Structure and stability of a new set of noble gas insertion compounds, XNgOPO(OH)2 (X = F, Cl, Br; Ng = Kr, Xe, Rn): an in silico investigation

An in silico strategy of handling the thermochemical stability of XOPO(OH) 2 compounds (X = F, Cl, Br) is performed by insertion of noble gas (Ng) atoms (Ng = Kr, Xe and Rn) within the X–O bond. The theoretical prediction of the set of new compounds, XNgOPO(OH) 2 (X = F, Cl, Br; Ng = Kr, Xe, Rn) and their thermochemical stability are investigated using both ab initio and density-functional theory techniques considering different possible dissociation channels. The Ng (Kr–Rn) inserted analogues show that these compounds exist in their corresponding minima on their respective potential-energy surfaces. Most importantly, the release of Ng atom resulting in the formation of the bare XOPO(OH) 2 and free Ng is thermochemically favorable. However, this process has very high activation energy barriers, thus kinetically protecting it from undergoing the said dissociation at room temperature. All other possible two-body and three-body ionic as well as neutral dissociation pathways are endergonic at 298 K. The generation of new Ng-based insertion compounds offers a hitherto unknown strategy of the metastable behavior of these compounds. A thorough description of the X–Ng and Ng–O bonds in XNgOPO(OH) 2 compounds is provided with the help of natural bond orbital, Wiberg bond index, electron density, and energy decomposition analyses, and the more favorable representation of the compounds is proclaimed in our present discussion.