Synthesis And Structure Of Late Transition Metal Complexes

In recent years, olefin polymerization and oligomerization promoted by late transition metal complexes have attracted much attention in both the academic research and industrial application. Brookhart and Gibbson have made great contributions in designing highly active ethylene polymerization catalysts based on iron(II) and cobalt(II) complexes bearing 2,6-(imino)pyridyl ligands. Moreover, Grubbs reported new neutral Ni(II) salicylaldimiminato complexes as catalysts for the ethylene polymerization to obtain high molecular weight polyolefins under moderate conditions. Unfortunately, most of these catalysts were protected by patent. Therefore, it is necessary for us to design and synthesize our own catalyst to develop our polyolefm industry. In this thesis, thirteen new 2,6-bis(imino) phenoxy ligands [L=2,6-(ArNCH)2C6H2OH(CH)(CH3)3], as well as their cobalt(II), nickel(II), Iron (II) and copper(II) complexes were synthesized and characterized. Additionally, nine complexes structures were determined by X-ray diffraction analysis. On the other hand, seven of these complexes were studied on the activity for the ethylene oligerization. The results are presented as follow: (1) The structures of the late transition metal complexes of 2,6-bis(imino)phenoxy ligands depend obviously on the substitute of the ligands. (2) The nickel and cobalt complexes of 6-(imino) phenoxy ligands both display binuclear conformation. (3) The metal ion has significant influence on the structure of complexes. For example, the same ligand can form either complex or double salt when coordinating to cobalt, nickel or iron. (4) Study of the activity shows that the examed catalysts have moderate activities in mild conditions, up to 1.2xl04-2.1xl05g/mol-h-atm for Ni (II) complexes and 103g/molhatm for Co (II) complexes. The oligomers were olefins of C4 to C16-...