Carbon dioxide activation by discandium dioxide cations in the gas phase: a combined investigation of infrared photodissociation spectroscopy and DFT calculations.

We present a combined computational and experimental study of CO ₂ activation at the Sc ₂ O ₂ ⁺ metal oxide ion center in the gas phase. Density functional theory calculations on the structures of [Sc ₂ O ₂ (CO ₂ ) _n ] ⁺ ( n = 1-4) ion-molecule complexes reveal a typical end-on binding motif as well as bidentate and tridentate carbonate-containing configurations. As the number of attached CO ₂ molecules increases, activated forms tend to dominate the isomeric populations. Distortion energies are unveiled to account for the conversion barriers from molecularly bound isomers to carbonate structures, and show a monotonically decreasing trend with successive CO ₂ ligand addition. The infrared photodissociation spectra of target ion-molecule complexes were recorded in the 2100-2500 cm ^-1 frequency region and interpreted by comparison with simulated IR spectra of low-lying isomers representing distinct configurations, demonstrating a high possibility of carbonate structure formation in current experiments.