Preparation, Characterization and Reactivities of Early Transition Metal Silyl Compounds
This dissertation focuses on syntheses, characterization and reactivities of Groups 4 and 5 metal amide silyl complexes free of anionic π-ligands.
A summary of the research in this dissertation is provided in Chapter 1. Chapter 2 reports an unusual reaction between Ta(NMe2)4SiButPh2 (1) and O2. Three products (Me2N)4Ta(OSiButPh2) (2), (Me2N)3Ta(ONMe2)(OSiButPh2) (3) and (Me2N)2(Ph2ButSiO)2(Me2NCH2NMe)2Ta2(μ-O)2 (4) were isolated from the reaction.
Preparation and characterization of Hf and Ta disilyl complexes are presented in Chapter 3. Novel exchange processes of Zr and Hf amides with silyl ligands were are described in this Chapter.
Chapter 4 describes the kinetics studies of complex (Me2N)3Ta[Si(SiMe3)3]2 (11) complexes with LiSiButPh2 (7). The reaction mechanism was found to follow a dissociative pathway. Tetrahydrofuran (THF) was found to promote the substitution.
Chapter 5 reports the studies of the thermal decomposition of (Me2N)3Ta(SiButPh2)2 (15) and (Me2N)3Ta(SiButPh2)[Si(SiMe3)3] (16). First-order kinetics was observed and the activation parameters ΔH≠, ΔS≠, and ΔG≠ 298 K for the reaction have been obtained. Heating the mixture of W(CH2SiMe3)3(≡CSiMe3)(PMe2Ph) (18a) and its bis(alkylidene) tautomer W(CH2SiMe3)2(=CHSiMe3)2(PMe2Ph) (18b) in the presence of excess PMe2Ph leads to the formation of W(CH2SiMe3)(=CHSiMe3)(≡CSiMe3)(PMe2Ph)2 (19). The reaction process was found to follow first-order kinetics, and the rate constant is independent of the concentrations of PMe2Ph. A possible mechanistic pathway is discussed.
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