MICROWAVE INVESTIGATION OF CIS, TRANS-1,4-DIFLUOROBUTADIENE AND A PARTIAL STRUCTURE FOR THE MOLECULE
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Date
2000
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Publisher
Ohio State University
Abstract
The cis, trans isomer of 1,4-difluorobutadiene has been investigated with a pulsed-beam, Fourier transform microwave spectrometer in the spectral range of 5-17 GHz. This molecule is a near-symmetric top with $\kappa = -0.9744$. Sufficient b-type and a-type transitions for the parent species have been observed to fit a Watson-type Hamiltonian with $A = 12.982.1$, $B=1467.82$, and $C=1318.64$ MHz. From a Stark-effect study of three transitions of the parent, the two components of the dipole moment have been determined as $\mu_{b}=2.213$ (5) D and $\mu_{a}=0.660$ (4) D. Fewer transitions have been observed for each of the four different $^{13} C$ isotopomers in natural abundance. Fitting Hamiltonians for the $^{13} C$ isotopomers has required the transfer of some centrifugal distortion constants from the parent. Cartesian coordinates and geometric parameters for the carbon-atom backbone have been found by the substitution method. All the bond angels and bond lengths differ in this planar molecule. Thus, its complete structure is an eighteen-parameter problem. Partially deuterated material has been prepared by isotopic exchange in basic $D_{2}O$. From a study of this mixture a full structure should be determinable.
Description
Author Institution: Department of Chemistry, Kent State University, Oberlin College, Oberlin, OH 44074; Department of Chemistry, Oberlin College