Fluorosulfates Explained

The fluorosulfates or fluorosulfonates are a set of salts of fluorosulfuric acid with an ion formula SO₃F⁻. The fluorosulfate anion can be treated as though it were a hydrogen sulfate anion with hydroxyl substituted by fluorine.^[1] 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.^[2] Most metal ions, and quaternary ammonium ions, can form fluorosulfate salts.^[2] Different ways to make these salts include treating a metal chloride with anhydrous fluorosulfuric acid, which releases 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.^[2]

The fluorosulfate anion is weakly coordinating, and is 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 However, by the twenty-first century fluorosulfate was superseded in this use, in particular by BARF.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 including those of halogens and xenon.

Some pseudoternary fluorosulfates exist including Cs[Sb(SO₃F)₆], Cs[Au(SO₃F)₄], Cs₂[Pt(SO₃F)₆]

Related ionic compounds are the fluoroselenites SeO₃F⁻ and the fluorosulfites SO₂F⁻. The sulfate fluorides are distinct, as they contain fluoride ions without a bond to the sulfate groups.

One fluorosulfate containing mineral called reederite-(Y) exists. It is a mixed anion compound that also contains carbonate and chloride.^[3]

Compounds

Formula	Name	Colour	Decomposition temperature (°C)	Decomposition product	Crystal	Ref
LiSO3F	lithium fluorosulfate				C2/m a=8.54 b=7.62 c=4.98 β=90.0 V=81
Be(SO3F)2				SO3
CF3(SO3F)
CF2(SO3F)2
CF(SO3F)3
C(SO3F)4
NH4SO3F	ammonium fluorosulfate				Orthorhombic Pnma a=8.97 b=6.00 c=7.54 V=101.4 Z=4
	tetramethylammonium fluorosulfate				Orthorhombic Pnma a=8.38 b=8.38 c=5.86 V=102.88 Z=4
N^IIIOSO3F	nitrosyl fluorosulfonate		melts 156		density 1.96	^[4]
N^VO2SO3F	nitronium fluorosulfinate
S2O6F2	bis(fluorosulfuryl) peroxide
NaSO3F	sodium fluorosulfate				Hexagonal a=5.4812 b=5.4812 c=6.5172 V=169.57 Z=2 D=2.390
Mg(SO3F)2	magnesium fluorosulfonate			SO3
Al(SO3F)2.3CH3CN						^[5]
Al(SO3F)3	aluminium fluorosulfate	white			polymeric, fluorosulfate is bidentate and bridged	^[6]
Si(SO3F)4	silicon tetrafluorosulfonate			S2O5F2 SiO2		^[7]
P^VO(SO3F)3	phosphoryl trifluorosulfonate			S2O5F2
PO(SO3F)
ClSO3F	chlorosulfuryl fluoride
ClO2SO3F	chloryl fluorosulfate	red or pale yellow	low melting point			^[8]
KSO3F	potassium fluorosulfate				Pnma a=8.62 b=5.84 c=7.35 V=92.5
Ca(SO3F)2				CaF2 SO3
Ti^IV(SO3F)4	titanium tetrafluorosulfonate titanium(IV) fluorosulfonate			S2O5F2
VO(SO3F)3		deep red liquid				^[9] ^[10]
Cr^VIO2(SO3F)2	chromyl fluorosulfate	green or brown				^[11]
Mn(SO3F)2
MnO(SO3F)		brownish black
Mn(SO3F)3						^[12]
Mn^I(CO)4(SO3F)
Mn^I(CO)5(SO3F)
Rb2Mn(SO3F)5
Cs2Mn(SO3F)5
Fe^III(SO3F)3	ferric fluorosulfate	green grey	230	S2O5F2 SO3 FeF3		^[13]
CoO(SO3F)		chocolate brown
Ni(SO3F)2
Ni(py)4(SO3F)2 py=pyridine						^[14]
NiO(SO3F)		dark grey
Cu^II(SO3F)2	cupric fluorosulfate copper(II) fluorosulfate	pale yellow/white	210	S2O5F2 SO3 CuSO4 CuF2
Cu^II(py)4(SO3F)2 py=pyridine
Cu(SO3F).CH3CN
Zn(SO3F)2	zinc fluorosulfate	white	280	SO3 ZnF2
Zn(py)4(SO3F)2 py=pyridine
Ga^III(SO3F)3	gallium fluorosulfate	white	240	SO3	polymeric	^[15] ^[16]
As^III(SO3F)3	arsenic trifluorosulfonate arsenic(III) fluorosulfonate			S2O5F2
As^VF2(SO3F)3
As^VF3(SO3F)2
BrSO3F	bromosulfuryl fluoride	red liquid
RbSO3F	rubidium fluorosulfate				Orthorhombic Pnma a=8.7812 b=6.0318 c=7.5108 V=397.82 Z=4 D=3.081
Sr(SO3F)2				SO2F2
MoO2(SO3F)2
Nb^V(SO3F)5	niobium pentafluorosulfonate niobium(V) fluorosulfate	colourless solution	25	SO3		^[17]
NbO(SO3F)3		yellow liquid
Ru(SO3F)3		very dark red				^[18]
CsRu(SO3F)4		dark brown
ClO2Ru(SO3F)4		black
CsRu(SO3F)5		red brown
Cs2Ru(SO3F)6		bright orange
K2Ru(SO3F)6		bright orange
Rh(SO3F)3		bright orange	190			^[19]
Pd(SO3F)2		purple	250	SO3 PdF2		^[20]
Pd(SO3F)3		dark brown	180
Pd(CO)2(SO3F)2	bis(carbonyl)palladium(II) fluorosulfate	yellow
c-Pd2(μ-CO)2](SO3F)2	cyclo-Bis(μ-carbonyl)dipalladium(I) Fluorosulfate	orange			monoclinic C2/c a=11.495 b=8.255 c=9.556 β =91.94 Z=8	^[21]
Ag^ISO3F	silver fluorosulfate				P21/m a=5.413 b=8.174 c=7.544 β=94.60 V=83.17 Z=4
Ag^II(SO3F)2	silver(II) fluorosulfate	dark brown	room temperature fast >120	Ag3(SO3F)4 SO3F^•	monoclinic a=10.5130 Å, b= 7.7524 Å, c = 8.9366 Å, β = 117.867° V =643.88 Å^3, Z = 4, d = 3.15 gcm^−3	^[22]
Ag2O(SO3F)2	black
	silver(I, II) fluorosulfate	black
KAg^I2Ag^II(SO3F)5					orthorhombic P 2221, a = 6.4736 b = 7.3915 c = 17.7736	^[23]
RbAg^I2Ag^II(SO3F)5					orthorhombic P 2221, a = 6.4828 b = 7.3551c = 18.0262
RbAg^II(SO3F)3					monoclinic P 21/m, a = 15.815 b = 15.486 c = 17.021 β = 101.513
CsAg^II(SO3F)3					triclinic P1_, a = 14.9241 b = 9.7046 c = 17.8465 α = 109.116°, β = 84.655° γ = 119.171°
Cd(SO3F)2
In^III(SO3F)3	Indium tri(fluorosulfate)				polymeric	^[24]
Sn^IV(SO3F)4	tin tetrafluorosulfonate tin(IV) fluorosulfonate			S2O5F2
SbF4SO3F
Sb(SO3F)2.2CH3CN
Cs[Sb(SO<sub>3</sub>F)<sub>6</sub>]	Cesium hexakis(fluorosulfato)antimonate(V)				trigonal, R3̄ a = 12.0317 Å, c = 12.026 Å, Z = 3
TeF5SO3F
ISO3F						^[25]
ICl2SO3F
IBr2SO3F		rust brown	90	ISO3F, Br2
IO2SO3F	iodyl fluorosulfate		100		yellow	^[26]
I^VF3(SO3F)2	iodine trifluoride bisfluorosulfonate
FXe(SO3F)
Xe^II(SO3F)2	xenon(II) fluorosulfate					^[27]
F5Xe^VI(SO3F)
CsSO3F	caesium fluorosulfate				l41/a a=5.611 b=5.611 c=14.13 V=111.3 Z=4
Cs[H(SO<sub>3</sub>F)<sub>2</sub>]						^[28]
Ba(SO3F)2				BaSO4 SO2F2
Ho(SO3F)3	holmium fluorosulfate					^[29]
Ta^V(SO3F)5	tantalum pentafluorosulfonate pentakis(fluorosulfonato)tantalum(V)	colourless solution
Ta^VO(SO3F)3		yellow liquid
W^VIO(SO3F)4	oxo tetrakis(fluorosulfato)tungsten(VI)	colourless liquid				^[30]
Re^VIIO2(SO3F)3	dioxo trisfluorosulfato rhenium(VII)	white solid
Re^VIIO3(SO3F)	trioxo fluorosulfato rhenium(VII)	yellow liquid
Re^I(CO)5(SO3F)
Os(SO3F)3		bright green	130
Ir(SO3F)3						^[31]
Ir(SO3F)4						^[32]
Cs2Ir(SO3F)6
BaIr(SO3F)6
(ClO2)2Ir(SO3F)6
mer-Ir(CO)3(SO3F)3	mer-Tris(carbonyl)iridium(III) Fluorosulfate	colourless			Monoclinic P21/c, Z = 4, a = 8.476 b = 12.868 c = 12.588 β = 108.24°, V = 1304.0 MW 573.42
Pt(SO3F)4						^[33]
Cs2[Pt(SO<sub>3</sub>F)<sub>6</sub>]	cesium hexakis(fluorosulfato)platinate(IV)
Pt(CO)2(SO3F)2	bis(carbonyl)platinum(II) fluorosulfate	creamy white
Au^ICO(SO3F)
Au^II(SO3F)2	gold(II) fluorosulfate	yellow red				^[34]
Au^III(SO3F)3
Cs[Au(SO<sub>3</sub>F)<sub>4</sub>]	Cesium Tetrakis(fluorosulfato)aurate(III)				monoclinic, C2/c a = 17.725 Å, b = 5.822 Å, c = 14.624 Å, β = 102.120°, Z = 4
Hg(SO3F)2	mercuric fluorosulfate				density 3.715
TlSO3F	thallium fluorosulfate				Orthorhombic a=5.2205 b=5.5141 c=13.4378 V=386.83 Z=4 D=5.210
TlO(SO3F)		brown
Tl^III(SO3F)3	thallium tri(fluorosulfate) thallium(III) fluorosulfonate
Pb^IV(SO3F)4	lead(IV) fluorosulfate					^[35]
Bi^III(SO3F)3	bismuth(III) fluorosulfate tris(fluorosulfonato)bismuth(III)					^[36]
Th^IV(SO3F)4	thorium(IV) fluorosulfate
U^II(SO3F)2					yellow	^[37]
U^III(SO3F)3					green
U^IV(SO3F)4	uranium(IV) fluorosulfate				tan	^[38]
Na2U^IV(SO3F)6
U^IVO(SO3F)2	oxouranium(IV) fluorosulfate
U^VIO2(SO3F)2	uranyl fluorosulfate dioxouranium(VI) fluorosulfate

Notes and References

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