Journal article

Publication year: 2018

Pages: 1663-1667

Journal: Journal of Physical Chemistry Letters

Volume number: 9

Issue number: 7

ISSN: 1948-7185

DOI Link: https://doi.org/10.1021/acs.jpclett.8b00295

Publisher: American Chemical Society

Abstract: 
Disentangling internal and external effects is a key requirement for understanding conformational tunneling processes. Here we report the s-trans/s-cis tunneling rotamerization of carbonic acid monomethyl ester (1) under matrix isolation conditions and make comparisons to its parent carbonic acid (3). The observed tunneling rate of 1 is temperature-independent in the 3-20 K range and accelerates when using argon instead of neon as the matrix material. The methyl group increases the effective half life (tau(eff)) of the energetically disfavored s-trans-conformer from 3-5 h for 3 to 11-13 h for 1. Methyl group deuteration slows the rotamerization further (tau(eff) approximate to 35 h). CCSD(T)/cc-pVQZ//MP2/aug-cc-pVTZ computations of the tunneling probability suggest that the rate should be almost unaffected by methyl substitution or its deuteration. Thus the observed relative rates are puzzling, and they disagree with previous explanations involving fast vibrational relaxation after the tunneling event facilitated by the alkyl rotor.

Harvard Citation style: Linden, M., Wagner, J., Bernhardt, B., Bartlett, M., Allen, W. and Schreiner, P. (2018) Intricate Conformational Tunneling in Carbonic Acid Monomethyl Ester, Journal of Physical Chemistry Letters, 9(7), pp. 1663-1667. https://doi.org/10.1021/acs.jpclett.8b00295

APA Citation style: Linden, M., Wagner, J., Bernhardt, B., Bartlett, M., Allen, W., & Schreiner, P. (2018). Intricate Conformational Tunneling in Carbonic Acid Monomethyl Ester. Journal of Physical Chemistry Letters. 9(7), 1663-1667. https://doi.org/10.1021/acs.jpclett.8b00295