Predicted compounds of radon with acetylene and water.

It is found that HRnCCH and HRnOH are metastable, chemically bound compounds of radon. These molecules are studied by multi-reference ab initio methods. Equilibrium geometry, NBO partial charges and bond orders, harmonic frequencies, are calculated. Intrinsic life-times are obtained by calculating the dissociation barriers and related partition functions, and by applying transition state theory. HRnCCH and HRnOH are found to be protected by an energy barrier of 2.1 and 0.79 eV, respectively. Using transition state theory, HRnOH is predicted to have a half-life of 1 h at about 230 K. HRnCCH is found to be kinetically stable at room temperature with its lifetime limited by the lifetime of the radioactive Rn atom. The significance of compound formation of radon with acetylene and water is discussed.