title: Preparation of "Constrained Geometry" Titanium Complexes of [1,2]Azasilinane Framework for Ethylene/1-Octene Copolymerization.
abstract: The Me₂Si-bridgedansa-Cp/amido half-metallocene, [Me₂Si(η⁵-Me₄C₅)(NtBu)]TiCl₂, termed a "constrained-geometry catalyst (CGC)", is a representative homogeneous Ziegler catalyst. CGC derivatives with the [1,2]azasilinane framework, in which the amide alkyl substituent is joined by the Si-bridge, were prepared, and the catalytic performances of these species was studied. Me₄C₅HSi(Me)(CH₂CH=CH₂)-NH(C(R)(R')CH=CH₂) (R, R' = H or methyl; Me₄C₅H = tetramethylcyclopentadienyl) was susceptible to ring closure metathesis (RCM) when treated with Schrock's Mo-catalyst to afford -Si(Me₄C₅H)(Me)CH₂CH=CHC(R)(R')NH- containing a six-membered ring framework. Using the precursors and the products of RCM, various CGC derivatives, i.e., [-Si(η⁵-Me₄C₅)(Me)CH₂CH=CHC(R)(H)N-]TiMe₂ (13, R = H;15, R = Me), [-Si(η⁵-Me₄C₅)(Me)CH₂CH₂CH₂CH₂N]TiMe₂ (14), [(η⁵-Me₄C₅)Si(Me)(CH₂CH=CH₂)NCH₂CH=CH₂]TiMe₂ (16), [(η⁵-Me₄C₅)Si (Me)(CH=CH₂)NCH₂CH=CH₂]TiMe₂ (17), and [(η⁵-Me₄C₅)Si(Me)(CH₂CH₃)NCH₂CH₂CH₃]TiMe₂ (18), were prepared. The catalytic activity of the newly prepared complexes was lower than that of CGC when activated with [Ph₃C][B(C₆F₅)₄]/iBu₃Al. However, the catalytic activity of these species was improved by using tetrabutylaluminoxane ([iBu₂Al]₂O) instead of iBu₃Al and the activity of14/[Ph₃C][B(C₆F₅)₄]/[iBu₂Al]₂O was comparable to that of CGC/[Ph₃C][B(C₆F₅)₄]/iBu₃Al (4.7 and 5.0 × 10⁶ g/mol-Ti, respectively). Advantageously, the newly prepared complexes produced higher molecular weight poly(ethylene-co-1-octene)s than CGC.
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea. dew6745@ajou.ac.kr.
authors.forename: Seul
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea. zerg113@ajou.ac.kr.
authors.forename: Seung Soo
authors.initials: SS
authors.lastname: Park
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea. juniori@ajou.ac.kr.
authors.forename: Jin Gu
authors.initials: JG
authors.lastname: Kim
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea. fubu50f@ajou.ac.kr.
authors.forename: Chung Sol
authors.initials: CS
authors.lastname: Kim
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea. bunyeoul@ajou.ac.kr.
authors.forename: Bun Yeoul
authors.initials: BY
authors.lastname: Lee
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D005030:Ethylenes / Q000737:chemistry*; D015394:Molecular Structure; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: D000475:Alkenes; D005030:Ethylenes; D011108:Polymers; C036216:ethylene; D014025:Titanium; C037690:1-octene
keywords: constrained geometry; half-metallocene; olefin polymerization; titanium complex