans and cis orientation of the OdCsCdC dihedral angle. At the B3LYP/6-311++G(d,p) level of theory, the trans form was computed to be ca. 4 kJ mol -1 more stable than the cis form. The relative stability of the two conformers was explained using the natural bond orbital (NBO) method. In fair agreement with their calculated relative energies and the high barrier of rotamerization (ca. 34 kJ mol -1 from trans to cis), the trans and cis conformers were trapped in an argon matrix from the compound room temperature gas phase in proportion ∼7:1. The experimentally observed vibrational signatures of the two forms are in a good agreement with the theoretically calculated spectra. Broad-band UV-irradiation (λ > 234 nm) of the matrix-isolated compound resulted in partial trans f cis isomerization, which ended at a photostationary state with the trans/cis ratio being ca. 1.85:1. This result was interpreted based on results of time-dependent DFT calculations. Irradiation at higher energies (λ > 200 nm) led to decarbonylation of the compound, yielding furan, cyclopropene-3-carbaldehyde, and two C 3 H 4 isomers: cyclopropene and propadiene.

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“…2(a) and 2(b)]. Now the case of furfural may be interesting, since for this molecule the C N D O /~ method gives a qualitatively correct potential function [35,36]. Therefore, we compare in Table I …”

Section: Details Of Calculationmentioning

confidence: 95%

Critical examination of approximate LCAOMO methods. I. Reasons for the failure of the CNDO and INDO methods in theoretical conformational analysis of conjugated compounds

Birner

Hofmann

1982

Int J of Quantum Chemistry

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It is well known that the CNDO and INDO methods fail in the field of theoretical conformational analysis of conjugated compounds. The NDDO approximation, however, can be applied very successfully to this problem. In this paper, a comparative analysis of these three approximations is performed to clarify the reasons for the failure of the former two methods. It is shown that the defects are inherent in their formalisms, and there is no reasonable possibility to compensate th-em (e.g, by reparametrization) at the level of the CNDO and INDO approximations. The central inadequacy is the oversimplified treatment of the two-center exchange interaction. In the case of molecules containing heteroatoms with lone-pair electrons the known defects concerning the description of Coulombic interactions of anisotropic charge distributions can additionally influence the results. To overcome these shortcomings, at least an extension of the formalism to the level of the NDDO method is necessary.

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Rotational isomerism—XIII

Cited by 75 publications

References 19 publications

Microwave spectrum and structure of furfural

Microwave spectrum and structure of furfural

Photoisomerization and Photochemistry of Matrix-Isolated 3-Furaldehyde

Critical examination of approximate LCAOMO methods. I. Reasons for the failure of the CNDO and INDO methods in theoretical conformational analysis of conjugated compounds

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