HNgBeF3 (Ng = Ar-Rn): Superhalogen-supported noble gas insertion compounds

Ab initio and density functional theory-based calculations are performed to study the structure, stability, and nature of bonding of superhalogen-supported noble gas (Ng) compounds of the type HNgY where (Ng = Ar-Rn; Y = BeF3). Here, BeF3 acts as the superhalogen. Calculations show that the HNgBeF3 spontaneously dissociates into product following the dissociation channels: HNgBeF3 → HBeF3 + Ng and HNgBeF3 → Ng + HF + BeF2. The transition states are optimized and the energy barriers are computed to show the metastable behavior of HNgBeF3. HNgBeF3 molecules are kinetically stable with respect to the first dissociation process having energy barriers of 1.0, 5.0, 10.6, and 13.9 kcal/mol for Ar, Kr, Xe, and Rn analogues, respectively, at CCSD(T)/Aug-cc-pVTZ level. These calculations suggest that the HXeBeF3 and HRnBeF3 can be shown to be stable up to ∼100 K temperature with a half-life of ∼102 seconds. The nature of HNg and two different types of NgF bonds in HNgBeF3 molecules is explored through the natural bond orbital and electron density analyses. The large Wiberg bond index (WBI) values for the HNg bond indicate the formation of almost a single bond in between H-atoms and Ng-atoms, whereas small WBI values for the two NgF bonds indicate a noncovalent interaction in between them. The electron density analysis further supports the covalency of the HNg bond and noncovalent interaction in the two NgF bonds in HNgBeF3.