CO activation by atomic Thorium: Ground and excited state reaction pathways
Isuru R. Ariyarathna and Evangelos Miliordos
Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849
High level multi-reference calculations were performed to study the ground and excited states of ThCO molecule, its OThC isomer, and the intermediates connecting them. The 3Σ − ground state of ThCO molecule has ~23 kcal/mol binding energy with respect to the lowest energy Th(3F)+CO(1Σ + ) fragments, and it is followed by the 1Δ, 5Δ, 3Φ, 1Σ + , 3Π, and 1Π electronic states. The origin of all them is investigated by producing multi-reference configuration interaction potential energy profiles with respect to the Th−CO distance, which converge to the Th(3F)+CO(1Σ + ), Th(3P)+CO(1Σ + ), Th(1D)+CO(1Σ + ), and Th(5F)+CO(1Σ + ) asymptotes. We show that by supplying only ~30 kcal/mol, the C−O bond of ThCO is disrupted forming the bent OThC(3A’) isomer, which lies just ~6 kcal/mol above the ThCO(3Σ − ) global minimum. We examined the pathways from ThCO to OThC for the first five electronic states (3A’, 5A”, 3A”, 3A”, and 1A’) of OThC. Simply put, gas phase atomic Th is shown to activate rather easily the triple bond of carbon monoxide.