Theoretical and spectroscopic UV study of the EtInd(2)ZrCl(2)/MAO, EtInd(2)ZrCl(2)/MAO-AlCl3 and EtInd(2)ZrCl(2)/MAO-ethyl benzoate interaction

:Full Paper: This work presents a theoretical and experimental study of the active sites formation in the system EtInd(2)ZrCl(2)/MAO. Results about th e effect of additives as a Lewis acid (AlCl3) or a Lewis base (EB) are also analyzed. The theoretical study takes into account all the known steps in the active site formation: alkylation of zirconocene, formation of a polari zed complex metallocene: MAO, formation of a contact ion pair and finally a solvent separated ion pair. Other reactions of the zirconocene with other aluminium alkyls (AlCl3 and AlMe3) are also presented and studied. UV-vis e xperimental results of the additive effects are reported and explained taki ng into account the theoretical results. A short review of our results and others is presented to complete and discuss the ideas. The most probable si tes are loosened contact ion pairs, not the solvent separated ion pairs. [GRAPHICS] V/Visble spectrum of zirconocene, zirconocene with MAO at Al/Zr = 3363 with AlCl3/Zr = 33, zirconocene with MAO at Al/Zr = 8400, ziconocene with MAO a t Al/Zr = 8400 with AlCl3/Zr = 13 and zirconocene with MAO at Al/Zk = 3363 and EB/Zr = 5. [Zr] = 3 E-05 M.