Synthesis of some halogenated tetraarylborates

The reactions of 3,4-dichlorophenylmagnesium bromide and 3,5-dichlorophenylmagnesium bromide with B(OEt)3 and NaBF4 were studied The corresponding tetraarylborates [(3,4-Cl2C6H3)4B]NH4 and [(3,5-Cl2C6H3)4B]Na were obtained and characterized. The significant influence of the substituents inductive effect on the reaction course was revealed. NaBF4 was found to be a valuable boron reagent in the synthesis of tetraarylborates containing highly electronegative substituents. The molecular structure of [(3-CF3C6H4)4B]NH4 obtained from the reaction of 3-trifluoromethylbromobenzene with NaBF4 and Mg was determined using X-ray analysis.