Vibrational spectra and assignments of diethyl sulfide, 2-chlorodiethyl sulfide and 2, 2′-dichlorodiethyl sulfide

Raman and infrared (IR) spectra of diethyl sulfide (CH3CH2SCH2CH3), 2‐chlorodiethyl sulfide (ClCH2CH2SCH2CH3), and 2,2′‐dichlorodiethyl sulfide (mustard gas) (ClCH2 CH2SCH2CH2Cl) were measured and their vibrational frequencies were compared to calculated frequencies reported by Sosa et al. the calculated frequencies were used to make probable assignments of the vibrational bands to normal modes of the molecules. Raman depolarization ratios for diethyl sulfide and 2‐chlorodiethyl sulfide also aided in their vibrational assignments. Good agreement of the calculated frequencies with the experimental values was found except for the CS and CCl stretching frequencies, which were consistently calculated to be lower than the experimentally found values. The experimental spectra also provide evidence for the presence of more than one stable molecular conformation in the liquid phase for each of the three sulfides. This has been observed for diethyl sulfide in previous studies.