Monocyclopentadienylzirconium Amidinate Catalysts

Catalytic synthesis of block copolymers from norbomene and propylene using 7/dMMAO- 

In addition to simple a-olefins such propylene, Sita and coworkers showed that lla-c/ [PhNMe2H][B(C6F5)4] were active for the cyclopolymerization of 1,5-hexadiene at —10°C (Jayaratne et al, 2000). The polymers produced possessed 98% MCP units, and exhibited narrow polydispersities MJM = 1.03-1.09). The selectivity of ring closure was ubiquitously trans, the stereoselectivity increasing with increasing steric bulk of the amidinate ligand (lla % trans = 6A llc % trans = S2). 

Utilizing the living behavior of Hb/[PhNMe2H] [B(CeF5)4], Sita and coworkers were able to prepare diblock and triblock copolymers of 1-hexene and 1,5-hexadiene (Jayaratne et al., 2000). At —10°C, isotactic poly(l-hexene)-hIock-PMCP and isotactic poly(l-hex-ene)-block-PMCP-block-poly(l-hexem) were obtained from Hb/[PhNMe2H][B(C6F5)4] through sequential monomer addition. The diblock copolymer possessed MJM = 1.05 and Mn = 22 800 g/mol with Tm = 91 °C. The triblock copolymer had M JM = 1.10, = 30 900 

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SCHEME 2.16 Monocyclopentadienylzirconium amidinate catalysts for bving olefin polymerization. 

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