Tricoordinate Organochromium(III) Complexes Supported by a Bulky Silylamido Ligand Produce Ultra-High-Molecular Weight Polyethylene in the Absence of Activators
Tricoordinate Organochromium(III) Complexes Supported by a Bulky Silylamido Ligand Produce Ultra-High-Molecular Weight Polyethylene in the Absence of Activators
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DOI：
10.1002/hlca.201600199
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发表时间：
2016-11-01
影响因子：
1.8
通讯作者：
Tilley, T. Don
中科院分区：
文献类型：
--
作者：
Liu, Hsueh-Ju;Cai, Irene C.;Tilley, T. Don
由甲硅烷基酰胺基配体 - N(SiMe3)DIPP (DIPP = 2,6-二异丙基苯基) 负载的低配位有机Cr(III)配合物是乙烯聚合催化剂前体，无需额外的助催化剂。 CrCl3(THF)(3) 与 3 或 2 当量的反应。 LiN(SiMe3)DIPP 分别产生四元环金属化 Cr 配合物或 Cr[N(SiMe3)DIPP](2)Cl，且没有 Cr[N(SiMe3)DIPP](3) 的痕迹。添加 1 当量。 LiN(SiMe3) DIPP 转化为 Cr[N(SiMe3)DIPP](2)Cl 也会产生四元金属环，加热后可能通过 r 键复分解步骤转变成新的六元 Cr 金属环。 Cr[N(SiMe3)DIPP](2)Cl 可以很容易地转化为双（酰胺基）Cr(III) 乙烯基和烷基络合物 Cr[N(SiMe3)DIPP](2)R（R = 乙烯基、Bn 和 Me）。所有这些结构特征为具有 Cr-C 键的低配位 Cr(III) 配合物在没有活化剂或助催化剂的情况下引发乙烯聚合，产生超高分子量聚乙烯。
Low-coordinate organoCr(III) complexes supported by the silylamido ligand - N(SiMe3)DIPP (DIPP = 2,6-diisopropylphenyl) are ethylene polymerization catalyst precursors without the need of additional cocatalyst. The reaction of CrCl3(THF)(3) with 3 or 2 equiv. of LiN(SiMe3)DIPP yields either a four-membered cyclometalated Cr complex or Cr[N(SiMe3)DIPP](2)Cl, respectively, with no trace of Cr[N(SiMe3)DIPP](3). Addition of 1 equiv. of LiN(SiMe3) DIPP to Cr[N(SiMe3)DIPP](2)Cl also leads to the four-membered metallacycle, which upon heating transforms to a new sixmembered Cr metallacycle, likely via a r-bond metathesis step. Cr[N(SiMe3)DIPP](2)Cl can be readily converted to bis (amido) Cr(III) vinyl and alkyl complexes Cr[N(SiMe3)DIPP](2)R (R = vinyl, Bn, and Me). All of these structurally characterized low-coordinate Cr(III) complexes with a Cr-C bond initiate the polymerization of ethylene in the absence of activators or cocatalysts, producing ultra-high-molecular weight polyethylene.