New Ru Nanoparticles Stabilized by Organosilane Fragments

The decomposition of the organometallic ruthenium precursor [Ru(COD)(COT)] (COD = 1,5-cyclooctadiene; COT = 1,3,5-cyclooctatriene) in mild conditions (193 K, 3 bar H2) in n-pentane leads, in the presence of octylsilane (H3SiC8H17) as stabilizer (ligand), to the formation of nanoparticles of about 2.3 nm in diameter with a narrow size distribution as demonstrated by TEM observations. Infrared spectroscopy shows that all the (Si-H) bands disappeared and that some alkyl fragments remain grafted on the metallic surface. Both liquid and solid state 13C CP-MAS NMR could be successfully applied to characterize alkylsilane fragments grafted on the ruthenium nanoparticlesʹ surface. Similar results were obtained by the two techniques. Although the signal corresponding to the carbons in position was missing and the signal corresponding to the carbon in (beta)position was strongly lowered, the signals corresponding to the other carbons were clearly identified. This may be the result of both the lack of surface homogeneity and the weak "knight shift" of ruthenium. To our knowledge, it is the first time that ruthenium nanoparticles stabilized by surface-grafted alkylsilane fragments are synthesized and fully characterized by electron microscopy as well as solid state 13C MAS NMR.