Stereoselective propene polymerization at a metallocene/alumoxane catalyst derived from the chirally-substituted “meso-like” (p-R,p-S)-bis[1-(neoisopinocamphyl)-4,5,6,7-tetrahydroindenyl]-zirconium dichloride

Isopinocamphyl-tosylate (2) was treated with indenyllithium to yield 3-(neoisopinocamphyl)-indene (3). Treatment of 3 with methyllithium gave 1-(neoisopinocamphyl)indenyllithium (4) which was then treated with 0.5 molar equivalents of ZrCl₄(thf)₂ to give a 52:48 mixture of one of the “racemic-like” isomers of bis1-(neoisopinocamphyl)indenyl]ZrCl₂ (5A) and its “meso-like” diastereomer 5C. Hydrogenation of the 5A/5C mixture (50 bar H₂, Pt) furnished a mixture of the corresponding tetrahydroindenylzirconium complexes 6A and 6C, from which the “meso-like” bis1-(neoisopinocamphyl)-4,5,6,7-tetrahydroindenyl]zirconium dichloride diastereoisomer (6C) was isolated. Treatment of 6C with an excess of methylalumoxane in toluene/propene generated an active -olefin polymerization catalyst. At ?30°C partly isotactic polypropylene ( _η = 39000) was obtained. The catalyst derived from the chirally-substituted “meso-like” metallocene complex 6C produced polypropylene predominantly under enantiomorphic site control.