SELECTIVITY IN PROPYLENE POLYMERIZATION WITH GROUP-4 CP-AMIDO CATALYSTS

Mono-Cp-amido complexes [eta(5):eta(1)-Cp'SiMe2(NR)]MCl2 (M = Ti, Zr) have been synthesized by metathesis and amine elimination routes in lo w to moderate yields (5-50%). Two optically active examples based on ( S)-(-)-(alpha)-methylbenzylamine are presented, and the molecular stru cture of +)-(R)-[eta(5):eta(1)-(Ind)SiMe2-(S)-NCHMePh]TiCl2 (4) has be en determined by X-ray crystallography. These complexes are active in the presence of methylaluminoxane for propylene polymerization and yie ld high molecular weight atactic polymers with slight syndiotactic enr ichment. Productivities, molecular weights, and tacticities are depend ent on Cp' and NR. Incorporation of a chiral amine into the ligand fra mework has little effect on stereospecificity. Polypropylenes derived from the titanium catalysts show significant amounts of 2,1-monomer in sertion (2-5%).