Tantalum(V) chloride: Difference between revisions
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| Section1 = {{Chembox Identifiers |
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| CASNo = 7721-01-9 |
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| Section1 = {{Chembox Identifiers |
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| CASNo1_Ref = {{cascite|correct|CAS}} |
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| CASNo1 = 7721-01-9 |
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| CASNo1_Comment = TaCl<sub>5</sub> |
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| CASNo2_Ref = {{cascite|changed|??}} |
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| CASNo2 = 17499-29-5 |
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| CASNo2_Comment = Ta<sub>2</sub>Cl<sub>10</sub> |
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| CASNo_Ref = {{cascite}} |
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| ChemSpiderID = 22805 |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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| UNII = 9WXV40ZI4M |
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| PubChem = 24394 |
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| RTECS = |
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| InChI = 1S/5ClH.Ta/h5*1H;/q;;;;;+5/p-5 |
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| StdInChIKey = OEIMLTQPLAGXMX-UHFFFAOYSA-I |
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| SMILES = Cl[Ta](Cl)(Cl)(Cl)Cl |
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| Section2 = {{Chembox Properties |
| Section2 = {{Chembox Properties |
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| Formula = TaCl<sub>5</sub> |
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| Appearance = white [[monoclinic]] crystals<ref>{{RubberBible87th}}</ref> |
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| MolarMass = 358.213 g/mol |
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| Density = 3.68 g/cm<sup>3</sup> |
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| Solubility = reacts |
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| Solubility = reacts |
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| Solvent = |
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| SolubleOther = [[chloroform]], [[carbon tetrachloride|CCl<sub>4</sub>]] |
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| MeltingPt = 216 °C |
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| MeltingPtC = 216 |
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| BoilingPt = 239.4 °C (decomp) |
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| BoilingPtC = 239.4 |
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| BoilingPt_notes = (decomposes) |
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| MagSus = {{val|+140.0e-6|u=cm<sup>3</sup>/mol}} |
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| Section3 = {{Chembox Structure |
| Section3 = {{Chembox Structure |
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| CrystalStruct = [[Monoclinic]], [[Pearson symbol|mS72]] |
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| SpaceGroup = C2/m, No. 12 |
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| Section4 = {{Chembox Thermochemistry |
| Section4 = {{Chembox Thermochemistry |
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| DeltaHf = -858.98 kJ/mol |
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| Entropy = 221.75 J K<sup>−1</sup> mol<sup>−1</sup> |
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| Section7 = {{Chembox Hazards |
| Section7 = {{Chembox Hazards |
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| ExternalSDS = [https://ereztech.com/wp-content/uploads/chemical_sds/SDS-TA1019.pdf External SDS] |
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| ExternalMSDS = |
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| NFPA-H = 3 |
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| NFPA-F = 0 |
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| NFPA-R = 0 |
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| NFPA-R = |
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| LD50 = 1900 mg/kg (oral, rat) |
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| NFPA-O = |
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| GHSPictograms = {{GHS05}}{{GHS07}} |
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| GHSSignalWord = Danger |
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| HPhrases = {{H-phrases|302|314}} |
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| PPhrases = {{P-phrases|280|305 + 351 + 338|310}} |
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| Section8 = {{Chembox Related |
| Section8 = {{Chembox Related |
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| OtherAnions = [[Tantalum(V) fluoride]]<br/>[[Tantalum(V) bromide]]<br/>[[Tantalum(V) iodide]] |
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| OtherCations = [[Vanadium(IV) chloride]]<br/>[[Niobium(V) chloride]] |
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| OtherCompounds = [[Tantalum(III) chloride]], [[Tantalum(IV) chloride]] |
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'''Tantalum(V) chloride''', also known as '''tantalum pentachloride''', is |
'''Tantalum(V) chloride''', also known as '''tantalum pentachloride''', is an [[inorganic compound]] with the formula TaCl<sub>5</sub>. It takes the form of a white powder and is commonly used as a starting material in [[tantalum]] chemistry. It readily [[Hydrolysis|hydrolyzes]] to form tantalum(V) [[oxychloride]] (TaOCl<sub>3</sub>) and eventually [[tantalum pentoxide]] (Ta<sub>2</sub>O<sub>5</sub>); this requires that it be synthesised and manipulated under [[anhydrous]] conditions, using [[air-free technique]]s. |
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==Structure== |
==Structure== |
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TaCl<sub>5</sub> crystallizes in the monoclinic space group ''C''2/''m''.<ref>{{cite journal | |
TaCl<sub>5</sub> crystallizes in the [[monoclinic]] [[space group]] ''C''2/''m''.<ref>{{cite journal |first1=Susanne|last1 = Rabe|first2=Ulrich|last2=Müller|title = Crystal structure of tantalum pentachloride, (TaCl<sub>5</sub>)<sub>2</sub>|journal = [[Z. Kristallogr. - New Cryst. Struct.]]|year = 2000|volume = 215|issue=1|pages=1–2|doi=10.1515/ncrs-2000-0102|doi-access=free}}</ref> The ten chlorine atoms define a pair of octahedra that share a common edge. The tantalum atoms occupy the centres of the octahedra and are joined by two chlorine [[bridging ligand]]s. The dimeric structure is retained in non-complexing solvents and to a large extent in the molten state. In the vapour state, however, TaCl<sub>5</sub> is [[monomer]]ic. This monomer adopts a [[Trigonal bipyramidal molecular geometry|trigonal bipyramidal structure]], like that of [[Phosphorus pentachloride|PCl<sub>5</sub>]].<ref>{{cite book | author = F. Fairbrother | title = The Chemistry of Niobium and Tantalum | url = https://archive.org/details/chemistryofniobi0000fair | url-access = registration | publisher = Elsevier | year = 1967}}</ref> |
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==Physical |
==Physical Properties== |
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The solubility of tantalum pentachloride increases |
The solubility of tantalum pentachloride increases slightly for the following series of [[aromatic hydrocarbon]]s: |
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: [[benzene]] < [[toluene]] < [[m-Xylene|''m''-xylene]] < [[mesitylene]] |
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This is reflected in the deepening of colour of the solutions from pale yellow to orange. Tantalum pentachloride is less soluble in [[cyclohexane]] and [[carbon tetrachloride]] than in the aromatic hydrocarbons. Such solutions of tantalum pentachloride are also known to be poor conductors of electricity, indicating little ionization. TaCl<sub>5</sub> is purified by [[Sublimation (physics)|sublimation]] to give white needles. |
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==Synthesis== |
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Tantalum pentachloride can be prepared by reacting powdered metallic [[tantalum]] with [[chlorine]] gas at between 170 and 250 °C. This reaction can also be performed using [[hydrogen chloride|HCl]] at 400 °C.<ref>{{cite journal|last1=Young|first1=Ralph C.|last2=Brubaker|first2=Carl H.|journal=[[Journal of the American Chemical Society]]|title = Reaction of Tantalum with Hydrogen Chloride, Hydrogen Bromide and Tantalum Pentachloride; Action of Hydrogen on Tantalum Pentachloride|year=1952|volume=74|issue=19|page=4967|doi=10.1021/ja01139a524}}</ref> |
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: 2 Ta + 5 Cl<sub>2</sub> → 2 TaCl<sub>5</sub> |
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: 2 Ta + 10 HCl → 2 TaCl<sub>5</sub> + 5 H<sub>2</sub> |
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It can also be prepared by a reaction between [[tantalum pentoxide]] and [[thionyl chloride]] at 240 °C |
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: Ta<sub>2</sub>O<sub>5</sub> + 5 SOCl<sub>2</sub> → 2 TaCl<sub>5</sub> + 5 [[Sulfur dioxide|SO<sub>2</sub>]] |
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Tantalum pentachloride is commercially available, however samples can be contaminated with tantalum(V) [[oxychloride]] (TaOCl<sub>3</sub>), formed by hydrolysis. |
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==Reactions== |
==Reactions== |
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TaCl<sub>5</sub> is |
TaCl<sub>5</sub> is [[Electrophile|electrophilic]] and it behaves like a [[Friedel–Crafts catalyst]], similar to [[Aluminium chloride|AlCl<sub>3</sub>]]. It forms [[adduct]]s with a variety of [[Lewis base]]s.<ref>[[F. Albert Cotton|F. A. Cotton]], [[Geoffrey Wilkinson|G. Wilkinson]], ''Advanced Inorganic Chemistry'' (4th ed.), Wiley, New York, '''1980'''.</ref> |
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===Simple adducts=== |
===Simple adducts=== |
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TaCl<sub>5</sub> forms stable complexes with ethers: |
TaCl<sub>5</sub> forms stable complexes with [[ethers]]: |
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:TaCl<sub>5</sub> + R<sub>2</sub>O → TaCl<sub>5</sub>(OR<sub>2</sub>) (R = Me, Et) |
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TaCl<sub>5</sub> also reacts with phosphorus pentachloride and phosphorus oxychloride, the former |
TaCl<sub>5</sub> also reacts with [[phosphorus pentachloride]] and [[phosphorus oxychloride]], the former as a chloride donor and the latter serves as a ligand, binding through the oxygen: |
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:TaCl<sub>5</sub> + PCl<sub>5</sub> → [{{chem|PCl|4|+}}][{{chem|TaCl|6|-}}] |
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:TaCl<sub>5</sub> + OPCl<sub>3</sub> → [TaCl<sub>5</sub>(OPCl<sub>3</sub>)] |
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Tantalum pentachloride reacts with tertiary |
Tantalum pentachloride reacts with [[tertiary amine]]s to give crystalline adducts. |
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:TaCl<sub>5</sub> + 2 R<sub>3</sub>N → [TaCl<sub>5</sub>(NR<sub>3</sub>)] |
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===Chloride displacement reactions=== |
===Chloride displacement reactions=== |
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Tantalum pentachloride reacts at room temperature with an excess of |
Tantalum pentachloride reacts at room temperature with an excess of [[triphenylphosphine oxide]] to give oxychlorides: |
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:TaCl<sub>5</sub> + 3 OPPh<sub>3</sub> → [TaOCl<sub>3</sub>(OPPh<sub>3</sub>)]<sub>''x''</sub> ... |
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The presumed initial formation of adducts between TaCl<sub>5</sub> and hydroxyl compounds such as alcohols, phenols and carboxylic acids is followed immediately by the elimination of hydrogen chloride and the formation of |
The presumed initial formation of adducts between TaCl<sub>5</sub> and hydroxyl compounds such as [[alcohols]], [[phenols]] and [[carboxylic acids]] is followed immediately by the elimination of hydrogen chloride and the formation of Ta–O bonds: |
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:TaCl<sub>5</sub> + 3 HOEt → TaCl<sub>2</sub>(OEt)<sub>3</sub> + 3 HCl |
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In the presence of ammonia as |
In the presence of [[ammonia]] as a [[hydrogen chloride|HCl]] acceptor, all five chloride ligands are displaced with formation of Ta(OEt)<sub>5</sub>. Similarly TaCl<sub>5</sub> reacts with [[lithium methoxide]] in anhydrous [[methanol]] to form related methoxy derivatives: |
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:TaCl<sub>5</sub> + 4 LiOMe → Ta(OMe)<sub>4</sub>Cl + 4 LiCl |
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===Ammonolysis and |
===Ammonolysis and alcoholysis and related reactions=== |
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Ammonia will displace most of the chloride ligands from TaCl<sub>5</sub> to give a cluster. Chloride is displaced more slowly by primary or secondary |
[[Ammonia]] will displace most of the chloride ligands from TaCl<sub>5</sub> to give a cluster. Chloride is displaced more slowly by [[Primary amine|primary]] or [[secondary amine]]s but the replacement of all five chloride centers by amido groups has been achieved by the use of lithium dialkylamides, as illustrated by the synthesis of [[pentakis(dimethylamido)tantalum]]: |
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:TaCl<sub>5</sub> + 5 LiNMe<sub>2</sub> → Ta(NMe<sub>2</sub>)<sub>5</sub> |
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With alcohols, the pentachloride reacts to give [[alkoxide]]s. As shown for the preparation of [[tantalum(V) ethoxide]], such reactions are often conducted in the presence of base: |
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:10 EtOH + Ta<sub>2</sub>Cl<sub>10</sub> + 10 NH<sub>3</sub> → Ta<sub>2</sub>(OEt)<sub>10</sub> + 10 NH<sub>4</sub>Cl |
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===Reduction=== |
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Reduction of tantalum(V) chloride gives anionic and neutral clusters including [Ta<sub>6</sub>Cl<sub>18</sub>]<sup>4−</sup> and [Ta<sub>6</sub>Cl<sub>14</sub>](H<sub>2</sub>O)<sub>4</sub>.<ref>{{cite book |doi=10.1002/9781118744994.ch1|chapter=Octahedral Hexatantalum Halide Clusters|volume =36|year=2014|last1=Duraisamy|first1=Thirumalai|last2=Hay|first2=Daniel N. T.|last3=Messerle|first3=Louis|title=Inorganic Syntheses: Volume 36|pages=1–8|isbn=9781118744994}}</ref> |
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[[Image:EntryWithCollCode26094.png|left|200px|thumb|Structure of edge-capped octahedral clusters such as Ta<sub>6</sub>Cl<sub>18</sub><sup>2−</sup>.<ref>{{cite journal|title=The Crystal Structure of H<sub>2</sub>(Ta<sub>6</sub>Cl<sub>18</sub>)(H<sub>2</sub>O)<sub>6</sub>|author1=Thaxton, C. B. |author2=Jacobson, R. A. |journal=Inorganic Chemistry|year=1971|volume=10|pages=1460–1463|doi=10.1021/ic50101a029}}</ref>]] |
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==References== |
==References== |
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==Further reading== |
==Further reading== |
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* {{cite journal |
* {{cite journal|first1=G. A.|last1=Ozin|first2=R. A.|last2=Walton|journal=[[J. Chem. Soc. A]]|year=1970|pages=2236–2239|doi=10.1039/j19700002236|title = Vibrational spectra and structures of the 1:1 complexes of niobium and tantalum, pentachlorides and tantalum pentabromide with aceto-, perdeuterioaceto-, and propionitriles in the solid and solution states and a vibrational analysis of the species MX<sub>5</sub>, NC·CY<sub>3</sub> (Y = H or D)}} |
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* {{cite journal | |
* {{cite journal |first1=J. I.|last1 = Bullock |first2=F. W. |last2 = Parrett |first3=N. J. |last3 = Taylor | journal = [[J. Chem. Soc., Dalton Trans.]] |issue = 5 | year = 1973 | pages = 522–524|title = Some metal halide–phosphorus halide–alkyl halide complexes. Part II. Reactions with niobium and tantalum pentachlorides and tungsten hexachloride |doi = 10.1039/DT9730000522 }} |
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* {{cite journal | |
* {{cite journal |first1=C.|last1 = Đorđević |first2=V.|last2 = Katović | journal = [[J. Chem. Soc. A]] | year = 1970 | pages = 3382–3386 | doi = 10.1039/j19700003382 | title = Co-ordination complexes of niobium and tantalum. Part VIII. Complexes of niobium(IV), niobium(V), and tantalum(V) with mixed oxo, halogeno, alkoxy, and 2,2′-bipyridyl ligands}} |
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* {{cite journal | |
* {{cite journal |first1=A.|last1 = Cowley |first2=F.|last2 = Fairbrother |first3=N.|last3 = Scott | journal = [[J. Chem. Soc.]] |title = The halides of niobium (columbium) and tantalum. Part V. Diethyl ether complexes of the pentachlorides and pentabromides; the solubility of tantalum pentaiodide in ether | year = 1958 | pages = 3133–3137|doi = 10.1039/JR9580003133 }} |
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==External links== |
==External links== |
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{{Tantalum compounds}} |
{{Tantalum compounds}} |
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{{Chlorides}} |
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{{DEFAULTSORT:Tantalum(V) Chloride}} |
{{DEFAULTSORT:Tantalum(V) Chloride}} |
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[[Category:Tantalum compounds]] |
[[Category:Tantalum(V) compounds]] |
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[[Category:Chlorides]] |
[[Category:Chlorides]] |
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[[Category:Metal halides]] |
[[Category:Metal halides]] |
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[[de:Tantal(V)-chlorid]] |