Fourier transform microwave spectroscopy is used to obtain the rotational spectrum of the gas-phase heterodimer formed between 2-chloro-1,1-difluoroethylene and acetylene between 5.1 and 20.0 GHz. Rotational constants derived from the analysis of the spectra for the normal isotopologue, the singly substituted Cl-37 isotopologue, observed in natural abundance, and two isotopologues singly substituted with C-13, obtained using an isotopically enriched (HCCH)-C-13 sample, are used to determine the structure of the complex. Although the formation of a hydrogen bond to fluorine, considered in isolation, would be electrostatically favored, the angle strain induced in forming the secondary interaction between the acetylene triple bond and the hydrogen atom on 2-chloro-1,1-difluoroethylene coupled with the relaxed steric requirements of hydrogen bonding to chlorine lead to the heterodimer adopting what we have previously termed the side-binding configuration as the lowest energy structure. In this arrangement, the acetylene forms a hydrogen bond with the chlorine atom and a secondary interaction with the hydrogen atom, which is geminal to the chlorine. Comparisons with acetylene complexes of (Z)-1-chloro-2-fluoroethylene and vinyl chloride show the effects of increasing fluorine substitution on this bonding motif.