Monofluorophosphate

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

Monofluorophosphate

yellow (lightest): fluorine orange (darker): phosphorus red (darkest): oxygen
Names
IUPAC name Fluoro-dioxido-oxo-λ5-phosphane
Other names Fluorophosphate Fluorophosphonate Monofluorophosphate Phosphorofluoridate
Identifiers
CAS Number	15181-43-8
3D model (JSmol)	Interactive image
ChemSpider	58737
PubChem CID	65241
UNII	4964UZ79MI
CompTox Dashboard (EPA)	DTXSID90164882
InChI InChI=1S/FH2O3P/c1-5(2,3)4/h(H2,2,3,4)/p-2 Key: DWYMPOCYEZONEA-UHFFFAOYSA-L
SMILES [O-]P(=O)([O-])F
Properties
Chemical formula	PO3F2−
Molar mass	97.971 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Related ions include difluorophosphate (PO₂F−2) and hexafluorophosphate ([PF₆]⁻).^[1] 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 as found in most animals.^[2] Some of the organic esters are detoxified in mammals by an enzyme in the blood and liver called paraoxonase PON1.^[3]

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% SnF₂, 50% P₂O₅ forms a glass melting about 139 °C. PbO and PbF₂ can lower the melting temperature, and increase water resistance.^[4] 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.

PO₂F−2 + 2 MOH → M₂PO₃F + H₂O + F⁻

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

MF + MPO₃ → M₂PO₃F

Disodium hydrogen phosphate or tetrasodium pyrophosphate 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 monofluorophosphates.^[5]

Properties

Monofluorophosphates are stable at room temperature, but will decompose when heated. For example, at 450 K (177 °C), silver monofluorophosphate gives off phosphoryl fluoride (POF₃) as a gas leaving behind silver phosphate (Ag₃PO₄) and silver pyrophosphate (Ag₄P₂O₇).^[6]

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.^[7]

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.^[7]

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.^[7]

Compounds

Name	Formula	Crystal form	Formula weight	Density	Comment	ChemSpider	PubChem	CAS
fluorophosphoric acid	H2PO3F		99.986			22687	24267	13537-32-1
[8]	BePO3F-I	Pc a=4.9331 b=6.6283 c=4.7083 β=90.2007 Z=2			band gap 8.03 eV SHG 1.72×KDP
[8]	BePO3F-II	P63 a=4.9651 c=9.3236 Z=2
[8]	BePO3F-III	Cc a=4.9542 b=8.5812 c=10.0532 β=98.0674 Z=4
[8]	BePO3F-IV	Cc a=8.5892 b=4.9532 c=10.1526 β=92.4967 Z=4
[8]	BePO3F-V	Cm a=9.2837 b=5.1602 c=7.1809 β=143.9321 Z=2
[8]	BePO3F-VI	P63mc a=5.1519 c=8.8598 Z=2
ammonium monofluorophosphate[9]	(NH4)2PO3F	orthorhombic: a = 6.29 Å, b = 8.31 Å, c = 12.70 Å, β = 99.6°, Z = 4[10]	134.05	1.633		8324505
ammonium monofluorophosphate hydrate[11]	(NH4)2PO3F·H2O	monoclinic: a = 7.9481 Å, b = 11.3472 Å, c = 6.0425 Å, β = 117.55°, Z = 4 monoclinic: a = 6.3042 Å, b = 8.2942 Å, c = 12.760 Å, β = 98.415°, Z = 4, V = 657.416 Å3[12]	152.05	1.536
ammonium tetrafluoroborate-monofluorophosphate[13]	(NH4)3[PO3F][BF4]	monoclinic P21/m: a = 7.8384 Å, b = 6.0996 Å, c = 9.9079 Å, β = 111.990°, V = 439.24 Å3, Z = 2	238.91	1.806
[14]	(NH4)2PO3F·NH4NO3	monoclinic P21/n a=10.3145 b=6.1034 c=14.3299 β=103.885° Z=4	875.8	1.624	@−73
[14]	(NH4)2PO3F·NH4NO3	triclinic P1a=10.3414 b=6.1056 c=14.1704 α=91.248 β=101.016 γ=89.173 Z=4	877.98	1.620	@−98
[14]	(NH4)2PO3F·NH4NO3	monoclinic P21ppa=10.3182 b=6.0591 c=14.3715 β=98.563 Z=4	888.48	1.601	@−173
[15]	(N2H6)[HPO3F]2	monoclinic C12/c1 a=14.1326 b=7.0340 c=7.9877 β=96.763 Z=4	788.52	1.954	colourless; large birefringence
sodium monofluorophosphate	Na2PO3F					22686	24266	10163-15-2
sodium hydrogen monofluorophosphate	NaHPO3F		121.968				19860808	20859-36-3
sodium hydrogen monofluorophosphate dihydrate[16]	NaHPO3F·2H2O	monoclinic: a = 19.112 Å, b = 5.341 Å, c = 12.72 Å, α = 110.18°, V = 1219.4 Å3	167.01	1.819
magnesium monofluorophosphate	MgPO3F		122.28				23206079
diammonium manganese dimonofluorophosphate dihydrate[7]	(NH4)2Mg(PO3F)2·2H2O	monoclinic C2/m: a = 13.374 Å, b = 5.3541 Å, c = 7.385 Å, β = 113.758°, V = 484.01 Å3, Z = 2	292.37	2.006
potassium monofluorophosphate[9]	K2PO3F	orthorhombic: a = 7.554 Å, b = 5.954 Å, c = 10.171 Å, V = 457 Å3, Z = 4 (at 20 °C)[17]	176.17	2.57				20859-37-4 14306-73-1
	K2PO3F·KF[18]
Potassium hydrogen monofluorophosphate	KHPO3F	monoclinic: a = 7.273 Å, b = 14.086 Å, c = 7.655 Å, β = 90.13°, Z = 8, V = 784.233 Å3[19]
Tripotassium hydrogen monofluorophosphate	K3H(PO3F)2	monoclinic: a = 7.973 Å; b = 11.635 Å; c = 9.668 Å, β = 113.52°, Z = 4, V = 822.35 Å3[19]
Ammonium dipotassium hydrogen difluorophosphate[20]	NH4K2H(PO3F)2
calcium monofluorophosphate dihydrate[21]	CaPO3F·2H2O	triclinic: a = 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 = 2[12]		2.313		8096036	9920401	37809-19-1
calcium monofluorophosphate hemihydrate[21]	CaPO3F·0.5H2O
vanadium monofluorophosphate	VPO3F		148.91				20452625
chromium(III) monofluorophosphate[7]	Cr2(PO3F)3·18.8H2O	triclinic: a = 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 = 4	736.88	1.830
ammonium chromium(III) difluorophosphate hexahydrate[7]	NH4Cr(PO3F)2·6H2O	R3m: a = 6.5491 Å, c = 25.438 Å, Z = 3	9.4489	1.972	green
manganese(II) fluorophosphate dihydrate	MnPO3F·2H2O	triclinic: a = 5.528 Å, b = 5.636 Å, c = 8.257 Å, α = 81.279°, β = 75.156°, γ = 71.722°, Z = 2[22]	188.94
diammonium manganese monofluorophosphate[7]	(NH4)2Mn(PO3F)2·2H2O	monoclinic: P21/n a = 12.558 Å, b = 5.5456 Å, c = 7.422 Å, β = 99.918°, Z = 2	500.9	2.142	pink
ammonium trimanganese dimonofluorophosphate difluorophosphate difluoride[23]	(NH4)Mn3(PO3F)2(PO2F2)F2	monoclinic: a = 20.3151 Å, b = 7.6382 Å, c = 7.8312 Å, β = 103.589°, V = 1181.16 Å3	517.8	2.9116
diammonium cobalt dimonofluorophosphate dihydrate[7]	(NH4)2Co(PO3F)2·2H2O	monoclinic C2/m: a = 13.386 Å, b = 5.3476 Å, c = 7.390 Å, β = 114.02°, V = 483.2 Å3, Z = 2	326.99	2.247
ammonium tricobalt dimonofluorophosphate difluorophosphate difluoride[23]	(NH4)Co3(PO3F)2(PO2F2)F2	monclinic: a = 19.9678 Å, b = 7.4883 Å, c = 7.5679 Å, β = 102.676°, V = 1104.01 Å3	529.7	3.1871
Diammonium nickel dimonofluorophosphate hexahydrate[7]	(NH4)2Ni(PO3F)2·6H2O	monoclinic: a = 6.2700 Å, b = 12.2845 Å, c = 9.1894 Å, β = 106.033°, Z = 2	680.27	1.947	blue Tutton
copper monofluorophosphate[24]	CuPO3F·5H2O		251.59
basic copper potassium monofluorophosphate[24]	Cu2K(OH)(PO3F)2·5H2O	monoclinic: a = 9.094 Å, b = 6.333 Å, c = 7.75 Å, β = 117.55°, Z = 2			natrochalcite
diammonium diaquabis(monofluorophosphato) copper[25]	Cu(NH4)2(PO3F)2·2H2O	monoclinic: a = 13.454 Å, b = 5.243 Å, c = 7.518 Å, β = 114.59°, V = 482.2 Å3, Z = 2	331.6	2.28
basic tetraammonium dicopper dimonofluorophosphate[7]	NH4Cu2OH(PO3F)2·H2O	C2/m: a = 9.1012 Å, b = 6.4121 Å, c = 7.8506 Å, β = 116.277°, Z = 2	410.80	3.040	light blue natrochalcite
zinc monofluorophosphate[26][7]	ZnPO3F·2.5H2O	triclinic: a = 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	163.35	2.518			20846323	68705-59-9
anhydrous diammonium zinc tetramonofluorophosphate[7]	(NH4)2Zn3(PO3F)4	cubic: a = 11.4769 Å
diammonium zinc dimonofluorophosphate[7]	(NH4)2Zn(PO3F)2·0.2H2O	monoclinic C2/c: a = 18.936 Å, b = 7.6955 Å, c = 20.528 Å, β = 108.641° Z = 12	2834.4	2.117	colourless
diammonium trizinc tetramonofluorophosphate[7]	(NH4)2Zn3(PO3F)4·H2O	cubic I43d: a = 11.3693 Å, Z = 4	1469.6	2.902	colourless
rubidium monofluorophosphate[27]	Rb2PO3F	orthorhombic:[28] a = 7.8714 Å, b = 6.1236 Å, c = 10.5424 Å, V = 508.15 Å3, Z = 4 (at 17 °C)	268.9	3.514
Rubidium hydrogen monofluorophosphate	RbHPO3F	monoclinic: a = 7.465 Å, b = 15.551 Å, c = 7.563 Å, β = 105.38°, V = 846.533 Å3, Z = 8[19]
[29]	Na1.5Rb0.5PO3F·H2O	orthorhombic Pmn21: a = 6.015 Å, b = 8.965 Å, c = 4.9689 Å, Z = 2	267.97	2.398	colourless
strontium monofluorophosphate	SrPO3F	monoclinic[30]	185.59				18183579
strontium monofluorphosphate hydrate[31]	SrPO3F·H2O		185.59
silver monofluorophosphate[24]	Ag2PO3F	monoclinic: a = 9.245 Å, b = 5.585 Å, c = 14.784 Å, β = 90.178°, Z = 8[6]	313.7				44135907
trisilver ammonium monofluorophosphate	NH4Ag3(PO3F)2	monoclinic: a = 30.895 Å, b = 5.5976 Å, c = 9.7522 Å, β = 90.027°, V = 1686.6 Å3, Z = 8[32]	537.59	4.234
cadmium monofluorophosphate[7]	CdPO3F·2H2O	triclinic 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 = 2	246.40	3.430
cadmium ammonium monofluorophosphate chloride dihydrate[33]	Cd2.5(NH4)2(PO3F)3Cl·2H2O				colourless
tin monofluorophosphate	SnPO3F·2.5H2O	monoclinic	216.68				44717639	52262-58-5
caesium monofluorophosphate	Cs2PO3F[27]	orthorhombic: a = 8.308 Å, b = 6.3812 Å, c = 11.036 Å, V = 585.1 Å3, Z = 4 (at −33 °C)	363.8	4.129
caesium hydrogen monofluorophosphate	CsHPO3F	monoclinic: a = 14.478 Å, b = 5.929 Å, c = 5.413 Å, β = 103.30°, V = 452.2 Å3, Z = 4[34]	231.89
tricaesium diammonium hydrogen monofluorophosphate	Cs3(NH4)2H3(PO3F)4	monoclinic: a = 20.619 Å, b = 12.076 Å, c = 15.856 Å, β = 102.58°, V = 3853 Å3, Z = 8[34]	829.72
barium monofluorophosphate	BaPO3F	monoclinic: a = 11.3105 Å, b = 8.6934 Å, c = 9.2231 Å, β = 127.819°, Z = 4 orthorhombic[35]	235.299				20836124	15600-53-0[36]
Mercurous monofluorophosphate	Hg2PO3F	orthorhombic: a = 9.406 Å, b = 12.145 Å, c = 8.567 Å, V = 978.7 Å3, Z = 8[37]
lead monofluorophosphate	PbPO3F	orthorhombic: a = 6.95 Å, b = 8.52 Å, c = 5.47 Å[38]		6.24
dilead monofluorophosphate dichloride hydrate[7]	Pb2(PO3F)Cl2·H2O	orthorhombic Pnma: a = 20.486 Å, b = 5.3967 Å, c = 6.9722 Å, V = 770.8 Å3, Z = 4	601.27	5.181
ditheylammonium hydrogen monofluorophosphate[16]	[NH2(CH2CH3)2]HPO3F	orthorhombic: a = 12.892 Å, b = 9.530 Å, c = 13.555 Å, α = 90°, V = 1665 Å3	173.12	1.381
tetramethylammonium monofluorophosphate[16]	[N(CH3)4]2PO3F		246.26
tetraethylammonium monofluorophosphate[16]	[N(CH2CH3)4]2PO3F		358.47
tetrabutylammonium monofluorophosphate[16]	[N(CH2CH2CH2CH3)4]2PO3F		582.90
piperazinium hydrogen monofluorophosphate[16]	[PipzH2]HPO3F	monoclinic: a = 6.020 Å, b = 13.012 Å, c = 7.285 Å, α = 95.09°, V = 568.4 Å3	286.11	1.672
glutamine monofluorophosphate monohydrate	C5H12N2O3PFO3		246.131				19989732
glutamine monofluorophosphate disodium dichloride	C10H20Cl2FN4Na2O9P		507.146			143826	164002
anilinium hydrogen monofluorophosphate[39]	[C6H8N]+[HPO3F]−	monoclinic: a = 9.418 Å, b = 14.31 Å, c = 6.303 Å, β = 92.45°, V = 859 Å3, Z = 4	193.12	1.51
Tris(2-carbamoylguanidinium) hydrogen fluorophosphonate fluorophosphonate monohydrate[40]	[C2H7N4O+]3[HPO3F]−[PO3F]2−·H2O	triclinic: a = 6.7523 Å, b = 8.2926 Å, c = 9.7297 Å, α = 100.630°, β = 90.885°, γ = 99.168°, V = 528.05 Å3
bis(2-carbamoylguanidinium) fluorophosphonate dihydrate[41]	[C2H7N4O+]2[PO3F]2−·2H2O

Organic

Name	Formula	Formula weight			ChemSpider	PubChem	CAS
dimethyl fluorophosphate	(CH3)2PO2F	128.039			72304	80052	5954-50-7
methyl ethyl fluorophosphate	(CH3)(CH3CH2)PO2F
1-[ethoxy(fluoro)phosphoryl]oxyethane[42]	(CH3CH2)2PO2F	156.093				67752	358-74-7
isoflurophate	[(CH3)2CH]2PO2F	184.147			5723	5936	55-91-4
1-[fluoro(2-oxopropoxy)phosphoryl]oxypropan-2-one		212.113				129718773
isobutyl methyl fluorophosphate[43]		170.12				129684440
1-[fluoro(methoxy)phosphoryl]oxypentane	(CH3)(CH3CH2CH2CH2CH2)PO3F	184.147				129761096
1-[fluoro(propoxy)phosphoryl]oxypropane	(CH3CH2CH2)2PO3F	184.147			4954063	6451603	381-45-3
O-isopropyl propyl fluorophosphonate	(CH3)2CH(CH3CH2CH2)PO3F	184.147				88538036
O-1-methylbutyl ethyl fluorophosphonate		198.174				129761095
dibutyl fluorophosphate	(CH3CH2CH2CH2)2PO3F	212.201			11640560	13025172	674-48-6
di-sec-butyl fluorophosphate	[CH3CH2CH(CH3)]2PO3F	212.201			92528	102452	625-17-2
di(1,3-dimethyl-n-butyl) fluorophosphate	[(CH3)2CHCH2CH(CH3)]2PO3F	268.309			91838	101643	311-60-4
1-[fluoro(2-methylpentan-3-yloxy)phosphoryl]oxyoctane		296.363				129760905
methyl arachidonoyl fluorophosphonate		400.471				11741711	9916415
12-[fluoro(propan-2-yloxy)phosphoryl]oxydodec-1-ene		308.374				129892247
bis(4-phenylbutyl) fluorophosphate	(C6H5CH2CH2CH2CH2)2PO3F	364.397			162961	187452	85473-46-7
3′-fluoro-3′-deoxythymidine 5′-fluorophosphate		326.193			2339398	3081896	152829-59-9
cytidine 5′-fluorophosphate		325.189				87861929	68521-86-8
chlorofluoromethylideneamino-2-chloroethyl fluorophosphate	ClFC=NClCH2CH2PO3F		A-230 Novichok agent[44]
chlorofluoromethylideneamino-1-methyl-2-chloroethyl fluorophosphate	ClFC=NClCH2CH(CH3)PO3F		A-232 Novichok agent
chlorofluoromethylideneamino-1,2-dimethyl-2-chloroethyl fluorophosphate	ClFC=NCl(CH3)CHCH(CH3)PO3F		A-234 Novichok agent

Uses

Zinc monofluorophosphate can be used as a corrosion inhibitor for steel when salt is present.^[45]

Glutamine monofluorophosphate has been used as a fluoride-bearing medicine.