| Revision as of 14:28, 10 January 2012 editBeetstra (talk | contribs)Edit filter managers, Administrators172,031 edits Saving copy of the {{chembox}} taken from revid 465365223 of page Tris(pentafluorophenyl)boron for the Chem/Drugbox validation project (updated: 'CASNo'). |
Latest revision as of 04:32, 1 October 2023 edit LaundryPizza03 (talk | contribs)Extended confirmed users51,149 edits added Category:Acid catalysts using HotCat |
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{{short description|Chemical compound}} |
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{{ambox | text = This page contains a copy of the infobox ({{tl|chembox}}) taken from revid of page ] with values updated to verified values.}} |
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{{chembox |
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{{chembox |
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| Verifiedfields = correct |
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| verifiedrevid = 414858108 |
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| verifiedrevid = 470617436 |
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| Name = Tris(pentafluorphenyl)boron |
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| ImageFile = Tris(pentafluorophenyl)boron-2D-skeletal.png |
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| Name = Tris(pentafluorophenyl)borane |
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| ImageFile = Tris(pentafluorophenyl)boron-2D-skeletal.png |
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| ImageSize = 200px |
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| ImageSize = |
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| ImageFile1 = Tris(pentafluorophenyl)boron-3D-vdW.png |
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| ImageFile1 = Tris(pentafluorophenyl)boron-3D-vdW.png |
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| ImageSize1 = 200px |
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| ImageSize1 = |
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| ImageName = Tris(pentafluorphenyl)boron |
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| ImageName = Tris(pentafluorphenyl)boron |
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| IUPACName = Tris(pentafluorophenyl)borane |
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| PIN = Tris(pentafluorophenyl)borane |
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| OtherNames = Perfluorotriphenylboron<br>Tris(pentafluorophenyl)boron |
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| OtherNames = Perfluorotriphenylboron<br>Tris(pentafluorophenyl)boron |
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| Section1 = {{Chembox Identifiers |
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|Section1={{Chembox Identifiers |
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| SMILES = B(c1c(c(c(c(c1F)F)F)F)F)(c2c(c(c(c(c2F)F)F)F)F)c3c(c(c(c(c3F)F)F)F)F |
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| SMILES = B(c1c(c(c(c(c1F)F)F)F)F)(c2c(c(c(c(c2F)F)F)F)F)c3c(c(c(c(c3F)F)F)F)F |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID = 505917 |
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| ChemSpiderID = 505917 |
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| PubChem = 582056 |
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| PubChem = 582056 |
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| InChI = 1/C18BF15/c20-4-1(5(21)11(27)16(32)10(4)26)19(2-6(22)12(28)17(33)13(29)7(2)23)3-8(24)14(30)18(34)15(31)9(3)25 |
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| InChIKey = OBAJXDYVZBHCGT-UHFFFAOYAC |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChI = 1S/C18BF15/c20-4-1(5(21)11(27)16(32)10(4)26)19(2-6(22)12(28)17(33)13(29)7(2)23)3-8(24)14(30)18(34)15(31)9(3)25 |
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| StdInChI = 1S/C18BF15/c20-4-1(5(21)11(27)16(32)10(4)26)19(2-6(22)12(28)17(33)13(29)7(2)23)3-8(24)14(30)18(34)15(31)9(3)25 |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey = OBAJXDYVZBHCGT-UHFFFAOYSA-N |
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| StdInChIKey = OBAJXDYVZBHCGT-UHFFFAOYSA-N |
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| CASNo_Ref = {{cascite|correct|??}} |
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| CASNo_Ref = {{cascite|correct|Sigma-Aldrich}} |
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| CASNo = <!-- blanked - oldvalue: 1109-15-5 --> |
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| CASNo = 1109-15-5 |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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| RTECS = |
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| UNII = I3WU5E2578 |
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| RTECS = |
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}} |
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| Section2 = {{Chembox Properties |
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|Section2={{Chembox Properties |
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| Formula = C<sub>18</sub>F<sub>15</sub>B |
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| Formula = {{chem2|C18F15B}} |
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| MolarMass = 511.98 g/mol |
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| MolarMass = 511.98 g/mol |
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| Appearance = colorless solid |
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| Appearance = colorless solid |
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| Density = |
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| Density = |
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| Solubility = forms adduct |
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| Solubility = forms adduct |
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| MeltingPt = 126-131 °C |
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| MeltingPtC = 126 to 131 |
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| BoilingPt = |
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| MeltingPt_notes = |
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| Viscosity = |
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| BoilingPt = |
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| Viscosity = |
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| Section3 = {{Chembox Structure |
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|Section3={{Chembox Structure |
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| MolShape = trigonal planar |
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| MolShape = trigonal planar |
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| Dipole = 0 ] |
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| Dipole = 0 ] |
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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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| MainHazards = |
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| MainHazards = |
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| RPhrases = {{R36/37/38}} |
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| GHSPictograms = {{GHS07}} |
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| GHSSignalWord = danger |
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| SPhrases = {{S26}} {{S36}} |
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| HPhrases = {{HPhrases|H315|H319|H335|}} |
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| PPhrases = {{PPhrases|P261|P302 + P352|P280|P305 + P351 + P338}} |
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| GHS_ref = <ref>GHS: (07 Jan 2021)</ref> |
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}} |
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| Section8 = {{Chembox Related |
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|Section8={{Chembox Related |
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| OtherCpds = Triphenylboron (C<sub>6</sub>H<sub>5</sub>)<sub>3</sub>B<br />] |
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| OtherCompounds = ] {{chem2|(C6H5)3B}}<br />] |
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'''Tris(pentafluorophenyl)borane''', sometimes referred to as "BCF", is the ] {{chem2|(C6F5)3B}}. It is a white, volatile solid. The molecule consists of three pentafluorophenyl groups attached in a "paddle-wheel" manner to a central ] atom; the {{chem2|BC3}} core is ]. It has been described as the “ideal ]” because of its high thermal stability and the relative inertness of the B-C bonds. Related fluoro-substituted boron compounds, such as those containing {{chem2|B\sCF3}} groups, decompose with formation of B-F bonds. Tris(pentafluorophenyl)borane is thermally stable at temperatures well over 200 °C, resistant to oxygen, and water-tolerant.<ref name="Chivers-1997">{{cite journal |last1=Piers |first1=Warren E. |last2=Chivers |first2=Tristram |title=Pentafluorophenylboranes: from obscurity to applications |journal=Chemical Society Reviews |date=1997 |volume=26 |issue=5 |pages=345 |doi=10.1039/cs9972600345}}</ref> |
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==Preparation== |
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Tris(pentafluorophenyl)borane is prepared using a ] derived from ]: |
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: {{chem2|3C6F5MgBr + BCl3 → (C6F5)3B + 3MgBrCl}} |
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The synthesis originally employed {{chem2|C6F5Li}}, but this reagent can detonate with elimination of {{chem2|LiF}}.<ref name = "Chivers-1997" /> |
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==Structure== |
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The structure of tris(pentafluorophenyl)borane (BCF) was determined by gas electron diffraction.<ref>{{Cite journal|last1=Körte|first1=Leif A.|last2=Schwabedissen|first2=Jan|last3=Soffner|first3=Marcel|last4=Blomeyer|first4=Sebastian|last5=Reuter|first5=Christian G.|last6=Vishnevskiy|first6=Yury V.|last7=Neumann|first7=Beate|last8=Stammler|first8=Hans-Georg|last9=Mitzel|first9=Norbert W.|date=2017-06-09|title=Tris(perfluorotolyl)borane-A Boron Lewis Superacid|journal=Angewandte Chemie International Edition|volume=56|issue=29|pages=8578–8582|doi=10.1002/anie.201704097|pmid=28524451|issn=1433-7851|doi-access=free}}</ref> It has a propeller-like arrangement of its three pentafluorophenyl groups with a torsional angle of 40.6(3)° for the deviation of these groups from a hypothetically planar arrangement. Compared with a torsional angle of 56.8(4)° for {{chem name|tris(perfluoro-para-tolyl)borane}}, which is a stronger Lewis acid than BCF, this shows that there is some delocalization of electron density from the para-fluorine atoms to the boron atom that reduces its acidity. |
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==Lewis acidity== |
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The most noteworthy property of this molecule is its strong ]ity. Its Lewis acid strength, as quantified by experimental equilibrium constants, is by 7 orders of magnitude higher than the one of structurally analogous ].<ref>{{Cite journal|last1=Mayer|first1=Robert J.|last2=Hampel|first2=Nathalie|last3=Ofial|first3=Armin R.|title=Lewis Acidic Boranes, Lewis Bases, and Equilibrium Constants: A Reliable Scaffold for a Quantitative Lewis Acidity/Basicity Scale|journal= Chemistry – A European Journal|year=2020|volume=27|issue=12|pages=4070–4080|doi= 10.1002/chem.202003916|pmid=33215760|pmc=7985883|doi-access=free}}</ref> Experimental equilibrium measurements, its AN value (]) as well as quantum-chemical calculations all indicate that the Lewis acidity of {{chem2|B(C6F5)3}} is slightly lower than that of {{chem2|BF3}} and significantly reduced compared to {{chem2|BCl3}}. {{chem2|B(C6F5)3}} forms a strong Lewis adduct with water,<ref>{{Cite journal|last1=Beringhelli|first1=Tiziana|last2=Maggioni|first2=Daniela|last3=D’Alfonso|first3=Giuseppe|title=1H and 19F NMR Investigation of the Reaction of B(C6F5)3 with Water in Toluene Solution|journal=Organometallics|year=2001|volume=20|issue=23|pages=4927–4938|doi=10.1021/om010610n}}</ref> which was shown to be a strong Brønsted acid having an acidity comparable to ] (in acetonitrile).<ref>{{Cite journal|last1=Bergquist|first1=Catherine|last2=Bridgewater|first2=Brian M.|last3=Harlan|first3=C. Jeff|last4=Norton|first4=Jack R.|last5=Friesner|first5=Richard A.| last6=Parkin|first6=Gerard| title=Aqua, Alcohol, and Acetonitrile Adducts of Tris(perfluorophenyl)borane: Evaluation of Brønsted Acidity and Ligand Lability with Experimental and Computational Methods|journal=Journal of the American Chemical Society|year=2000|volume=122|issue=43|pages=10581–10590|doi=10.1021/ja001915g}}</ref> In consequence, even traces of moisture are able to deactivate {{chem2|B(C6F5)3}} and remaining catalytic activity might only be due to the Brønsted acidity of the water adduct. |
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===Applications in catalysis=== |
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In one application {{chem2|(C6F5)3B}} forms ]s by removing anionic ligands from metal centers.<ref>Fuhrmann, H.; Brenner, S.; Arndt, P.; Kempe, R. “Octahedral Group 4 Metal Complexes That Contain Amine, Amido, and Aminopyridinato Ligands: Synthesis, Structure, and Application in α-Olefin Oligo- and Polymerization”, ''Inorganic Chemistry'', 1996, '''35''', 6742-6745.{{doi|10.1021/ic960182r}}</ref> Illustrative is a reaction that give rise to ] catalysts where tris(pentafluorophenyl)boron is used as an ]: |
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: {{chem2|(C6F5)3B + (C5H5)2Zr(CH3)2 → ^{+}(−)}} |
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In this process, the strongly coordinating methyl group transfers to the boron to expose a reactive site on zirconium. The resulting cationic zirconocene species is stabilised by the non coordinating borane anion. The exposed site on the zirconium allows for coordination of ], whereupon migratory insertion into the remaining carbon-methyl ] gives rise to a propyl ligand this process continues resulting in the growth of a polymer chain. This reagent has led to the development of immobilised catalyst/activator species; where the catalyst/activator is immobilised on an inert inorganic support such as ].<ref>Severn, J. R., Chadwick, J. C., Duchateau, R., Friederichs, N., "Bound but Not Gagged‚ Immobilizing Single-Site α-Olefin Polymerization Catalysts", Chemical Reviews 2005, volume 105, p. 4073. {{doi|10.1021/cr040670d}}</ref> |
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{{chem name|Tris(pentafluorophenyl)borane}} is also capable of abstracting hydride to give {{chem2|(−)}}, and it catalyzes ] of aldehydes. Otherwise {{chem2|(C6F5)3B}} binds to a wide range of Lewis bases, even weak ones.<ref>Erker, G. "Tris(pentafluorophenyl)borane: A Special Boron Lewis Acid for Special Reactions", ''Dalton Transactions'', 2005, 1883-1890. {{doi|10.1039/B503688G}}</ref> The compound is hygroscopic, forming the trihydrate {{chem2|(H2O)2}}, wherein one water in coordinated to boron and the other two waters are hydrogen-bonded to the coordinated water. |
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Related compounds are {{chem name|pentafluorophenylboron}} halides.<ref>Chivers, T. “Pentafluorophenylboron halides: 40 years later”, ''Journal of Fluorine Chemistry'', 2002, '''115''', 1-8. {{doi|10.1016/S0022-1139(02)00011-8}}</ref> |
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==Frustrated Lewis pair== |
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Tris(pentafluorophenyl)borane is a key reagent leading to the concept of ]s. The combination of BCF and bulky basic phosphines, such as ] ({{chem2|PCy3}}) cleaves {{chem2|H2}}:<ref>Stephan, D. W., ""Frustrated Lewis Pairs": A New Strategy to Small Molecule Activation and Hydrogenation Catalysis", Dalton Trans. 2009, 3129.{{doi|10.1039/B819621D}}</ref> |
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: {{chem2|(C6F5)3B + PCy3 + H2 → (C6F5)3BH(−) + HPCy3^{+}|}} |
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Many related phosphines, boranes, and substrates participate in related reactions. |
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==Other reactions== |
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{{chem2|(C6F5)3B}} was used to prepare a compound containing a Xe-C bond: |
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: {{chem2|(C6F5)3B + XeF2 → ^{+}(−)}} |
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Upon reaction with {{chem name|pentafluorophenyllithium}}, the salt of the ] ] is formed. |
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: {{chem2|(C6F5)3B + C6F5Li → Li}} |
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{{chem2|B(C6F5)3}} reacts with {{chem name|di]phosphine}} to give the zwitterionic phosphonic-boronate (mes = {{chem2|C6H2Me3}}): |
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: {{chem2|(C6F5)3B + mes2PH → (C6F5)2B(F)\sC6F4\sP(H)mes2}} |
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This zwitterionic salt can be converted to a system that reversibly binds molecular {{chem2|H2}}: |
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: {{chem2|(C6F5)2B(F)\sC6F4\sP(H)mes2 + Me2SiHCl → (C6F5)2B(H)\sC6F4\sP(H)mes2 + Me2SiFCl}} |
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: {{chem2|(C6F5)2B(H)\sC6F4\sP(H)mes2 → (C6F5)2B\sC6F4\sPmes2 + H2}} |
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==References== |
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{{reflist}} |
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==Extra reading== |
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*{{cite journal|last1=Lawson|first1=James R.|last2=Melen|first2=Rebecca L.|title=Tris(pentafluorophenyl)borane and Beyond: Modern Advances in Borylation Chemistry|journal=Inorganic Chemistry|date=3 February 2017|volume=56|issue=15|pages=8627–8643|doi=10.1021/acs.inorgchem.6b02911|pmid=28157303|doi-access=free}}{{open access}} |
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] |
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] |
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] |
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] |