title: Preparation of ansa-metallocenes for production of poly(α-olefin) lubricants.
abstract: An ansa-zirconocene bearing methyl substituents at all positions adjacent to the bridgehead [(-C(Ph)HC(Ph)H-)(η(5)-2,5-Me2C5H2)2ZrCl2] (4) was prepared in high yields (78%) through the reductive dimerization of 1,4-dimethyl-6-phenylfulvene utilizing ZrCl2·DME generated in situ. The structure of 4 was subsequently confirmed using X-ray crystallography. 4 exhibited excellent catalytic performance with regard to 1-decene oligomerization, which was carried out with the intention of preparing lubricant base stocks. High activities (21 × 10(6) g mol(-1) Zr h(-1) activity; TON = 150 000; TOF = 42 s(-1)) were observed at temperatures as high as 120 °C and the oligomer distribution was appropriate for lubricant application. The simulated distillation (SIMDIS) data confirmed that a wide range of oligomers were formed, ranging from the dimer (2-mer) to 20-mer. A minimal amount of the dimer and oligomers larger than the 10-mer was formed (13 and 25 wt%, respectively). Alternatively, a typical unbridged complex such as (η(5)-nBuC5H4)2ZrCl2 primarily produced dimers (54 wt%), whereas the ansa-zirconocene (EBI)ZrCl2 primarily produced oligomers larger than 10-mer (62 wt%). The methyl substituents at the positions adjacent to the bridgehead in 4 played a significant role in the catalytic performance.
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749, South Korea. bunyeoul@ajou.ac.kr.
authors.forename: Ji Hae
authors.initials: JH
authors.lastname: Park
authors.forename: Young Eun
authors.initials: YE
authors.lastname: Jang
authors.forename: Jong Yeob
authors.initials: JY
authors.lastname: Jeon
authors.forename: Min Jeong
authors.initials: MJ
authors.lastname: Go
authors.forename: Junseong
authors.initials: J
authors.lastname: Lee
authors.forename: Sung Kwan
authors.initials: SK
authors.lastname: Kim
authors.forename: Sang-Ick
authors.initials: SI
authors.lastname: Lee
authors.forename: Bun Yeoul
authors.initials: BY
authors.lastname: Lee