Studies On The Synthesis And Characterization Of Side Chain Replaced By 2 - Imidazoline-based Cyclopentadienyl Ligands

The metal complexes which contain N-bidentate ligands play an unique role in both organic synthesis and olefin polymerization.Metallocene complexes exhibit more particular reactivity due to the introduction of the imidazole/imidazoline heterocycle,considering the regulation of the cyclopentadienyl ligands to structure and reactivity of transition complexes.According to the discussion which influences the Constrained Geometry Catalysts' catalytic activity by recent research results,we attempt to prove the relationship between the framework tension of ligands and the reactivity of Constrained Geometry Catalysts.It is hoped that new-type metallocene complexes which possess the high activity and selectivity for olefin polymerization are developed and that new exquisite polyolefin materials are obtained.The synthesis and characterization of 1,2-dimethylimidazoline, 2-(1-tert-butyloxycarbonyllimidazolin-2-yl)-1,1-dimethyl cyclopentadiene,the Lithium[2-(1-lithiolimidazolin-2-yl)-1,1-diphenylethyl]cyclopentadienide and Lithium[2-(1-methylimidazolin-2-yl)-1,1-diphenylethyl]cyclopentadienide have been studied in this thesis.And also the protection of 1-N of 2-methylimidazoline has been discussed.1,2-dimethylimidazoline which was characterized by IR,~1H NMR and GC-MS was successfully synthesized by the cyclization and dehydration of N-methyldiacetylethylenediamine at the presence of calcium oxide;the yield is 79.4%. Though the synthesis of 1,2-dimethylimidazoline has been reported by A.Ladenburg in 1894,another reference published in 1969 contested the result of A.Ladenburg.By far,no other citations for the synthesis of 1,2-dimethylimidazoline were found in the literature.we have successfully found that tert-butyloxycarbonyl was an effective protecting group by performing the 1 N protection reaction of 2-methylimidazoline with hexamethyldisilanamine,triethyl orthoformate,1,3-dioxolane tetrafluoroboranide and di-tert-butyl dicarbonate.We performed the deprotonation of methyl hydrogen of 2-(1-tert-butyloxycarbonylimidazolin-2-yl)-1,1-dimethyl cyclopentadiene with sec-BuLi in THF and the next reaction with fulvene.The(1-lithioimidazolin-2-yl)methyllithium,(1-methylimidazolin-2-yl)methyllithium and Lithium[2-(1-methylimidazolin-2-yl)-1,1-diphenylethyl]cyclopentadienide were successfully synthesized and characterized by ~1H NMR.The single crystal structure of N~1-methyl-N~2-[(1E,2E)-1-methyl-2-(1-methylimidazolidin-2-diene)ethylidene]-ethane -1,2-diamine and the thermal stability of the imidazoline ring of [2-(1-methylimidazolin-2-yl)-1,1-diphenylethyl]cyclopentadiene with the temperature above 40 degrees have been thoroughly studied in this thesis.The achievements of this thesis lay foundations for the synthesis of IVB complexes as olefin polymerization catalysts and the following olefin polymerization.