Stefan Faber

Metal centered molecules and their application in chemistry and physics

Monocyclic as well as polycyclic silylamides of a series of main group metals such as Li, Ge, Sn and Pb (the last three elements mostly in the oxidation state ˛II) have been synthesized, analyzed by spectroscopic means and structurally characterized over the last 20 years. All these molecular compounds have in common a Lewis acidic (electrophilic) metal center with at least one bond to nitrogen. In the case of the bis(amino)germylenes, -stannylenes and -plumbylenes, the metal centers are poorly coordinated (only two bonds to nitrogen) and may directly react with organic p-systems. This nonclassical behaviour will be discussed shortly. If the metal atoms are more highly coordinated by intramolecular nitrogen or oxygen bases, the oxidation to stable germaimines or germathiones is possible, whereas the corres- ponding tin compounds are only transient in nature. Finally, the use of special metal alkoxides (for example Ge(OtBu)2 or Sn(OtBu)2) or alkoxohydrides like (H2AlOtBu) as single source precursors in the chemical vapour deposition process to form biphasic nanocomposites of metal clusters in a metal oxide matrix is highlighted. The composites obtained from this technique have peculiar fractal structures.