Neighborhood matters: Steric effects on methyl internal rotation and chlorine nuclear quadrupole coupling in 2-fluoro-4-chlorotoluene

Research output: Contribution to journalArticleResearchpeer review

Authors

  • K. P.Rajappan Nair
  • Sven Herbers
  • Jens Uwe Grabow
  • Ha Vinh Lam Nguyen

External Research Organisations

  • Universite Paris XII
  • Institut Universitaire de France
  • Manipal Academy of Higher Education (MAHE)
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Details

Original languageEnglish
Article number131096
JournalJournal of molecular structure
Volume1246
Early online date15 Jul 2021
Publication statusPublished - 15 Dec 2021

Abstract

The rotational spectrum of 2-fluoro-4-chlorotoluene was studied in the frequency range 4 to 24 GHz by Fourier transform microwave spectroscopy. Fine torsional splittings into doublets were found for all rotational transitions due to methyl internal rotation hindered with a barrier of about 230 cm−1. In combination with the quadrupole coupling hyperfine splittings on the same order of magnitude originating from the chlorine nucleus, rich spectral features were observed. Rotational and quadrupole coupling constants for the 35Cl and 37Cl isotopologues studied in natural abundance were precisely determined. Results from the experiment were supported by quantum chemical calculations at several levels of theory for the rotational constants and by Bailey's semi-experimental method for the quadrupole coupling constants. The χcc quadrupole coupling tensor element and the barrier to methyl internal rotation were compared with those of other halogen-substituted toluene derivatives.

Keywords

    Chlorine nuclear quadrupole coupling, Internal rotation, Large amplitude motion, Microwave spectroscopy

ASJC Scopus subject areas

Cite this

Neighborhood matters: Steric effects on methyl internal rotation and chlorine nuclear quadrupole coupling in 2-fluoro-4-chlorotoluene. / Nair, K. P.Rajappan; Herbers, Sven; Grabow, Jens Uwe et al.
In: Journal of molecular structure, Vol. 1246, 131096, 15.12.2021.

Research output: Contribution to journalArticleResearchpeer review

Nair KPR, Herbers S, Grabow JU, Nguyen HVL. Neighborhood matters: Steric effects on methyl internal rotation and chlorine nuclear quadrupole coupling in 2-fluoro-4-chlorotoluene. Journal of molecular structure. 2021 Dec 15;1246:131096. Epub 2021 Jul 15. doi: 10.1016/j.molstruc.2021.131096
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abstract = "The rotational spectrum of 2-fluoro-4-chlorotoluene was studied in the frequency range 4 to 24 GHz by Fourier transform microwave spectroscopy. Fine torsional splittings into doublets were found for all rotational transitions due to methyl internal rotation hindered with a barrier of about 230 cm−1. In combination with the quadrupole coupling hyperfine splittings on the same order of magnitude originating from the chlorine nucleus, rich spectral features were observed. Rotational and quadrupole coupling constants for the 35Cl and 37Cl isotopologues studied in natural abundance were precisely determined. Results from the experiment were supported by quantum chemical calculations at several levels of theory for the rotational constants and by Bailey's semi-experimental method for the quadrupole coupling constants. The χcc quadrupole coupling tensor element and the barrier to methyl internal rotation were compared with those of other halogen-substituted toluene derivatives.",
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AU - Herbers, Sven

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AU - Nguyen, Ha Vinh Lam

N1 - Funding Information: The authors thank the Land Niedersachsen and the Deutsche Forschungsgemeinschaft (DFG) for funding. This work was supported by the Agence Nationale de la Recherche ANR (project ID ANR-18-CE29–0011). We greatly acknowledge Dr. V. Ilyushin for his help in performing the RAM36hf fits and for making his code available to the spectroscopic community. We also thank Dr. W.C. Bailey for checking our NQCC calculations.

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