ANALYSIS OF THE ROTATIONAL STRUCTURE IN SEVERAL BANDS IN THE HIGH-RESOLUTION INFRARED SPECTRA OF BUTADIENE-TRANS, TRANS-1,$4-d_{2}$ AND -CIS,CIS-1,$4-d_{2}$.

Author Institution: Department of Chemistry, Oberlin College; Department of Chemistry, EMSL, Pacific Northwest National LaboratoryButadiene-trans,trans-1,$4-d_{2}$ and -cis,cis-1,$4-d_{2}$ were prepared from trans,trans-1,4-dichlorobutadiene. Gas-phase spectra were recorded at $0.002 cm^{-1}$ resolution in the mid-infrared region on a Bruker IFS 120HR FT spectrometer at PNNL. For the trans,trans isotopomer the C-type band at $1002.553 cm^{-1}$ which was not perturbed near the band center, was more fully analyzed than another C-type band at $825.5 cm^{-1}$, which was extensively perturbed. Ground state rotational constants for this near-symmetric top $(\kappa = -0.9810)$ were fit to 1828 ground state combination differences (GSCDs) derived from the two bands. A, B and C rotational constants for the ground state are 1.3397796(7), 0.1306985(2), and $0.1191086(3) cm^{-1}$ respectively. For the cis,cis isotopomer the C-type band at $808.367 cm^{-1}$ was analyzed. Fitting 1559 GSCDs gave $\kappa = -0.9707$ and 1.1398737(6), 0.1380156(3), and $0.1231302(3) cm^{-1}$ for A, B and C, respectively. These rotational constants along with those of other deuterium and $^{13}C$ isotopomers will be used to determine a complete equilibrium rotational structure of butadiene