Complexes of tris(pentafluorophenyl)boron with nitrogen-containing compounds: Synthesis, reactivity and metallocene activation

The strong Lewis acid tris(pentafluorophenyl)boron, B(C6F5)3, reacts with several nitrogen-containing Lewis bases (nitriles, amines, imines, pyridines, etc.) and also with non-basic substrates (such as pyrroles and indoles) producing in both cases the BN coordination adduct. With particular substrates (some tertiary amines, the imine tBu(Me)CNBn, N-methyl-pyrrole and -indole,) the 1:1 borane/N-compound reaction produces zwitterions where a new BC bond is generated. Some of the borane–N-compound adducts present Brønsted acidity and can be reacted with di-methyl group 4 complexes with generation of weakly associated ion pairs, which are active catalysts for the polymerization of olefins.