Thermodynamics and Kinetics of Gas-Phase CO Oxidation on the Scandium Monoxide Carbonyl Complexes

The CO chemisorption onto the ScO⁺ cation was investigated using infrared photodissociation spectroscopy combined with density functional theory calculations. The spectra were recorded in the CO stretching vibrational region for the OSc(CO)⁺ (n = 4-6) complex series. Comparisons of the experimental spectra with the simulated ones have established the geometries and present strong evidence that all of the CO ligands are chemisorbed, which could not be readily oxidized by scandium monoxide core into CO₂. Complementary calculations demonstrate that, regardless of the thermodynamic feasibility, the CO oxidation on the scandium monoxide carbonyl complexes is kinetically unfavorable due to the significant barriers involved in the CO oxidation process. Nevertheless, the consecutive CO adsorption has a positive influence on the Sc-O bond activation.