Sonogashira cross-coupling over Au(1 1 1): from UHV to ambient pressure
Research output: Contribution to journal › Article
We have studied the reaction of phenylacetylene (PA) with chloro-, bromo-, and iodobenzene on the Au(1 1 1) surface as a model system for the gold-catalysed Sonogashira cross-coupling. Both ultrahigh vacuum-based and ambient pressure x-ray photoelectron spectroscopy show that iodo- and chlorobenzene (IB and CB) undergo the cross-coupling reaction towards diphenylacetylene. Bromobenzene (BB), in contrast, does not react in the UHV experiments. Further, at ambient pressure signs are found for poisoning of the Au(1 1 1) surface by a carbon species formed in the reaction. The understanding obtained in the reaction experiments are based on a thorough investigation of the adsorption of PA, IB, CB, and BB on the Au(1 1 1) surface by soft x-ray absorption spectroscopy and temperature-dependent x-ray photoelectron spectroscopy. In particular, the experiments provide the orientation of the intact adsorbates with respect to the surfaces at liquid nitrogen temperature. Dissociation in the temperature regime between −80 and −15 °C is observed for iodo- and chlorobenzene, but not for BB, in agreement with that only IB and CB, but not BB, react with PA to form diphenylacetylene. The difference is tentatively attributed to a difference in surface orientation of the different halobenzenes.
|Research areas and keywords||
Subject classification (UKÄ) – MANDATORY
|Journal||Journal of Physics: Condensed Matter|
|State||Published - 2017 Oct 5|
Related research output
Niclas Johansson, 2017 Oct, Lund: Lund University, Faculty of Science, Department of Physics. 216 p.
Research output: Thesis › Doctoral Thesis (compilation)