Tris(pentafluorophenyl)borane

Tris(pentafluorophenyl)borane

Names
IUPAC name Tris(pentafluorophenyl)borane
Other names Perfluorotriphenylboron Tris(pentafluorophenyl)boron
Identifiers
CAS Number	1109-15-5 Y[Sigma-Aldrich]
3D model (JSmol)	Interactive image
ChemSpider	505917 Y
ECHA InfoCard	100.116.286
PubChem CID	582056
UNII	I3WU5E2578 Y
InChI InChI=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 Y Key: OBAJXDYVZBHCGT-UHFFFAOYSA-N Y 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 Key: OBAJXDYVZBHCGT-UHFFFAOYAC
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
Properties
Chemical formula	C18F15B
Molar mass	511.98 g/mol
Appearance	colorless solid
Melting point	126 to 131 °C (259 to 268 °F; 399 to 404 K)
Solubility in water	forms adduct
Structure
Molecular shape	trigonal planar
Dipole moment	0 D
Hazards
R-phrases (outdated)	R36/37/38
S-phrases (outdated)	S26 S36
Related compounds
Related compounds	Triphenylboron (C6H5)3B BF3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Tris(pentafluorophenyl)borane, sometimes referred to as "BCF", is the chemical compound (C₆F₅)₃B. It is a white, volatile solid. The molecule consists of three pentafluorophenyl groups attached in a "paddle-wheel" manner to a central boron atom; the BC₃ core is planar. It has been described as the “ideal Lewis acid” because of its versatility and the relative inertness of the B-C bonds. Related fluoro-substituted boron compounds, such as those containing B-CF₃ groups, decompose with formation of B-F bonds.

Tris(pentafluorophenyl)borane is prepared using a Grignard reagent derived from bromopentafluorobenzene.

Originally the synthesis employed C₆F₅Li, but this reagent can detonate with elimination of LiF.

The most noteworthy property of this molecule is its strong Lewis acidity. Its acid strength, as determined by the Gutmann-Beckett method and the Childs method, is comparable to BF₃ but weaker than BCl₃. This property indicates that the electronegativity of the C₆F₅ group and a halide are similar.

In one application (C₆F₅)₃B forms noncoordinating anions by removing anionic ligands from metal centers. Illustrative is a reaction that give rise to alkene polymerization catalysts where tris(pentafluorophenyl)boron is used as an activator or cocatalyst:

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 Alkenes, whereupon migratory insertion into the remaining carbon-methyl ligand 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 silica.