THE LOW TEMPERATURE WAY TO OXIDES VIA ALCOHOLATE PRECURSORS: STRUCTURE, REACTIVITY, MORPHOLOGY. Heiko Thoms, Matthias Epple, Armin Reller, Institute of Inorganic and Applied Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, D - 20146 Hamburg, Germany

Different alcoholates of magnesium and mixed Mg/Si-, Mg/Ti-, Mg/Zr-and Ti/Si-diolates were prepared. A single-crystal X-ray structure analysis was so far only possible for the compound Mg(OCH₃)₂ . 2 CH₃OH in the orthorhombic space group Ccca with Z = 64 [1]. The main structural elements are isolated heterocubane units with Mg²⁺ and OCH₃^- ions in the corner. All magnesium alcoholates follow the same thermal decomposition pathway to magnesium oxide MgO via alkoxy-hydroxy intermediates, a fact also confirmed by EXAFS. Scanning electron microscopy of the magnesium oxides and mixed oxides prepared by thermal decomposition of the alcoholates at temperatures between 500deg.C and 600deg.C shows significant differences in morphology and domain size which are important for many applications of these oxides.

[ 1] H. Thoms, M. Epple, H. Viebrock, A. Reller, J. Mater. Chem., 5 ( 1995 ) 589-594