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 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 Sodium monofluorophosphate, commonly abbreviated SMFP, is an inorganic compound with the chemical formula Na2PO3F. Typical for a salt, MFP is odourless, colourless, and water-soluble. This salt is an ingredient in some toothpastes.Klaus Schrödter ...

, commonly used in toothpaste. Related ions include difluorophosphate () and

hexafluorophosphate Hexafluorophosphate is an anion with chemical formula of . It is an octahedral species that imparts no color to its salts. is isoelectronic with sulfur hexafluoride, , and the hexafluorosilicate dianion, , and hexafluoroantimonate . In this an ...

(). The related neutral molecule is phosphenic fluoride PO₂F. Organic derivatives can be highly toxic and include

diisopropyl fluorophosphate Diisopropyl fluorophosphate (DFP) or Isoflurophate is an oily, colorless liquid with the chemical formula C6H14FO3P. It is used in medicine and as an organophosphorus insecticide. It is stable, but undergoes hydrolysis when subjected to moisture ...

. Some of the

Novichok agent Novichok (russian: Новичо́к, lit=newcomer, novice, newbie) is a group of nerve agents, some of which are binary chemical weapons. The agents were developed at the GosNIIOKhT state chemical research institute by the Soviet Union and R ...

s 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 protease Serine proteases (or serine endopeptidases) are enzymes that cleave peptide bonds in proteins. Serine serves as the nucleophilic amino acid at the (enzyme's) active site. They are found ubiquitously in both eukaryotes and prokaryotes. Seri ...

s irreversibly. This prevents these enzymes from functioning. Such an important enzyme is acetylcholinesterase as found in most animals. Some of the organic esters are detoxified in mammals by an enzyme in the blood and liver called

paraoxonase Paraoxonases are a family of mammalian enzymes with aryldialkylphosphatase activity. There are three paraoxonase isozymes, which were originally discovered for their involvement in the hydrolysis of organophosphates. Research has indicated the ...

PON1 Serum paraoxonase and arylesterase 1 (PON1) also known as A esterase , homocysteine thiolactonase or serum aryldialkylphosphatase 1 is an enzyme that in humans is encoded by the ''PON1'' gene. Paraoxonase 1 has esterase and more specifically para ...

. 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 were developed. Fluorophosphate glasses are low melting point kinds of glass which are mixtures of fluoride and phosphate metal compounds. For example, the composition 10%

SnO Tin(II) oxide (stannous oxide) is a compound with the formula SnO. It is composed of tin and oxygen where tin has the oxidation state of +2. There are two forms, a stable blue-black form and a metastable red form. Preparation and reactions Blue ...

, 40% SnF₂, 50% P₂O₅ forms a glass melting about 139 °C. PbO 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, chloride, difluorophosphate or

tetrafluoroborate Tetrafluoroborate is the anion . This tetrahedral species is isoelectronic with tetrafluoroberyllate (), tetrafluoromethane (CF4), and tetrafluoroammonium () and is valence isoelectronic with many stable and important species including the perchlo ...

Production

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

metaphosphate A metaphosphate ion is an oxyanion that has the empirical formula . It was first postulated in 1955 but was not observed until 1979, when it was detected by mass spectrometry. Metaphosphate is an intermediate in the hydrolysis of phosphate esters b ...

. :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 formula Na4P2O7. As a salt, it is a white, water-soluble solid. It is composed of pyrophosphate anion and sodium ions. T ...

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

urea Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an important ...

to yield monofluorphosphates.

Properties

Monofluorophosphates are stable at room temperature, but will decompose when heated. For example, at , silver monofluorophosphate gives off

phosphoryl fluoride Phosphoryl fluoride (commonly called phosphorus oxyfluoride) is a compound with the chemical formula . It is a colorless gas that hydrolyzes rapidly. Synthesis and reactions Phosphorus oxyfluoride is prepared by partial hydrolysis of phosphorus p ...

(POF₃) as a gas leaving behind

silver phosphate 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 ...

(Ag₃PO₄) and silver pyrophosphate (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