Internal rotation and chlorine nuclear quadrupole coupling in 2-chloro-4-fluorotoluene explored by microwave spectroscopy and quantum chemistry

Publikation: Beitrag in FachzeitschriftArtikelForschungPeer-Review

Autoren

  • K. P.Rajappan Nair
  • Sven Herbers
  • William C. Bailey
  • Daniel A. Obenchain
  • Alberto Lesarri
  • Jens Uwe Grabow
  • Ha Vinh Lam Nguyen

Externe Organisationen

  • Kean University
  • Universidad de Valladolid
  • Institut Universitaire de France
  • Manipal Academy of Higher Education (MAHE)
  • Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA)
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Details

OriginalspracheEnglisch
Aufsatznummer119120
FachzeitschriftSpectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Jahrgang247
Frühes Online-Datum27 Okt. 2020
PublikationsstatusVeröffentlicht - 15 Feb. 2021

Abstract

2-Chloro-4-fluorotoluene was investigated using a combination of molecular jet Fourier transform microwave spectroscopy in the frequency range from 5 to 21 GHz and quantum chemistry. The molecule experiences an internal rotation of the methyl group, which causes fine splittings of all rotational transitions into doublets with separation on the order of a few tens of kHz. In addition, hyperfine effects originating from the chlorine nuclear quadrupole moment coupling its nuclear spin to the end-over-end rotation of the molecule are observed. The torsional barrier was derived using both the rho and the combined-axis-method, giving a value of 462.5(41) cm−1. Accurate rotational constants and quadrupole coupling constants were determined for the 35Cl and 37Cl isotopologues and compared with Bailey's semi-experimental quantum chemical predictions. The gas phase molecular structure was deduced from the experimental rotational constants supplemented with those calculated by quantum chemistry at various levels of theory. The values of the methyl torsional barrier and chlorine nuclear quadrupole coupling constants were compared with the theoretical predictions and with those of other chlorotoluene derivatives.

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Internal rotation and chlorine nuclear quadrupole coupling in 2-chloro-4-fluorotoluene explored by microwave spectroscopy and quantum chemistry. / Nair, K. P.Rajappan; Herbers, Sven; Bailey, William C. et al.
in: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, Jahrgang 247, 119120, 15.02.2021.

Publikation: Beitrag in FachzeitschriftArtikelForschungPeer-Review

Nair KPR, Herbers S, Bailey WC, Obenchain DA, Lesarri A, Grabow JU et al. Internal rotation and chlorine nuclear quadrupole coupling in 2-chloro-4-fluorotoluene explored by microwave spectroscopy and quantum chemistry. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy. 2021 Feb 15;247:119120. Epub 2020 Okt 27. doi: 10.1016/j.saa.2020.119120
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title = "Internal rotation and chlorine nuclear quadrupole coupling in 2-chloro-4-fluorotoluene explored by microwave spectroscopy and quantum chemistry",
abstract = "2-Chloro-4-fluorotoluene was investigated using a combination of molecular jet Fourier transform microwave spectroscopy in the frequency range from 5 to 21 GHz and quantum chemistry. The molecule experiences an internal rotation of the methyl group, which causes fine splittings of all rotational transitions into doublets with separation on the order of a few tens of kHz. In addition, hyperfine effects originating from the chlorine nuclear quadrupole moment coupling its nuclear spin to the end-over-end rotation of the molecule are observed. The torsional barrier was derived using both the rho and the combined-axis-method, giving a value of 462.5(41) cm−1. Accurate rotational constants and quadrupole coupling constants were determined for the 35Cl and 37Cl isotopologues and compared with Bailey's semi-experimental quantum chemical predictions. The gas phase molecular structure was deduced from the experimental rotational constants supplemented with those calculated by quantum chemistry at various levels of theory. The values of the methyl torsional barrier and chlorine nuclear quadrupole coupling constants were compared with the theoretical predictions and with those of other chlorotoluene derivatives.",
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note = "Funding Information: The authors thank the Land Niedersachsen and the Deutsche Forschungsgemeinschaft (DFG) for funding. A.L. acknowledges the funding of the Spanish MINECO-FEDER project PGC2018-098561-B-C22. D.A.O. thanks the Alexander von Humboldt Foundation for a post-doctoral fellowship. H.V.L.N. was supported by the Agence Nationale de la Recherche ANR (project ID ANR-18-CE29-0011). Dr. V.V. Ilyushin is greatly acknowledged for his help in performing the RAM36hf fits and for making his code available to the spectroscopic community. ",
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T1 - Internal rotation and chlorine nuclear quadrupole coupling in 2-chloro-4-fluorotoluene explored by microwave spectroscopy and quantum chemistry

AU - Nair, K. P.Rajappan

AU - Herbers, Sven

AU - Bailey, William C.

AU - Obenchain, Daniel A.

AU - Lesarri, Alberto

AU - Grabow, Jens Uwe

AU - Nguyen, Ha Vinh Lam

N1 - Funding Information: The authors thank the Land Niedersachsen and the Deutsche Forschungsgemeinschaft (DFG) for funding. A.L. acknowledges the funding of the Spanish MINECO-FEDER project PGC2018-098561-B-C22. D.A.O. thanks the Alexander von Humboldt Foundation for a post-doctoral fellowship. H.V.L.N. was supported by the Agence Nationale de la Recherche ANR (project ID ANR-18-CE29-0011). Dr. V.V. Ilyushin is greatly acknowledged for his help in performing the RAM36hf fits and for making his code available to the spectroscopic community.

PY - 2021/2/15

Y1 - 2021/2/15

N2 - 2-Chloro-4-fluorotoluene was investigated using a combination of molecular jet Fourier transform microwave spectroscopy in the frequency range from 5 to 21 GHz and quantum chemistry. The molecule experiences an internal rotation of the methyl group, which causes fine splittings of all rotational transitions into doublets with separation on the order of a few tens of kHz. In addition, hyperfine effects originating from the chlorine nuclear quadrupole moment coupling its nuclear spin to the end-over-end rotation of the molecule are observed. The torsional barrier was derived using both the rho and the combined-axis-method, giving a value of 462.5(41) cm−1. Accurate rotational constants and quadrupole coupling constants were determined for the 35Cl and 37Cl isotopologues and compared with Bailey's semi-experimental quantum chemical predictions. The gas phase molecular structure was deduced from the experimental rotational constants supplemented with those calculated by quantum chemistry at various levels of theory. The values of the methyl torsional barrier and chlorine nuclear quadrupole coupling constants were compared with the theoretical predictions and with those of other chlorotoluene derivatives.

AB - 2-Chloro-4-fluorotoluene was investigated using a combination of molecular jet Fourier transform microwave spectroscopy in the frequency range from 5 to 21 GHz and quantum chemistry. The molecule experiences an internal rotation of the methyl group, which causes fine splittings of all rotational transitions into doublets with separation on the order of a few tens of kHz. In addition, hyperfine effects originating from the chlorine nuclear quadrupole moment coupling its nuclear spin to the end-over-end rotation of the molecule are observed. The torsional barrier was derived using both the rho and the combined-axis-method, giving a value of 462.5(41) cm−1. Accurate rotational constants and quadrupole coupling constants were determined for the 35Cl and 37Cl isotopologues and compared with Bailey's semi-experimental quantum chemical predictions. The gas phase molecular structure was deduced from the experimental rotational constants supplemented with those calculated by quantum chemistry at various levels of theory. The values of the methyl torsional barrier and chlorine nuclear quadrupole coupling constants were compared with the theoretical predictions and with those of other chlorotoluene derivatives.

KW - 2-Chloro-4-fluorotoluene

KW - Chlorine nuclear quadrupole coupling

KW - Internal rotation

KW - Jet spectroscopy

KW - Microwave spectrum

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U2 - 10.1016/j.saa.2020.119120

DO - 10.1016/j.saa.2020.119120

M3 - Article

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VL - 247

JO - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

JF - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

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M1 - 119120

ER -