Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 49: Surface Chemical Reactions and Heterogeneous Catalysis III
O 49.8: Vortrag
Mittwoch, 2. April 2014, 12:15–12:30, PHY C 213
Structure and Reactivity of K[VO(O2)Hheida]: DFT Studies on the Interpretation of IR and NEXAFS Spectra — •Lili Sun and Klaus Hermann — Inorganic Chemistry Department, Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin
The identification of structural details of catalyst particles is important for a reliable description of structure-reactivity relationships. Here we consider an oxoperoxovanadium(V) compound chelated with N-(2-hydroxyethyl) iminodiacetic acid, [VO(O2)Hheida]. This complex is an efficient functional model for the vanadium haloperoxidase enzyme which acts as a halide oxidant. It includes various oxygen species next to its vanadium atom in very different local coordination. Thus, the [VO(O2)Hheida] complex offers an ideal test case for examining differently coordinated oxygen in the same system.
DFT calculations are performed to obtain the equilibrium geometry of the [VO(O2)Hheida]− ion and the results agree well with experiments for a K[VO(O2)Hheida] single crystal where potassium ions form the positive counterpart. The analysis of vibrational modes allows an identification of differently coordinated oxygen species, such as vanadyl and di-oxo, although corresponding modes are not well localized. The theoretical spectrum fits with experimental data from IR and Raman measurements. Theoretical O 1s NEXAFS spectra are also evaluated. The corresponding partial NEXAFS spectra show substantial differences amongst the different oxygen species which allows an easy discrimination. These results confirm the experimental O K-shell NEXAFS data.