Isotopic Dependence of the Hydrogen-Transfer-Triggered Methyl-Group Rotation in Deuterated 5-Methyltropolone
Francis J. Lovas, Vadim V. Ilyushin, Alyssa M. Johnson, Jenna Hohl, Emily A. Cloessner, Richard Lavrich
We present here the first experimental study of the microwave spectrum of deuterated 5-methyltropolone, a molecule which exhibits two large-amplitude motions: an intramolecular hydrogen transfer (deuterium transfer in the current case of deuterated 5-methyltropolone) and a methyl torsion. The main goal of this study was to get information on the isotopic dependence of the main tunneling parameters of 5-methyltropolone in the framework of two dimensional tunneling formalism, which previously has shown some counterintuitive results for isotopic dependence of tunneling parameters in 2- methylmalonaldehyde. Measurements were carried out by Fourier-transform microwave spectroscopy in the 9 to 26 GHz frequency range. Theoretical analysis was carried out using a tunneling-rotational Hamiltonian based on a G12m extended-group-theory formalism. Our global fit of 384 transitions to 17 molecular parameters gave a weighted root-mean-square deviation of 0.8. The current study on the isotopic dependence of the main tunneling parameters in 5-methyltropolone supports the assumption of possible leakage between tunneling parameters in the two-dimensional tunneling formalism in use.
, Ilyushin, V.
, Johnson, A.
, Hohl, J.
, Cloessner, E.
and Lavrich, R.
Isotopic Dependence of the Hydrogen-Transfer-Triggered Methyl-Group Rotation in Deuterated 5-Methyltropolone, Journal of Molecular Spectroscopy, [online], https://doi.org/10.1016/j.jms.2017.09.004
(Accessed December 6, 2023)