Carbon-carbon bond forming reactions on Cu(110) surfaces

The coupling of one-carbon (C1 fragments to form carbon-carbon bonds has been studied on a Cu(110) surface. In these studies, methyl (CH3 and methylene (CH2 groups have been generated on Cu(110) by the dissociative adsorption of CH3I and CH2I2 respectively. Formation of CH3a) below 200 K on this surface is inferred from the lack of molecular desorption as well as the lack of recombinative hydrogen desorption in temperature-programmed reaction (TPR) experiments. Similar low temperature C-I bond dissociation in CH2I2 to form CH2o) is implicated based on the evolution of ethylene at 300 K in TPR studies. By studying the reactions of CD3a) and CH2a) coadsorbed and adsorbed separately on Cu( 110), three C-C bond forming reactions have been identified: Methyl coupling above 400 K to form ethane, methylene coupling at —300 K to form ethylene, and methyl/ methylene coupling (methylene insertion) at 300–350 K to produce ethyl groups. To our knowledge, this is the first time that methylene insertion, a potentially important chain growth step in hydrocarbon syntheses, has been definitively established on metal surfaces.