Thermal decomposition of [M-3(CO)(12)] (M = Ru, Os) physisorbed onto porous Vycor glass: a route to a glass/RuO2 nanocomposite

This paper reports the preparation and characterization of oxide/glass nano composites, obtained by the impregnation and thermal decomposition of the t rinuclear metal carbonyl clusters [M-3(CO)(12)] (M = Ru, Os) inside the por es of porous Vycor glass (PVG). The intermediate species formed during the thermal treatment of the [M-3(CO)(12)] adsorbed PVG materials were studied by UV-VIS-NIR and diffuse reflectance infrared (DR-IR) spectroscopy. At 65 degrees C (M = Ru) and 110 degrees C (M = Os), formation of surface bound [ HM3(CO)(10)(mu-OSi=)] species occurs, as a result of oxidative addition of a PVG surface silanol group to a cluster M-M bond. At T > 130 degrees C (M = Ru) and T > 200 degrees C (M = Os) cluster breakdown is observed, with fo rmation of [M(CO)(n)(OSi=)(2)] (n = 2 and/or 3) species. When [Ru-3(CO)(12) ] incorporated PVG is heated in air at T > 250 degrees C, decomposition of the cluster and formation of RuO2 nanoparticles are observed. At 1200 degre es C, collapse of the glass pores leads to the formation of a transparent s ilica glass/RuO2 nanocomposite of particle average size 45 Angstrom.