Heterobimetallic Molecular Cages for the Deposition of Cu/Ti and Cu/Zn Mixed-Metal Oxides

Heterobimetallic molecular precursors [Ti₄(dmae)₆(μ-OH)(μ-O)₆Cu₆(OAc)₉·H₂O] (1) and [Zn₇(OAc)₁₀(μ-OH)₆Cu₅(dmae)₄Cl₄] (2) for the deposition of metal oxide thin films of Cu₆Ti₄O₁₂ (Cu₃TiO₄, TiO₂) and Cu₅Zn₇O₁₂ (ZnO, CuO) were prepared by the interaction of Ti(dmae)₄ with Cu(OAc)₂·2H₂O for 1 and tetrameric (N,N-dimethylamino)ethanolatocopper(II) chloride, [(dmae)CuCl]₄ [where dmae = (N,N-dimethylamino)ethanolate] with Zn(OAc)₂·2H₂O (where OAc = acetate) for 2 in dry toluene. Both complexes were characterized by melting point, elemental analysis, Fourier transform IR, fast atom bombardment mass spectrometry, thermal analysis (TGA), and single-crystal X-ray diffraction. TGA and XRD prove that complexes 1 and 2 undergo facile thermal decomposition at 300 and 460 °C to form thin films of Cu/Ti and Cu/Zn mixed-metal oxides, respectively. Scanning electron microscopy and XRD of the thin films suggest the formation of impurity-free crystallite mixtures of Cu₃TiO₄ and TiO₂, with average crystallite sizes of 22.2 nm from complex 1 and of ZnO and CuO with average crystallite sizes of 26.1 nm from complex 2.