Hexafluorotitanic acid

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| ImageFile = (H3O)(H5O2)TiF6.svg

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| IUPACName = Hexafluorotitanic acid

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| Section1 = {{Chembox Identifiers

| CASNo = 17439-11-1

| CASNo_Ref = {{Cascite|changed|ECHA}}

| index_label = anhydrous

| ChemSpiderID = 19989125

| EC_number = 241-460-4

| PubChem = 161221

| SMILES = [H+].[H+].F[Ti-2](F)(F)(F)(F)F

| InChI = 1/6FH.Ti/h6*1H;/q;;;;;;+4/p-4/f6F.Ti.2H/h6*1h;;;/q6*-1;m;2*+1

| StdInChIKey = PFSXARRIPPWGNC-UHFFFAOYSA-J

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| Section2 = {{Chembox Properties

| H=8 | Ti=1 | F=6|O=3

| MolarMass =

| Appearance = colorless solid

| Density = 2.10 g/cm³

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| Section3 = {{Chembox Hazards

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| Section8 = {{Chembox Related

| OtherAnions = Hexafluorosilicic acid
Ammonium hexafluorotitanate

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Hexafluorotitanic acid (systematically named oxonium hexafluoridotitanate(2-)) is an inorganic compound with the chemical formula (H₃O)(H₅O₂)[TiF₆]. According to X-ray crystallography, the salt consists of [TiF₆]^2- octahedral and two kinds of oxonium cations, (H₃O)⁺ and (H₅O₂)⁺.{{cite journal |doi=10.1002/zaac.19885640103|title=Hexafluorotitan(IV)-Saure: Untersuchungen zur Bildung und Struktur kristalliner Hydrate |year=1988 |last1=Mootz |first1=D. |last2=Oellers |first2=E.-J. |last3=Wiebcke |first3=M. |journal=Zeitschrift für Anorganische und Allgemeine Chemie |volume=564 |pages=17–25 }}

As with most oxonium salts, it is only stable in acidic solution. Under basic conditions, closely related salts hydrolyse to a hydrated titanium dioxide:{{cite book |doi=10.1002/9780470132364.ch22|chapter=Extraction of Titanium(IV) Oxide from Ilmenite |year=1957 |last1=Bichowsky |first1=Foord Von |title=Inorganic Syntheses |pages=79–82 |isbn=9780470132364|volume=V }}

:{{chem2|(NH4)2TiF6 + 4 NH3 + 2 H2O -> TiO2 + 6 NH4F}}

A related salt is the anhydrous fluoronium hexafluoridotitanate(2-) or (H₂F)₂[TiF₆].