Tetrakis(3,5-bis(trifluoromethyl)phenyl)borate

Tetrakis[3,5-bis(trifluoromethyl)phenyl]borate is an anion with chemical formula [{3,5-(CF3)2C6H3}4B]−, which is commonly abbreviated as [BArF4]−, indicating the presence of fluorinated aryl (ArF) groups.

However, for a small group of chemists, the anion is abbreviated as TFPB otherwise, short for Tetrakis[3,5-bis(triFluoromethyl)Phenyl]Borate.

The motivation for its preparation was the search for an anion that coordinates more weakly than the then-available ions hexafluorophosphate, tetrafluoroborate, or perchlorate.

A popular method is summarized in the following equation:[6] Brookhart's acid is the salt of the BARF anion with the diethyl ether oxonium cation, [(Et2O)2H]BArF4.

[4] BARF salts with hexakis(acetonitrile)metal(II) cations, [M(CH3CN)6]2+, are known for vanadium, chromium, manganese, iron, cobalt, and nickel.

The [BAr F 4 ] − anion with four fluorinated aryl groups distributed tetrahedrally about a central boron atom
Lithium tetrakis(pentafluorophenyl)borate , containing the BARF-20 anion, is used similarly to the BARF-24 anion.