A series of unsymmetrical 2,6-bis(imino)pyridylcobalt(II) complexes, 2-[2,6-(CH(C6H5)2)2-4-Me–C6H2NC(CH3)]-6-(2,6-R12-4-R2–C6H2NCCH3)–C5H3NCoCl2} where R1 = Me, Et or iPr, R2 = H or Me, together with the new symmetrical complex 2,6-[2,6-(CH(C6H5)2)2-4-Me–C6H2NC(CH3)]2–C5H3NCoCl2, were synthesized. All of the compounds were fully characterized by 1H NMR and IR spectroscopy, as well as by elemental analysis. The molecular structures of Co1 (R1 = Me, R2 = H) and Co5 (R1 = Et, R2 = Me) were further confirmed by single crystal X-ray diffraction, which indicated that the cobalt centres were penta-coordinate with a pseudo square-pyramidal geometry. Upon treatment with MAO or MMAO, these cobalt pre-catalysts exhibited higher activities than any previously reported cobalt pre-catalysts, with values as high as 4.64 × 106 g PE mol−1(Co) h−1 for ethylene polymerization at atmospheric pressure. The polyethylenes obtained were of high molecular weight and narrow molecular weight distribution.
一系列不对称的 2,6-双(亚
氨基)
吡啶基
钴(II)配合物,2-[2,6-(CH(
C6H5)2)2-4-Me-C6H2NC(
CH3)]-6-(2,6-R12-4-R2-C6H2NC )-C5H3NCoCl2},其中 R1 = Me、其中 R1 = Me、Et 或 iPr,R2 = H 或 Me,同时合成了新的对称复合物 2,6-[2,6-(CH( )2)2-4-Me-C6H2NC( )]2-C5H3NCoCl2。所有化合物都通过 1H NMR 和 IR 光谱以及元素分析进行了全面表征。单晶 X 射线衍射进一步证实了 Co1(R1=Me,R2=H)和 Co5(R1=Et,R2=Me)的分子结构,表明
钴中心为五配位,几何形状为假方阵。经
MAO 或
MMAO 处理后,这些
钴前
催化剂的活性高于之前报道的任何
钴前
催化剂,在常压下进行
乙烯聚合时,活性值高达 4.64 × 106 g PE mol-1(Co) h-1。获得的聚
乙烯分子量高,分子量分布窄。