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

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.