The hydroalumination of the allyl ethers CH 2 dCHCH 2 OR with i Bu 2 AlH yields the (3alkoxypropyl)diisobutylaluminum complexes i Bu 2 Al(CH 2 ) 3 OR (R ) Me (1), Et (2), Bu (3)). Et 2 AlCl and i Bu 2 AlCl react with (2-(methoxymethyl)phenyl)lithium and (2-methoxybenzyl)magnesium chloride, yielding (2-(methoxymethyl)phenyl)diethylaluminum ( 4), (2-(methoxymethyl)phenyl)diisobutylaluminum (5), and (2-methoxybenzyl)diisobutylaluminum ( 7), respectively. The reaction of i Bu 2 AlCl with (2-methoxyphenyl)lithium affords the dimeric bis((2-methoxyphenyl)diisobutylaluminum) (6). Et 2 AlCl and (8-ethoxynaphthyl)lithium form (8-ethoxynaphthyl)diethylaluminum ( 10) along with a few crystals of bis(8-ethoxynaphthyl)aluminum chloride (13). AlCl 3 reacts with 2 equiv of (2-methoxybenzyl)magnesium chloride, yielding bis(2-methoxybenzyl)aluminum chloride (9). Ligand redistribution followed by metathesis was observed for the reactions of Me 2 AlCl and Et 2 AlCl with (2-methoxybenzyl)magnesium and (8-methoxynaphthyl)lithium, yielding bis(2-methoxybenzyl)methylaluminum (8), bis(8-methoxynaphthyl)methylaluminum (11), and bis(8-methoxynaphthyl)ethylaluminum (12), respectively. The new compounds have been characterized by elemental analysis, NMR spectroscopy, and mass spectrometry. The solid-state structures of 6, 8, 9, and 11-13 were determined by single-crystal X-ray diffraction. The new aluminum alkyls are very active cocatalysts in the TiCl 4 -catalyzed ethylene polymerization. 7 and 10 cause a higher productivity compared to the common cocatalyst Al 2 Et 6 . The activity depends strongly on the structure of the oxygen-stabilized aluminum alkyls and is also influenced by the Al/Ti ratio.

A number of organoaluminum compounds, stabilized with intramolecular nitrogen-or oxygendonor functions, have been used as cocatalysts for the MgCl 2 /TiCl 4 -catalyzed homopolymerization of propene as well as for the copolymerization of ethene with propene. The polymerization behavior of these aluminum alkyls was examined at different Al/Ti ratios within the range of 2 to 50 and compared with the reference of triethylaluminum (TEA). Especially (2) show the highest activities at very low Al/Ti ratios in the homopolymerization of propene, whereas TEA is almost inactive. The species [8-(N,N-dimethylamino)naphthyl]dimethylaluminum (4) reaches the highest activity of all examined alkyls and is very close to the highest value obtained with TEA. Bulky iso-butyl groups at the aluminum center are responsible for the very poor performance of the nitrogen stabilized cocatalysts [8-(N,N-The properties of the polypropenes synthesized with the stabilized organoaluminum species are similar to those produced with TEA but with a distinctly higher molar mass. In the case of 1, it was possible to increase the molar mass by a factor of three. For the copolymerizations, the compounds [2-(N,N-diethylaminomethyl)phenyl]diethylaluminum (7) and (2-methoxybenzyl)diisobutylaluminum (8) were found to be most suitable, producing polymers with significantly higher activities than TEA. For all copolymers two fractions were obtained, one crystalline fraction with a low and an amorphous part with a high amount of comonomer. In both fractions, 7 and 8 provide a higher comonomer incorporation than TEA.

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