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Journal Articles ChemPhysChem Year : 2011

The Rotational Spectrum of Diethyl Ketone


We report on the rotational spectrum of diethyl ketone, C2H5-C(=O)-C2H5, as observed by Fourier transform microwave spectroscopy under pulsed molecular beam conditions. Almost all lines were split into narrow quartets in a range from 10 kHz up to 2 MHz arising from the hindered rotation of the two equivalent terminal methyl groups. In a global analysis using the xiam code based on the rho axis method three rotational constants, five quartic centrifugal distortion constants, the torsional barrier of the terminal methyl groups, and the angles between the principal inertial axes and the internal rotor axes were determined. The methyl torsional barrier was found to be 771.93(27) cm-1. In total 199 lines were fitted to a standard deviation of 3.5 kHz. The experimental work was supplemented by quantum chemical calculations. Two-dimensional potential energy surfaces describing the rotation of both ethyl groups against the C=O frame were calculated with the MP2 method as well as the DFT method using the 6-311++G(d,p) basis set and the B3LYP functional, respectively. Combining the experimental and theoretical results, an effective structure with C2v symmetry was deduced for the diethyl ketone molecule. Moreover, the torsional barrier of the methyl groups was determined by ab initio methods.
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hal-03183171 , version 1 (27-03-2021)



Ha Vinh Lam Nguyen, Wolfgang Stahl. The Rotational Spectrum of Diethyl Ketone. ChemPhysChem, 2011, 12 (10), pp.1900-1905. ⟨10.1002/cphc.201001021⟩. ⟨hal-03183171⟩
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