Surface chemistry of organic carbonyl compounds and their derivatives on Ni (111)

Abstract

The adsorption and reactions of acetaldehyde, acetone, 2,2-dimethoxypropane (DMP), 1,1-dimethoxyethane (DME), acetaldehyde (acacH), hexafluoroacetylacetone (hfacH) and trifluoroacetylacetone (tfacH) on clean and O-precovered Ni(111) have been investigated by Reflection Absorption Infrared Spectroscopy (RAIRS). Surface O is found to initiate polymerisation of acetaldehyde; while for acetone, it promotes production of eta-1(O,O)-propane-2,2-diyldioxy and stabilizes the acetone enolate formed. Coadsorbed O also facilitates the deprotonation of acacH, tfacH and hfacH on Ni(111) and stabilizes the corresponding beta-diketonate ligands, which eventually decompose through beta-scission of C-CH bond as is observed on the clean surface. On O-precovered Ni(111), DMP decomposes to yield methoxy, eta-1(O)-acetone and a methoxycarbyne species; while for DME, methoxy, eta-1(O)-acetaldehyde and methoxycarbyne are produced. Similar reaction products are observed on clean Ni(111), except that eta-1(O)-acetone and eta-1(O)-acetaldehyde are not formed.