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{{short description|Chemical compound}} |
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| verifiedrevid = 390833027 |
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| Name = Niobium(V) chloride |
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| verifiedrevid = 431997260 |
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| ImageFile = Niobium pentachloride solid.jpg |
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| Name = Niobium(V) chloride |
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| ImageFile = Niobium pentachloride solid.jpg |
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| ImageName = Sample of niobium(V) chloride |
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| ImageFile1 = Niobium-pentachloride-dimer-2D.png |
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| ImageName = Sample of niobium(V) chloride |
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| ImageFile1 = Niobium-pentachloride-dimer-2D.png |
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<!-- ImageFile2 = Niobium pentachloride2.jpg --> |
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<!-- ImageFile2 = Niobium pentachloride2.jpg --> |
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| ImageName2 = Niobium pentachloride liquid and vapor |
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| ImageName2 = Niobium pentachloride liquid and vapor |
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| IUPACName = Niobium(V) chloride<br/>Niobium pentachloride |
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| IUPACName = Niobium(V) chloride<br/>Niobium pentachloride |
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| Section1 = {{Chembox Identifiers |
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|Section1={{Chembox Identifiers |
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| CASNo1_Ref = {{cascite|correct|chemspider}} |
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| CASNo = 10026-12-7 |
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| CASNo1 = 10026-12-7 |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| CASNo1_Comment = NbCl<sub>5</sub> |
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| EINECS = 233-059-8 |
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| CASNo_Ref = {{cascite}} |
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| RTECS = QU0350000 |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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| UNII = 9S1BC7865F |
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| EINECS = 233-059-8 |
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| RTECS = QU0350000 |
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| PubChem = 24818 |
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| ChemSpiderID = 23203 |
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| StdInChI=1S/5ClH.Nb/h5*1H;/q;;;;;+5/p-5 |
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| StdInChIKey = YHBDIEWMOMLKOO-UHFFFAOYSA-I |
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| SMILES = Cl(Cl)(Cl)(Cl)Cl |
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| SMILES1 = Cl1(Cl)(Cl)(Cl)(1)(Cl)(Cl)(Cl)Cl |
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| SMILES1_Comment = ] |
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| Section2 = {{Chembox Properties |
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|Section2={{Chembox Properties |
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| Formula = NbCl<sub>5</sub> |
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| Formula = NbCl<sub>5</sub> |
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| Appearance = yellow ] crystals <br> ] |
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| Appearance = yellow ] crystals <br /> ] |
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| MolarMass = 270.17 g/mol |
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| MolarMass = 270.17 g/mol |
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| Density = 2.75 g/cm<sup>3</sup> |
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| Density = 2.75 g/cm<sup>3</sup> |
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| Solubility = decomposes |
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| Solubility = decomposes |
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| SolubleOther = soluble in ], ], ], ] |
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| SolubleOther = ], ], ] |
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| MeltingPt = 204.7 °C |
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| MeltingPtC = 204.7 |
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| BoilingPt = 248.2 °C |
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| BoilingPtC = 248.2 |
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| Section4 = {{Chembox Thermochemistry |
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|Section4={{Chembox Thermochemistry |
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| DeltaHf = -797.47 kJ/mol |
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| DeltaHf = -797.47 kJ/mol |
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| Entropy = 214.05 J K<sup>−1</sup> mol<sup>−1</sup> |
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| Entropy = 214.05 J K<sup>−1</sup> mol<sup>−1</sup> |
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| Section7 = {{Chembox Hazards |
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|Section7={{Chembox Hazards |
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| ExternalMSDS = |
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| ExternalSDS = |
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| FlashPt = Non-flammable |
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| EUIndex = Not listed |
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| PEL = |
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| FlashPt = Non-flammable |
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| GHSPictograms = {{GHS05}}{{GHS07}} |
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| PEL = |
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| GHSSignalWord = Danger |
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| HPhrases = {{H-phrases|302|312|314|332}} |
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| 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}} |
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| Section8 = {{Chembox Related |
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|Section8={{Chembox Related |
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| OtherAnions = ]<br/>]<br/>] |
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| OtherAnions = ]<br/>]<br/>] |
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| OtherCations = ]<br/>] |
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| OtherCations = ]<br/>] |
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| OtherFunctn = ]<br/>] |
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| OtherFunction = ]<br/>] |
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| Function = niobium chlorides |
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| OtherFunction_label = niobium chlorides |
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'''Niobium(V) chloride''', also known as '''niobium pentachloride''', is a yellow crystalline solid. It hydrolyzes in air, and samples are often contaminated with small amounts of NbOCl<sub>3</sub>. It is often used as a precursor to other compounds of ]. NbCl<sub>5</sub> may be purified by ].<ref>{{Cotton&Wilkinson4th}}</ref> |
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'''Niobium(V) chloride''', also known as '''niobium pentachloride''', is a yellow crystalline solid. It hydrolyzes in air, and samples are often contaminated with small amounts of ]. It is often used as a precursor to other compounds of ]. NbCl<sub>5</sub> may be purified by ].<ref>{{Cotton&Wilkinson4th}}</ref> |
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==Structure and properties== |
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==Structure and properties== |
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Niobium(V) chloride forms chloro-bridged dimers in the solid state (''see'' figure). Each niobium centre is six-coordinate, but the octahedral coordination is significantly distorted. The equatorial niobium–chlorine ]s are 225 pm (terminal) and 256 pm (bridging), whilst the axial niobium-chlorine bonds are 229.2 pm and are deflected inwards to form an angle of 83.7° with the equatorial plane of the molecule. The Nb–Cl–Nb ] at the bridge is 101.3°. The Nb–Nb distance is 398.8 pm, too long for any metal-metal interaction.<ref name = cotton>{{cite journal | author = Cotton, F.A., P. A. Kibala, M. Matusz and R. B. W. Sandor | year = 1991 | title = Structure of the Second Polymorph of Niobium Pentachloride | journal = ] | volume = C47 | pages = 2435–2437 | doi = 10.1107/S0108270191000239}}</ref> NbBr<sub>5</sub>, ] and TaBr<sub>5</sub> are isostructural with NbCl<sub>5</sub>, but NbI<sub>5</sub> and TaI<sub>5</sub> have different structures. |
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Niobium(V) chloride forms chloro-bridged dimers in the solid state (''see'' figure). Each niobium centre is six-coordinate, but the octahedral coordination is significantly distorted. The equatorial niobium–chlorine ]s are 225 pm (terminal) and 256 pm (bridging), whilst the axial niobium-chlorine bonds are 229.2 pm and are deflected inwards to form an angle of 83.7° with the equatorial plane of the molecule. The Nb–Cl–Nb ] at the bridge is 101.3°. The Nb–Nb distance is 398.8 pm, too long for any metal-metal interaction.<ref name = cotton>{{cite journal | author = Cotton, F.A., P. A. Kibala, M. Matusz and R. B. W. Sandor | year = 1991 | title = Structure of the Second Polymorph of Niobium Pentachloride | journal = ] | volume = 47 | pages = 2435–2437 | doi = 10.1107/S0108270191000239 | issue = 11}}</ref> NbBr<sub>5</sub>, NbI<sub>5</sub>, ] TaBr<sub>5</sub> and TaI<sub>5</sub> are isostructural with NbCl<sub>5</sub>. |
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==Preparation== |
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==Preparation== |
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Industrially, niobium pentachloride is obtained by direct chlorination of niobium metal at 300 to 350 °C:<ref name=Ullmann>Joachim Eckert, Hermann C. Starck "Niobium and Niobium Compounds" Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. {{DOI|10.1002/14356007.a17_251}}</ref> |
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Industrially, niobium pentachloride is obtained by direct chlorination of niobium metal at 300 to 350 °C:<ref name=Ullmann>{{cite encyclopedia|author=Joachim Eckert |author2=Hermann C. Starck |chapter=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=3-527-30673-0}}</ref> |
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:2 Nb + 5 Cl<sub>2</sub> → 2 NbCl<sub>5</sub> |
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:2{{nbsp}}Nb + 5{{nbsp}}Cl<sub>2</sub> → 2{{nbsp}}NbCl<sub>5</sub> |
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In the laboratory, niobium pentachloride is often prepared from Nb<sub>2</sub>O<sub>5</sub>, the main problem being incomplete reaction to give the oxyhalides. The conversion can be effected with ]:<ref>D. Brown "Niobium(V) Chloride and Hexachloroniobates(V)" Inorganic Syntheses, 1957 Volume 9, pp. 88–92.{{DOI|10.1002/9780470132401.ch24}}</ref> It also can be prepared by chlorination of ] in the presence of carbon at 300°C. The products, however, contain small amounts of ]. |
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In the laboratory, niobium pentachloride is often prepared from Nb<sub>2</sub>O<sub>5</sub>, the main challenge being incomplete reaction to give ]. The conversion can be effected with ]:<ref>{{cite book|doi=10.1002/9780470132401.ch24|volume=9|chapter=Niobium(V) Chloride and Hexachloroniobates(V)|year=1957|last1=Brown|first1=D.|title=Inorganic Syntheses|pages=88–92|isbn=978-0-470-13240-1}}</ref> It also can be prepared by chlorination of ] in the presence of carbon at 300 °C. |
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==Uses== |
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==Uses== |
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Niobium(V) chloride is the main precursor to the alkoxides of niobium, which find niche uses in sol-gel processing. It is also the precursor to many other laboratory reagents. |
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Niobium(V) chloride is the main precursor to the alkoxides of niobium, which find uses in ]. It is also the precursor to many other Nb-containing reagents, including most ]s. |
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In ], NbCl<sub>3</sub> is a specialized ] in activating ]s for the ] and the ] reaction. Niobium chloride can also generate N-acyliminium compounds from certain ]s which are substrates for ]s such as allyltrimethylsilane, ], or the ] of ].<ref>{{cite journal | author = Andrade, C. K. Z.; Rocha, R. O.; Russowsky, D.; & Godoy, M. N. | year = 2005 | title = Studies on the Niobium Pentachloride-Mediated Nucleophilic Additions to an Enantiopure Cyclic N-acyliminium Ion Derived from (''S'')-malic acid | journal = J. Braz. Chem. Soc. | volume = 16 | pages = 535–539 | url = http://jbcs.sbq.org.br/online/2005/vol16_n3B/06-144-04.pdf | doi = 10.1590/S0103-50532005000400007}}</ref> |
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In ], NbCl<sub>5</sub> is a very specialized ] in activating ]s for the ] and the ] reaction. Niobium chloride can also generate N-acyliminium compounds from certain ]s which are substrates for ]s such as allyltrimethylsilane, ], or the ] of ].<ref>{{cite journal | author1 = Andrade, C. K. Z. | author2 = Rocha, R. O. | author3 = Russowsky, D. | author4 = Godoy, M. N. | name-list-style = amp | year = 2005 | title = Studies on the Niobium Pentachloride-Mediated Nucleophilic Additions to an Enantiopure Cyclic N-acyliminium Ion Derived from (''S'')-malic acid | journal = J. Braz. Chem. Soc. | volume = 16 | pages = 535–539 | doi = 10.1590/S0103-50532005000400007 | issue = 3b | doi-access = free | hdl = 10183/24558 | hdl-access = free }}</ref> |
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==References== |
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==References== |
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{{Niobium compounds}} |
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{{Niobium compounds}} |
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{{Chlorides}} |
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