Trans-1,4 selective polymerization of 1,3-butadiene with symmetry pincer chromium complexes activated by MMAO
作者:Dirong Gong、Xiaoyu Jia、Baolin Wang、Xuequan Zhang、Kuo-Wei Huang
DOI:10.1016/j.jorganchem.2014.05.018
日期:2014.9
Tridentate chromium complexes (Cr1–Cr7) incorporated with symmetrical pincer ligand bis(arylimino)pyridine and bis(pyrzaolyl)pyridine have been synthesized and characterized by elemental analyis, FT-IR as well as ESI-MS. X-ray diffraction reveals solids-state structures of Cr2, Cr4 and Cr6 all adopt pseudo-octahedral coordination environment with respect to metal center. All complexes have been tested
通过元素分析,FT-IR和ESI-MS合成并表征了三齿铬配合物(Cr1 - Cr7),该配合物与对称的钳位配体双(芳基氨基)吡啶和双(吡唑基)吡啶结合。X射线衍射显示Cr2,Cr4和Cr6的固态结构相对于金属中心均采用伪八面体配位环境。在各种聚合条件下,所有配合物均已在丁二烯的立体调节聚合中进行了测试。该反式-1,4-和顺发现所得聚合物的-1,4链取决于配体的结构和所用活化剂的量。在最佳条件下,自由邻位取代的Cr催化剂Cr1,Cr3,Cr4和Cr6能够引发高反式-1,4选择性(反式-1,4:89.2%-92.0%),且聚合物的收率高(71.5%- 78.0%),而具有邻位烷基Cr2,Cr5和Cr7的对应物具有适度的聚合物收率的混合选择性。还通过共轭二烯聚合机理阐明了配体的空间效应和MMAO的量对催化性能,特别是立体选择性和聚合物产率的影响。