Silylmethyl and related complexes. Part I. Kinetically stable alkyls of titanium(IV), zirconium(IV), and hafnium(IV)

Abstract

Complexes of the type Cp₂M(CH₂M′Me₃)₂(Cp =π-C₅H₅; M = Ti, Zr, or Hf; M′= Si or Ge) have been prepared from Me₃M′CH₂Li, or less satisfactorily from the Grignard reagent, and Cp₂MCl₂ in ether. Cp₂Zr(Cl)CH₂SiMe₃ was prepared via Me₃SiCH₂MgCl in ether–methylene chloride. Isoleptic complexes (R_nMe_{3 –n}SiCH₂)₄M (M = Ti, Zr, or Hf; n= 0–2; R = Ph or PhCH₂) have been prepared by the reaction of MCl₄ with Me₃SiCH₂Li in ether or hexane, R_nMe_{3 –n}SiCH₂MgCl in ether, or (R_nMe_{3 –n}SiCH₂)₂Mg in hexane. The complexes are thermally more stable than their methyl analogues; oxidative stabilities of the isoleptic compounds correlate with the degree of steric shielding at the metal centre. Spectroscopic data are provided, and the reactions of the isoleptic compounds with water, iodine, and acetylacetone are described.