d0/fn-Mediated Ring-Opening Ziegler Polymerization (ROZP) and Copolymerization with Mono- and Disubstituted Methylenecyclopropanes. Diverse Mechanisms and a New
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- 作者：Tryg R. Jensen ; James J. O'Donnell III ; and Tobin J. Marks
- 刊名：Organometallics
- 出版年：2004
- 出版时间：February 16, 2004
- 年：2004
- 卷：23
- 期：4
- 页码：740 - 754
- 全文大小：318K
- 年卷期：v.23,no.4(February 16, 2004)
- ISSN：1520-6041
文摘
The mono- and disubstituted methylenecyclopropane derivatives 2-phenyl-1-methylenecyclopropane (A) and 7-methylenebicyclo[4.1.0]heptane (B) have been successfully implemented in ring-opening Ziegler polymerization. Homogeneous ethylene + 2-phenyl-1-methylenecyclopropane (A) random copolymerizations are mediated efficiently by the single-site catalysts Cp*2ZrMe+B(C6F5)4-, [Cp*2LuH]2, [Cp*2SmH]2, and [Cp*2YH]2 (Cp* = C5Me5)to produce a copolymer (C) with A enchained in a ring-opened fashion. Single-site coordinativepolymerization of 7-methylenebicyclo[4.1.0]heptane (B) proceeds via either ring-opened orring-unopened pathways. In the presence of Cp*2ZrMe+ MeB(C6F5)3- at 0 
f">C, B undergoespolymerization to afford the insoluble, ring-unopened homopolymer D, which was characterized by CPMAS NMR, DSC, elemental analysis, FTIR, TGA, and XRD. The melting point ofpolymer D lies above its decomposition temperature (>300 f">C). Random copolymerizationsof B and ethylene mediated by Cp*2ZrMe+MeB(C6F5)3- at room temperature result in polymerE, a polyethylene capped by a ring-opened B fragment. The formation of B-capped polymerE is a consequence of a new chain transfer mechanism, as evidenced by a linear relationshipbetween Mn and [B]-1. The rate constant for insertion of ethylene is ~25× greater than therate constant for insertion of monomer B into the metal-alkyl bond. Random copolymers(F) of ring-opened B and ethylene are produced when the catalysts Me2Si(Me4C5)(tBuN)ZrMe2, Me2Si(Me4C5)(tBuN)TiMe2 (activated by either (C6H5)3C+ B(C6F5)4- or B(C6F5)3), and[Cp*2LuH]2 are employed.
f">C, B undergoespolymerization to afford the insoluble, ring-unopened homopolymer D, which was characterized by CPMAS NMR, DSC, elemental analysis, FTIR, TGA, and XRD. The melting point ofpolymer D lies above its decomposition temperature (>300 f">C). Random copolymerizationsof B and ethylene mediated by Cp*2ZrMe+MeB(C6F5)3- at room temperature result in polymerE, a polyethylene capped by a ring-opened B fragment. The formation of B-capped polymerE is a consequence of a new chain transfer mechanism, as evidenced by a linear relationshipbetween Mn and [B]-1. The rate constant for insertion of ethylene is ~25× greater than therate constant for insertion of monomer B into the metal-alkyl bond. Random copolymers(F) of ring-opened B and ethylene are produced when the catalysts Me2Si(Me4C5)(tBuN)ZrMe2, Me2Si(Me4C5)(tBuN)TiMe2 (activated by either (C6H5)3C+ B(C6F5)4- or B(C6F5)3), and[Cp*2LuH]2 are employed.