Knowledge Bank

We seek an equilibrium structure {\it cis,cis}-1,4-difluorobutadiene. Rotational structure of a C-type band centered at 762.8 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ in the high-resolution infrared spectrum (0.0015 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$) has been analyzed as a first step. A sequence of strong hot bands of the torsional mode (78 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$) complicate the analysis of this band. Provisional ground state rotational constants are reported. The spectrum of a second C-type band at 328 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ may also be analyzable. Ground state rotational constants for a full set of isotopomers are needed. A procedure for synthesizing these species is being explored.