Phase effects on conformational equilibriums. Nuclear magnetic resonance studies of methyl nitrite

Chauvel, J.; True, Nancy S.

doi:10.1021/j100232a033

Cited by 27 publications

(24 citation statements)

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“…However, the properly calculated 4-21G and 4-31G conformer energy differences are respectively much higher and somewhat lower than the experimental value (12.27 [12] and 2.69kJmol 1, vs. 4.18kJmo1-1 [14]). …”

Section: Geometries and Energiesmentioning

confidence: 56%

“…The gas-phase AHtrans_cis, Agtrans_ci s and AGtrans_ci s obtained by 1H NMR spectroscopy * Corresponding author. are 4.18kJmol -l, 9.62JK-lmo1-1, and 2.18kJ mol -~, respectively [14]. The trans conformer was found to have a methyl top barrier to internal rotation much lower than that of the cis conformer (120-790Jmol -1 vs. 8.74kJmo1-1 [6,20]), and this has been correlated with its significantly higher entropy.…”

Section: Introductionmentioning

confidence: 91%

“…1). The smaller members of this family of molecules have been the subject of several experimental studies [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], and the most recent results consistently demonstrate that the cis conformer of methyl nitrite corresponds to the most stable form [8][9][10][11][12][13][14][15][17][18][19]. The gas-phase AHtrans_cis, Agtrans_ci s and AGtrans_ci s obtained by 1H NMR spectroscopy * Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

“…Exp (gas phase lNMR [14]) 5.44 4.18 4-21G [12] 14.63 12.27 4-31G/4-21G [20] 5 analysis has still not been performed on these molecules. Although the results of normal coordinate analyses have been presented previously [9,13], such studies used the simplified valence force field approach (SVFF), thus neglecting several interaction force constants, which are chosen by a criterion that is necessarily not free of subjectivity.…”

Section: Introductionmentioning

confidence: 99%

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Vibrational spectra and structure of the cis and trans conformers of methyl nitrite: an ab initio MO study

Silva

Costa

Ramos

et al. 1996

Journal of Molecular Structure: THEOCHEM

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The vibrational and conformational properties exhibited by nethyl nitrite (CH3ON~O) were studied by ab initio MO methods (HF-SCF and MP2) using both the 6-31G and 6-311G basis sets without or with the inclusion of diffuse and/or polarization functions. Fully optimized geometries, relative stabilities, dipole moments and harmonic force fields for both the cis and trans conformers of this molecule were determined and the results compared with available experimental data. In agreement with the experimental results, the calculations involving polarization functions at the MP2 level of theory indicate that the most stable conformer of methyl nitrite is the planar cis conformer, where the methyl group is eclipsing the N--~-O bond, while the trans form was predicted to have a higher energy than this form by about 4 kJ mol 1. The conformational dependence of some relevant structural parameters was used to characterize the most important intramolecular interactions present in the studied conformers, and their calculated infrared spectra were used to review previous assignments of the experimentally observed bands for both the normal and deuterated (CDaON~-O) species. Chemometrics methods (principal components and two-level factorial designing) were used both to analyze the effect of changing the basis set and level of theory used to perform the calculations, and to aid comparison between the experimental and calculated vibrational spectra.

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Section: Geometries and Energiesmentioning

confidence: 56%

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Vibrational spectra and structure of the cis and trans conformers of methyl nitrite: an ab initio MO study

Silva

Costa

Ramos

et al. 1996

Journal of Molecular Structure: THEOCHEM

View full text Add to dashboard Cite

show abstract

“…(3). Measurements of the cistrans equilibrium by 1 H NMR determined the thermodynamic parameters to be DH ¼ 4:18 kJ/mol and DS ¼ 9:62 J/mol K [2].…”

Section: Introductionmentioning

confidence: 99%