15min:

MARK D. MARSHALL, HELEN O. LEUNG, TASHA L. DRAKE, TADEUSZ PUDLIK, NAZIR SAVJI AND DANIEL W. MCCUNE, Department of Chemistry, Amherst College, P.O. Box 5000, Amherst, MA 01002-5000.

The rotational spectra of six isotopomers of 1,1-difluoroethylene--HF have been collected in the 7 - 22 GHz region with a Fourier transform microwave spectrometer. These include the most abundant isotopomer, its DF counterpart, and four singly substituted ¹³C species in natural abundance. Both a- and b-type transitions have been observed for all species. In addition, the hydrogen-fluorine spin-spin coupling interaction in the HF subunit for CH₂CF₂--HF and the deuterium nuclear quadrupole coupling interaction in CH₂CF₂--DF have been observed and analyzed. The rotational constants are consistent with a planar complex, with the two subunits interacting through a hydrogen bond formed between the H atom of HF and an F atom in 1,1-difluoroethylene and via a secondary interaction between the F atom in HF and the H atom located cis to the hydrogen-bonded F atom in 1,1-difluoroethylene. The rotational constants, hyperfine coupling constants, and results from the analogous complex, CH₂CF₂--HCCH, are combined to determine the structural parameters of 1,1-difluoroethylene--HF and 1,1-difluoroethylene--DF, which are found to be slightly different.