Difluorides are chemical compounds with two fluorine atoms per molecule (or per formula unit). Metal difluorides are all ionic. Despite being highly ionic, the

alkali earth metal The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).. The elements have very similar properties: they are all ...

difluorides generally have extremely high lattice stability and are thus

insoluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubil ...

in water. One exception is beryllium difluoride. In addition, many

transition metal In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that ca ...

difluorides are water-soluble. Calcium difluoride is a notable compound. In the form of the mineral

fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs sca ...

it is the major source of commercial fluorine. It also has an eponymic crystal structure, which is an end member of the spectrum starting from

bixbyite Bixbyite is a manganese iron oxide mineral with chemical formula: (Mn,Fe)2O3. The iron/manganese ratio is quite variable and many specimens have almost no iron. It is a metallic dark black with a Mohs hardness of 6.0 - 6.5. It is a somewhat rare ...

and progressing through

pyrochlore Pyrochlore () is a mineral group of the niobium end member of the pyrochlore supergroup. The general formula, (where A and B are metals), represent a family of phases isostructural to the mineral pyrochlore. Pyrochlores are an important class of ...

List of the difluorides

Examples of the difluorides include:

Alkaline earth metal difluorides

The alkaline earth metals all exhibit the oxidation state +2, and form difluorides. The difluoride of

radium Radium is a chemical element with the symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rathe ...

is however not well established due to the element's high radioactivity. * Beryllium difluoride *

Magnesium fluoride Magnesium fluoride is an inorganic compound with the formula MgF2. The compound is a white crystalline salt and is transparent over a wide range of wavelengths, with commercial uses in optics that are also used in space telescopes. It occurs natur ...

Calcium fluoride Calcium fluoride is the inorganic compound of the elements calcium and fluorine with the formula CaF2. It is a white insoluble solid. It occurs as the mineral fluorite (also called fluorspar), which is often deeply coloured owing to impurities. ...

* Strontium difluoride *

Barium fluoride Barium fluoride (BaF2) is an inorganic compound with the formula BaF2. It is a colorless solid that occurs in nature as the rare mineral frankdicksonite. Under standard conditions it adopts the fluorite structure and at high pressure the PbCl2 s ...

* Radium fluoride :

Lanthanide difluorides

* Samarium difluoride *

Europium difluoride Europium(II) fluoride is an inorganic compound with a chemical formula EuF2. It was first synthesized in 1937.Zhao Yongzhi, Ma Ying, Hou Shaochun, Zhang Wenjuan, Wang Jingjing, Ding Yanrong, Hao Yifan氟化亚铕研究现状(''lit''. Research Progr ...

* Ytterbium difluorideGeorg Brauer: Handbuch der Präparativen Anorganischen Chemie. 3., umgearb. Auflage. Band I. Enke, Stuttgart 1975, , p. 255.

Transition metal difluorides

Compounds of the form MF₂: * Cadmium difluoride * Chromium(II) fluoride * Cobalt difluoride * Copper(II) fluoride *

Iron(II) fluoride Iron(II) fluoride or ferrous fluoride is an inorganic compound with the molecular formula FeF2. It forms a tetrahydrate FeF2·4H2O that is often referred to by the same names. The anhydrous and hydrated forms are white crystalline solids.Dale L. ...

Manganese(II) fluoride Manganese(II) fluoride is the chemical compound composed of manganese and fluoride with the formula MnF2. It is a light pink solid, the light pink color being characteristic for manganese(II) compounds. It is made by treating manganese and diverse ...

* Mercury difluoride *

Nickel difluoride Nickel(II) fluoride is the chemical compound with the formula NiF2. It is an ionic compound of nickel and fluorine and forms yellowish to green tetragonal crystals. Unlike many fluorides, NiF2 is stable in air. Nickel(II) fluoride is also produc ...

* Palladium difluoride *

Silver difluoride Silver(II) fluoride is a chemical compound with the formula AgF2. It is a rare example of a silver(II) compound. Silver usually exists in its +1 oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical char ...

* Zinc difluoride

Post-transition metal difluorides

* Lead difluoride * Tin(II) fluoride

Nonmetal and metalloid difluorides

Dinitrogen difluoride Dinitrogen difluoride is a chemical compound with the formula N2F2. It is a gas at room temperature, and was first identified in 1952 as the thermal decomposition product of the azide N3F. It has the structure F−N=N−F and exists in both a ' ...

Oxygen difluoride Oxygen difluoride is a chemical compound with the formula . As predicted by VSEPR theory, the molecule adopts a "bent" molecular geometry. It is strong oxidizer and has attracted attention in rocketry for this reason. With a boiling point of -144.7 ...

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

* Selenoyl difluoride *

Sulfur difluoride Sulfur difluoride is an inorganic compound with the chemical formula SF2. It can be generated by the reaction of sulfur dichloride and potassium fluoride or mercury(II) fluoride at low pressures: :SCl2 + 2 KF → SF2 + 2 KCl :SCl2 + HgF2 → SF2 + ...

* Disulfur difluoride * Thionyl difluoride *

Germanium difluoride Germanium difluoride (GeF2) is a chemical compound of germanium and fluorine. It is a white solid with a melting point of 110 °C, and can be produced by reacting germanium tetrafluoride with germanium powder at 150–300 °C. Structure ...

Noble gas difluorides

* Helium difluoride (hypothetical) * Argon difluoride (predicted) *

Krypton difluoride Krypton difluoride, KrF2 is a chemical compound of krypton and fluorine. It was the first compound of krypton discovered. It is a volatile, colourless solid at room temperature. The structure of the KrF2 molecule is linear, with Kr−F distances ...

Xenon difluoride Xenon difluoride is a powerful fluorinating agent with the chemical formula , and one of the most stable xenon compounds. Like most covalent inorganic fluorides it is moisture-sensitive. It decomposes on contact with water vapor, but is otherw ...

Radon difluoride Radon difluoride () is a compound of radon, a radioactive noble gas. Radon reacts readily with fluorine to form a solid compound, but this decomposes on attempted vaporization and its exact composition is uncertain. Calculations suggest that it ...

Bifluorides

The

bifluoride The bifluoride ion is an inorganic anion with the chemical formula . The anion is colorless. Salts of bifluoride are commonly encountered in the reactions of fluoride salts with hydrofluoric acid. The commercial production of fluorine involves e ...

s contain the two fluorine atoms in a covalently bound HF₂⁻

polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zero. The term molecule may or may no ...

rather than as F⁻ anions. *

Ammonium bifluoride Ammonium hydrogen fluoride is the inorganic compound with the formula or . It is produced from ammonia and hydrogen fluoride. This colourless salt is a glass- etchant and an intermediate in a once-contemplated route to hydrofluoric acid. Structu ...

Potassium bifluoride Potassium bifluoride is the inorganic compound with the formula . This colourless salt consists of the potassium cation () and the bifluoride anion (). The salt is used as an etchant for glass. Sodium bifluoride is related and is also of commercial ...

Sodium bifluoride Sodium bifluoride is the inorganic compound with the formula . It is a salt of sodium cation () and bifluoride anion (). It is a white, water-soluble solid that decomposes upon heating . Sodium bifluoride is non-flammable, hygroscopic, and has a ...

Organic difluorides

* Ethanedioyl difluoride * Ethylidene difluoride * Carbonyl difluoride * Carbon dibromide difluoride (dibromodifluoromethane) * Carbon dichloride difluoride (dichlorodifluormethane) * Methyl difluoride *

Methylphosphonyl difluoride Methylphosphonyl difluoride (DF), also known as EA-1251 or difluoro, is a chemical weapon precursor. Its chemical formula is CH3POF2. It is a Schedule 1 substance under the Chemical Weapons Convention. It is used for production of sarin and so ...

* Polyvinylidene difluoride

References

Bibliography

* * * {{Chemistry index Fluorides