Internal methyl rotation and molecular structure of trifluorotoluenes: microwave rotational spectra of 2,3,4- and 2,4,5-trifluorotoluene

doi:10.1139/cjp-2019-0477

Paper

Internal methyl rotation and molecular structure of trifluorotoluenes: microwave rotational spectra of 2,3,4- and 2,4,5-trifluorotoluene

Published Jun 1, 2020 · K.P. Rajappan Nair, S. Herbers, D. Obenchain

Canadian Journal of Physics

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Abstract

The microwave rotational spectra of 2,3,4- and 2,4,5-trifluorotoluenes, along with all13C isotopic species in natural abundance, have been recorded in the frequency range 8–27 GHz employing pulsed-jet Fourier transform microwave spectroscopy. The analysis of the spectra in the lowest torsional state has yielded the rotational constants, centrifugal distortion constants, three-fold barrier to methyl rotation, and the direction of the internal rotation axis in the moment of inertia principal axes systems of these trifluorotoluenes. For both molecules, the molecular constants of their eight isotopologues have been used to obtain the substitution rsstructures of the ring and the methyl-carbon. The potential barriers hindering the internal rotation of the methyl top in 2,3,4- and 2,4,5-trifluorotluene are 2.5878(80) and 2.2809(23) kJ/mol, respectively.

Study Snapshot

The microwave rotational spectra of 2,3,4- and 2,4,5-trifluorotoluenes reveal their rotational constants, centrifugal distortion constants, three-fold barrier to methyl rotation, and the direction of the internal rotation axis in their moment of inertia principal

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

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Paper

Internal methyl rotation and molecular structure of trifluorotoluenes: microwave rotational spectra of 2,3,4- and 2,4,5-trifluorotoluene

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References

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The tunneling splitting in 2,3-difluorotoluene can be identified and the three-fold potential barrier hindering internal rotation of the methyl top is determined as 2518.70(15) J/mol.

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The potential barrier hindering internal rotation of the methyl group in 2,5-difluorotoluene is comparatively low, as shown by large internal rotation splittings in the microwave spectrum.

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The new IMPACT technique rapidly captures high-resolution rotational FT-MW spectra of 2,6-difluorophenol, revealing its intramolecular hydrogen bond and tunneling motion.

Citations

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