POLYMERIZATION OF PROPYLENE WITH THE [ARN(CH2)(3)NAR]TICL2 (AR = 2,6-(PR2C6H3)-PR-I) COMPLEX USING R3AL PH3CB(C6F5)(4) (R = ME, ET, BU-I) AS COCATALYST/

Polymerization of propylene was conducted at 0 similar to 150 degrees C with the [ArN(CH2)(3)NAr]TiCl2 (Ar = 2,6-(Pr2C6H3)-Pr-i) complex usi ng a mixture of trialkylaluminium (AlR3, R = methyl, ethyl and isobuty l) and Ph3CB(C6F5)(4) as cocatalyst. When AlMe3 or AlEt3 was employed, atactic polypropylene (PP) was selectively produced, whereas the use of Al(Bu-i)(3) gave a mixture of atactic and isotactic PP. The isotact ic index (I.I.; weight fraction of isotactic polymer) depended strongl y upon the polymerization temperature, and the highest LI. was obtaine d at ca. 40 degrees C. The C-13 NMR analysis of the isotactic polymer suggests that the isotactic polymerization proceeds by an enantiomorph ic-site mechanism. It was also demonstrated that the present catalyst shows a very high regiospecificity.