(inorganic chemistry) SbF5 A corrosive, hygroscopic, moderately viscous fluid; reacts violently with water; forms a clear solution with glacial acetic acid; used in the fluorination of organic compounds.
| Antimony pentafluoride | |
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antimony(V) fluoride |
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Other names
antimony pentafluoride |
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| Identifiers | |
| CAS number | 7783-70-2 |
| ChemSpider | 10617727 |
| UN number | 1732 |
| RTECS number | CC5800000 |
| Jmol-3D images | Image 1 Image 2 |
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| Properties | |
| Molecular formula | SbF5 |
| Molar mass | 216.74 g/mol |
| Appearance | colorless oily liquid hygroscopic |
| Odor | pungent |
| Density | 2.99 g/cm3 [1] |
| Melting point |
8.3 °C, 281 K, 47 °F |
| Boiling point |
149.5 °C, 423 K, 301 °F |
| Solubility in water | Reacts |
| Solubility | soluble in KF, liquid SO2 |
| Hazards | |
| MSDS | ICSC 0220 |
| EU Index | 051-003-00-9 |
| EU classification | Harmful (Xn) Dangerous for the environment (N) |
| R-phrases | R20/22, R51/53 |
| S-phrases | (S2), S61 |
| NFPA 704 | |
| Related compounds | |
| Other anions | Antimony pentachloride |
| Other cations | Phosphorus pentafluoride Arsenic pentafluoride Bismuth pentafluoride |
| Related compounds | Antimony trifluoride |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Antimony pentafluoride is the inorganic compound with the formula SbF5. This colourless, viscous liquid is a valuable Lewis acid and a component of the superacid fluoroantimonic acid, the strongest known acid. It is notable for its Lewis acidity and its ability to react with almost all known compounds.[2]
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Contents
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Antimony pentafluoride is prepared by the reaction of antimony pentachloride with anhydrous hydrogen fluoride:[3]
It can also be prepared from antimony trifluoride and fluorine.[4]
In the gas phase, SbF5 adopts a trigonal bipyramidal structure of D3h point group symmetry (see picture). The material adopts a more complicated structure in the liquid and solid states. The liquid contains polymers wherein each Sb is octahedral, the structure being described with the formula [SbF4(μ-F)2]n ((μ-F) denotes the fact that fluoride centres bridge two Sb centres). The crystalline material is a tetramer, meaning that it has the formula [SbF4(μ-F)]4. The Sb-F bonds are 2.02 Å within the eight-membered Sb4F4 ring; the remaining fluoride ligands radiating from the four Sb centers are shorter at 1.82 Å.[5] The related species PF5 and AsF5 are monomeric in the solid and liquid states, probably due to the smaller sizes of the central atom, which limits their coordination number. BiF5 is a polymer.[6]
SbF5 is a strong Lewis acid, exceptionally so toward sources of F− to give the very stable anion [SbF6]−, called hexafluoroantimonate. [SbF6]− reacts with additional SbF5 to give [Sb2F11]−:
In the same way that SbF5 enhances the Brønsted acidity of HF, it enhances the oxidizing power of F2. This effect is illustrated by the oxidation of oxygen:[7]
Antimony pentafluoride has also been used in the first discovered chemical reaction that produces fluorine gas from fluoride compounds:
The driving force for this reaction is the high affinity of SbF5 for F−, which is the same property that recommends the use of SbF5 to generate superacids.
SbF5 reacts violently with many compounds, often releasing dangerous hydrogen fluoride. It is corrosive to the skin and eyes.[8][9]
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