Novel Nickel Catalysts For Addition Polymerization Of Norbornene

In this dissertation, a series of new olefin polymerization catalysts based on nickel or palladium have been synthesized and characterized, and the molecular structures of nine complexes have been confirmed by single crystal X-ray analyses. Among them, two rare three-coordinate nickel(I) complexes and two novel nickel(II) complexes of intramolecular C-H activation were found. Mainly, catalytic activities of these complexes as catalyst for the addition polymerization of norbornene were investigated. The effects of catalyst structures, molar ratio of catalyst/cocatalyst, reaction temperature etc. on polymerization reaction have been discussed in detail. In addition, the immobilization of Cp₂ZrCl₂ using spherical MCM-41 as carrier has been attempted. The full dissertation was summarized as follows:1. Two neutral nickel(II) complexes bearing P,N-chelate ligands have been synthesized and characterized. The molecular structure of complex 1 has been confirmed by single crystal X-ray analyses. After being activated with methylaluminoxane (MAO) these catalytic precursors could polymerize norbornene to afford addition-type polynorbornene (PNB) with high molecular weight M_W (10⁶ g·mol^-1). At optimized polymerization conditions, the catalytic activity was up to 4.43×10⁷ g PNB·mol^-1Ni·h^-1.2. A series of nickel(II) complexes with β-enaminoketonato ligands have been synthesized and characterized. The molecular structures of complex 1, 2 and 4 have been confirmed by single crystal X-ray analyses. After being activated with MAO, these catalytic precursors could polymerize norbornene to afford addition-type PNB. Interestingly, catalytic activities and PNB productivity were greatly enhanced due to the introduction of strong electron-withdrawing group - trifluoro methyl into the ligands.3. Two rare three-coordinate nickel(I) complexes have been synthesized and characterized by EPR spectrum and element analysis. The molecular structures ofthese two complexes have been confirmed by single crystal X-ray analyses. These complexes also could polymerize norbornene to afford addition-type PNB with MAO as cocatalyst.4. Reaction of lithium salts of the anilido-imine and β-diketiminato ligands bearing bulky substitutes on the nitrogen donor atoms with trans-chloro(phenyl)bis(tri -phenylphosphane)nickel(II) results in the formation of two novel nickel(II) complexes of intramolecular C-H activation. The single crystal X-ray analyses confirmed the molecular structures of these two complexes.5. Some new anilido-imine-based neutral palladium(II) complexes have been synthesized and characterized. After being activated with MAO, these complexes showed very high catalytic activities for the addition polymerization of norbornene. Compared with nickel catalysts, palladium catalysts exhibited higher activity for the norbornene polymerization.6. The immobilization of Cp₂ZrCl₂ utilizing spherical MCM-41 as carrier has been attempted. The preliminary experiments showed that some quasi-spherical polyethylene particles and polyethylene fibers could be observed when using supported metallocene catalyst to polymerize ethylene.