Knowledge Bank

The rotational spectra of four isotopomers of HCCH-CH$2$CF$2$ (the most abundant isotopomer, HCCD-CH$2$CF$2$, DCCD-CH$2$CF$2$, and H$\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}$C$\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}$CH-CH$2$CF$2$) have been collected in the 6-18 GHz region with a pulsed molecular beam, Fourier transform microwave spectrometer. The nuclear quadrupole hyperfine structure due to the deuterium nuclei in two of the isotopomers is observed. The spectroscopic constants are consistent with a planar structure in which the primary interaction is between H in HCCH and one of the F atoms in 1,1-difluoroethylene. There is also a secondary interaction between the acetylenic bond and the H atom $cis$ to the F atom involved in the hydrogen bond with HCCH.