Generating a new chiral ligand system for high-valent early transition metals - Synthesis and structural characterization of C-3-symmetrical tripodalalky/silyl amido complexes

The novel G-chiral tripodal amine HC{SiMe2NH[(S) -3,3-dimethyl-2-butyl]}(3) (1) and its trilithium triamido derivative [HC(SiMe2N(Li)[(S) -3,3-dimethy l-2-buty1]}(3)] (2) have been synthesized and characterized by X-ray diffra ction. The Lithium reagent was used for the synthesis of a C-3-chiral amido -zirconium complex [HC{SiMe2N[(s)-3,3-dimethyl-2-butyl]}(3)ZrCl] (3); the p reparation of the analogous titanium compound was precluded by the redox ac tivity of the metal. Instead, the lithium amide-lithium chloride adduct [HC {siMe(2)N(Li)[(s)-3,3-dimethyl-2-butyl]}(3)LiCl(Et2O)(3)] (4) was isolated from these reactions and structurally characterized by X-ray structure anal ysis. In this cage compound the chloride ion bridges the three amido lithiu m atoms and is itself coordinated to an {(Et2O)(3)Li}(+) fragment. Its isol ation sheds new light upon the complex reaction sequences leading to halide substitution by a polydentate amido ligand.