Syntheses, structures, and reactivities of early-transition-metal silyl, amide, and imide complexes.

摘要

This dissertation describes syntheses, characterization and reactivities of Groups 4 and 5 metal amide silyl complexes free of anionic pi-ligands such as cyclopentadienyl (Cp).; Chapter 2 reports unusual equilibria involving zirconium amides, silyl anions, and zirconium silyl complexes through amide-silyl ligand exchange reactions. Silyl anion SiButPh2- (2) was found to substitute an amide ligand in Zr(NMe2) 4 to give (Me2N)3Zr(SiButPh 2)2 (1a) and Zr(NMe2)5 in THF. Silyl anion 2 also selectively attacks the -N(SiMe 3)2 ligand in (Me2N)sZr[N(SiMe3) 2] to give 1a and N(SiMe3)2 -. Both reactions are reversible, leading to unusual ligand exchange equilibria. The thermodynamics of these equilibria has been investigated.; Silyl amide complexes (Me2N)3Ta[N(SiMe3) 2](SiButPh2) and (Me2N)M[N(SiMe 3)2]2(SiButPh2) (M = Zr, Hf) were found to undergo gamma-H abstraction by the silyl ligands to give metallaheterocyclic complexes (Me2N)3-T Me2N3 -TaNSiMe 3SiMe2CH2 and &cubl0;Me2N Me3Si 2NM&sqbl0;N SiMe3SiMe2 CH2&sqbr0;&cubr0;2 (M = Zr, Hf), respectively. The kinetics of these gamma-H abstraction reactions has been studied. The Zr silyl amide complex provided a rare case of consecutive reaction. The reactions of 18a and 18b with O2 were found to give complexes &cubl0;Me2N Me3Si 2NM&sqbl0;N SiMe3SiMe2 CH2O&sqbr0;&cubr0;2 (M = Zr, Hf) with cis- and trans-configurations, respectively. These results are in Chapter 3.; In Chapter 4, the formation of per-amides H2N-M[N(SiMe 3)2]3 (M = Zr, 21a; Hf, 21b ) from ammonolysis reactions and formation of imides Li+(THF) n{lcub}HN--M[N(SiMe3)2]3 {rcub} (M = Zr, 22a; Hf, 22b) from deprotonation of 21a--b by LiN(SiMe3)2 or Li(THF) 3SiButPh2 are reported. One -SiMe3 group in 22a--b undergoes silyl migration to give Li +(THF)2{lcub}Me3SiN--M(NH(SiMe 3)][N(SiMe3)2]2{rcub} (M = Zr, 23a ; Hf, 23b) containing an imide =N(SiMe3) ligand. The first-order kinetics of the 22a → 23a conversion was investigated. THF in the mixed solvent was found to promote the conversion, and the effect of THF on the rate constants was studied.; Preparation, characterization, and X-ray crystal structures of Group 4 amide chloride complexes {lcub}Hf[N(SiMe3)2](NMe2 )2Cl{rcub}2, [(Me3Si)2N] 2MCl2Li(THF)3Cl (M = Zr, Hf) and [(Me3Si) 2N]2MCl2(THF) (M = Zr, Hf) are reported in Chapter 5. Kinetic studies of the decomposition of (Me2N)2Zr[N(SiMe 3)2](SiButPh2), prepared from {lcub}Zr[N(SiMe 3)2](NMe2)2Cl{rcub}2 and LiSiBu tPh2, have been carried out.