Tripodal amido-titanium and -zirconium complexes containing a trisilylsilane-derived ligand framework

Abstract

A series of amido-titanium and -zirconium complexes containing a tripodal amide with a trisilylsilane ligand framework has been prepared. The primary isolable products in the reaction of SiMe (SiMe₂NHR)₃(R = 4-MeC₆H₄, 2-FC₆H₄ or 4-MeOC₆H₄) with LiBuⁿ and ZrCl₄ in diethyl ether are the [Li(OEt₂)₂Cl] adducts of which the five-co-ordinate complex [{(4-MeOC₆H₄NSiMe₂)₃MeSi}Zr(µ-Cl)₂Li(OEt₂)₂] and the six-co-ordinate [{(2-FC₆H₄NSiMe₂)₃MeSi}Zr(µ-Cl)₂Li(OEt₂)₂] have been characterised by X-ray crystallography. In the latter one of the fluorine atoms of the peripheral 2-FC₆H₄ groups is weakly co-ordinated to the metal. Stirring of the (Et₂O)₂LiCl adducts in toluene generates the four-co-ordinate complexes [Zr{SiMe(SiMe₂NR)₃}Cl]. Upon reaction of [M{SiMe[SiMe₂N(C₆H₄F-2)]₃}Cl](M = Ti or Zr) with AgO₃SCF₃ the corresponding triflates were obtained which are sufficiently stable to be isolated. The halide ligand may be readily substituted to give the corresponding methyl, ethynyl and cyclopentadienyl complexes.