UV VISIBLE SPECTROSCOPIC STUDY OF THE RAC-ET(IND)(2)ZRCL2/MAO OLEFIN POLYMERIZATION CATALYTIC-SYSTEM, 2 - INVESTIGATION IN CH2CL2/

The bathochromic shift of the metallocene absorption band of the syste m rac-Et(Ind)(2)ZrCl2/methylaluminoxane (MAO) in CH2Cl2 at 20 degrees C proceeds in two distinct steps: for Al/Zr mole ratios in the range 2 0-50, a first bathochromic shift up to 440 nm is observed. It is expla ined by the formation of stable and unreactive ionic type species, mos t likely mixed dimer species (Zr-Al). Further addition of MAO (MAO/Zr > 50) is accompanied by a new and continuous bathochromic shift of the maximal wavelength corresponding to the formation of more dissociated zirconocenium species. In agreement with the results reported in tolu ene, the lambda(max) changes of the U.V./visible spectrum of the rac-E t(Ind)(2)ZrCl2/MAO system were correlated with the catalytic activity obtained for the hex-1-ene polymerization.