Abstract
Oxide clusters such as [n-Bu4N]2[ { (η 3-C4H7)2Rh}2(V4O12)], [( MCp*)4V6O19] (M = Rh, Ir), and [(MCP*)4 Mo4O16]( M = Rh, Ir) were attached on a silica surface as a molecular model for oxide catalysts and supported metal catalysts. The structure and electronic state of the attached clusters were investigated by EXAFS, FT-IR, XPS, TPD, and FT-Raman spectroscopies. Kinetic studies of catalytic reactions such as hydroformylation, oxidation, hydration, and metathesis were carried out. Coordination unsaturated sites appeared upon evacuation of attached vanadium oxide clusters or the photo-reduction of attached molybdenum oxide cluster under CO, which were characterized on a molecular level. The kinetic study related to the cluster structure revealed that the coordinatively unsaturated sites produced by the thermal evacuation or the photo-reduction were catalytically active for selective propene oxidation and metathesis reactions. This study showed that attached oxide clusters were promising model, which can be well characterized on a molecular level, of oxide catalysts and/or supported metal catalysts.
