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

Abstract

We present a combined computational and experimental study of CO₂ activation at the Sc₂O₂⁺ metal oxide ion center in the gas phase. Density functional theory calculations on the structures of [Sc₂O₂(CO₂)_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 CO₂ 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 CO₂ 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.