We report the synthesis, molecular structures and applications of bis(pyrazolylmethyl)pyridine Zn(II) and Cu(II) complexes in the ring-opening polymerization (ROP) of ε-carprolactone (ε-CL). Reactions of bis(3,5-dimethyl-pyrazol-1-ylmethyl)pyridine (L1) with the appropriate Zn(II) and Cu(II) carboxylates afforded the corresponding complexes; [Zn(L1)(C₆H₅COO)₂] (1), [Zn(L1)(2-Br-C₆H₄COO)₂] (2), [Cu(L1)(C₆H₅COO)₂] (3) and [Cu(L1)(2-Br-C₆H₄COO)₂] (4) in good yields. Solid state structures of complexes 1 and 2 reveal that the complexes are polymeric and monomeric respectively. EPR analyses of the paramagnetic Cu(II) complexes 3 and 4 were consistent with anisotropic coupling and confirm that the compounds are monomeric both in solution and solid states. Complexes 1–4 formed active catalysts for the polymerization of ε-CL at 110 °C to give polymers with moderate molecular weight and molecular weight distributions. Kinetic analyses of the polymerization reactions indicate pseudo first-order dependency on both monomer and catalyst.

中文翻译：

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双（吡唑基甲基）吡啶Zn（II）和Cu（II）配合物：ε-己内酯开环聚合的分子结构和动力学研究

我们报告了合成，分子结构和双（吡唑基甲基）吡啶Zn（II）和Cu（II）配合物在ε-丙内酯（ε-CL）的开环聚合（ROP）中的应用。双（3,5-二甲基-吡唑-1-基甲基）吡啶（L1）与适当的Zn（II）和Cu（II）羧酸盐的反应得到相应的配合物；[Zn（L1）（C ₆ H ₅ COO）₂ ]（1），[Zn（L1）（2-Br-C ₆ H ₄ COO）₂ ]（2），[Cu（L1）（C ₆ H ₅ COO）₂ ]（3）和[Cu（L 1）（2-Br-C ₆ H ₄ COO）₂ ]（4）的产率很高。配合物1和2的固态结构表明，配合物分别是聚合物的和单体的。顺磁性Cu（II）配合物3和4的EPR分析与各向异性偶合一致，并确认该化合物在溶液和固态下均为单体。配合物1-4形成了活性催化剂，可在110°C下使ε-CL聚合，从而得到分子量和分子量分布适中的聚合物。聚合反应的动力学分析表明是假的 一阶对单体和催化剂的依赖性。