What discovery by Neil Bartlett showed that xenon could form compounds?

In 1962, British chemist Neil Bartlett discovered that platinum hexafluoride (${\text{PtF}}_6$) could remove an electron from molecular oxygen to form the salt $[{\text{O}}_2^{+}][{\text{PtF}}_6^{-}]$.1

Recognizing that the first ionization energy of xenon is very similar to that of oxygen, Bartlett hypothesized that xenon could be oxidized in a similar fashion. He subsequently demonstrated that the interaction of ${\text{PtF}}_6$ vapor with xenon gas at room temperature produced a yellow-orange solid compound, which he formulated as $[{\text{Xe}}^{+}][{\text{PtF}}_6^{-}]$. This landmark achievement proved that noble gases—previously considered chemically inert—could indeed form chemical compounds.12