Reversible formation of OSIP 3 provides a mechanism for exposing these nucleophilic anions and we wondered whether a coordinating anion might be trapped through reaction with excess neutral activator like 16,6 or 6,4 to furnish a more weakly coordinating anion, especially at higher Al:Zr ratios. This idea has precedent in the case of discrete activators such as Al(C6F5)3 and Me2AlF, while the effect of charge dispersal is well known for trityl activators with di-vs. mono-nuclear anions. However, in the specific case of MAO the idea has also been discounted, see the discussion in ref.