 The most common trialkyl aluminum reagents for this transformation are trimethyl aluminum, triethyl aluminum, and sometimes triisobutyl aluminum.When using trialkylaluminum reagents that have beta-hydrides, eliminations and hydroaluminum reactions become competing processes.The general mechanism of the ZMA reaction can be described as first the formation of the active catalytic species from the pre-catalyst zirconocene dichloride through its reaction with trimethyl aluminum.