June 2009   (Technical report   )

Olefin-Metathesis Activity of Double Bond Contacts to a Conducting Solid: Alkylidenes on β-Mo2C. J. Phys. Chem. C 2009, 113, 12339

Mohamed Siaj, Nathalie Dubuc, Peter McBreen

We report a surface spectroscopy investigation of metathesis reactions among propene, ethene, 1-butene, 1,3-butadiene, norbornene, and cyclopentylidene on a planar polycrystalline beta-Mo2C surface. Surface cyclopentylidene was prepared by exposure of the clean metal carbide to cyclopentanone. Propagator species, surface methylidene, ethylidene, propylidene, propylidiene, and ring-opened norbornene were detected using reflectance absorbance infrared spectroscopy. High-resolution X-ray photoelectron data were obtained for the interaction between propene and surface cyclopentylidene. Vibrational and thermal desorption measurements as a function of the number of exposure cycles were carried out for the reaction with propene. Turnover to yield butene was detected. The carbonyl bond dissociative adsorption of propanal and acrolein was used to prepare propylidene and propylidiene to further identify the metathesis propagator species. Given that molybdenum carbide displays metallic conductance, olefin metathesis at the chemisorption bond may find use in the design of devices in which good electrical contact between an electrode and an organic phase is desired. More generally, it offers the opportunity to use routine surface science techniques to study olefin metathesis on extended surfaces.

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http://pubs.acs.org/doi/abs/10.1021/jp900740w