The molecular conformation and dipole moment of thiane from the microwave spectrum

Kitchin, R.W.; Malloy, Thomas B.; Cook, Robert L.

doi:10.1016/0022-2852(75)90022-3

Cited by 27 publications

(14 citation statements)

References 7 publications

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“…The C-C-C-C torsion angles are 55.9°, compared with 60°for the ideal chair conformation. 19 ] Microwave spectroscopy (although the chair conformation of 2 was deduced from the microwave spectroscopic investigation, the rotational constants proved insufficient to specify the molecular conformation uniquely 20 ), gasphase electron diffraction studies, 21 molecular mechanics calculations 11,21,22 and molecular orbital calculations indicate that the chair conformation of 2 is the most stable form (Table 2). Frequency calculations show that the boat conformer 4 has one imaginary frequency, that the twist boat structure 6 does not have an imaginary frequency and that the planar C 2v structure 7 has three imaginary frequencies.…”

Section: Resultsmentioning

confidence: 99%

Molecular orbital study of the conformational energies (−ΔG° orA values) of 2-alkyltetrahydro-2H-thiopyrans (tetrahydrothiopyrans, thiacyclohexanes, thianes)

Freeman

Phornvoranunt

Hehre

1999

J. Phys. Org. Chem.

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Ab initio 6-31G* and MP2/6-31G*// 6-31G* methods and density functional (pBPDN**) theory were used to calculate the geometries and relative energies of the chair, boat, and twist-boat conformations of tetrahydro-2H-thiopyrans (tetrahydrothiopyrans, thiacyclohexanes, thianes). The chair conformation of thiacyclohexane is 5.3 and 8.0 kcal mol À1, respectively, (1 kcal = 4.184 kJ) more stable than the twist-boat and boat structures at the MP2/6-31G*// 6-31G* level. Ab initio methods were used to calculate the relative energies of the rotamers in the chair conformations of 2-alkylthiacyclohexanes (CH 3 , C 2 H 5 , i-C 3 H 7 , t-C 4 H 9 , neo-C 5 H 11 , SiMe 3 ). The MP2/6-31G*// 6-31G* conformational energies (ÀDG°or A values, kcal mol À1 ) of the 2-alkylthiacyclohexanes (Me = 1.00; Et = 1.16; i-Pr = 1.02; t-Bu = 3.56; neo-Pent = 1.04; SiMe 3 = 2.05) are smaller than those calculated for the corresponding alkylcyclohexanes and 4-alkylthiacyclohexanes. Plots of the calculated conformational energies (ÀDG°) for the 2-alkylthiacyclohexanes versus the calculated conformational energies for the corresponding alkylcyclohexanes are linear (slope = 0.680 and r = 0.983 for 6-31G* and slope = 0.667 and r = 0.989 for MP2/6-31G*// 6-31G*). The C(2)-S(1) bond lengths are in the range 1.827-1.840 Å and the C(6)-S(1) bond lengths are in the range 1.815-1.819 Å . With the exception of the axial 2-t-Bu substituent (103.0°), the C-S-C angles vary from 98.6°to 100.4°. The S(1)-C(2)-C(7) angle in the most stable axial conformer is larger that the corresponding angle in its most stable equatorial conformer.

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Section: Resultsmentioning

confidence: 99%

Molecular orbital study of the conformational energies (−ΔG° orA values) of 2-alkyltetrahydro-2H-thiopyrans (tetrahydrothiopyrans, thiacyclohexanes, thianes)

Freeman

Phornvoranunt

Hehre

1999

J. Phys. Org. Chem.

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“…In order to determine the structure of the complexes from the rotational constants of Tables 3 and 4, we assumed that the structures of PMS [8,9] and HCl [11] remain unchanged upon complexation. It proved impossible to determine the position of the hydrogen atom because of the small contribution that this atom makes to the rotational constants.…”

Section: Structurementioning

confidence: 99%

“…Preliminary rotational constants were estimated from the structures of PMS [8,9] and HCl. [11] The geometrical parameters of the hydrogen bond were taken from the related tetrahydrothiophene´´´HCl complex [3] using a linear hydrogen bond structure.…”

Section: Rotational Spectramentioning

confidence: 99%

“…However, these rules do not deal with a situation where there are nonequivalent nonbonded pairs, and thus it should be interesting to examine what happens when one attempts to apply these rules to complexes in which the acceptor molecule B carries two nonequivalent electron pairs. The six-membered rings tetrahydropyran and pentamethylene sulfide (PMS) [8,9] fall into this category with two nonequivalent binding sites at the oxygen or sulfur atom. When complexed with HCl, the hydrogen bond would be formed to the nonbonding electron pair localized at the axial and/or equatorial position.…”

Section: Introductionmentioning

confidence: 99%

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Axial and Equatorial Hydrogen Bonds in Pentamethylene Sulfide⋅⋅⋅Hydrogen Chloride Complex

Sanz

López

Alonso

1999

Chemistry A European J

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“…The microwave (MW) spectrum is available for the asymmetrically substituted deuterated species [3]. Studies of the structure and conformations of several ring-mono-substituted hetero-derivatives have been performed by ED and/or MW spectroscopy: tetrahydropiran [4,5], tetrahydrothian [6], piperidine [7], silacyclohexane [8], and germacyclohexane [9]. All of them have been observed predominantly in the chair form.…”

Section: Introductionmentioning

confidence: 99%

The rotational spectrum of silacyclohexane

Favero

Camináti

Arnason

et al. 2005

Journal of Molecular Spectroscopy

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The molecular conformation and dipole moment of thiane from the microwave spectrum

Cited by 27 publications

References 7 publications

Molecular orbital study of the conformational energies (−ΔG° orA values) of 2-alkyltetrahydro-2H-thiopyrans (tetrahydrothiopyrans, thiacyclohexanes, thianes)

Molecular orbital study of the conformational energies (−ΔG° orA values) of 2-alkyltetrahydro-2H-thiopyrans (tetrahydrothiopyrans, thiacyclohexanes, thianes)

Axial and Equatorial Hydrogen Bonds in Pentamethylene Sulfide⋅⋅⋅Hydrogen Chloride Complex

The rotational spectrum of silacyclohexane

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