The NMR spectroscopic investigation of solutions of the iminium ions Me2N+=C(H)Cl (1(+)), Me2N+= C(H)Ph (2a(+)), and Et2N+=CH2 (3(+)) in aprotic solvents shows that the replacement of the weakly nucleophilic counterions SbCl6-, AlCl4-, BF4-, or CF3SO3- by halide ions (I-, Br-, Cl-) causes a deshielding of the proton at the iminium carbon atom (Delta delta(max) = +2.8 for 2a(+) in CD2Cl2) while the chemical shifts of all other H-1 and C-13 nuclei remain almost unaffected. The solvent dependence of these effects, N-14 NMR investigations, and ab initio MO calculations suggest that iminium halides form CH ... Y- hydrogen bonds (Y = Cl, Br, and I) and thus exist as contact ion pairs in acetonitrile, chloroform, dichloromethane, and dimethyl sulfoxide solutions. In liquid sulfur dioxide, specific anion-cation interactions cannot be observed due to the superior solvation of the anions by SO2.