Synthesis of chiral unbridged zirconocene complexes: Applications in the polymerization of ethylene and propylene

Preparation and Structural Studies of Non-Symmetric Guanidinate-Supported Zirconium Complexes

The new lithium guanidinate salt [Li{μ-κ1,κ2,N,N′-(NEt)(N-t-Bu)CNMe2}(THF)]2 (1) was obtained by the reaction of HNMe2 with n-BuLi and further reaction with the asymmetric carbodiimide EtN=C=N-t-Bu. Guanidinate-supported zirconium complexes [Zr{κ2,N,N′-(NEt)(N-t-Bu)CNMe2}(μ-Cl)Cl2]2 (2), [Zr{κ2,N,N′-(NEt)(N-t-Bu)CNMe2}3Cl] (4), [Zr{κ2,N,N′-(NEt)(N-t-Bu)CNMe2}2(η5-C5H5)Cl] (5) and [Zr{κ2,N,N′-(NEt)(N-t-Bu)CNMe2}(η5-C5H5)2Cl] (6) were prepared. Complexes 2, 4, and 6 were synthesized by the metathesis reaction of ZrCl4 or [ZrCl2(η5-C5H5)2] with 1. The previously described complex [Zr{κ2,N,N′-(NEt)(N-t-Bu)CNMe2}2Cl2] (3), which was prepared by the insertion reaction of EtN=C=N-t-Bu into a metal–amido bond of [Zr(NMe2)2Cl2(THF)2], allowed the new complex 5 to be obtained by reaction with NaC5H5. All of the new complexes were characterized spectroscopically and the molecular structures of 1, 4, and 6 were determined by single-crystal X-ray diffraction.

Synthesis of Bulky Zirconocene Dichloride Compounds and Their Applications in Olefin Polymerization

The bulky substituted cyclopentadienyllithium derivatives, LiC5H4(CHMeR) (R = C6H5 (1), 1-naphthyl (2), 9-anthryl (3)), were synthesized from the reaction of 6-phenylfulvene, 6-(1-naphthyl)fulvene or 6-(9-anthryl)fulvene with LiMe. The ansa-bis(cyclopentadiene) ligands Me2Si(C5HMe4){C5H4(CHMeR)} (R = C6H5 (4), 1-naphthyl (5), 9-anthryl (6)), and their lithium derivatives Li2(Me2Si(C5Me4){C5H3(CHMeR)}) (R = C6H5 (7), 1-naphthyl (8), 9-anthryl (9)) have been prepared. The zirconocene complexes, [Zr(η5-C5H5){η5-C5H4- (CHMeR)}Cl2] (R = C6H5 (10), 1-naphthyl (11), 9-anthryl (12)) and [Zr{η5-C5H4(CHMeR)}2Cl2] (R = C6H5 (13), 1-naphthyl (14), 9-anthryl (15)), were synthesized by the reaction of lithium derivatives 1-3 and [Zr(η5-C5H5)Cl3] or ZrCl4, respectively. The reaction of the lithium ansa-derivatives 7-9 and zirconium tetrachloride yielded the ansa-zirconocene complexes, [Zr(Me2Si(η5-C5Me4){η5-C5H3(CHMeR)})Cl2] (R = C6H5 (16), 1-naphthyl (17), 9-anthryl (18)). The zirconocene complexes have been tested in the polymerization of ethene and propene. The polymerization of propene with the ansa-zirconocene catalysts 16-18 gave polypropylene with 70% mmmm pentads and the symmetric zirconocene catalysts 13-15 30-60% mmmm pentads.