Mono-, Di-, and Trimetallic Methacrylate-Substituted Metal Oxide Clusters Derived from Hafnium Butoxide

The methacrylate-substituted clusters Hf4O2(OMC)(12), Hf6O4(OH)(4)(OMc)(12)(BuOH), Ti4Hf4O6(OBu)(4)(OMc)(16), and Ti2Zr5HfO6(OMc)(20) (OMc = methacrylate) were prepared by reacting Hf(OBu)(4), or Hf(OBu)(4)/Ti(OBu)(4) and Hf(OBu)(4)/Zr(OBu)(4)/Ti(OBu)(4) mixtures, respectively, with methacrylic acid. All clusters were characterized by X-ray structure analyses and are basically isostructural, although hot in each case isomorphous, with the corresponding oxozirconium clusters. Low-temperature NMR studies revealed that the methacrylate ligands of Hf4O2(OMc)(12) are highly dynamic even at - 80degreesC.