Synthesis, properties and crystal structures of 6-, 7- and 8-coordinate Zr(iv) and Hf(iv) complexes involving thioether and selenoether ligands

Abstract

A series of 6-, 7- and 8-coordinate complexes of the form [MCl₄(L–L)] (M = Zr, Hf; L–L = MeE(CH₂)₂EMe), [ZrCl₄([9]aneS₃)] and [MCl₄{MeE(CH₂)₂EMe}₂] (E = S or Se) has been obtained in moderate to high yield by reaction of [MCl₄(Me₂S)₂] with one (or three for the 1 ∶ 2 M ∶ L–L species) molar equivalents of L–L in rigorously anhydrous CH₂Cl₂. The poorly soluble products have been characterised by far IR spectroscopy, diffuse reflectance UV-Vis spectroscopy and microanalyses. ¹H NMR data are reported for certain systems, although in the majority of cases the very poor solubility prevented useful NMR experiments. The crystal structures of six representative examples, the distorted octahedral [ZrCl₄(Me₂S)₂] and [HfCl₄{MeSe(CH₂)₂SeMe}], the metallocyclic [(ZrCl₄)₂{μ-MeS(CH₂)₃SMe}₂], the flattened dodecahedral [ZrCl₄{MeS(CH₂)₂SMe}₂] and [HfCl₄{MeS(CH₂)₂SMe}₂] and the 7-coordinate [ZrCl₄([9]aneS₃)] are also described. The crystal structure of [Me₂SCH₂Cl]₂[Zr₂Cl₁₀], formed during reaction of [ZrCl₄(Me₂S)₂] with MeSe(CH₂)₂SeMe in CH₂Cl₂ is also presented.