1. VIBRATIONAL SPECTRA AND ASSIGNMENTS OF FUNDAMENTALS OF 1,1-DIFLUOROCYCLOPROPANE AND ITS d2 AND d4 ISOTOPOMERS and Equilibrium Structure
NORMAN C. CRAIG,Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH 44074, USA
DONALD C. MCKEAN, School of Chemistry, University of Edinburgh, EH9 3JJ, U. K.
PETER GRONER, Department of Chemistry, University of Missouri at Kansas City, Kansas City, MO , USA

2. 1,1-Difluorocyclopropane

3. STRUCTURE Substitution from MWa C1C2 1.464 (2) Å C2C3 1.553 (1) Å
cyclopropaneb Å
Equilibrium – semi-experimental
GS rotational consts. from MWa
Vib.-rot. consts. from QC calcs.
aA. T. Perretta; V. W. Laurie, J. Chem. Phys. 1975, 62, 2469.
bW. T. Jones; B. P. Stoicheff, Can. J. Phys. 1964, 42, 2259.

4. VIBRATIONAL SPECTROSCOPY
Assignment of vibrational fundamentals of the d0, d2, and d4 isotopomers.
Infrared and Raman spectra.
Scaled quadratic force fields – in symmetry coordinate space.

6. IR spectrum DFCP-d2 in the gas phase

7. Far-IR spectrum of DFCP-d2 in the gas phase

8. Raman spectrum of DFCP-d2 in the liquid phase

9. Raman spectrum of DFCP in the gas phase

13. Semi-Experimental Equilibrium Structure
GS rotational consts. from MW spectraa for d0, d0-1-13C1, d4,
d4-1-13C1, d4-2-13C1
’s from QC force fields - scaled harmonic, unscaled cubic
GS rot. consts. ––’s––> equil. rot. consts.
a A. T. Perretta; V. W. Laurie, J. Chem. Phys. 1975, 62, 2469.

15. Conclusions
Assignments complete for vibrational fundamentals of DFCP-d0, d2, and d4.
New harmonic force fields from QC calcs. and selective scaling in symmetry coord. space.
Excellent agreement between predicted and observed frequencies.
Semi-experimental equilibrium structure derived from GS rot. consts. (MW) of 5 isotopomers.
Bond parameters agree to ±0.001 Å and ±0.1° for ’s computed with 2 DFT models and 2 MP2 models.

16. Acknowledgments Hong Yuan Hsin - spectroscopy
Deacon Nemchick - spectroscopy
Dreyfus Foundation - funding
Oberlin College - funding