A Noble-Gas Hydride in a Nitrogen Medium: Structure, Spectroscopy, and Intermolecular Vibrations of HXeBr@(N₂)₂₂

Noble-gas hydrides have been extensively studied in noble gas matrices. However, little is known on their stability and properties in molecular hosts. Here, HXeBr in the N₂ environment is modeled at the B3LYP-D level of theory in a complete single shell of 22 N₂ molecules. The system is compared to similar models of HXeBr in CO₂ and Xe clusters. The optimized structure of (HXeBr)@(N₂)₂₂ is of low symmetry and is highly anisotropic. None of the N₂ molecules are freely rotating, and the host molecules are not symmetrically positioned with respect to the HXeBr axis. The axes of the N₂ molecules are nonuniformly distributed. The computed anharmonic H-Xe stretching frequency of HXeBr in the N₂ cluster is in good accord with the experimental value. The soft-mode frequencies of the cluster including both intermolecular vibrations and librations, have a broad distribution that ranges from 8.7 to 107 cm^-1. It is expected that these findings and specifically, the single-shell model, may shed light also on the local structure and vibrations of other impurities in a molecular media.