Spectroscopic and structural characterization of the formation of olefin metathesis initiating sites on unsupported β-Mo2C

Abstract

Reflection absorption infrared spectroscopy (RAIRS), X-ray photoelectron spectroscopy (XPS) and thermal desorption spectrometry (TDS) measurements were used to follow the preparation of surface alkylidenes on β-Mo₂C. Treating the molybdenum carbide surface with acrolein and acetone respectively formed propylidiene and 2-propylidene groups. The propylidiene functionalised surface was found to be active for a ring opening insertion reaction with 1,3,5,7-cyclooctatetraene (COT). Helium ion microscopy (HIM) was used to determine the topological features of the surface. The surface region giving the XPS and RAIRS data is composed of large grains of several microns in diameter. In turn, the surface of these grains shows finer structure in the form of small grains suggesting that the olefin metathesis reactivity is related to the morphology of the sample.