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 [email protected]Thomas A. Blake and Robert L. Sams Environmental Moleculat Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352
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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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Rotational Analysis of Bands in the High-Resolution Infrared Spectra of trans,trans-
and cis,cis-1,4-Butadiene-2-d1
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 [email protected]
Thomas A. Blake and Robert L. Sams
Environmental Moleculat Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352
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 C3 and C4 rings.)
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
Rotational Constants for cis,cis-1,4-Difluorobutadiene-2-d1 ground state 13(a') – A-type 20(a") – C-type A 0.4195784(5) 0.420147(1) 0.418391(6) B 0.0536490(5) 0.05366108(6) 0.053651(6) C 0.0475823(6) 0.04753482(7) 0.047602(6)
J ×108 0.10848a 0.10848a 0.10848a K ×107 0.22351a 0.22351a 0.22351a K ×106 0.6442(3) 0.626(6) 0.075(19) J K ×107 -0.806(1) -1.050(2) -0.63(2) J ×108 0.774(3) 0.7975(4) 0.764(6) -0.96738 -0.96712 -0.96737 0 865.78495(4) 775.4 . .s d 0.00039 0.00045 0.00037 b -0.1145 0.3645 -0.3603
No. lines 1357c 1328 427 Ka' 0–34 0–13 10–15 Jmax 88 90 80 a Calculated wit h 3B L /YP cc-pVTZ model. b Inertial defect, = Ic – Ia – Ib. c 426 GSCDsfro mth eA-type band.
IR spectrum (0.1 cm-1 resol.) trans,trans-2-d1 species
C-type
C-type Band (0.0013 cm-1 resol.) of trans,trans-2-d1 Species
C-type Band (0.0013 cm-1 resol.) of trans,trans-2-d1 Species
Rotational Constants for trans,trans-1,4-Difluorobutadiene-2-d1 ground state 18(a") – C-type 21(a") – C-type A 0.939012(1) 0.93539(4) 0.937033(2) B 0.0389226(4) 0.03902(1) 0.03892105(4) C 0.0373779(3) 0.03729(1) 0.03738859(3)
J ×1010 0.63702a 0.63702a 0.63702a K ×108 0.73286a 0.73286a 0.73286a K ×106 2.766(2) -3.2(5) 3.36(3) J K ×107 -0.279(3) 1.5(2) -0.321(3) J ×108 0.133(3) 0.19(1) 0.1351(3) -0.99657 -0.99614 -0.99660 0 914.3 709.01914(4) . .s d 0.00037 0.0020 0.00040 b -0.0539 2.0199 -0.2212
No. lines 1158c 380 974 Ka' 0–21 4–8 0–9 Jmax 88 50 96 a Calculated wit h 3B L /YP cc-pVTGZ model. b Inertial defec ,t = Ic – Ia –
Ib. c 153 GSCDsfro mth eA-type band.
Conclusions
Analysis of the rotational structure in the high-resolution (0.0013 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.2
1. N. C. Craig, M. C. Moore, C. F. Neese, D. C. Oertel, L. Pedraza, T. Masiello J. Mol.
Spectrosc. 2009, 254, 39-46.
2. N. C. Craig, P. Groner, D. C. McKean, M. J. Tubergen Int. J. Quant. Chem. 2003, 95, 837-