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Rotational Analysis of Bands in the High- Resolution Infrared Spectra of trans,trans- and cis,cis-1,4-Butadiene-2-d 1 Norman C. Craig, Deacon J. Nemchick,

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Presentation on theme: "Rotational Analysis of Bands in the High- Resolution Infrared Spectra of trans,trans- and cis,cis-1,4-Butadiene-2-d 1 Norman C. Craig, Deacon J. Nemchick,"— Presentation transcript:

1 Rotational Analysis of Bands in the High- Resolution Infrared Spectra of trans,trans- and cis,cis-1,4-Butadiene-2-d 1 Norman C. Craig, Deacon J. Nemchick, Clay C. Easterday, Ethan C. Glor, and Drew F. K. Williamson, Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH 44074, USA Thomas A. Blake and Robert L. Sams Environmental Moleculat Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352

2 Overall Goal Determine semi-experimental equilibrium structures for the isomers of 1,4- difluorobutadiene (DFBD). Evaluate the influence of fluorine substitution on the CC bond lengths and bond angles in butadiene. (Strong influence of fluorine on C 3 and C 4 rings.)

3 Steps in Determining Semi- Experimental Equilibrium Structures Obtain ground state rotational constants from high- resolution IR or MW spectra. Do so for a full series of isotopomers. Use quantum chemistry (triple zeta level) to compute vibration-rotation constants (alphas). Find equilibrium rotational constants Obtain an r e structure from a global fit of all equilibrium rotational constants.

4 Synthesis Isotopomers of DFBD are made by modification of an assembly strategy. 1 1 H.-G.Viehe and E. Franchimont Chem. Ber. 1964, 97,

5 IR spectrum (0.1 cm -1 resol.) cis,cis-2-d 1 species A-type C-type

6 C-type Band ( cm -1 resol.) of cis,cis-2-d 1 Species

7 A-type Band ( cm -1 resol.) of cis,cis-2-d 1 Species

8 Loomis-Wood Display for A-Type Band of cis-2-d 1 Species K a 6lo yellow, 6hi magenta, 7 red, 8 green, 9 blue, 10 brown, 11 pink, 12 orange, 13 purple

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10 IR spectrum (0.1 cm -1 resol.) trans,trans-2-d 1 species C-type

11 C-type Band ( cm -1 resol.) of trans,trans- 2-d 1 Species

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14 Conclusions Analysis of the rotational structure in the high- resolution ( cm -1 ) infrared spectra of the cis,cis and trans,trans isomers of 1,4- difluorobutadiene has yielded ground state rotational constants. Prior work gave ground state rotational constants for the normal species. 1 The polar cis,trans isomer was investigated by MW spectroscopy N. C. Craig, M. C. Moore, C. F. Neese, D. C. Oertel, L. Pedraza, T. Masiello J. Mol. Spectrosc. 2009, 254, N. C. Craig, P. Groner, D. C. McKean, M. J. Tubergen Int. J. Quant. Chem. 2003, 95,

15 Support Dreyfus Foundation National Science Foundation Oberlin College Washington State University


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