Internal Rotation Of The Acetyl Methyl Group In Methyl Alkyl Ketones: The Microwave Spectrum Of Octan-2-one

Kleiner, Isabelle

Permalink

https://hdl.handle.net/2142/111111 Copy

Description

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

Issue Date

2021-06-23

Keyword(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.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Permalink

http://hdl.handle.net/2142/111111

DOI

10.15278/isms.2021.WH07

Owning Collections