An ab initio study on the insertion of radon atoms into hypohalous acids

The noble-gas molecules, HRnOX (X = F, Cl, Br or I), have been investigated by ab initio method. Equilibrium geometry, harmonic and anharmonic frequencies, partial charges and bond orders are calculated. The H–Rn stretching mode is predicted to be the most intense band and has a large anharmonicity. The two-body decomposition reaction is exothermic and lead to products of Rn + HOX, while the three-body decomposition reaction is endothermic with respect to the neutral decomposition products (H + Rn + OX). Moreover, HRnOX is kinetically stable with respect to the decomposition reactions due to the enough high energy barriers, which indicates the possibility to identify these HRnOX compounds in noble-gas matrices. The bonding in HRnOX is studied using the Löwdin population analysis and the localized molecular orbital energy decomposition analysis (LMO-EDA) method at the MP2 level of theory. It is found that HRnOX is a typical ionic bond, denotes as (HRn)+(OX)−, and the main contribution comes from the electrostatic interaction between (HRn)+ and (OX)−.