Synthesis And Application Of Nickel(Ⅱ) And Titanium(Ⅳ) Complexes For Olefin Polymerization

In this thesis, a series of nickel complexes and titanium complexes were designed and synthesized. Based on these complexes, we studied the relationship between catalyst structure and catalytic activity and selectivity in olefin polymerization.Part Ⅰ, a series of β-ketoimine-derived nickel(Ⅱ) complexes have been synthesized and characterized by NMR, element analysis and IR. The X-ray structure of116,122and123also had been studied. The single crystal structures show that the heteroatom on the side-arm was coordinated to nickel except the oxygen atom on the side-arm and bridged-phenyl. When activation by MAO, these complexes promote the polymerization of ethylene very smothly and the main products are butenes, in which the highest selectivtity of1-butene reached90.2%with up to9.35×106g/molNi·h·atm. Under optimized the polymerization condition, the highest selectivtity of both hexenes and octenes reached14.7%.Part Ⅱ, we syntheis a series of nickel(Ⅱ) complexes bearing β-diimine anion and neutral β-diimine ligand. The X-ray structures of those nickel complexes show that central nickel adopts distorted square planar geometry when sulfur atom is on the side-arm, but the distorted tetrahedron has been adopted in the presence of oxygen sidearm or absence of sidearm. Unfortunately, those β-diimine nickel complexes are inactive in ethylene polymerization.These complexes proned to be oxygenated by oxygen and give new di-nickel(Ⅱ) complexes have been obtained. Of these complexes,141has been confirmed by X-ray single crystal diffraction. In the presence of MMAO, those dinickel complexes show high activity (>105g/molNi·h·atm) under atmospheric pressure. Under optimal conditions, the activity can reach1.0×106g/molNi·h·atm.Part Ⅲ, a series of2,6-disubstituented-4-methylphenolate titanium(Ⅳ) complexes have been synthesized. Upon treatment with MMAO, those non-cyclopentadienyl Ti(Ⅳ) complexes succesfully catalyze styrene bulk polymerization even at higher temperture and long time, showing modest activity(105g sPS/molTi·h) and high syndiotacticity(>99%).