Formation of a stabilized coordinatively unsaturated metal carbonyl cluster, H2Ru4(CO)12, by photochemical reaction of H2Ru4(CO)13 adsorbed on the surface of silica

Abstract

The photochemical formation of coordinatively unsaturated metal carbonyl clusters on the surface of metal oxide supports has the potential of leading to interesting new materials that can be used as selective catalysts. In line with the authors' work on this theme, the photochemical reaction of dihydrotetraruthenium tridecacarbonyl, H[sub 2]Ru[sub 4](CO)[sub 13], adsorbed on the surface of silica was investigated by DRS UV-visible, FT-IR, and EXAFS spectroscopies. When irradiated by UV-visible light, H[sub 2]Ru[sub 4](CO)[sub 13] loses one carbon monoxide ligand, producing selectively a coordinatively unsaturated H[sub 2]Ru[sub 4](CO)[sub 12] on the surface of silica. The initial photoproduct, H[sub 2]Ru[sub 4](CO)[sub 12], is interacting weakly with surface hydroxyl groups, which are the only functionality available to act as a stabilizing ligand, and the dissociated carbon monoxide is lost from the surface. This process prevents secondary reactions, thus leading to the selective formation and stabilization of the coordinatively unsaturated H[sub 2]Ru[sub 4](CO)[sub 12], which is unstable in solutions and undergoes secondary reactions. 20 refs., 4 figs., 2 tabs.