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

The sodium salt is the starting point for most BARF derivatives. It is prepared by treating Grignard reagents derived from 3,5- (X = Br, I) with . A popular method is summarized in the following equation: :{{chem2|NaBF4 + 4 Ar^{F}MgBr -> 4 MgBrF + Na[BAr^{F}4]}} Additional procedures emphasizing purification and control of residual water content for Na[BArF4] have been reported, Brookhart's acid is the salt of the BARF anion with the diethyl ether oxonium cation, {{chem2|[(Et2O)2H][BAr^{F}4]}}. It can be formed from the sodium salt in diethyl ether in the presence of hydrogen chloride as sodium chloride is insoluble in diethyl ether, facilitating cation exchange. BARF salts with hexakis(acetonitrile)metal(II) cations, , are known for vanadium, chromium, manganese, iron, cobalt, and nickel. They are produced by salt metathesis reactions. ==Properties==

Non-coordinating anions are anions that interact only weakly with cations, a useful property when studying highly electrophilic cations. In coordination chemistry, the term can also be used to refer to anions which are unlikely to bind directly to the metal center of a complex. Hexafluorophosphate is a non-coordinating anion in both senses of the term. Three widely used non-coordinating anions are hexafluorophosphate, tetrafluoroborate (), and perchlorate (); of these, the hexafluorophosphate () ion has the least coordinating ability and it is deliberately used for this property. BARF was developed as a new non-coordinating anion in the 1990s, and is far less coordinating than even the hexafluorophosphate anion. {{chem2|Na[BAr^{F}4]}} can be used in deprotection of acetal or ketal-protected carbonyl compounds. For example, deprotection of 2-phenyl-1,3-dioxolane to benzaldehyde can be achieved in water in five minutes at . :->[\ce{Na[BAr4]}][\text{30 °C / 5 min}] ==References==