Polydentate Nitrogen Ligand Complexes:Synthesis,Characterization And Their Catalytic Behaviors

This dissertation focuses on the designing and synthesis of several polydentate nitrogen-containing ligands (aminosilyl substituted aminopyridines,2-pyridine-carboxaldehyde phenylhydrazone,2-furane-carboxaldehyde phenylhydrazone and aminosilyl substituted phenyl-acetaldehyde phenylhydrazone) and the corresponding transition metal complexes. The structures of the obtained new compounds were characterized; In addition, the synthesized group4metal compounds were used as catalysts for the olefin polymerization reaction. Moreover, a series Scheme1Synthesis of the metal compounds2c-2f and2j-2m of mono(ferrocenoyl thiourea) and bis(ferrocenoyl thiourea) compounds were synthesized, the structures and the electrochemical behaviors of the compounds were also investigated. Four main parts are included in this dissertation:Part1:The polyolefins mainly consumed in the world are summarized. The progresses of the olefin polymerization and several important catalyst systems of olefin polymerization are also overviewed in this section.Part2:A series of metal compounds of aminosilyl substituted aminopyridinato ligands were synthesized and characterized by NMR, elemental analysis and X-ray diffraction (Scheme1). The corresponding titanium compound2g was an interesting product, the (N,N-dimethylamino)-dimethylsilyl group was eliminated from the original ligand during the reaction process (Scheme2). Upon treatment with MAO, the ethylene polymerization activities of the obtainted group4metal compounds (zirconium compounds2f and2m, titanium compound2g) were studied. And these three complexes exhibited good activities for ethylene homopolymerization [1.52×105g mol (Zr)-1h-1,1.24×105g mol (Ti)-1h-1and1.44×105g mol (Zr)-1h-1], respectively. The copolymerization activity of2m for ethylene and1-hexene was1.40×105g mol (Zr)-1h-1. The resultant poylethylenes in this section possessed high molecular weight and broad molecular weight distributions (MWDs). Scheme2Synthesis of the titanium compound2g Part3:A series of metal compounds of phenylhydrazone ligands, such as2-pyridinecarboxaldehyde phenylhydrazone,2-furanecarboxaldehyde phenylhydrazone and aminosilyl substituted phenylacetaldehyde, were synthesized, respectively. The obtainted new compounds were characterized by NMR, elemental analysis and X-ray diffraction (Scheme3-Scheme7). An unusual1,2-silyl migration reaction was observed during Scheme3Synthesis of the metal compounds3c-3f and the carbon bridged compound3g Scheme4Synthesis of the zirconium compound3h the reaction of compound3n with LDA. The driving force for this rearrangement reaction was also discussed in this part. Upon treatment with MAO, the zirconium compound3k showed moderate activity up to 1.96x105g mol (Zr)-1h-1for ethylene polymerization and produced ultra-high molecular weight polyethylenes with broad molecular weight distributions between2300and7300kg/mol. Scheme5Synthesis of the zirconium compound3k Scheme6Synthesis of the lithium compound3o Scheme7Synthesis of the zinc compound3pPart4:A series of mono(ferrocenoyl thiourea) and bis(ferrocenoyl thiourea) compounds have been synthesized and characterized by NMR, IR, elemental analysis and single-crystal X-ray crystallography (Scheme8-Scheme9), respectively. Comparing with ferrocene, the obtained compounds show red-shift in the absorption peaks and increasing anodic peak potentials (Epa) values in the cyclic voltammetry studies. The electrochemical data showed that the obtained compounds in this part exhibited one-electron reversible or quasi-reversible electrochemical redox behaviors. Scheme8Synthesis of the mono(ferrocenoyl thiourea) compounds4a-4d Scheme9Synthesis of the bis(ferrocenoyl thiourea) compounds4e-4j...