TY - JOUR

T1 - Reactivity and rotational spectra

T2 - The old concept of substitution effects

AU - Herbers, Sven

AU - Buschmann, Philipp

AU - Wang, Juan

AU - Lengsfeld, Kevin Gregor

AU - Nair, K. P.Rajappan

AU - Grabow, Jens Uwe

N1 - Funding Information: J. W. wants to thank the China Scholarships Council (CSC) for financial support. K. G. L. wants to thank the Fonds der Chemischen Industrie (FCI) for his fellowship. We want to acknowledge the financial support of the Land Niedersachsen, the Deutsche Forschungsgemeinschaft (DFG) and the support of the cluster system team at the Leibniz University IT services (LUIS) Hannover, Germany.

PY - 2020/5/28

Y1 - 2020/5/28

N2 - The internal rotation of methyl groups and nuclear quadrupole moments of the halogens Cl, Br, I in o-halotoluenes cause complex spectral fine and hyperfine structures in rotational spectra arising from angular momentum coupling. Building on the existing data regarding o-fluorotoluene and o-chlorotoluene, the investigations of o-bromotoluene and o-iodotoluene allow for a complete analysis of the homologous series of o-halogenated toluenes. The trend in the methyl barriers to internal rotation rising with the size of the halogen can be rationalised by repulsion effects as predicted by MP2 calculations. Furthermore, the analysis of the observed quadrupole coupling serves as a quantitative intra-molecular probe, e.g. for the explanation of the relative reaction yields in the nitration of halotoluenes, related to the different π-bond character of the C-X bond depending on the position of substitution.

AB - The internal rotation of methyl groups and nuclear quadrupole moments of the halogens Cl, Br, I in o-halotoluenes cause complex spectral fine and hyperfine structures in rotational spectra arising from angular momentum coupling. Building on the existing data regarding o-fluorotoluene and o-chlorotoluene, the investigations of o-bromotoluene and o-iodotoluene allow for a complete analysis of the homologous series of o-halogenated toluenes. The trend in the methyl barriers to internal rotation rising with the size of the halogen can be rationalised by repulsion effects as predicted by MP2 calculations. Furthermore, the analysis of the observed quadrupole coupling serves as a quantitative intra-molecular probe, e.g. for the explanation of the relative reaction yields in the nitration of halotoluenes, related to the different π-bond character of the C-X bond depending on the position of substitution.

UR - http://www.scopus.com/inward/record.url?scp=85085534978&partnerID=8YFLogxK

U2 - 10.1039/d0cp01145b

DO - 10.1039/d0cp01145b

M3 - Article

C2 - 32391831

AN - SCOPUS:85085534978

VL - 22

SP - 11490

EP - 11497

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 20

ER -