Synthesis Of Novel Half-sandwich Chromocene Complexes Bearing Pendant Thienyl Group And Catalysis For Ethylene Polymerization

This thesis includes two sections:1) The synthesis, characterization of novel half-sandwich chromocene complexes bearing pendant thienyl group; 2) The catalytic performance of these complexes for ethylene polymerization.Eight cyclopentadienyl ligands (L1-L8) with pendant thienyl group were synthesized. Subsequently five novel half-sandwich chromocene complexes C1, C3, C4, C6 and C7 bearing these ligands were synthesized successfully. All of the ligands were characterized by 1H NMR, and all of the complexes passed the MS, EA or HRMS.The chromium complexes were used to catalyze ethylene polymerization. All complexes displayed high catalytic activities similar to Cp2ZrCl2 upon the activation of MAO. Among them the complex C6 showed the highest activity up to 21.3×105 g PE-mol-Cr-1h-1 under the conditions of 90℃,30 min,2 bar, Al/Cr= 1000. The effects of polymerization temperature, the radio of Al/Cr, polymerization time and the structure of complexes on the catalytic activities were also studied. The activities increased with the increase of polymerization temperature, the radio of Al/Cr and polymerization time. In addition, the activities of these catalysts were closely related to the steric structure and electronic effect of the complexes. The molecular weights of polymers varied from 0.49 to 4.26×l04 g-mol-1. The highest molecular weight of 4.26x104 g-mol"1 was obtained by complex C4 under the conditions of 80℃,30 min,2 bar and Al/Cr=1000:1.