The predicted clathrate structures are included as CIF files in the supplementary information. They should be valuable when experimentally searching for new clathrates of these compounds, since simulated powder X-ray diffraction patterns, NMR-, Raman-and THz-spectra of these structures may allow identification of new phases by direct comparison between simulated and experimental data . The adsorption of gases in clathrates depends on both enthalpic and entropic contributions. We calculated the static temperature-free adsorption energy, a vibrational energy, as This structure is predicted to adsorb CO2 even at above room temperature and at reduced pressures.