Matrix isolation vibrational spectra of alkyl chalcogenides complexed with HCl Structure of alkyl sulfide and alkyl selenide complexes with hydrochloric acid in ar matrices from infrared spectra

The matrix isolation technique has been used to isolate the hydrogen-bonded complexes of hydrochloric acid with some methyl and ethyl sulfides and selenides. In the ir spectra the perturbed vibrational mode of the complexed acid was observed as a rather complicated, broad band which exhibits multiplet structure. Evidence was obtained for the coexistence of 1:1, 2:1 and 1:2 complexes. The shifts ∆ ν_ClH… of the 1:1 complexes correlate with the proton affinity values of the chalcogenide bases. Isotopic dilution experiments using DCl allowed us to determine a bifide structure for the 1:2 R ₂X · (HCl) ₂ complexes.