NANOCOMPOSITES CONTAINING NANOCLUSTERS OF AG, CU, PT, OS, CO3C, FE2P, NI2P, GE, OR PT/SN

Neutral, low-valent complexes of transition metals or an organometallic compound of Ge are prepared containing ancillary ligands which bear silicate ester or (alkoxy)silicon functional groups. Inclusion of these molecules as dopant species in a conventional sol-gel synthesis of silica xerogels affords silica xerogels in which dopant molecules have presumably been covalently incorporated into the xerogel matrix with uniform and high dispersion. Subsequent thermal treatment of these molecularly doped xerogels under reducing or oxidizing/reducing conditions gives nanocomposites containing nanoclusters of metals or semiconductor substances. Nanocomposites containing nanoclusters of Ag, Cu, Pt, Os, Co3C, Fe2P, Ni2P, or Ge have been prepared. Preliminary evidence for the formation of a nanocomposite containing Pt-Sn nanoclusters derived from a bimetallic molecular precursor is also presented. These results support the hypothesis that covalent incorporation of molecular precu,aors containing low-valent metals into a silica xerogel can afford nanocluster phases with high dispersion, relatively small particle size, and unusual elemental composition.