Niobium(V) fluoride
{{chembox
| Watchedfields = changed
| verifiedrevid = 436917297
| Name = Niobium(V) fluoride
| ImageFile = Niobium(V) fluoride.png
| ImageSize = 300px
| ImageName =
| ImageFile1 =
| IUPACName = Niobium(V) fluoride
Niobium pentafluoride
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|??}}
| CASNo = 7783-68-8
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = T86H76439H
| PubChem = 82217
| EINECS = 232-020-2
| RTECS =
| ChemSpiderID = 74197
| StdInChI=1S/5FH.Nb/h5*1H;/q;;;;;+5/p-5
| StdInChIKey = AOLPZAHRYHXPLR-UHFFFAOYSA-I
| SMILES = F[Nb](F)(F)(F)F
}}
|Section2={{Chembox Properties
|Nb=1|F=5
| Appearance = colorless hygroscopic solid
| MolarMass =
| Density = 3.293 g/cm3
| Solubility = reacts
| SolubleOther = slightly soluble in chloroform, carbon disulfide, sulfuric acid
| MeltingPtC = 72 to 73
| MeltingPt_notes =
| BoilingPtC = 236
}}
|Section4={{Chembox Thermochemistry
| DeltaHf =
| Entropy =
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|Section7={{Chembox Hazards
| ExternalSDS =
| FlashPt = Non-flammable
| PEL =
| GHSPictograms = {{GHS05}}{{GHS07}}
| GHSSignalWord = Warning
| HPhrases = {{H-phrases|302|312|314|332}}
| PPhrases = {{P-phrases|260|261|264|270|271|280|301+312|301+330+331|302+352|303+361+353|304+312|304+340|305+351+338|310|312|321|322|330|363|405|501}}
}}
|Section8={{Chembox Related
| OtherAnions = Niobium(V) chloride
Niobium(V) bromide
Niobium(V) iodide
| OtherCations = Vanadium(V) fluoride
Tantalum(V) fluoride
| OtherFunction = Niobium(III) fluoride
Niobium(IV) fluoride
| OtherFunction_label = niobium fluorides
}}
}}
Niobium(V) fluoride, also known as niobium pentafluoride, is the inorganic compound with the formula NbF5. It is a colorless solid.{{cite encyclopedia|author1=Joachim Eckert |author2=Hermann C. Starck|title=Niobium and Niobium Compounds|encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry|year=2005|publisher=Wiley-VCH|place=Weinheim|doi=10.1002/14356007.a17_251|isbn=3527306730}}
Preparation and structure
Niobium pentafluoride is obtained by treatment of any niobium compound with fluorine:{{cite book|chapter=Anhydrous Metal Fluorides|author=Homer F. Priest|title=Inorganic Syntheses |year=1950|volume=3|page=171|doi=10.1002/9780470132340.ch47}}
:2 Nb + 5 F2 → 2 NbF5
:2 NbCl5 + 5 F2 → 2 NbF5 + 5 Cl2
As shown by X-ray crystallography, the solid consists of tetramers [NbF5]4. This structure is related to that for WOF4.{{cite journal |doi=10.1039/jr9640003714 |title=717. The structures of niobium and tantalum pentafluorides |year=1964 |last1=Edwards |first1=A. J. |journal=Journal of the Chemical Society (Resumed) |page=3714 }}
Reactions
It reacts with hydrogen fluoride to give H2NbF7, a superacid. In hydrofluoric acid, NbF5 converts to [NbF7]2- and [NbF5O]2-. The relative solubility of {{chem2|K2[MFO]}} (M = Nb, Ta) is the basis of the Marignac process for separation of Nb and Ta.
NbCl5 forms a dimeric structure (edge-shared bioctahedron) in contrast to the corner-shared tetrameric structure of the fluoride.
External links
- [http://webbook.nist.gov/chemistry/ NIST Standard Reference Database]
References
{{Niobium compounds}}
{{fluorine compounds}}