Low torsional barrier challenges in the microwave spectrum of 2,4-dimethylanisole - Université Paris-Est-Créteil-Val-de-Marne Accéder directement au contenu
Article Dans Une Revue Journal of Chemical Physics Année : 2019

Low torsional barrier challenges in the microwave spectrum of 2,4-dimethylanisole

Lynn Ferres
  • Fonction : Auteur
Wolfgang Stahl

Résumé

Low barriers to internal rotations are especially challenging for both the experimental and theoretical determinations because they result in large tunneling splittings which are hard to assign and in potential functions that can be difficult to model. In the present work, the internal rotations of two methyl groups of 2,4-dimethylanisole were analyzed and modeled using a newly developed computer code, called ntop, adapted for fitting the high-resolution torsion-rotation spectra of molecules with two or more methyl rotors. The spectrum was measured using a pulsed molecular jet Fourier transform microwave spectrometer operating in the frequency range of 2.0–26.5 GHz, revealing internal rotation tunneling quintets with splittings of up to several gigahertz. The V3 potential barriers are 441.139(23) cm−1 and 47.649(30) cm−1 for the o- and p-methyl groups, respectively. Quantum chemical calculations predicted only one conformer with the methoxy group in the anti position related to the neighboring o-methyl group. While the results from geometry optimizations were reliable, ab initio calculations at the MP2 level did not reproduce the low torsional barriers, calling for further experiments on related systems and additional theoretical models.
Fichier principal
Vignette du fichier
24DMA_HAL.pdf (1.79 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-03183052 , version 1 (26-03-2021)

Identifiants

Citer

Lynn Ferres, Wolfgang Stahl, Ha Vinh Lam Nguyen. Low torsional barrier challenges in the microwave spectrum of 2,4-dimethylanisole. Journal of Chemical Physics, 2019, 151 (10), pp.104310. ⟨10.1063/1.5116304⟩. ⟨hal-03183052⟩
29 Consultations
121 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More