Decomposition of 2-hexyne on clean Ru(0 0 1) studied by RAIRS

The decomposition of 2-hexyne on clean Ru(0 0 1), under ultra-high-vacuum, was studied by reflection–absorption infrared spectroscopy (RAIRS). The spectra obtained at 100 K are compatible with the formation of a non-dissociative di-σ/π complex. Evidence was obtained for two decomposition paths. By annealing the low temperature complex above 110 K, the weakened C–C bonds adjacent to the anchor atoms (C1–C2 and C3–C4 bonds) break, eventually yielding methylidyne (RuC–H) and ethylidyne (RuC–CH3), at 220 K. By direct adsorption of 2-hexyne at 130 K or higher temperatures, the C–C triple bond is the first to break, ethylidyne being the major surface species identified by RAIRS. These results are compared to those obtained for 1- and 3-hexyne isomers.