Varied Thermal Chemistry of Hydrocarbons on Nickel Single-Crystal Surfaces

Temperature programmed desorption (TPD) results are reported for the conversion of styrene, bromocyclopentane, 1-pentene, 1,5-pentadiene, and 1,5-diiodopentane on Ni(100), and of iodoethane and 1- and 2-iodopropane on Ni(110) single-crystal surfaces. The purpose of these experiments was to illustrate the versatility of nickel in promoting a variety of surface steps for the conversion of adsorbed hydrocarbons. Our examples include the selective hydrogenolysis of styrene to toluene, the migration of carbon-carbon double bonds in cyclopentene and 1-pentene, the ring closure of C-5 metallacyclic surface intermediates, the coupling of alkyl groups, and the growth of hydrocarbon chains starting from ethyl and propyl surface intermediates. Additional information is reported on the relative rates of the hydrogenation and dehydrogenation surface steps responsible for multiple H-D exchange steps.