Tandem vinyl insertion-/ring-opening metathesis copolymerization with ansa-6-[2-(dimesitylboryl)-phenyl]pyrid-2-ylamido zirconium complexes: role of trialkylaluminum and MAO
Tandem vinyl insertion-/ring-opening metathesis copolymerization with ansa-6-[2-(dimesitylboryl)-phenyl]pyrid-2-ylamido zirconium complexes: role of trialkylaluminum and MAO
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DOI：
10.1039/c6py00078a
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发表时间：
2016-03
影响因子：
4.6
通讯作者：
Min Wang;Dongren Wang;Laura Widmann;W. Frey;M. Buchmeiser
中科院分区：
文献类型：
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作者：
Min Wang;Dongren Wang;Laura Widmann;W. Frey;M. Buchmeiser
合成了新型二烷基锆配合物L′ ZrR 2，（R = CH 3，Bn =苄基，CH 2 SiMe 3，L′ = Me 2 Si {η5-四甲基硅}{6-[2-（二均三甲苯基硼基）苯基]吡啶-2-基氨基}）。用1当量活化后，在[Ph 3C]+[B（C6 F5）4]-的情况下，L′Zr（CH 3）2和L′Zr（Bn）2均原位定量转化为[L′Zr（CH 3）]+[B（C6 F5）4]-和[L′Zr（Bn）]+[B（C6 F5）4]-，而L′Zr（CH 2SiMe 3）2的转化率仅为28 mol%。不含铝的阳离子催化剂[L′Zr（CH 3）]+[B（C6 F5）4]−、[L′Zr（Bn）]+[B（C6 F5）4]−和[L′Zr（CH 2SiMe 3）]+[B（C6 F5）4]−引发NBE的开环易位聚合（ROMP），主要形成顺式聚（NBE）ROMP。在[Ph 3C]+[B（C6 F5）4]-和AliBu 3的活化下，L′Zr（CH 3）2、L′Zr（Bn）2和L′Zr（CH 2SiMe 3）2在乙烯（E）与NBE的共聚反应中也表现出中等的催化活性。所得共聚物不含任何ROMP衍生的聚（NBE），这与络合物对NBE的均聚倾向形成鲜明对比。当用甲基铝氧烷（MAO）活化时，L′Zr（CH 3）2和L′Zr（Bn）2产生纯乙烯基插入聚合衍生的聚（NBE）-共-聚（E），而L′Zr（CH 2SiMe 3）2允许通过α-H+消除/加成过程合成主要基于反式聚（NBE）ROMP-共-聚（NBE）VIP-共-聚（E）的共聚物。我们的研究结果进行了讨论的基础上的不稳定性的亚烷基在E的存在下和阻断作用的烷基铝的ROMP通过协调的吡啶基部分的阳离子配合物。
The novel dialkylzirconium complexes L′ZrR2, (R = CH3, Bn = benzyl, CH2SiMe3, L′ = Me2Si{η5-tetramethylcyclopentadienyl}{6-[2-(dimesitylboryl)phenyl]pyrid-2-ylamido}) were synthesized. Upon activation with 1 equiv. of [Ph3C]+[B(C6F5)4]−, both L′Zr(CH3)2 and L′Zr(Bn)2 are quantitatively converted in situ into [L′Zr(CH3)]+[B(C6F5)4]− and [L′Zr(Bn)]+[B(C6F5)4]− while only 28 mol% conversion is observed with L′Zr(CH2SiMe3)2. The aluminum-free cationic catalysts [L′Zr(CH3)]+[B(C6F5)4]−, [L′Zr(Bn)]+[B(C6F5)4]− and [L′Zr(CH2SiMe3)]+[B(C6F5)4]− initiate ring-opening metathesis polymerization (ROMP) of NBE to form predominantly cis-poly(NBE)ROMP. Upon activation with [Ph3C]+[B(C6F5)4]− and AliBu3, L′Zr(CH3)2, L′Zr(Bn)2 and L′Zr(CH2SiMe3)2 also exhibit moderate catalytic activity in the copolymerization of ethylene (E) with NBE. The resulting copolymers do not contain any ROMP-derived poly(NBE), which is in stark contrast to the complexes’ homopolymerization propensity for NBE. Upon activation with methylalumoxane (MAO), L′Zr(CH3)2 and L′Zr(Bn)2 produce pure vinyl-insertion polymerization-derived poly(NBE)-co-poly(E) while L′Zr(CH2SiMe3)2 allows for the synthesis of predominantly trans-poly(NBE)ROMP-co-poly(NBE)VIP-co-poly(E)-based copolymers via an α-H+ elimination/addition process. Our findings are discussed on the basis of the instability of the alkylidenes in the presence of E and the blocking effect of aluminum alkyls on ROMP via coordination to the pyridyl-moiety in the cationic complexes.