Xenon tetrafluoride is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

. It was the first discovered

binary compound In materials chemistry, a binary phase or binary compound is a chemical compound containing two different elements. Some binary phase compounds are molecular, e.g. carbon tetrachloride (CCl4). More typically binary phase refers to extended soli ...

of a

noble gas The noble gases (historically the inert gases, sometimes referred to as aerogens) are the members of Group (periodic table), group 18 of the periodic table: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn) and, in some ...

. It is produced by the

chemical reaction A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ...

xenon Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

with

fluorine Fluorine is a chemical element; it has Chemical symbol, symbol F and atomic number 9. It is the lightest halogen and exists at Standard temperature and pressure, standard conditions as pale yellow Diatomic molecule, diatomic gas. Fluorine is extre ...

: : Xe + 2 → This reaction is

exothermic In thermodynamics, an exothermic process () is a thermodynamic process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), electricity (e ...

, releasing an

energy Energy () is the physical quantity, quantitative physical property, property that is transferred to a physical body, body or to a physical system, recognizable in the performance of Work (thermodynamics), work and in the form of heat and l ...

of 251 kJ/mol. Xenon tetrafluoride is a colorless

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

line solid that

sublimes Sublimation is the Phase transition, transition of a substance directly from the solid to the gas state, without passing through the liquid state. The verb form of sublimation is ''sublime'', or less preferably, ''sublimate''. ''Sublimate' ...

at 117 °C. Its structure was determined by both

NMR spectroscopy Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy or magnetic resonance spectroscopy (MRS), is a spectroscopic technique based on re-orientation of atomic nuclei with non-zero nuclear spins in an external magnetic f ...

and

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

in 1963. The structure is

square planar In chemistry, the square planar molecular geometry describes the stereochemistry (spatial arrangement of atoms) that is adopted by certain chemical compounds. As the name suggests, molecules of this geometry have their atoms positioned at the co ...

, as has been confirmed by

neutron diffraction Neutron diffraction or elastic neutron scattering is the application of neutron scattering to the determination of the atomic and/or magnetic structure of a material. A sample to be examined is placed in a beam of Neutron temperature, thermal or ...

studies. According to

VSEPR theory Valence shell electron pair repulsion (VSEPR) theory ( , ) is a conceptual model, model used in chemistry to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms. It is also named the Gill ...

, in addition to four fluoride ligands, the xenon center has two lone pairs of electrons. These lone pairs are mutually ''trans''.

Synthesis

The original synthesis of xenon tetrafluoride occurred through direct 1:5-molar-ratio combination of the elements in a nickel (

Monel Monel is a group of alloys of nickel (from 52 to 68%) and copper, with small amounts of iron, manganese, carbon, and silicon. Monel is not a cupronickel alloy because it has less than 60% copper. Stronger than pure nickel, Monel alloys are res ...

) vessel at 400 °C. The nickel does not

catalyze Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

the reaction, but rather protects the container surfaces against fluoride corrosion. Controlling the process against impurities is difficult, as

xenon difluoride Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as th ...

(), tetrafluoride, and

hexafluoride A hexafluoride is a chemical compound with the general formula QXnF6, QXnF6m−, or QXnF6m+. Many molecules fit this formula. An important hexafluoride is hexafluorosilicic acid (H2SiF6), which is a byproduct of the mining of phosphate rock. In t ...

() are all in chemical equilibrium, the difluoride favored at low temperatures and little fluorine and the hexafluoride favored at high temperatures and excess fluorine. Fractional sublimation (xenon tetrafluoride is particularly involatile) or other equilibria generally allow purification of the product mixture. The elements combine more selectively when γ- or UV-irradiated in a nickel container or dissolved in anhydrous

hydrogen fluoride Hydrogen fluoride (fluorane) is an Inorganic chemistry, inorganic compound with chemical formula . It is a very poisonous, colorless gas or liquid that dissolves in water to yield hydrofluoric acid. It is the principal industrial source of fluori ...

with catalytic

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

. That reaction is believed selective because

dioxygen difluoride Dioxygen difluoride is a compound of fluorine and oxygen with the molecular formula O2F2. It can exist as an orange-red colored solid which melts into a red liquid at . It is an extremely strong oxidant and decomposes into oxygen and fluorine e ...

at standard conditions is too weak an oxidant to generate xenon(VI) species. Alternatively, fluoroxenonium perfluorometallate salts pyrolyze to XeF₄.

Reactions

Xenon tetrafluoride

hydrolyzes Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

at low temperatures to form elemental

hydrofluoric acid Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colorless, acidic and highly corrosive. A common concentration is 49% (48–52%) but there are also stronger solutions (e.g. 70%) and pure HF has a boiling p ...

, and aqueous

xenon trioxide Xenon trioxide is an unstable compound of xenon in its +6 oxidation state. It is a very powerful oxidizing agent, and liberates oxygen from water slowly, accelerated by exposure to sunlight. It is dangerously explosive upon contact with organic m ...

: :

\rm \ 6XeF_4 + 12H_2O \rightarrow 2XeO_3 + 4Xe\uparrow + 3O_2\uparrow + 24HF

It is used as a precursor for synthesis of all tetravalent Xe compounds. Reaction with

tetramethylammonium fluoride Tetramethylammonium (TMA) is the simplest quaternary ammonium cation. It has the chemical formula and consists of four methyl groups (, denoted Me) attached to a central nitrogen atom. The cation is isoelectronic with neopentane (). It is positi ...

gives tetramethylammonium pentafluoroxenate, which contains the pentagonal anion. The anion is also formed by reaction with

cesium fluoride Caesium fluoride (cesium fluoride in American English) is an inorganic compound with the formula CsF. A hygroscopic white salt, caesium fluoride is used in the synthesis of organic compounds as a source of the fluoride anion. The compound is no ...

: :CsF + → Reaction with

bismuth pentafluoride Bismuth pentafluoride is an inorganic compound with the formula BiF5. It is a white solid that is highly reactive. The compound is of interest to researchers but not of particular value. Structure BiF5 is polymeric and consists of linear chains ...

() forms the cation: : + → XeF₃BiF₆ The cation in the salt XeF₃Sb₂F₁₁ has been characterized by NMR spectroscopy. At 400 °C, reacts with xenon to form : :XeF₄ + Xe → 2 XeF₂ The reaction of xenon tetrafluoride with

platinum Platinum is a chemical element; it has Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name origina ...

yields

platinum tetrafluoride Platinum tetrafluoride is the inorganic compound with the chemical formula . In the solid state, the compound features platinum(IV) in octahedral coordination geometry. Preparation The compound was first reported by Henri Moissan by the fluorin ...

and xenon: :XeF₄ + Pt → PtF₄ + Xe

Applications

Xenon tetrafluoride has few applications. It has been shown to degrade

silicone rubber Silicone rubber is an elastomer composed of silicone—itself a polymer—containing silicon together with carbon, hydrogen, and oxygen. Silicone rubbers are widely used in industry, and there are multiple formulations. Silicone rubbers ar ...

for analyzing trace metal impurities in the rubber. reacts with the silicone to form simple gaseous products, leaving a residue of metal impurities.

References

External links

WebBook page for XeF₄
{{DEFAULTSORT:Xenon Tetrafluoride Fluorides Nonmetal halides Xenon(IV) compounds