Characterization of Two Isomers of the Vinyl Fluoride···Carbon Dioxide Dimer by Rotational Spectroscopy

Rotational spectra of two different structural forms of the 1:1 weak complex between vinyl fluoride (C₂H₃F) and carbon dioxide were measured using 480 MHz bandwidth chirped-pulse and resonant cavity Fourier-transform microwave spectroscopy in the 5–17 GHz region. Both structures have the CO₂ molecule situated in the plane of the vinyl fluoride, such that the CO₂ is interacting either with a CHF side or with a HCCF edge of the vinyl fluoride subunit. Both observed structures are close to those predicted by <i>ab initio</i> geometry optimizations (corrected for basis set superposition error) at the MP2/6-311++G­(2d,2p) level. Dipole moment measurements and structural fits, including determinations of principal axis coordinates for all three carbon atoms, confirm the geometries of the assigned species