Rotational Spectra of Argon Acetone: A Two-Top Internally Rotating Complex

Kang, Lu; Keimowitz, Alison R.; Munrow, Michaeleen R.; Novick, Stewart E.

doi:10.1006/jmsp.2002.8551

Cited by 10 publications

(5 citation statements)

References 26 publications

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“…The details of the internal rotation Hamiltonian were described in ref. 23. The standard deviation of the fit is 1.8 kHz, similar to the experimental uncertainty.…”

Section: Rotational Spectrasupporting

confidence: 68%

Rotational spectrum of a chiral α-hydroxyester: conformation stability and internal rotation barrier heights of methyl lactate

Borho

2007

Phys. Chem. Chem. Phys.

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High resolution spectrum of methyl lactate, a chiral alpha-hydroxyester, has been investigated using a molecular jet Fourier transform microwave spectrometer. High level ab initio calculations were employed to study the conformational isomerism of methyl lactate. The observed rotational spectrum confirms that the most stable conformer has an intramolecular hydrogen bond of OH...O==C type, as predicted by the ab initio calculations. The internal rotation barrier heights of the ester methyl group and the alpha-carbon methyl group were calculated to be 5.4 and 14.5 kJ mol(-1) at the MP2/aug-cc-pVDZ level of theory for the most stable conformer. The internal rotation splittings due to the ester methyl group were observed and analyzed and the ester methyl group tunneling barrier height was determined experimentally to be 4.762 (3) kJ mol(-1).

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“…The details of the internal rotation Hamiltonian were described in ref. 23. The standard deviation of the fit is 1.8 kHz, similar to the experimental uncertainty.…”

Section: Rotational Spectrasupporting

confidence: 68%

Rotational spectrum of a chiral α-hydroxyester: conformation stability and internal rotation barrier heights of methyl lactate

Borho

2007

Phys. Chem. Chem. Phys.

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“…Severalg roups have endeavored to reach as atisfactory interpretation of the rotational spectrumo f acetone,w hich displays quartets of rotational transitions due to the coupling of internal rotations of the two equivalent methyl groups. [18] Replacing argon with neon,t he rotational spectra show unambiguously that the two CH 3 tops are equivalent, as evidenced by the splitting of each transitioni nto four components. For example, the corresponding V 3 barriers to the internal rotationo ft he CH 3 top in acetic acid decreasec onsiderably when forming ac omplex with one or more water molecules [14] or with another carboxylic acid.…”

Section: Introductionmentioning

confidence: 91%

“…The slightly decreased V 3 barrier (ca. 260 cm −1 ) with respect to that of the acetone monomer (266 cm −1 ) suggests that the Ar–H 3 C interaction generates an additional V′ 3 term, out of phase with the V 3 term of the monomer . Replacing argon with neon, the rotational spectra show unambiguously that the two CH 3 tops are equivalent, as evidenced by the splitting of each transition into four components.…”

Section: Introductionmentioning

confidence: 93%

Interactions between Ketones and Alcohols: Rotational Spectrum and Internal Dynamics of the Acetone–Ethanol Complex

Gou

Favero

Feng

et al. 2017

Chemistry A European J

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The rotational spectra of two isotopologues of the 1:1 complex formed between acetone and ethanol have been recorded and analyzed by using Fourier-transform microwave spectroscopy. One rotamer was detected, in which ethanol adopts the gauche form. The two subunits are linked by a conventional O-H⋅⋅⋅O and a weak C-H⋅⋅⋅O hydrogen bond, forming a six-membered ring. Each rotational transition is split into five component lines due to the internal rotations of two nonequivalent acetone methyl groups. The V barriers to internal rotation of the two CH tops of acetone were determined to be 252(4) and 220(1) cm , which are noticeably lower than the value for the monomer (266 cm ).

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“…Acetone, [54] difluoroacetone, [55] and trifluoroacetone [56] are candidates for an "acetone class" with barrier heights of approximately 250 cm À 1 . Complexation with water [50,57,58] or noble gases [59,60] changes the barrier by less than 40 cm À 1 . Further systematic investigations will be needed to fully understand the acetyl methyl torsion in ketones and to propose new classifications.…”

Section: Structure-barrier Dependencementioning

confidence: 99%

Internal Rotation of the Acetyl Methyl Group in Methyl Alkyl Ketones: The Microwave Spectrum of Octan‐2‐one

et al. 2020

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Methyl n-alkyl ketones form a class of molecules with interesting internal dynamics in the gas-phase. They contain two methyl groups undergoing internal rotations, the acetyl methyl group and the methyl group at the end of the alkyl chain. The torsional barrier of the acetyl methyl group is of special importance, since it allows for the discrimination of the conformational structures. As part of the series, the microwave spectrum of octan-2-one was recorded in the frequency range from 2 to 40 GHz, revealing two conformers, one with C 1 and one with C s symmetry. The barriers to internal rotation of the acetyl methyl group were determined to be 233.340(28) cm À 1 and 185.3490(81) cm À 1 , respectively, confirming the link between conformations and barrier heights already established for other methyl alkyl ketones. Extensive comparisons to molecules in the literature were carried out, and a small overview of general trends and rules concerning the acetyl methyl torsion is given. For the hexyl methyl group, the barrier height is 973.17(60) cm À 1 for the C 1 conformer and 979.62(69) cm À 1 for the C s conformer.

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Rotational Spectra of Argon Acetone: A Two-Top Internally Rotating Complex

Cited by 10 publications

References 26 publications

Rotational spectrum of a chiral α-hydroxyester: conformation stability and internal rotation barrier heights of methyl lactate

Rotational spectrum of a chiral α-hydroxyester: conformation stability and internal rotation barrier heights of methyl lactate

Interactions between Ketones and Alcohols: Rotational Spectrum and Internal Dynamics of the Acetone–Ethanol Complex

Internal Rotation of the Acetyl Methyl Group in Methyl Alkyl Ketones: The Microwave Spectrum of Octan‐2‐one

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