|M.Sc Student||Domeshek Elena|
|Subject||Organoactinine Aryl-Amidinate Complexes|
|Department||Department of Chemistry||Supervisor||Professor Moris Eisen|
|Full Thesis text|
Various transition metals, lanthanides and actinides amidinate complexes are known as effective catalysts toward diverse reactions such as isomerization of a-olefins, olefins and ε-caprolactone polymerization. In this work we present our studies of various catalytic reactions mediated by amidinate complexes of Titanium, Thorium and Uranium. Although the large number of studies that were carried out, there is still a lack of information concerning the synthesis and reactivity of actinide complexes containing other ligands than Cp* or its derivatives. Despite the large variety of reaction catalyzed by organoactinides, the common belief was that if oxygen containing substrates will be introduced, a decrease in catalytic activity will be expected due to the high oxophilic nature of the early actinides.
This work describes the synthesis of new organoactinide aryl-amidinate complexes and their catalytic activity toward ε-caprolactone and ethylene polymerization. Moreover, synthesis of a new N,N'-bis(trimethylsilyl)-2-thiophene-amidinate-TMEDA ligand and its corresponding titanium-bis-amidinate complex is introduced. Propylene polymerization studies mediated by the N,N'-bis(trimethylsilyl)-2-thiophen-amidinate titanium dichloride complex are shown in this work, as well.
The new synthesized N,N'-bis(trimethylsilyl)-2-pirydyl-amidinate thorium(μ-Cl)2Li(TMEDA) dichloride complex shows interesting activity towards ε-caprolactone polymerization. Mechanistic studies of ε-caprolactone polymerization revealed a cyclic polycaprolactone product. Combination of diverse NMR experiments and GPC results helped us to propose a relevant mechanism for this polymerization process.
Ethylene polymerization studies mediated by N,N'-bis(trimethylsilyl)-2-pirydyl-amidinate uranium(μ-Cl)2Li(TMEDA) dichloride complex with various co-catalysts were performed. Appropriate mechanistic investigations were carried out for every catalytic mixture. To shed light on the ethylene polymerization mechanisms nature, intertwinement of spectroscopic and physical method was used. Among the investigated co-catalyst for ethylene polymerization with uranium amidinate complex we used MAO, TTPB and TIBA. Furthermore, activity comparison between the actinide-amidinate thorium and uranium complexes toward ethylene polymerization are discussed in this work.
Another aspect of this work focuses on propylene polymerization mediated by N,N'-bis(trimethylsilyl)-2-thiophene-amidinate titanium dichloride complex. Effect of different polymerization condition on the nature of the resulted polymers is presented.