Monofluorophosphate

Monofluorophosphate (fluorophosphate) is an anion with the formula , 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. The most well-known compound containing monofluorophosphate is sodium monofluorophosphate, commonly used in toothpaste, and mouthwash.

Related ions include difluorophosphate () and hexafluorophosphate (). The related neutral molecule is monofluorophosphoric acid .

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 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 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, 40% , 50% forms a glass melting about 139 °C. PbO and 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 are known with other anions like fluoride, chloride, difluorophosphate or tetrafluoroborate.

Production

Hydrolysis of difluorophosphate with an alkali produces monofluorophosphate.

Industrial production is by reaction of a fluoride with a metaphosphate.

Disodium hydrogen phosphate or tetrasodium pyrophosphate can react with hydrogen fluoride to form the sodium salt.

or

Phosphoric acid reacts with metal fluorides dissolved in molten urea to yield monofluorophosphates.

Properties Monofluorophosphates are stable at room temperature, but will decompose when heated. For example, at , silver monofluorophosphate gives off phosphoryl fluoride () as a gas leaving behind silver phosphate () and silver pyrophosphate ().

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 3m 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 NameFormulaFormula weightspace groupCrystal formDensityCommentrefCASfluorophosphoric acidH2PO3F99.98613537-32-1BePO3F-IPca=4.9331 b=6.6283 c=4.7083 β=90.2007 Z=2band gap 8.03 eV SHG 1.72×KDPBePO3F-IIP63a=4.9651 c=9.3236 Z=2BePO3F-IIICca=4.9542 b=8.5812 c=10.0532 β=98.0674 Z=4BePO3F-IVCca=8.5892 b=4.9532 c=10.1526 β=92.4967 Z=4BePO3F-VCma=9.2837 b=5.1602 c=7.1809 β=143.9321 Z=2BePO3F-VIP63mca=5.1519 c=8.8598 Z=2ammonium monofluorophosphate(NH4)2PO3F134.05orthorhombica = 6.29 Å, b = 8.31 Å, c = 12.70 Å, β = 99.6°, Z = 41.633ammonium monofluorophosphate hydrate(NH4)2PO3F·H2O152.05monoclinica = 7.9481 Å, b = 11.3472 Å, c = 6.0425 Å, β = 117.55°, Z = 4monoclinic: a = 6.3042 Å, b = 8.2942 Å, c = 12.760 Å, β = 98.415°, Z = 4, V = 657.416 Å31.536ammonium tetrafluoroborate-monofluorophosphate(NH4)3[PO3F][BF4]238.91P21/ma = 7.8384 Å, b = 6.0996 Å, c = 9.9079 Å, β = 111.990°, V = 439.24 Å3, Z = 21.806(NH4)2PO3F·NH4NO3875.8P21/na=10.3145 b=6.1034 c=14.3299 β=103.885° Z=41.624@−73(NH4)2PO3F·NH4NO3877.98P1a=10.3414 b=6.1056 c=14.1704 α=91.248 β=101.016 γ=89.173 Z=41.620@−98(NH4)2PO3F·NH4NO3888.48P21ppa=10.3182 b=6.0591 c=14.3715 β=98.563 Z=41.601@−173(N2H6)[HPO3F]2788.52C12/c1a=14.1326 b=7.0340 c=7.9877 β=96.763 Z=41.954colourless; large birefringencesodium monofluorophosphateNa2PO3F10163-15-2sodium hydrogen monofluorophosphateNaHPO3F121.96820859-36-3sodium hydrogen monofluorophosphate dihydrateNaHPO3F·2H2O167.01monoclinica = 19.112 Å, b = 5.341 Å, c = 12.72 Å, α = 110.18°, V = 1219.4 Å31.819magnesium monofluorophosphateMgPO3F122.28diammonium manganese dimonofluorophosphate dihydrate(NH4)2Mg(PO3F)2·2H2O292.37C2/ma = 13.374 Å, b = 5.3541 Å, c = 7.385 Å, β = 113.758°, V = 484.01 Å3, Z = 22.006potassium monofluorophosphateK2PO3F176.17orthorhombica = 7.554 Å, b = 5.954 Å, c = 10.171 Å, V = 457 Å3, Z = 4 (at 20 °C)2.5720859-37-4 14306-73-1K2PO3F·KFPotassium hydrogen monofluorophosphateKHPO3Fmonoclinica = 7.273 Å, b = 14.086 Å, c = 7.655 Å, β = 90.13°, Z = 8, V = 784.233 Å3Tripotassium hydrogen monofluorophosphateK3H(PO3F)2monoclinica = 7.973 Å; b = 11.635 Å; c = 9.668 Å, β = 113.52°, Z = 4, V = 822.35 Å3Ammonium dipotassium hydrogen difluorophosphateNH4K2H(PO3F)2calcium monofluorophosphate dihydrateCaPO3F·2H2Otriclinica = 8.6497 Å, b = 6.4614 Å, c = 5.7353 Å, α = 119.003°, β = 110.853°, γ = 94.146°, V = 249.943 Å3, Z = 22.31337809-19-1calcium monofluorophosphate hemihydrateCaPO3F·0.5H2Ovanadium monofluorophosphateVPO3F148.91chromium(III) monofluorophosphateCr2(PO3F)3·18.8H2O736.88triclinica = 11.594 Å, b = 15.292 Å, c = 15.360 Å, α = 83.804°, β = 84.203, γ = 82.597, V = 2674.1 Å3, Z = 41.830ammonium chromium(III) difluorophosphate hexahydrateNH4Cr(PO3F)2·6H2O9.4489R3ma = 6.5491 Å, c = 25.438 Å, Z = 31.972greenmanganese(II) fluorophosphate dihydrateMnPO3F·2H2O188.94triclinica = 5.528 Å, b = 5.636 Å, c = 8.257 Å, α = 81.279°, β = 75.156°, γ = 71.722°, Z = 2diammonium manganese monofluorophosphate(NH4)2Mn(PO3F)2·2H2O500.9P21/na = 12.558 Å, b = 5.5456 Å, c = 7.422 Å, β = 99.918°, Z = 22.142pinkammonium trimanganese dimonofluorophosphate difluorophosphate difluoride(NH4)Mn3(PO3F)2(PO2F2)F2517.8monoclinic: a = 20.3151 Å, b = 7.6382 Å, c = 7.8312 Å, β = 103.589°, V = 1181.16 Å32.9116(NH4)4Fe5(PO4)2(PO3F)2F4(OH)2C2/ca = 19.6961 b = 6.4340 c = 17.9922 β = 117.567°diammonium cobalt dimonofluorophosphate dihydrate(NH4)2Co(PO3F)2·2H2O326.99C2/ma = 13.386 Å, b = 5.3476 Å, c = 7.390 Å, β = 114.02°, V = 483.2 Å3, Z = 22.247ammonium tricobalt dimonofluorophosphate difluorophosphate difluoride(NH4)Co3(PO3F)2(PO2F2)F2529.7monclinica = 19.9678 Å, b = 7.4883 Å, c = 7.5679 Å, β = 102.676°, V = 1104.01 Å33.1871Diammonium nickel dimonofluorophosphate hexahydrate(NH4)2Ni(PO3F)2·6H2O680.27monclinica = 6.2700 Å, b = 12.2845 Å, c = 9.1894 Å, β = 106.033°, Z = 21.947blue Tuttoncopper monofluorophosphateCuPO3F·5H2O251.59basic copper potassium monofluorophosphateCu2K(OH)(PO3F)2·5H2Omonclinica = 9.094 Å, b = 6.333 Å, c = 7.75 Å, β = 117.55°, Z = 2natrochalcitediammonium diaquabis(monofluorophosphato) copperCu(NH4)2(PO3F)2·2H2O331.6monclinica = 13.454 Å, b = 5.243 Å, c = 7.518 Å, β = 114.59°, V = 482.2 Å3, Z = 22.28basic tetraammonium dicopper dimonofluorophosphateNH4Cu2OH(PO3F)2·H2O410.80C2/ma = 9.1012 Å, b = 6.4121 Å, c = 7.8506 Å, β = 116.277°, Z = 23.040light blue natrochalcitezinc monofluorophosphateZnPO3F·2.5H2O163.35triclinica = 7.6020 Å, b = 7.6490 Å, c = 9.4671 Å, α = 88.633°, β = 88.888°, γ = 87.182°, V = 549.58 Å3, Z = 4 2.51868705-59-9anhydrous diammonium zinc tetramonofluorophosphate(NH4)2Zn3(PO3F)4cubica = 11.4769 Ådiammonium zinc dimonofluorophosphate(NH4)2Zn(PO3F)2·0.2H2O2834.4C2/ca = 18.936 Å, b = 7.6955 Å, c = 20.528 Å, β = 108.641° Z = 122.117colourlessdiammonium trizinc tetramonofluorophosphate(NH4)2Zn3(PO3F)4·H2O1469.6I43da = 11.3693 Å, Z = 42.902colourlessrubidium monofluorophosphateRb2PO3F268.9orthorhombic: a = 7.8714 Å, b = 6.1236 Å, c = 10.5424 Å, V = 508.15 Å3, Z = 4 (at 17 °C)3.514Rubidium hydrogen monofluorophosphateRbHPO3Fmonoclinic: a = 7.465 Å, b = 15.551 Å, c = 7.563 Å, β = 105.38°, V = 846.533 Å3, Z = 8Na1.5Rb0.5PO3F·H2O267.97orthorhombic Pmn21: a = 6.015 Å, b = 8.965 Å, c = 4.9689 Å, Z = 22.398colourlessstrontium monofluorophosphate SrPO3F185.59monoclinicstrontium monofluorphosphate hydrateSrPO3F·H2O185.59silver monofluorophosphateAg2PO3F313.7monoclinic: a = 9.245 Å, b = 5.585 Å, c = 14.784 Å, β = 90.178°, Z = 8trisilver ammonium monofluorophosphateNH4Ag3(PO3F)2537.59monoclinic: a = 30.895 Å, b = 5.5976 Å, c = 9.7522 Å, β = 90.027°, V = 1686.6 Å3, Z = 84.234cadmium monofluorophosphateCdPO3F·2H2O246.40triclinic P1_: a = 5.2678 Å, b = 6.6697 Å, c = 7.7037 Å, α = 65.506°, β = 85.919°, γ = 75.394°, V = 238.584 Å3, Z = 23.430cadmium ammonium monofluorophosphate chloride dihydrateCd2.5(NH4)2(PO3F)3Cl·2H2OP21/c a=14.3778 b=11.227 c=9.1992 β=97.204°colourlesstin monofluorophosphateSnPO3F·2.5H2O216.68monoclinic52262-58-5caesium monofluorophosphateCs2PO3F363.8orthorhombic: a = 8.308 Å, b = 6.3812 Å, c = 11.036 Å, V = 585.1 Å3, Z = 4 (at −33 °C) 4.129caesium hydrogen monofluorophosphateCsHPO3F231.89monoclinic: a = 14.478 Å, b = 5.929 Å, c = 5.413 Å, β = 103.30°, V = 452.2 Å3, Z = 4tricaesium diammonium hydrogen monofluorophosphateCs3(NH4)2H3(PO3F)4829.72monoclinic: a = 20.619 Å, b = 12.076 Å, c = 15.856 Å, β = 102.58°, V = 3853 Å3, Z = 8barium monofluorophosphate BaPO3F235.299monoclinic: a = 11.3105 Å, b = 8.6934 Å, c = 9.2231 Å, β = 127.819°, Z = 4orthorhombic15600-53-0Ba2Mn2(PO3F)F6P21/c a=12.2502 b=7.5652 c=9.8385 β=102.592°Ba2Co2(PO3F)F6P21/c a=12.0976 b=7.4462 c=9.6777 β=102.157)°Ba2Ni2(PO3F)F6P21/n a=12.2625 b=7.2639 c=9.4763 β=99.745°Ba2Cu2(PO3F)F6P21/c a=12.2053 b =7.3547 c=9.6569 β =102.838°KBaSr(PO2F2)(PO3F)2P21/ca = 7.0638, b = 7.4306 c = 21.3633 β = 93.386°, V = 1119.37(3) Å3 Z = 4,birefringence 0.042@550 nmMercurous monofluorophosphateHg2PO3Forthorhombic: a = 9.406 Å, b = 12.145 Å, c = 8.567 Å, V = 978.7 Å3, Z = 8lead monofluorophosphatePbPO3Forthorhombic: a = 6.95 Å, b = 8.52 Å, c = 5.47 Å6.24dilead monofluorophosphate dichloride hydratePb2(PO3F)Cl2·H2O601.27orthorhombic Pnma: a = 20.486 Å, b = 5.3967 Å, c = 6.9722 Å, V = 770.8 Å3, Z = 45.181ditheylammonium hydrogen monofluorophosphate[NH2(CH2CH3)2]HPO3F173.12orthorhombic: a = 12.892 Å, b = 9.530 Å, c = 13.555 Å, α = 90°, V = 1665 Å31.381tetramethylammonium monofluorophosphate[N(CH3)4]2PO3F246.26tetraethylammonium monofluorophosphate[N(CH2CH3)4]2PO3F358.47tetrabutylammonium monofluorophosphate[N(CH2CH2CH2CH3)4]2PO3F582.90piperazinium hydrogen monofluorophosphate[PipzH2]HPO3F286.11 monoclinic: a = 6.020 Å, b = 13.012 Å, c = 7.285 Å, α = 95.09°, V = 568.4 Å31.672glutamine monofluorophosphate monohydrateC5H12N2O3PFO3246.131glutamine monofluorophosphate disodium dichlorideC10H20Cl2FN4Na2O9P507.146anilinium hydrogen monofluorophosphate[C6H8N]+[HPO3F]−193.12monoclinic: a = 9.418 Å, b = 14.31 Å, c = 6.303 Å, β = 92.45°, V = 859 Å3, Z = 4 1.51Tris(2-carbamoylguanidinium) hydrogen fluorophosphonate fluorophosphonate monohydrate[C2H7N4O+]3[HPO3F]−[PO3F]2−·H2Otriclinic: a = 6.7523 Å, b = 8.2926 Å, c = 9.7297 Å, α = 100.630°, β = 90.885°, γ = 99.168°, V = 528.05 Å3bis(2-carbamoylguanidinium) fluorophosphonate dihydrate[C2H7N4O+]2[PO3F]2−·2H2O

Organic