Catalytic syntheses of alternating, stereoregular ethylene/cycloolefin copolymers

The alternating stereospecific copolymerization of ethylene with cycloolefins (cyclopentene, cycloheptene, and cyclooctene) has been investigated with a series of constrained geometry titanium catalysts (CGCs). The metallocene IndSiMe2(tBuN)TiCl2 was found to generate highly alternating and stereoregular cycloolefin-co-ethylene polymers while Me4CpSiMe2(tBuN)TiCl2 produced alternating atactic polymers. In addition, novel Ti-complexes of the general formula benz[6.7]indenylSiMe2(tBuN)TiMe2 were synthesized and fully characterized. The chiral indenyl Ti complexes were found to produce exclusive 1,2-enchainment of the cycloolefin to generate highly stereoregular and alternating copolymers.