Synthesis and Applications of Ultrafine Particles Derived From Organometallic Complexes

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Group 10 metal complexes with a siloxo ligand, M(Me)(OSiPhィイD23ィエD2)(cod) [1:M = Pt, 2 : M = Pd, cod = 1,5-cyclooctadiene] are newly prepared by the metathetical reaction of M(Me)(Cl)(cod) with NaOSiPhィイD23ィエD2. These complexes are found to form nano-scale ultrafine Pt or Pd particles with concomitant formation of cyclooctane, methane and triphenylsilanol by exposure to molecular hydrogen (1 atm) under ambient conditions. Adsorption of complex 1 on the surface of silica followed by exposure to HィイD22ィエD2 results in the formation of ultrafine Pt particles on silica (mean diameter = 8.2 ± 6.2 nm). These silica-supported Pt particles act as catalyst for hydrogenation of olefins and for reduction of nitrogen oxides. On the other hand, hydrogenolysis of polymer films containing 1 also gives polymer containing highly dispersed Pt particles with mean diameters of 1-8 nm. The Pt metal particles size decreases with decrease of reduction temperature and concentration of 1 in the polymer. The polar polymer such as poly(methyl methacrylate) gives the smallest particles less than 1 nm diameters. These particles are characterized as pure Pt crystals by TEM, FE-TEM, and XPS analyses.