An Alternative Route to Methylalumoxane: Synthesis, Structure, and the Use of Model Methylalumoxanes as Cocatalysts for Transition Metal Complexes in Polymerization Reactions

Methylalumoxane (MAO) is commonly produced by controlled hydrolysis of AlMe 3; it is widely used as a cocatalyst for metallocene complexes and complexes of late transition metals in polymerization reactions of alkenes and styrene. This article explores alternative routes to MAO synthesis in reactions of AlMe 3 with bis(trialkyltin)oxides R 3 Sn−O−SnR 3 or with Me 3 SnOH. The products of these reactions, when prepared at molar ratios [AlMe 3 ]:[Sn compound] > 1, are efficient cocatalysts for metallocene complexes in alkene polymerization reactions and for various Ti compounds in syndiospecific styrene polymerization reactions. A multinuclear NMR study of the reaction products in both cocatalyst mixtures prepared at different reactant ratios provided information about the chemical structure of the MAO analogues and MAO itself.