Mo(VI) oxide, dispersed as discrete metal oxide sites on silica is of considerable interest as a heterogeneous catalyst for olefin metathesis. As such, understanding the structure of the mononuclear Mo site on the silica support is of considerable interest in understanding the mechanism of the metathesis process. It has been suggested that two sites are present on the, a dioxo site with two terminal oxygens and two Si–O–Mo bridges and a mono-oxo site with as single terminal oxo group and four bridges to silica. To aid in the spectroscopic analysis of these two species we have synthesized Mo(VI)/SiO<sub>2</sub> catalyst using the sol-gel process. This generates optically transparent monoliths that greatly enhance the ability to perform optical spectroscopy. Using these materials, characterization of the Mo(VI) site was carried out using UV-vis spectroscopy (absorption and emission) to understand the electronic structure. Structural characterization of the site was done by EXAFS and by non-resonant and resonant Raman spectroscopy, with the normal modes of vibration assigned though isotopic labeling and normal coordinate analysis based on density functional calculations.

Spectroscopic properties and coordination environment of silica supported MoO3 catalyst

253rd National Meeting (2017)

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