To increase the structural diversity of dinucleating platforms that are used in the construction of olefin polymerization catalysts, we are exploring new ligand designs that feature non-alkoxide/phenoxide bridging groups. In the current study, we demonstrate that 1,2,3-triazole-4-carboxamidate donors are excellent N,N-chelators for nickel and can readily bind secondary metal ions. We found that sterically bulky nickel triazolecarboxamidate complexes are active as ethylene homopolymerization catalysts and can afford low molecular weight polyethylene with about 80–130 branches per 1000 carbon atoms. The addition of zinc salts to our nickel complexes led to catalyst inhibition in some cases, which we have attributed to the formation of catalytically inactive mixed-metal species. To circumvent this problem, we anticipate that further elaboration of the triazolecarboxamidate ligand could provide discrete heterobimetallic complexes that will be useful as single-site catalysts with unique reactivity patterns.

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三唑氨基甲酸酯供体作为镍烯烃聚合催化剂的辅助配体

为了增加用于烯烃聚合催化剂构建的双核平台的结构多样性，我们正在探索具有非烷氧基/酚盐桥联基团的新型配体设计。在目前的研究中，我们证明了1,2,3-三唑-4-氨基甲酸酯供体是极好的N，N镍螯合剂，可以很容易地结合二级金属离子。我们发现，空间体积大的三唑氨基甲酸酯镍配合物可作为乙烯均聚催化剂发挥作用，并且可以提供低分子量聚乙烯，每1000个碳原子具有约80-130个支链。在某些情况下，向我们的镍配合物中添加锌盐会导致催化剂受到抑制，这归因于形成了催化惰性的混合金属。为了解决这个问题，我们预计对三唑氨基甲酸酯配体的进一步加工可以提供离散的异双金属配合物，将其用作具有独特反应性模式的单中心催化剂。