The fluorosulfates or fluorosulfonates are a set of salts of fluorosulfuric acid containing the fluorosulfonate anion SO3F−. The fluorosulfate anion can be treated as though it were a hydrogen sulfate anion with hydroxyl substituted by fluorine. The fluorosulfate ion has a low propensity to form complexes with metal cations. Since fluorine is similar in size to oxygen, the fluorosulfate ion is roughly tetrahedral and forms salts similar to those of the perchlorate ion. It is isoelectronic with sulfate, . When an organic group is substituted for the anions, organic fluorosulfonates are formed.
In solution the fluorosulfate anion is completely ionised. The volume of the ions is 47.8 cm3/mol. Quaternary ammonium and most metal ions can form fluorosulfate salts. Different ways to make these salts include treating a metal chloride with anhydrous fluorosulfuric acid, releasing hydrogen chloride gas. Double decomposition methods utilising a metal sulfate with barium fluorosulfate, or a metal chloride with silver fluorosulfate, leave the metal salt in solution.
The fluorosulfate anion is weakly coordinating and difficult to oxidise. It is important historically as a model weakly coordinating anion. However, by the twenty-first century fluorosulfate was superseded in this use, in particular by BARF.
Many pseudobinary fluorosulfate salts are known. They are called pseudobinary because, although there is one other element, there are four kinds of atoms. Nonmetal pseudobinary fluorosulfates are known for including those of halogens and xenon.
Some pseudoternary fluorosulfates exist, including Cs[Sb(SO3F)6], Cs[Au(SO3F)4], Cs2[Pt(SO3F)6].
Fluoroselenates (SeO3F−) are unknown as of 2023. Known related compounds include fluorooxotellurates, hydroxyfluorooxotellurates, fluorochromates (CrO3F−), fluoroselenites (SeO2F−) and fluorosulfites (SO2F−). Sulfate fluorides are distinct, as they contain fluoride ions without a bond to the sulfate groups.
There exists one fluorosulfate mixed anion compound, which also contains carbonate and chloride, containing mineral called reederite-(Y).
Compounds FormulaNameColourDecomposition temperature (°C)Decomposition productCrystalRefLiSO3Flithium fluorosulfateC2/m a=8.54 b=7.62 c=4.98 β=90.0 V=81Be(SO3F)2SO3CF3(SO3F)CF2(SO3F)2CF(SO3F)3C(SO3F)4NH4SO3Fammonium fluorosulfateOrthorhombic Pnma a=8.97 b=6.00 c=7.54 V=101.4 Z=4tetramethylammonium fluorosulfateOrthorhombic Pnma a=8.38 b=8.38 c=5.86 V=102.88 Z=4NIIIOSO3Fnitrosyl fluorosulfonatemelts 156density 1.96NVO2SO3Fnitronium fluorosulfinateC(NH2)3SO3Fguanidinium fluorosulfinateSHQ: 5 × KDP; birefringence: 0.133@1064 nmS4(SO3F)2tetrasulfur fluorosulfateS2O6F2bis(fluorosulfuryl) peroxideNaSO3Fsodium fluorosulfateHexagonal a=5.4812 b=5.4812 c=6.5172 V=169.57 Z=2 D=2.390Mg(SO3F)2magnesium fluorosulfonateSO3Al(SO3F)2.3CH3CNAl(SO3F)3aluminium fluorosulfatewhitepolymeric, fluorosulfate is bidentate and bridgedSi(SO3F)4silicon tetrafluorosulfonateS2O5F2SiO2PVO(SO3F)3phosphoryl trifluorosulfonateS2O5F2PO(SO3F)ClSO3Fchlorosulfuryl fluorideClO2SO3Fchloryl fluorosulfatered or pale yellowlow melting pointKSO3Fpotassium fluorosulfatePnma a=8.62 b=5.84 c=7.35 V=92.5Ca(SO3F)2CaF2 SO3TiIV(SO3F)4titanium tetrafluorosulfonatetitanium(IV) fluorosulfonateS2O5F2VO(SO3F)3deep red liquidCrVIO2(SO3F)2chromyl fluorosulfategreen or brownMn(SO3F)2MnO(SO3F)brownish blackMn(SO3F)3MnI(CO)4(SO3F)MnI(CO)5(SO3F)Rb2Mn(SO3F)5Cs2Mn(SO3F)5FeIII(SO3F)3ferric fluorosulfategreen grey230S2O5F2SO3FeF3CoO(SO3F)chocolate brownNi(SO3F)2Ni(py)4(SO3F)2 py=pyridineNiO(SO3F)dark greyCuII(SO3F)2cupric fluorosulfatecopper(II) fluorosulfatepale yellow/white210S2O5F2SO3CuSO4CuF2CuII(py)4(SO3F)2 py=pyridineCu(SO3F).CH3CNZn(SO3F)2zinc fluorosulfatewhite280SO3ZnF2Zn(py)4(SO3F)2 py=pyridineGaIII(SO3F)3gallium fluorosulfatewhite240SO3polymericAsIII(SO3F)3arsenic trifluorosulfonatearsenic(III) fluorosulfonateS2O5F2AsVF2(SO3F)3AsVF3(SO3F)2BrSO3Fbromosulfuryl fluoridered liquidRbSO3Frubidium fluorosulfateOrthorhombic Pnma a=8.7812 b=6.0318 c=7.5108 V=397.82 Z=4 D=3.081Sr(SO3F)2SO2F2MoO2(SO3F)2NbV(SO3F)5niobium pentafluorosulfonateniobium(V) fluorosulfatecolourless solution25SO3NbO(SO3F)3yellow liquidRu(SO3F)3very dark redCsRu(SO3F)4dark brownClO2Ru(SO3F)4blackCsRu(SO3F)5red brownCs2Ru(SO3F)6bright orangeK2Ru(SO3F)6bright orangeRh(SO3F)3bright orange190Pd(SO3F)2purple250SO3 PdF2Pd(SO3F)3dark brown180Pd(CO)2(SO3F)2bis(carbonyl)palladium(II) fluorosulfateyellowc-Pd2(μ-CO)2](SO3F)2cyclo-Bis(μ-carbonyl)dipalladium(I) Fluorosulfateorangemonoclinic C2/c a=11.495 b=8.255 c=9.556 β =91.94 Z=8AgISO3Fsilver fluorosulfateP21/m a=5.413 b=8.174 c=7.544 β=94.60 V=83.17 Z=4AgII(SO3F)2silver(II) fluorosulfatedark brownroom temperaturefast >120Ag3(SO3F)4SO3F•monoclinic a=10.5130 Å, b= 7.7524 Å, c = 8.9366 Å, β = 117.867° V =643.88 Å3, Z = 4, d = 3.15 gcm−3Ag2O(SO3F)2blacksilver(I, II) fluorosulfateblackKAgI2AgII(SO3F)5orthorhombic P 2221, a = 6.4736 b = 7.3915 c = 17.7736RbAgI2AgII(SO3F)5orthorhombic P 2221, a = 6.4828 b = 7.3551c = 18.0262RbAgII(SO3F)3monoclinic P 21/m , a = 15.815 b = 15.486 c = 17.021 β = 101.513CsAgII(SO3F)3triclinic P1_ , a = 14.9241 b = 9.7046 c = 17.8465 α = 109.116°, β = 84.655° γ = 119.171°Cd(SO3F)2InIII(SO3F)3Indium tri(fluorosulfate)polymericSnIV(SO3F)4tin tetrafluorosulfonatetin(IV) fluorosulfonateS2O5F2SbF4SO3FSb(SO3F)2.2CH3CNCs[Sb(SO3F)6]Cesium hexakis(fluorosulfato)antimonate(V)trigonal, R3̄ a = 12.0317 Å, c = 12.026 Å, Z = 3TeF5SO3FISO3FICl2SO3FIBr2SO3Frust brown90ISO3F, Br2IO2SO3Fiodyl fluorosulfate100yellowIVF3(SO3F)2iodine trifluoride bisfluorosulfonateFXe(SO3F)XeII(SO3F)2xenon(II) fluorosulfateF5XeVI(SO3F)CsSO3Fcaesium fluorosulfatel41/a a=5.611 b=5.611 c=14.13 V=111.3 Z=4Cs[H(SO3F)2]Ba(SO3F)2BaSO4 SO2F2Ho(SO3F)3holmium fluorosulfateTaV(SO3F)5tantalum pentafluorosulfonatepentakis(fluorosulfonato)tantalum(V)colourless solutionTaVO(SO3F)3yellow liquidWVIO(SO3F)4oxo tetrakis(fluorosulfato)tungsten(VI)colourless liquidReVIIO2(SO3F)3dioxo trisfluorosulfato rhenium(VII)white solidReVIIO3(SO3F)trioxo fluorosulfato rhenium(VII)yellow liquidReI(CO)5(SO3F)Os(SO3F)3bright green130Ir(SO3F)3Ir(SO3F)4Cs2Ir(SO3F)6BaIr(SO3F)6(ClO2)2Ir(SO3F)6mer-Ir(CO)3(SO3F)3mer-Tris(carbonyl)iridium(III) FluorosulfatecolourlessMonoclinic P21/c, Z = 4, a = 8.476 b = 12.868 c = 12.588 β = 108.24°, V = 1304.0 MW 573.42Pt(SO3F)4Cs2[Pt(SO3F)6]cesium hexakis(fluorosulfato)platinate(IV)Pt(CO)2(SO3F)2bis(carbonyl)platinum(II) fluorosulfatecreamy whiteAuICO(SO3F)AuII(SO3F)2gold(II) fluorosulfateyellow redAuIII(SO3F)3Cs[Au(SO3F)4]Cesium Tetrakis(fluorosulfato)aurate(III)monoclinic, C2/c a = 17.725 Å, b = 5.822 Å, c = 14.624 Å, β = 102.120°, Z = 4Hg(SO3F)2mercuric fluorosulfatedensity 3.715TlSO3Fthallium fluorosulfateOrthorhombic a=5.2205 b=5.5141 c=13.4378 V=386.83 Z=4 D=5.210TlO(SO3F)brownTlIII(SO3F)3thallium tri(fluorosulfate)thallium(III) fluorosulfonatePbIV(SO3F)4lead(IV) fluorosulfate(not consulted)BiIII(SO3F)3bismuth(III) fluorosulfatetris(fluorosulfonato)bismuth(III)(not consulted)ThIV(SO3F)4thorium(IV) fluorosulfateUII(SO3F)2yellowUIII(SO3F)3greenUIV(SO3F)4uranium(IV) fluorosulfatetanNa2UIV(SO3F)6UIVO(SO3F)2oxouranium(IV) fluorosulfateUVIO2(SO3F)2uranyl fluorosulfatedioxouranium(VI) fluorosulfate
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