Xenon dioxide

Xenon dioxide, or xenon(IV) oxide, is a compound of xenon and oxygen with formula XeO2 which was synthesized in 2011. It is synthesized at 0 °C by hydrolysis of xenon tetrafluoride in aqueous sulfuric acid:

Structure
has an extended (chain or network) structure in which xenon and oxygen have coordination numbers of four and two respectively. The geometry at xenon is square planar, consistent with VSEPR theory for four ligands and two lone pairs (or AX4E2 in the notation of VSEPR theory).

In addition, the existence of an XeO2 molecule was predicted by an ab initio quantum chemistry method several years earlier by Pyykkö and Tamm, but these authors did not consider an extended structure.

Properties
is a yellow-orange solid. It is an unstable compound, with a half-life of about two minutes, disproportionating into xenon trioxide and xenon gas. Its structure and identity was confirmed by cooling it to −150 °C so that Raman spectroscopy could be performed before it decomposed.

At -78 °C, the majority of XeO2 decomposed over a period of 72 hours, which was identified by the fading of the original yellow product to a pale yellow. Almost all yellow color indicating pure XeO2 disappeared over the span of 1 week.


 * 3 XeO2 → Xe + 2 XeO3