Activation of dihydrogen by scandium ions

The interaction of 3D, 1D, 3F, and 1D states of Sc+ with H2 has been explored through the generation of ab initio potential energy surfaces for two different interaction geometries. We find that all components of the ground 3D and lowest 1D react in an endothermic process to form ScH+ (ΔH0=48.6 kcal/mol for the lowest product state from 3D Sc+) from a collinear interaction, and that four of the five components of each state are likely to proceed to this product from any interaction geometry. The remaining component of 1D Sc+ will form ScH+2 in an activated process (ΔH0=−4.4 kcal/mol; E° =12.8 kcal/mol). Inclusion of the effects of spin-orbit interactions reveals that the last 3D component may also proceed adiabatically to ScH+2 (ΔH0=+1.8 kcal/mol; E° =19.0 kcal/mol) within a very narrow energy window. At least eight H2 adduct states are also formed in the interaction with excited singlet and triplet Sc+ states. We explore in detail the means by which Sc+ activates the H2 bond, and relate our results to other metal–H2 systems.