Gadolinium Cation (Gd⁺) Reaction with CO₂: Potential Energy Surface Mapped from Experiment and Theory

Understanding the activation of CO₂ is of interest because of the role of CO₂ as a greenhouse gas and its potential use as a carbon source in chemical synthesis. In gas phase experiments, the interactions and thermochemistry of CO₂ with metals can be probed without complicating effects from solvent or substrate molecules. Such studies can provide details about the activation processes at a molecular level. This information can potentially be extended to more complicated systems and be valuable in the design of new and improved catalysts. Here, guided ion beam tandem mass spectrometry is used to investigate the energy dependent reaction of gas-phase lanthanide gadolinium cation (Gd⁺) with CO₂ to form GdO⁺ and CO. Results show that ground state products are formed in an exothermic and barrierless process, with an electronically excited product ion produced efficiently at high collision energies. Additional experiments on the reverse process as well as Gd⁺(CO₂) and OGd⁺(CO) intermediates allow for an experimental potential energy surface to be determined. Electronic structure calculations help identify the structures and electronic states of these species and help explain the reactivity observed. Periodic trends in reactivity will be briefly discussed.