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Abstract：
A family of pyridine-oxazoline-ligated cobalt complexes L2CoCl23a-h were synthesized and characterized. Determined via single-crystal X-ray diffraction, complexes 3a and 3d, ligated by two ligands, displayed a distorted tetrahedral coordination of a cobalt center. The X-ray structure indicated the pyridine-oxazoline ligands acted as unusual mono-dentate ligands by coordinating only to Noxazoline. Upon activation with AlEt2Cl (diethylaluminum chloride), these cobalt complexes all exhibited high catalytic activity (up to 2.5 × 106 g·molCo-1·h-1), affording cis-1,4-co-3,4-polyisoprene with molecular weights of 4.4-176 kg mol-1 and a narrow Ð of 1.79-3.42, suggesting a single-site nature of the active sites. The structure of cobalt catalysts and reaction parameters, especially co-catalysts and the reaction temperature, all have significant influence on the polymerization activity but not on the microstructure of polyisoprene.
摘要：
合成并表征了一系列吡啶-恶唑啉连接的钴配合物L2CoCl23a-h。通过单晶X射线衍射测定，复合物3a和3d，由两个配体连接，显示出钴中心的扭曲四面体配位。X射线结构表明吡啶-恶唑啉配体通过仅与N恶唑啉配位而充当不寻常的单齿配体。用AlEt2Cl（氯化二乙基铝）活化后，这些钴配合物均表现出较高的催化活性（高达2.5×106g·molCo-1·h-1），提供顺式-1,4-co-3,4-聚异戊二烯，分子量为4.4-176kgmol-1，窄-1.79-3.42，表明活性位点具有单位点性质。钴催化剂的结构和反应参数,特别是助催化剂和反应温度，均对聚合活性有显著影响,但对聚异戊二烯的微观结构影响不大。
