Abstract
A series of chiral ansa-zirconocene ester enolate complexes incorporating C 2- or C s-symmetric ligands, including neutral rac-(EBI)ZrCl[OC(O i Pr) CMe 2] ( 1), rac-(EBI)Zr(OTf)[OC(O i Pr) CMe 2] ( 2), rac-(EBI)Zr(OTf)[OC(OMe) C(Me)CH 2C(Me 2)C(O i Pr) O] ( 3), [Me 2C(Cp)(Flu)]ZrMe[OC(O i Pr) CMe 2] ( 4), and cationic [Me 2C(Cp)(Flu)]Zr +(THF)[OC(O i Pr) CMe 2][MeB(C 6F 5) 3] − ( 5), have been synthesized. Within the neutral C 2-ligated zirconocene ester enolate series, the chloride derivative 1 is inactive toward any methyl methacrylate (MMA) additions, the methyl derivative rac-(EBI)ZrMe[OC(O i Pr) CMe 2] adds cleanly only 1 equiv. of MMA, and the triflate derivative 2 can add either 1 equiv. of MMA to form the single-MMA-addition product 3 or multiple equivalents of MMA to form P(MMA). Unlike the C s-ligated methyl cation [Me 2C(Cp)(Flu)ZrMe] +, which is inactive for MMA polymerization under various conditions, the C s-ligated ester enolate cation 5 is moderately active for polymerization of MMA and N, N-dimethylacrylamide at ambient temperature; the resulting P(MMA) has a high molecular weight of M n = 388 000 Da but a low syndiotacticity of [ rr] = 64%, and the polymerization conforms to a chain-end control mechanism.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
