Two Coupled Low-Barrier Large Amplitude Motions in 3,5-Dimethylanisole Studied by Microwave Spectroscopy
The microwave spectrum of 3,5-dimethylanisole was recorded using a pulsed molecular jet Fourier transform microwave spectrometer, covering the frequency range from 2.0 to 26.5 GHz. Splittings from internal rotations of the <i>syn</i>-<i>m</i> and <i>anti</i>-<i...
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MDPI AG
2025-03-01
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| author | Safa Khemissi Lynn Ferres Ha Vinh Lam Nguyen |
| author_facet | Safa Khemissi Lynn Ferres Ha Vinh Lam Nguyen |
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| description | The microwave spectrum of 3,5-dimethylanisole was recorded using a pulsed molecular jet Fourier transform microwave spectrometer, covering the frequency range from 2.0 to 26.5 GHz. Splittings from internal rotations of the <i>syn</i>-<i>m</i> and <i>anti</i>-<i>m</i>-methyl groups were observed, analyzed, and modeled using the <i>XIAM</i> and the <i>ntop</i> programs for a data set including 622 rotational lines. The torsional barriers of the <i>syn</i>-<i>m</i> and <i>anti</i>-<i>m</i>-methyl groups were determined to be 58.62367(53) cm<sup>−1</sup> and 36.28449(69) cm<sup>−1</sup>, respectively. The low barriers to internal rotation of both methyl groups posed significant challenges for spectral analysis and modeling. The successful assignment was achieved using combination difference loops and separately fitting the five torsional components. Comparing the torsional barriers observed in various toluene derivatives with methyl groups at <i>meta</i>-positions supports the assumption that electrostatic effects contribute more significantly than steric effects in the low-barrier cases of aromatic molecules. |
| format | Article |
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| institution | DOAJ |
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| language | English |
| publishDate | 2025-03-01 |
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| series | Molecules |
| spelling | doaj-art-d22ad6451b43453d8da089c4645295652025-08-20T02:42:22ZengMDPI AGMolecules1420-30492025-03-01306119510.3390/molecules30061195Two Coupled Low-Barrier Large Amplitude Motions in 3,5-Dimethylanisole Studied by Microwave SpectroscopySafa Khemissi0Lynn Ferres1Ha Vinh Lam Nguyen2Univ Paris Est Créteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, FranceInstitute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52074 Aachen, GermanyUniv Paris Est Créteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, FranceThe microwave spectrum of 3,5-dimethylanisole was recorded using a pulsed molecular jet Fourier transform microwave spectrometer, covering the frequency range from 2.0 to 26.5 GHz. Splittings from internal rotations of the <i>syn</i>-<i>m</i> and <i>anti</i>-<i>m</i>-methyl groups were observed, analyzed, and modeled using the <i>XIAM</i> and the <i>ntop</i> programs for a data set including 622 rotational lines. The torsional barriers of the <i>syn</i>-<i>m</i> and <i>anti</i>-<i>m</i>-methyl groups were determined to be 58.62367(53) cm<sup>−1</sup> and 36.28449(69) cm<sup>−1</sup>, respectively. The low barriers to internal rotation of both methyl groups posed significant challenges for spectral analysis and modeling. The successful assignment was achieved using combination difference loops and separately fitting the five torsional components. Comparing the torsional barriers observed in various toluene derivatives with methyl groups at <i>meta</i>-positions supports the assumption that electrostatic effects contribute more significantly than steric effects in the low-barrier cases of aromatic molecules.https://www.mdpi.com/1420-3049/30/6/1195microwave spectroscopylarge amplitude motionsinternal rotationlow barriers |
| spellingShingle | Safa Khemissi Lynn Ferres Ha Vinh Lam Nguyen Two Coupled Low-Barrier Large Amplitude Motions in 3,5-Dimethylanisole Studied by Microwave Spectroscopy Molecules microwave spectroscopy large amplitude motions internal rotation low barriers |
| title | Two Coupled Low-Barrier Large Amplitude Motions in 3,5-Dimethylanisole Studied by Microwave Spectroscopy |
| title_full | Two Coupled Low-Barrier Large Amplitude Motions in 3,5-Dimethylanisole Studied by Microwave Spectroscopy |
| title_fullStr | Two Coupled Low-Barrier Large Amplitude Motions in 3,5-Dimethylanisole Studied by Microwave Spectroscopy |
| title_full_unstemmed | Two Coupled Low-Barrier Large Amplitude Motions in 3,5-Dimethylanisole Studied by Microwave Spectroscopy |
| title_short | Two Coupled Low-Barrier Large Amplitude Motions in 3,5-Dimethylanisole Studied by Microwave Spectroscopy |
| title_sort | two coupled low barrier large amplitude motions in 3 5 dimethylanisole studied by microwave spectroscopy |
| topic | microwave spectroscopy large amplitude motions internal rotation low barriers |
| url | https://www.mdpi.com/1420-3049/30/6/1195 |
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