To model catalyst speciation, we invoked the mechanism shown in Scheme 3. We propose that the total activator concentration is 1.0 mol% of MAO and in this example, the concentration of 6,4 = 7,5 = 0.005×[Al], with a total Me3Al content of 15 mol% as is found in MAO from W. R. Grace. We then used COPASI to numerically simulate concentrations, requiring the barriers to conversion between different species were all low such that equilibrium was rapidly established.