The inert pair effect on the heavy noble gases: New insights from radon tetroxide.

Abstract A quantum chemical survey of radon and xenon tetroxides (NgO4, Ng = Xe,Rn) is reported herein. The intermediate species that will form in their explosive decomposition back to their elemental states (Ng and O2) were also studied and their energetics compared. While Td symmetric RnO4 is a minimum energy structure, its standard enthalpy of formation is 88.6 kJ mol− 1 higher than for XeO4. The reason for this higher instability lies in what is known as the inert pair effect. This work adds to what is established wisdom in inorganic chemistry textbooks, a feature of the heavy elements of groups 13–15, extending it to include group 18.