The microwave spectra and molecular structures of (E)-1-chloro-1,2-difluoroethylene and its complex with the argon atom

•Rotational spectra analyzed for 4 isotopologues of (E)-1-chloro-1,2-difluoroethylene.•Rotational spectra analyzed for 2 isotopologues of Ar-(E)-1-chloro-1,2-difluoroethylene.•Molecular structure determined for Ar-(E)-1-chloro-1,2-difluoroethylene.•Argon atom does not seek to maximize heavy atom contacts, but rather polarizable electrons.