Direct Information on Structure and Energetic Features of Cu⁺−Xe Species Formed in MFI-Type Zeolite at Room Temperature

Abstract

The interacted species of Xe with metal ions that are stable at room temperature are not known and are a subject of interest for fundamental chemistry. We have experimentally found a new and stable Xe species, XeCu⁺, which was formed at room temperature in a copper ion-exchanged MFI-type zeolite. The presence of a prominent interaction between Cu⁺ in MFI and Xe, which has a covalent nature, was for the first time evidenced from experimental in situ synchrotron X-ray absorption fine structure and heat of adsorption measurements: the Cu⁺−Xe bond length of 2.45 Å and the bonding energy of ca. 60 kJ mol⁻¹. The bonding nature between Xe and Cu⁺ in the MFI zeolite was discussed utilizing density functional theory; the observed significant stabilization comes from the d(Cu⁺ in MFI)−p(Xe) orbital interaction. These new findings may pave a new way to developing fundamental chemistry of Xe compounds