ANALYSIS OF THE ROTATIONAL STRUCTURE IN THE HIGH-RESOLUTION INFRARED SPECTRA OF $cis,cis$- AND $trans,trans$-1,4-DIFLUOROBUTADIENE-1-$d$$_{1}$ AND $trans,trans$-1,4-DIFLUOROBUTADIENE-1,4-$d$$_{2}$
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Date
2013
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Publisher
Ohio State University
Abstract
Samples of {\em cis,cis}- and {\em trans,trans}-1,4-difluorobutadiene-1-d$_{1}$ (DFBD) and {\em trans,trans}-DFBD-1,4-d$_{2}$ have been synthesized and investigated with high-resolution (0.0015 cm$^{-1}$) infrared spectroscopy. For the first two species the rotational structure in more than one band has been analyzed. For the 1,4-d$_{2}$ species the spectrum of only one C-type band was available in an isotopic mixture. Ground state rotational constants are reported for all three molecules. It is proposed that quartic centrifugal distortion constants computed with a B3LYP/cc-pVTZ model can be used to assess the quality of observed rotational constants. The favorable comparison of predicted and observed ground state rotational constants for all four $^{13}$C species of {\em cis,trans}-DFBD, which is MW active, demonstrates that the ground state rotational constants for the $^{13}$C species of the {\em cis,cis} and {\em trans,trans} isomers can be successfully predicted with high accuracy. Rotational constants for a full set of isotopologues will be used to determine accurate semiexperimental equilibrium structures of the {\em cis,cis} and {\em trans,trans} species of DFBD.
Description
Author Institution: Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH 44074; Pacific Northwest National Laboratory, Richland, WA 99352