Monofluorophosphate is an anion with the formula PO₃F²⁻, which is a phosphate group with one oxygen atom substituted with a fluoride atom. The charge of the ion is −2. The ion resembles sulfate in size, shape and charge, and can thus form compounds with the same structure as sulfates. These include

Tutton's salts Tutton's salts are a family of salts with the formula M2M'(SO4)2(H2O)6 (sulfates) or M2M'(SeO4)2(H2O)6 (selenates). These materials are double salts, which means that they contain two different cations, M+ and M'2+ crystallized in the same regular ...

and

langbeinites Langbeinites are a family of crystalline substances based on the structure of langbeinite with general formula , where M is a large univalent cation (such as potassium, rubidium, caesium, or ammonium), and M' is a small divalent cation (for examp ...

. The most well-known compound of monofluorophosphate is sodium monofluorophosphate, commonly used in toothpaste. Related ions include

difluorophosphate Difluorophosphate or difluorodioxophosphate or phosphorodifluoridate is an anion with formula . It has a single negative charge and resembles perchlorate () and monofluorosulfonate (SO3F−) in shape and compounds. These ions are isoelectronic, a ...

() and hexafluorophosphate (). The related neutral molecule is phosphenic fluoride PO₂F. Organic derivatives can be highly toxic and include diisopropyl fluorophosphate. Some of the Novichok agents are monofluorophosphate esters. Names are given to these by naming the groups attached as esters and then adding "fluorophosphonate" to the end of the name. Two organic groups can be attached. Other related nerve gas substances may not be esters, and instead have carbon-phosphorus or nitrogen-phosphorus bonds. The organic fluorophosphonates react with serine esterases and serine proteases irreversibly. This prevents these enzymes from functioning. Such an important enzyme is

acetylcholinesterase Acetylcholinesterase (HGNC symbol ACHE; EC 3.1.1.7; systematic name acetylcholine acetylhydrolase), also known as AChE, AChase or acetylhydrolase, is the primary cholinesterase in the body. It is an enzyme Enzymes () are proteins that a ...

as found in most animals. Some of the organic esters are detoxified in mammals by an enzyme in the blood and liver called paraoxonase PON1. Willy Lange from Berlin discovered sodium monofluorophosphate in 1929. He fruitlessly tried to make monofluorophosphoric acid. However, he did discover the highly toxic organic esters. Following this discovery various nerve gases like

sarin Sarin (NATO designation GB G-series, "B"">Nerve_agent#G-series.html" ;"title="hort for Nerve agent#G-series">G-series, "B" is an extremely toxic synthetic organophosphorus compound.SnO, 40% SnF₂, 50% P₂O₅ forms a glass melting about 139 °C.

PbO Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula Pb O. PbO occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure. Modern ap ...

and PbF₂ can lower the melting temperature, and increase water resistance. These glasses can also be coloured by various other elements, and organic dyes. Some

mixed anion compounds Mixed anion compounds, heteroanionic materials or mixed anion materials are chemical compounds containing cations and more than one kind of anion. The compounds contain a single phase, rather than just a mixture. Use in materials science By havin ...

are known with other anions like

fluoride Fluoride (). According to this source, is a possible pronunciation in British English. is an inorganic, monatomic anion of fluorine, with the chemical formula (also written ), whose salts are typically white or colorless. Fluoride salts typ ...

, chloride, difluorophosphate or tetrafluoroborate.

Production

Hydrolysis of

with an alkali produces monofluorophosphate. : + 2 MOH → M₂PO₃F + H₂O + F⁻ Industrial production is by reaction of a

with a metaphosphate. :MF + MPO₃ → M₂PO₃F

Disodium hydrogen phosphate Disodium phosphate (DSP), or disodium hydrogen phosphate, or sodium phosphate dibasic, is the inorganic compound with the formula Na2HPO4. It is one of several sodium phosphates. The salt is known in anhydrous form as well as forms with 2, 7, 8, ...

tetrasodium pyrophosphate Tetrasodium pyrophosphate, also called sodium pyrophosphate, tetrasodium phosphate or TSPP, is an inorganic compound with the chemical formula, formula Na4P2O7. As a salt, it is a white, water-soluble solid. It is composed of pyrophosphate anion an ...

can react with hydrogen fluoride to form the sodium salt. :Na₂HPO₄ or Na₄P₂O₇ Phosphoric acid reacts with metal fluorides dissolved in molten urea to yield monofluorphosphates.

Properties

Monofluorophosphates are stable at room temperature, but will decompose when heated. For example, at ,

silver monofluorophosphate Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical co ...

gives off phosphoryl fluoride (POF₃) as a gas leaving behind silver phosphate (Ag₃PO₄) and

silver pyrophosphate Silver phosphate or silver orthophosphate is a light sensitive, yellow, water-insoluble chemical compound composed of silver and phosphate ions of formula Ag3PO4. Synthesis, reactions and properties Silver phosphate is formed as a yellow solid p ...

(Ag₄P₂O₇). In inorganic compounds the monofluorophosphate ion has an average P–O bond length of 1.51 Å. The P–F bond is longer, on average 1.58 Å. The O P F angle is 104.8°, smaller than the tetrahedral 109.47°. To compensate the O P O bond angle is 113.7° on average. Most commonly the monofluorophosphtae ion takes on point group 1, but a significant number have point group ''m''. Only two are known with 3''m'' and one with 3. When compared to sulfates, some are isotypical with the monofluorophosphates. Yet others have sulfates that take on a different form. But most know monofluorophosphates have no known equivalent sulfate.

Compounds

Organic

Uses

Zinc monofluorophosphate can be used as a corrosion inhibitor for steel when salt is present. Glutamine monofluorophosphate has been used as a fluoride-bearing medicine.

Production

Properties

Compounds

Organic

Uses

References

Other reading