Abstract We report the synthesis of structurally well-characterized di-nuclear nickel bis(benzotriazole iminophenolate) (BiIBTP) complexes containing diverse mono- or bi-dentate monoanionic coligands for the utilization of copolymerization of carbon dioxide (CO2) with internal epoxides. The molecular structures of complexes 1–3 can be ascribed to bimetallic nickel(II) species containing a hexadentate BiIBTP main ligand and two homo-coligands of pentafluorobenzoate, pentafluorophenolate or chloride, whereas 4 and 5 are BiIBTP-ligated di-nickel chloride analogues mixed with carboxylate coligands. Di-nickel complexes 1 and 3 supported by O2CC6F5 and Cl coligands were demonstrated to be efficient catalysts for alternating copolymerization of CO2 with cyclohexene oxide (CHO) to afford CO2-based poly(cyclohexene carbonate)s (PCHCs) with >99% carbonate repeated units. Particularly, di-Ni di-chloride complex 3 was capable of giving high activity with a turnover frequency of 688 h−1 for such copolymerization under the optimal conditions. Interestingly, di-Ni catalyst 1 enables us to produce the low molecular weight di-hydroxyl end-capped PCHCs with unimodal molecular weight distributions while commercially available CHO without further purification was used as the epoxide monomer. In addition to CO2-CHO copolymerization, bimetallic complex 1 was also found to effectively copolymerize CO2 with cyclopentene oxide, generating highly alternating poly(cyclopentene carbonate)s with molecular weights in a broad range. Kinetic studies of CO2/CHO copolymerization catalyzed by 1 were investigated using 1H NMR spectroscopy and revealed the first-order dependence for both catalyst 1 and CHO concentrations.

中文翻译：

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镍催化二氧化碳与内环氧化物通过双核双（苯并三唑亚氨基酚酸酯）配合物共聚

摘要 我们报告了结构良好表征的双核双（苯并三唑亚氨基苯酚）镍 (BiIBTP) 配合物的合成，该配合物含有多种单齿或双齿单阴离子共配体，用于利用二氧化碳 (CO2) 与内环氧化物的共聚。配合物 1-3 的分子结构可归因于双金属镍 (II) 物种，其中包含一个六齿 BiIBTP 主要配体和两个五氟苯甲酸、五氟苯酚或氯化物的同配体，而 4 和 5 是 BiIBTP 连接的二氯化镍类似物混合与羧酸盐共配体。由 O2CC6F5 和 Cl 共配体负载的二镍配合物 1 和 3 被证明是 CO2 与氧化环己烯 (CHO) 交替共聚的有效催化剂，以提供基于 CO2 的聚（碳酸环己烯碳酸酯）（PCHC），具有 > 99% 碳酸盐重复单元。特别是，在最佳条件下，二氯化镍配合物 3 能够以 688 h-1 的周转频率为这种共聚提供高活性。有趣的是，二镍催化剂 1 使我们能够生产具有单峰分子量分布的低分子量二羟基封端的 PCHC，而无需进一步纯化的市售 CHO 用作环氧化物单体。除了 CO2-CHO 共聚外，还发现双金属配合物 1 可以有效地将 CO2 与氧化环戊烯共聚，生成分子量范围很广的高度交替的聚（碳酸环戊烯碳酸酯）。