Abstract
ABSTRACTA pulsed molecular beam Fourier transform microwave spectrometer operating in the frequency range 2–26.5 GHz was used to measure the spectrum of phenetole (ethyl phenyl ether or ethoxybenzene, C6H5OC2H5). The conformational landscape is completely determined by the orientations of the phenyl ring and the ethyl group. A two-dimensional potential energy surface was calculated at the MP2/6-311++G(d,p) level of theory. Two conformers were found: the trans conformer has a Cs symmetry, and the gauche conformer has the ethyl group tilted out of the phenyl plane by about 70°. Totally, 186 rotational transitions were assigned to the more stable planar trans conformer, and fitted using a semi-rigid rotor model to measure accuracy. Highly accurate rotational and centrifugal distortion constants were determined. Several method and basis set combinations were applied to check for convergence and to compare with the experimentally deduced molecular parameters.
Highlights
The conformational landscape is completely determined by the orientations of the phenyl ring and the ethyl group
Average value of the line widths is about 20 kHz measurement accuracy: 2 kHz Doppler effect; carrier gas: helium
Four other equivalent minima> 4 kJ/mol trans - gauche transformation 883 cm-1 (barrier to internal rotation of the methyl group in anisole: 735 cm 1)
Summary
The conformational landscape is completely determined by the orientations of the phenyl ring and the ethyl group. Desyatnyk et al PCCP 7, 1708 (2005). Out-of-plane ethyl group diethyl amine Nguyen et al JCP 135, 024310 (2011). Kannengießer et al PCCP 14, 11753 (2012). Kannengießer et al ChemPhysChem 16, 1906 (2015)
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