Transition metal guanidinate complexes of groups 4 and 5.

Abstract

The reaction of LiN(SiMe3)2 with RNCNR [R = iPr, Cy] resulted in formation of the new tetra substituted guanidinate ligands Li(RN)2CN(SiMe3)2. Chapter 2 describes the reactions of these ligands with MCl4 [M = Zr, Hf] to give Cl2M[(RN)2CN(SiMe3)2] 2 or [Cl4M(CyN)2CN(SiMe3)2] - depending on the metal ligand ratio employed. Reaction of [Cl4Zr(CyN)2CN(SiMe3)2] - with 3 equivalents of BzMgCl gave the first example of an organo-zirconium complex supported by a guanidinate ligand. Chapter 3 reports on the reaction between triisopropyl guanidine ( iPrN)C(NHiPr)2 and group 5 metal alkyl precursors such as Me3TaCl2 and Me2NbCl3. These species react by protonation/elimination of metal bonded chloride groups and incorporation of a monoanionic guanidinate ligand. Reactions of triisopropyl guanidine with ZrBz4 and ZrCl 4 are reported in chapter 4. The products isolated from these reactions are Bz2Zr[(iPrN)2C(NHiPr)] 2 or the mixture Cl3Zr[(iPrN)2C(NH iPr)] + (iPrNH)3CCl. Also reported in chapter 4 are the results obtained when the dilithium salt of triisopropyl guanidine was reacted with ZrCl4: a unique dimer [Cl2Zr(iPrN)3C]2 which possessed a bridging dianionic guanidinate ligand. Preliminary reactions of this dimer with ethylene and propylene in the presence of MAO showed encouraging catalytic properties. (Abstract shortened by UMI.)