Thermal decomposition of [M3(CO)12] (M=Ru, Os) physisorbed onto porous Vycor glass: a route to a glass/RuO2 nanocomposite

Abstract

This paper reports the preparation and characterization of oxide/glass nanocomposites, obtained by the impregnation and thermal decomposition of the trinuclear metal carbonyl clusters [M ₃ (CO) ₁₂ ] (M=Ru, Os) inside the pores 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 °C (M=Ru) and 110 °C (M=Os), formation of surface bound [HM ₃ (CO) ₁₀ (µ-OSi}}n3)] species occurs, as a result of oxidative addition of a PVG surface silanol group to a cluster M-M bond. At T>130 °C (M=Ru) and T >200 °C (M=Os) cluster breakdown is observed, with formation of [M(CO) _n (OSi}}n3) ₂ ] (n=2 and/or 3) species. When [Ru ₃ (CO) ₁₂ ] incorporated PVG is heated in air at T >250 °C, decomposition of the cluster and formation of RuO ₂ nanoparticles are observed. At 1200 °C, collapse of the glass pores leads to the formation of a transparent silica glass/RuO ₂ nanocomposite of particle average size 45 Å.