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Jacobsen, Stuart M.; Andresen, U.; Mäder, H.

doi:10.1023/a:1022150801925

Cited by 32 publications

(33 citation statements)

References 7 publications

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“…Comparison of the methyl torsional barrier of two equivalent methyl groups in 26DMFB with the values of other toluene derivatives where the fluorine atom and the methyl group are adjacent. (1) 26DMFB (this work), (2) 2-fluorotoluene, [6] (3) 2,4,5-trifluorotoluene, [14] (4) 2,3,4trifluorotoluene, [14] (5) 2,3-difluorotoluene, [9] (6) 2,4-difluorotoluene, [10] (7) 2,5difluorotoluene, [11] and (8) 2,6-difluorotoluene. [13]…”

Section: Methodsmentioning

confidence: 70%

“…Especially for spectroscopy, the rotational spectrum of toluene has always attracted attention since its microwave spectrum was recorded and analyzed for the first time by Rudolph et al [1] Not only the structure of toluene was determined to great accuracy, several theoretical models and program codes have been also developed to reproduce the V 6 potential arising from the internal rotation of the C 3v methyl group attached to a phenyl frame with C 2v symmetry. [2][3][4][5] To gain insights into the substitution effect on this large amplitude motion (LAM) of toluene, studies on many fluorinated derivatives have been performed, such as the investigations on three isomers of fluorotoluene, [6][7][8] a systematic microwave investigation on the six isomers of difluorotoluene, [9][10][11][12][13] and the work on two isomers of trifluorotoluene. [14] All these studies have shown a variety of the potentials of the methyl torsion in both shape and height, which depend on the substituted position(s) of the fluorine atom(s).…”

Section: Introductionmentioning

confidence: 99%

“…[8] The ortho isomer with its V 3 potential of 227.28(2) cm À 1 could be easily modeled. [6] Finally, m-fluorotoluene has remained over half a century a challenge due to the low V 3 and V 6 terms which are comparable in magnitude. [7] Investigations on toluene derivatives with two methyl groups attached on the phenyl ring are scarce, such as those on the three isomers of dimethylbenzaldehyde [15] and the three isomers of dimethylanisole.…”

Section: Introductionmentioning

confidence: 99%

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Two Equivalent Internal Rotations in the Microwave Spectrum of 2,6‐Dimethylfluorobenzene

Khemissi

Nguyen

2020

ChemPhysChem

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Large amplitude motion of methyl groups in isolated molecules is a fundamental phenomenon in molecular physics. The methyl torsional barrier is sensitive to the steric and electronic environment in the surrounding of the methyl group, making the methyl group a detector of the molecular structure. To probe this eﬀect, the microwave spectrum of 2,6‐dimethylfluorobenzene, one of the six isomers of dimethylfluorobenzene, was measured using two pulsed molecular jet Fourier transform microwave spectrometers operating in the frequency range from 2 to 40 GHz. Due to internal rotations of two equivalent methyl groups with relatively low torsional barriers, all rotational transitions split into quartets with separations of up to several hundreds of MHz. The splittings were analyzed and modeled to deduce a torsional barrier of 236.7922 (21) cm−1. The results are compared to those obtained from quantum chemical calculations and with other fluorine substituted toluene derivatives of the current literature where the methyl group is adjacent to a fluorine atom.

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Section: Methodsmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Two Equivalent Internal Rotations in the Microwave Spectrum of 2,6‐Dimethylfluorobenzene

Khemissi

Nguyen

2020

ChemPhysChem

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“…In molecules where syn-a nd anti-conformers co-exist in the spectrum, the anti-conformer has lower internal rotation barrier,b ecause the ortho substituent is much closer to the methyl group, and the steric hindering increases, while the electronic contribution should be similarf or both conformers. An electronic effect is, however,n ot excluded, as can be seen from the different V 3 potentialo fo-fluorotoluene [23] and 2,4-difluorotoluene [4] or o-xylene [26] and 3,4-dimethyl-benzaldehyde. [27] Nevertheless, these differences are less significant.…”

mentioning

confidence: 99%

Methyl Internal Rotation in the Microwave Spectrum of o‐Methyl Anisole

et al. 2017

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The microwave spectrum of o-methyl anisole (2-methoxytoluene), CH OC H CH has been measured by using a pulsed molecular jet Fourier transform microwave spectrometer operating in the frequency range 2-26.5 GHz. Conformational analysis using quantum chemical calculations at the MP2/6-311++G(d,p) level of theory yields only one stable conformer with a C structure, which was assigned in the experimental spectrum. A-E splittings due to the internal rotation of the ring methyl group could be resolved and the barrier to internal rotation was determined to be 444.05(41) cm . The experimentally deduced molecular parameters such as rotational and centrifugal distortion constants as well as the torsional barrier of the ring methyl group are in agreement with the calculated values.

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“…However, considering related radical cations, specifically the molecule reactions of cluster ion (Kr·CO) + [43] show it to have the significant dissociation energy of 103 ± 8 kJ/mol. Jacobsen et al discuss o-fluorotoluene [44]. The enthalpy of formation of this species as well as its p-isomer, have been studied in the same paper [17].…”

Section: Issuementioning

confidence: 99%