Hydrogen isotope separation at exceptionally high temperature using an unsaturated organometallic complex

Abstract

A new approach for hydrogen isotope separation using an unsaturated organometallic complex was proposed. Adsorption measurements of [Mn(dppe)₂(CO)(N₂)](BArF²⁴) (Mn-dppe) (dppe = 1,2-bis(diphenylphosphino)ethane, BArF²⁴ = B[C₆H₃(3,5-CF₃)₂]₄) using H₂ and D₂ revealed a significant difference in the adsorption enthalpy of H₂/D₂ at much higher room temperatures than in previous studies, with D₂ molecules being more strongly adsorbed on unsaturated metal sites. Mixed gas adsorption isotherms were calculated at each temperature using IAST, and it was predicted that D₂ uptake was much larger than H₂ uptake. Column chromatographic separation using the difference in adsorption enthalpy indicated that deuterium could be concentrated, and DFT calculations suggest that this difference in adsorption force is due to the difference in vibrational potentials involved in metal–dihydrogen bonding. This study introduces a new separation approach that could enable hydrogen isotope separation in the ambient temperature range.