Chemistry of 1-Iodopropane on Cu(110): Formation, Bonding, and Reactions of Adsorbed Propyl Groups

The adsorption and thermal decomposition of 1-iodopropane on Cu(110) has been investigated under ultrahigh vacuum conditions using temperature-programmed desorption/reaction spectroscopy and reflection-absorption infrared spectroscopy. Adsorption is molecular at 100 K, but at 110 K the 1-iodopropane decomposes to form surface-bound propyl groups and coadsorbed iodine and the propyl groups assume an orientation such that the methyl group is upright. The subsequent chemistry of the propyl moieties is dominated by the evolution of propylene at 200–230 K and H₂ at 315 K. At higher coverages, in addition to molecular desorption, hexane evolution is observed at 130 K, propane forms at 220 K, and a pathway for propylene formation at 390 K opens up. Isotope labeling studies were used to confirm that β-H elimination is the mechanism for propylene formation.