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MO: Fachverband Molekülphysik

MO 15: Linear and nonlinear Raman Spectroscopy

MO 15.2: Vortrag

Mittwoch, 16. März 2011, 15:00–15:15, MER 02

Investigation of the Interaction of a Group IV Transition Metal-Containing Polyoxometalate with H₂O₂ Using Raman Spectroscopy — •Awatef S. Assran, Ghada Al-Kadamany, Natalya V. Izarova, Rasha Hassanein, Arnulf Materny, and Ulrich Kortz — Center of Functional Materials and Nanomolecular Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany

Raman spectroscopy is a powerful and fast technique for the identification of molecules based on their vibrational “fingerprint”; it is also sensitive to changes in the bond structure. We report the application of Raman spectroscopy to Polyoxometalates (POMs). POMs are discrete metal-oxygen clusters with a large structural and compositional diversity and a unique combination of properties. POMs are able to activate readily available and ecologically clean oxidants: hydrogen peroxide and dioxygen. Such properties render POMs very attractive for application in heterogeneous and homogeneous catalysis, material science, and medicine. Recently, we have synthesized a novel Ti-containing [Ti2(OH)2As2W19O67(H2O)]8-POM, which has shown very interesting catalytic properties. In particular, this polyanion was very active and selective in the epoxidation of alkenes, especially cyclohexene with aqueous H₂O₂. The investigation of the interaction of the polyanion with hydrogen peroxide using Raman spectroscopy provided evidence of the formation of a Ti-peroxo species. In oxidation reactions, the peroxo complex formation is followed by an oxygen transfer to the organic substrate according to the proposed mechanism.