Coordination of ε-Caprolactone to a Cationic Niobium(V) Alkoxide Complex: Fundamental Insight into Ring-Opening Polymerization via Coordination-Insertion.
Coordination of ε-Caprolactone to a Cationic Niobium(V) Alkoxide Complex: Fundamental Insight into Ring-Opening Polymerization via Coordination-Insertion.
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DOI：
10.1021/acs.inorgchem.3c02491
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发表时间：
2023-09-25
影响因子：
4.6
通讯作者：
Mckeown, Paul
中科院分区：
文献类型：
--
作者：
Buchard, Antoine;Davidson, Matthew G.;du Sart, Gerrit Gobius;Jones, Matthew D.;Kociok-Kohn, Gabriele;Mccormick, Strachan N.;Mckeown, Paul
报道了三种用于ε-己内酯开环聚合的金属离子引发剂，它们具有良好的催化活性和分子量控制。特别是，我们已经在克级上制备并充分表征了单重阳离子烷氧基-Nb（V）ε-己内酯加合物，据我们所知，该加合物代表了具有完整内酯单体和在金属中心同时配位的官能ROP引发基团的金属络合物的前所未有的实例。在80 °C下，所有三个系统都通过配位-插入机制引发ε-己内酯的不朽溶液状态ROP，这已经通过实验研究得到证实，并得到计算数据的支持。自然键轨道计算进一步表明，聚合可能需要异构化的金属中心之间的醇盐链和配位单体。在这项工作中所作的观察，预计通知机械的理解都胺三（酚盐）支持的金属醇盐ROP引发剂，包括各种高度立体选择性的系统，用于聚合的丙交酯和配位插入型ROP协议更广泛。报道了阳离子铌（V）配合物作为催化剂用于ε-己内酯的可控、不灭开环聚合。特别是，一个前所未有的稳定的金属络合物，同时轴承配位单体分子和醇盐引发基团的克级隔离，是在环境温度下容易。催化剂的研究和机械审问这个物种和其他人已经进行。
We report three niobium-based initiators for the catalytic ring-opening polymerization (ROP) of ε-caprolactone, exhibiting good activity and molecular weight control. In particular, we have prepared on the gram-scale and fully characterized a monometallic cationic alkoxo-Nb(V) ε-caprolactone adduct representing, to the best of our knowledge, an unprecedented example of a metal complex with an intact lactone monomer and a functional ROP-initiating group simultaneously coordinated at the metal center. At 80 °C, all three systems initiate the immortal solution-state ROP of ε-caprolactone via a coordination–insertion mechanism, which has been confirmed through experimental studies, and is supported by computational data. Natural bond orbital calculations further indicate that polymerization may necessitate isomerization about the metal center between the alkoxide chain and the coordinated monomer. The observations made in this work are expected to inform mechanistic understanding both of amine tris(phenolate)-supported metal alkoxide ROP initiators, including various highly stereoselective systems for the polymerization of lactides and of coordination–insertion-type ROP protocols more broadly. Cationic niobium(V) complexes are reported as catalysts for the controlled, immortal ring-opening polymerization of ε-caprolactone. In particular, gram-scale isolation of an unprecedented stable metal complex, simultaneously bearing a coordinated monomer molecule and an alkoxide initiating group, is facile at ambient temperature. Catalytic studies and mechanistic interrogation of this species and others have been undertaken.
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影响因子：
13.6
作者：
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