To unravel the intermolecular interactions at play in the assemblies of EMIM-based ionic liquids, we report the vibrational spectra of the cryogenically cooled, cationic ternary complexes with halide ions, (EMIM+)2X-, X = Cl, Br, and I. This series specifically addresses the spectral response of the acidic C(2)H group upon complexation with an atomic anion, which is isolated by selective deuteration at this position. Unlike the behavior of the related BF4- complex, the halide systems display large (∼175 cm-1) red-shifts and dramatic (∼30X) intensity enhancements in the C(2)D stretch (relative to that of the bare d(2)-EMIM+ cation), which are largest for the chloride anion. Electronic structure calculations indicate that, while the spectroscopic signatures of the interaction follow those expected for a traditional hydrogen bond to the C(2)H group, the C-H-X docking arrangement deviates substantially from linearity due to a "double contact" motif involving a weaker interaction to the nearby methyl group [Hunt et al., Chem. Soc. Rev. 44(5), 1257-1288 (2015)].