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Title:Resolving a long-standing ambiguity: the non-planarity of gauche-1,3-butadiene revealed by microwave spectroscopy
Author(s):Martin-Drumel, Marie-Aline
Contributor(s):Stanton, John F.; Ellison, Barney; Baraban, Joshua H.; Buckingham, Grant; Eibenberger, Sandra; Patterson, David; McCarthy, Michael C.
Subject(s):Structure determination
Abstract:The preferred conformation of \textit{cis}-1,3-butadiene (CH$_2$=CH$-$CH=CH$_2$) has been of long-standing importance in organic chemistry because of its role in Diels-Alder transition states. The molecule could adopt a planar \textit{s-cis} conformation, in favor of conjugations in the carbon chain, or a non-planar \textit{gauche} conformation, as a result of steric interactions between the terminal H atoms. To resolve this ambiguity, we have now measured the pure rotational spectrum of this isomer in the microwave region, unambiguously establishing a significant inertial defect, and therefore a \textit{gauche} conformation. Experimental measurements of \textit{gauche}-1,3-butadiene and several of its isotopologues using cavity Fourier-transform microwave (FTMW) spectroscopy in a supersonic expansion and chirped-pulse FTMW spectroscopy in a 4 K buffer gas cell will be summarized, as will new quantum chemical calculations.
Issue Date:2016-06-20
Publisher:International Symposium on Molecular Spectroscopy
Genre:Conference Paper/Presentation
Rights Information:Copyright 2016 by the authors
Date Available in IDEALS:2016-08-22

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