A Theoretical Study on the Equilibrium Structures and Relative Stabilities of H2SO

摘要

MP2 and DFT/B3LYP calculations with Aug-cc-pvTz and Aug-cc-pvQz basis set levels are used to investigate the equilibrium structures and isomerization of H2SO isomers. All of the transition states have been calculated and confirmed by the intrinsic reaction coordinate (IRC). The calculated results show that H2SO isomers have three equilibrium structures and the linear structure is the most stable while the branched H2OS is the most unstable (the relative energies are 0.0, 82.1 and 155.3 kJ/mol for HSOH, H2SO and H2OS, respectively with the zero point vibrational energy correction at B3LYP/Aug-cc-pvQz level). It is difficult for the linear HSOH to convert to the branched H2SO and H2OS isomers due to the high activation energies (higher than ca. 200 and 160 kJ/mol, respectively). The predicted thermodynamic results also suggest that the linear structure is the most stable and may be the only species that can be found experimentally. The kinetic results demonstrate that the isomerization is a unimolecular one, and the reaction rate is slow.