Theoretical study on the dehydrogenation reaction of H2S by VS+ (3Σ-)

The dehydrogenation reaction of H2S by the (3)Sigma(-) ground state of VS+: VS+ + H2S ->) VS2+ + H-2 has been studied by using Density Functional Theory (DFT) at the B3LYP/DZVP level. It is found that the reaction proceeds along two possible pathways (A and 13) yielding two isomer dehydrogenation products VS2+-1 ( 3 132) and VS2+-2 ((3)A(1)), respectively. For both pathways, the reaction has a two-step-reaction mechanism that involves the migration of two hydrogen atoms from S2 to V+, respectively. The migration of the second hydrogen via TS3 and that of the first via TS4 are the rate-determining steps for pathways A and 13, respectively. The activation energy is 17.4 kcal/mol for pathway A and 22.8 kcal/mol for pathway B relative to the reactants. The calculated reaction heat of 9.9 kcal/mol indicates the endothermicity of pathway A and that of -11.9 kcal/mol suggests the exothermicity of pathway B.