Fluoride ion complexation by a cationic borane in aqueous solution

The phosphonium borane [p-Mes(2)B(C6H4)PMePh2](+) complexes fluoride in water containing 10% methanol with a binding constant of 1.0(+/- 0.1) x 10(3) M-1 to afford the zwitterion p- Mes(2)FB(C6H4) PMePh2.