Polymerizable group 4 ansa-cyclopentadienyl-amido catalysts for the copolymerization of ethylene with 1-octene

A styrene unit has been successfully incorporated into the half metallocene constrained-geometry framework as [(η5-C5Me4)SiMe2(η1-NC6H4CHCH2)]MX2 (M = Ti, X = NMe2, 6a; M = Zr, X = NMe2, 6b; M = Ti, X = Cl, 7a; M = Zr, X = Cl, 7b). These complexes have been characterized with 1H NMR, 13C NMR spectroscopy together with single crystal X-ray diffraction studies of 6a and 6b. A polystyrene-immobilized constrained-geometry catalyst 8 was formed by the radical copolymerization of 7a with styrene using AIBN as the initiator. The complexes 6a, 6b, 7a and 8 gave active homogeneous catalysts for the copolymerization of ethylene with 1-octene when treated with excess methylalumoxane (MAO). The polymerization results showed that 7a was highly active and effective for the incorporation of comonomer 1-octene whereas the zirconium complex 6b and the immobilized catalyst 8 yield low activities and low incorporations of 1-octene in the products with broad molecular weight distributions.

A styrene unit has been successfully incorporated into the half metallocene constrained-geometry framework as [(η5-C5Me4)SiMe2(η1-NC6H4CHCH2)]MX2 (M = Ti, Zr). A polystyrene-immobilized constrained-geometry catalyst was also formed by the radical copolymerization with styrene using AIBN as the initiator. These complexes have been tested as active homogeneous catalysts for the copolymerization of ethylene with 1-octene.Figure optionsDownload as PowerPoint slideHighlights
► First example of incorporation of a labile styrene unit into the constrained-geometry framework.
► BCl3 as the efficient regent for the chlorination of group 4 metal amides to chlorides.
► Immobilization of the constrained-geometry catalyst on polystyrene by the radical copolymerization with styrene using AIBN as the initiator.
► Two single crystal structures were reported.
► These complexes were tested as active homogeneous catalysts for the copolymerization of ethylene with 1-octene.