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Title:Internal Rotation Of The Acetyl Methyl Group In Methyl Alkyl Ketones: The Microwave Spectrum Of Octan-2-one
Author(s):Kleiner, Isabelle
Contributor(s):Nguyen, Ha Vinh Lam; Stahl, Wolfgang; SCHWELL, Martin; Schoengen, Damian; Andresen, Maike
Subject(s):Mini-symposium: Large Amplitude Motions
Abstract:Methyl \textit{n}-alkyl ketones form a class of molecules with interesting internal dynamics in the gas-phase. They contain two methyl groups undergoing internal rotations. To explore the link between structure and barrier heights in ketones, investigations on a series of saturated methyl \textit{n}-alkyl ketones were performed, i.e. pentan-2-one\footnote{M. Andresen, I. Kleiner, M. Schwell, W. Stahl, H. V. L. Nguyen, J. Phys. Chem. A 2018, 122, 7071-7078} hexan-2-one\footnote{M. Andresen, I. Kleiner, M. Schwell, W. Stahl, H. V. L. Nguyen, ChemPhysChem 2019, 20, 2063-2073}, heptan-2-one\footnote{M. Andresen, I. Kleiner, M. Schwell, W. Stahl, H. V. L. Nguyen, J. Phys. Chem. A 2020, 124, 1353-1361.} and octan-2-one\footnote{M. Andresen, D. Schöngen, I. Kleiner, M. Schwell, W. Stahl, H. V. L. Nguyen, ChemPhysChem 2020, 21, 2206-2216}. The molecular jet Fourier-transform microwave spectrum of octan-2-one was recorded between 2.0 and 40.0 GHz, revealing two conformers, one with C$_{1}$ and one with C$_{s}$ symmetry. The barriers to internal rotation of the acetyl methyl group were determined to be 233.340(28) cm$^{-1}$ and 185.3490(81) cm$^{-1}$, respectively, confirming the link between conformation and barrier height already established for other methyl alkyl ketones. The study combined high level \textit{ab initio} calculations with experimentally dervived rotational and torsional parameters using the XIAM\footnote{H. Hartwig, H. Dreizler, Z. Naturforsch. 1996, 51a, 923-932} and BELGI-C$_{1}$ (or BELGI-C$_{s}$)\footnote{I. Kleiner, J. T. Hougen, J. Chem. Phys. 2003, 119, 5505-5509.} codes. Results from the various fits will be presented. Finally comparisons to molecules in the literature and structural aspects of the conformers generally observed in methyl \textit{n}-alkyl ketones will be reviewed.
Issue Date:2021-06-23
Publisher:International Symposium on Molecular Spectroscopy
Genre:Conference Paper / Presentation
Type:Text
Language:English
URI:http://hdl.handle.net/2142/111111
Date Available in IDEALS:2021-09-24


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