title: The Structure and Torsional Dynamics of Two Methyl Groups in 2-Acetyl-5-methylfuran as Observed by Microwave Spectroscopy.
abstract: The molecular-beam Fourier transform microwave spectrum of 2-acetyl-5-methylfuran is recorded in the frequency range 2-26.5 GHz. Quantum chemical calculations calculate two conformers with trans or cis configuration of the acetyl group, both of which are assigned in the experimental spectrum. All rotational transitions split into quintets due to the internal rotations of two nonequivalent methyl groups. By using the program XIAM, the experimental spectra can be simulated with standard deviations within the measurement accuracy, and yield well-determined rotational and internal rotation parameters, inter alia the V3potentials. Whereas the V3barrier height of the ring-methyl rotor does not change for the two conformers, that of the acetyl-methyl rotor differs by about 100 cm-1. The predicted values from quantum chemistry are only on the correct order of magnitude.
authors: Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany.
authors: Vinh
authors: V
authors: Van
authors: Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany.
authors: Wolfgang
authors: W
authors: Stahl
authors: Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), CNRS UMR 7583, Université Paris-Est Créteil, Université Paris Diderot, 61 avenue du Général de Gaulle, 94010, Créteil cedex, France. lam.nguyen@lisa.u-pec.fr.
authors: Ha Vinh Lam
authors: http://orcid.org/0000-0002-5493-8905
authors: HV
authors: Nguyen
keywords: ab initio calculations; density functional calculations; microwave spectroscopy; oxygen heterocycles; rotational spectroscopy