Di- and polynuclear complexes as precursors to nanocomposite materials: An overview

Molecularly doped silica xerogels can be prepared via sol-gel procedures by the addition of low-valent di- or polynuclear complexes containing bifunctional Iigands to conventional silica sor-gel formulations. These bifunctional ligands contain distal (alkoxy) silyl groups, so that the dopant complexes can become covalently incorporated into the silica xerogel matrix as it is being formed. Subsequent thermal treatment under solely reducing conditions leads to decomposition of the precursor complex and to the formation of crystalline nanoparticulate material which is highly dispersed throughout the silica xerogel matrix. Such dopant complexes act as single-source precursors for silica xerogel nanocomposites containing nanoclusters of Ru, PtSn, CCo3 or Co2P. An overview of the synthesis and characterization of these nanocomposites is described.