A photo‐ionization study of organosulfur ring compounds: Thiirane, thietane and tetrahydrothiophene

The gas phase heats of formation of several organosulfur cations were determined from thiirane, thietane and tetrahydrothiophene precursor molecules by photoionization mass spectrometry. Heats of formation at 0 K and 298 K are reported for the following ions: [H 2 CS] +˙ , [H 3 CS] + , [C 2 H 3 S] + , [C 2 H 4 S] +˙ , [C 3 H 5 S] + , [C 3 H 6 S] +˙ , [C 4 H 7 S] + and [C 4 H 8 S] +˙ . The [C 4 H 7 S] + ( m/z 87), [C 2 H 4 S] +˙ ( m/z 60), [C 2 H 3 S] + ( m/z 59), [C 4 H 7 ] + ( m/z 55), [C 4 H 6 ] +˙ ( m/z 54) and [CH 2 S] +˙ ( m/z 46) ions are produced from metastable tetrahydrothiophene ions at photon energies between 10.2 and 10.7 eV. Decay rates of internal energy selected parent ions to the m/z 60, 59, 55 and 54 fragments were measured by threshold photoelectron‐photoion coincidence, the results of which are compared to statistical theory (RRKM/QET) calculations. The [C 2 H 4 S] +˙ ion from tetrahydrothiophene is found to have the thioacetaldehyde structure. From the measured [C 2 H 4 S] +˙ onset a Δ H   1298 0= 50±8 kJ mol −1 was calculated for the thioacetaldehyde molecule.