Xenon Tetrafluoride
Properties
| State | Solid (sublimes near its 117 °C melting point at 1 atm) |
| Color | Colorless |
| Solubility | Reacts explosively with water to form XeO3 and HF; soluble in anhydrous HF |
| Melting Point | 117.1 °C |
About Xenon Tetrafluoride
Xenon tetrafluoride, XeF4, is the colorless crystalline noble-gas compound that became the canonical inorganic-chemistry example of square-planar AX4E2 geometry the moment its X-ray and neutron diffraction structures landed in 1963. Around the central xenon you have four equatorial Xe-F bonds and two axial lone pairs locked trans to each other, which is exactly what VSEPR predicts when six electron pairs surround a central atom and two of them are lone pairs that prefer to sit as far apart as possible. Synthesis comes from heating xenon and fluorine at roughly 400 °C and 6 atm in a nickel vessel, with the product distribution among XeF2, XeF4, and XeF6 controlled by reaction time and pressure — longer time and higher pressure pushes you toward XeF6, shorter time toward XeF2, and the sweet spot in between gives clean XeF4. The compound is thermally stable to over 400 °C in dry containers and sublimes cleanly near 115 °C, but it reacts explosively with water to give the shock-sensitive high explosive XeO3 plus HF, which means anhydrous handling is non-negotiable. As a fluorinating agent XeF4 sits between XeF2 and XeF6 in oxidizing power, useful for difluorinating arenes and for taking transition-metal halides to high-oxidation-state fluorides like AuF5 and IrF7.
Where you'll encounter it
If you've ever sat through a graduate inorganic lecture and watched the professor draw an octahedron with two trans lone pairs to derive square-planar geometry, the example was almost certainly XeF4. In a teaching lab equipped for noble-gas chemistry — perhaps a dozen institutions worldwide — students prepare microgram quantities by direct fluorination in a nickel reactor, sublime the product onto a cold finger, and run a Raman spectrum to confirm the D4h symmetry through the absence of IR-Raman coincidences. Synthetic inorganic groups studying the upper edges of the periodic table use XeF4 to push gold and iridium into oxidation states that simply cannot be reached with elemental F2 or ClF3, generating exotic fluorides that show up in subsequent papers on superconductivity and catalysis. Most chemists never touch the compound directly, but its structure shows up on every comprehensive exam in inorganic chemistry.
Common Uses
- Powerful fluorinating agent for specialty inorganic and organic synthesis where XeF2 is too mild
- Precursor to xenon oxyfluorides XeOF2 and XeOF4 and to XeO3 by controlled hydrolysis
- Graduate inorganic chemistry teaching example of AX4E2 VSEPR square-planar geometry
- Oxidizer for preparing high-oxidation-state transition-metal fluorides such as AuF5 and IrF7
- Research reagent for oxidative-fluorination studies of hypervalent main-group chemistry
- Source of activated fluorine for generating xenon-fluorocation salts of weakly coordinating anions
Safety Information
XeF4 is acutely toxic and reacts explosively with water to form XeO3, a shock-sensitive high explosive, plus HF. GHS classifications: Acute Toxicity Inhalation Category 1, Skin Corrosion 1A, Eye Damage 1, Water-reactive (with risk of explosive decomposition products). No specific OSHA PEL exists for XeF4 itself; the HF byproduct is governed by the OSHA HF PEL of 3 ppm TWA, and any XeO3 that accumulates is treated as a primary explosive. Store exclusively under strictly anhydrous conditions in PFA, FEP, or nickel vessels behind a blast shield. Handle only in a glove box or dedicated dry-line fume hood with calcium gluconate gel for HF first aid, neoprene gloves, full face shield, and an evacuation plan if any moisture intrusion is suspected.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.