Details
| Original language | English |
|---|---|
| Article number | 119120 |
| Journal | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy |
| Volume | 247 |
| Early online date | 27 Oct 2020 |
| Publication status | Published - 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.
Keywords
- 2-Chloro-4-fluorotoluene, Chlorine nuclear quadrupole coupling, Internal rotation, Jet spectroscopy, Microwave spectrum
ASJC Scopus subject areas
- Chemistry(all)
- Analytical Chemistry
- Physics and Astronomy(all)
- Atomic and Molecular Physics, and Optics
- Physics and Astronomy(all)
- Instrumentation
- Chemistry(all)
- Spectroscopy
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In: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, Vol. 247, 119120, 15.02.2021.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
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
UR - http://www.scopus.com/inward/record.url?scp=85095915976&partnerID=8YFLogxK
U2 - 10.1016/j.saa.2020.119120
DO - 10.1016/j.saa.2020.119120
M3 - Article
C2 - 33189979
AN - SCOPUS:85095915976
VL - 247
JO - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
JF - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
SN - 1386-1425
M1 - 119120
ER -