PF5. A notable Lewis acid of this genre is tris(pentafluorophenyl)borane, B(C6F5)3, which abstracts alkyl ligands: (C5H5)2Zr(CH3)2 + B(C6F5)3 → [(C5H5)2Zr(CH3)]+[(CH3)B(C6F5)3]− Other types of non-coordinating anions Another large class of non-coordinating anions are derived from carborane anion . Using this anion, the first example of a three-coordinate silicon compound, the salt [(mesityl)3Si][HCB11Me5Br6] contains a non-coordinating anion derived from a carborane. References Coordination chemistry