Vibrational spectroscopy of 1,1-difluorocyclopropane-d0, -d2, and -d4: The equilibrium structure of difluorocyclopropane

Abstract

IR and Raman spectra are reported for 1,1-difluorocyclopropane-d0, -d2, and -d4, and complete assignments of vibrational fundamentals are given for these species. These assignments are consistent with predictions of frequencies, intensities, and Raman depolarization ratios computed with the B3LYP/cc-pVTZ quantum chemical (QC) model. Ground state rotational constants for five 13C and deuterium isotopomers, obtained from published microwave spectra, were “corrected” into equilibrium rotational constants. The needed vibration−rotation interaction constants were computed with QC models after scaling the force constants. A semi-experimental equilibrium structure, fitted to the equilibrium moments of inertia, is rC1C = 1.470(1) Å, rCC = 1.546(1) Å, rCF = 1.343(1) Å, rCH = 1.078(1) Å, αFCF = 109.5(1), αFCC = 119.4(1)°, αHCH = 116.7(1)°, αC1CH = 117.4(1)°, and αCCH = 117.1(1)°. This structure agrees within the indicated uncertainties with the ab initio structure obtained from an extrapolated set of CCSD(T)/aug-cc-pVnZ calculations except for rCC = 1.548 Å. The F2C−CH2 bonds are significantly shortened and strengthened; the H2C−CH2 bond is significantly lengthened and weakened.

Publisher

American Chemical Society

Publication Date

1-1-2007

Publication Title

Journal of Physical Chemistry A

Department

Chemistry and Biochemistry

Document Type

Article

DOI

https://dx.doi.org/10.1021/jp0686947

Language

English

Format

text

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