The Reaction of H₂S with SO₂: Molecular Structures, Energies, and Vibrational Data of Seven Isomeric Forms of H₂S₃O

Abstract

Abstract High‐level ab initio MO calculations (MP2/6‐311G ** //MP2/6‐311G ** ) on 16 isomeric forms of H 2 S 3 O (including rotamers) have been performed. The nonhelical hydroxotrisulfane HOSSSH 1a (motif + + −) is the most stable isomer, while the chains with motifs + + + and + − + are less stable by 1.7 and 3.7 kJ mol −1 , respectively. The other isomers of H 2 S 3 O increase in energy in the order HSS(O)SH < HOS(S)SH < HSOSSH < HS(O)SSH < HS(S)SOH < HS(S)OSH. The trisulfane‐2‐oxide HSS(O)SH 2a (symmetry C 1 ) is less stable than 1 a by 67 kJ mol −1 . These molecules may be formed from H 2 S and SO 2 via H 2 S 2 O 2 by condensation with H 2 S. The calculated reaction energies support the view that H 2 S 3 O is a key intermediate in the room‐temperature reaction of H 2 S and SO 2 resulting in the formation of lower oxoacids of sulfur and finally in sulfane oxides.