Theoretical study of the reaction mechanism of ScO with molecular hydrogen

B3LYP and CCSD(T) calculations with various basis sets have been performed to investigate the potential energy surface for the ScO+H2→Sc+H2O reaction, which is shown to proceed by formation of the HScOH molecule. HScOH can isomerize to the molecular Sc–OH2 complex and dissociate to Sc atoms and water with endothermicity of 51–59 kcal/mol. The HScOH molecule is thermodynamically stable and the barrier required to release H2, ∼28 kcal/mol, is much lower than the energy needed for the Sc+H2O dissociation. The Sc–OH2 molecular complex has a binding energy of 7–11 kcal/mol and is stabilized kinetically with respect to isomerization to HScOH by a significant barrier.