Knowledge Bank

The Raman spectra $(3500-40cm-1)$ of gaseous, liquid, and solid methyl and methyl-$d3$ vinyl sulfide, $CH2CHSCD3$, have been recorded, and assignments are provided for the observed bands. From a temperature study of the Raman spectrum of the ""light"" compound, the enthalpy difference between the low energy s-cis conformer and the high energy gauche conformer was found to be $750\pm 68cm-1(2.14\pm 0.19kcal/mol)$. The far infrared spectra of both $CH2CHSCH3$ and $CH2CHSCD3$ have been collected at a resolution of $0.1cm-1$ for the gases and $1.0cm-1$ for the solids. The potential function governing the asymmetric torsion in the gas phase has been determined and the s-cis/gauche, gauche/gauche, and gauche/s-cis barriers are 1803 (5.15 kcal/mol), 508 (1.45 kcal/mol), and $1022cm-1(2.92kcal/mol)$, respectively. The dihedral angle for the gauche conformer was determined to be $132\circ$. The barriers to internal rotation of the methyl group have been determined for both conformers in both the gas and solid states.