Crystal structure of the strongly hydrogen bonded complex anion [(C6F5)3B(H3O2)B(C6F5)3]−

The highly electrophilic borane B(C6F5)3 reacts with water to form the aqua complex H2OB(C6F5)3·2H2O, which is deprotonated by 1,8-bis(dimethylamino)naphthalene (proton sponge) to form the salt [C10H6(NMe2)2H][(C6F5)3B(H3O2)B(C6F5)3]. The complex anion is characterized crystallographically and asymmetry is found, suggesting that this is the first example of the theoretically predicted asymmetrically hydrogen bonded [H3O2]− ion. There also appears to be evidence for significant CF⋯HO hydrogen bonding in the complex anion that may be responsible in part for the overall structure of the anion.