xenon oxides and oxofluorides

Once xenon was shown to bond fluorine, the obvious next question was whether it could bond oxygen too — and it can, though far more touchily. Hydrolysing the fluorides opens a small but striking family of xenon oxides and oxofluorides, compounds in which xenon is tied to oxygen, sometimes alongside fluorine, and sits in high positive oxidation states of +6 or +8.

Two examples show the range. Xenon trioxide, XeO3, forms when XeF6 reacts with water; xenon is in the +6 state, the molecule is pyramidal (three bonds and one lone pair, by VSEPR), and it is a dangerously explosive solid — a vivid reminder that pulling oxygen onto a noble gas stores a lot of energy. Oxofluorides such as XeOF4 (xenon +6, square-pyramidal) and XeO2F2 are intermediate species combining oxygen and fluorine on the same xenon. At the top sits xenon in the +8 state: XeO4 is a volatile, explosive gas, and the perxenate ion XeO6^4-, made in alkaline solution, is one of the most powerful oxidising agents known and is reasonably stable as a salt.

These compounds matter as the furthest reach of noble-gas chemistry, proving xenon can support its highest oxidation states and behave, in its oxoanions, much like a normal main-group element forming oxoacids. Perxenate is even a useful, very strong oxidiser in analysis. The honest cautions: every one of these is a strong oxidiser and several (XeO3, XeO4) are violently explosive, so they are made and handled only in tiny amounts. As with the fluorides, the bonding is polar and best treated with molecular-orbital ideas, and this rich oxo-chemistry is essentially unique to xenon — the lighter noble gases cannot reach these states at all.