Trimethyltin-Mediated Covalent Gold-Carbon Bond Formation

We study the formation of covalent goldcarbon bonds in benzyltrimethylstannane (C10H16Sn) deposited on Au in ultra-high-vacuum conditions. Through X-ray photoemission spectroscopy and X-ray absorption measurements, we find that the molecule fragments at the Snbenzyl bond when exposed to Au surfaces at temperatures as low as -110 degrees C. The resulting benzyl species is stabilized by the presence of Au(111) but only forms covalent AuC bonds on more reactive Au surfaces like Au(110). We also present spectroscopic proof for the existence of an electronic gateway state localized on the AuC bond that is responsible for its unique electronic properties. Finally, we use DFT-based nudged elastic band calculations to elucidate the crucial role played by the under-coordinated Au surface in the formation of AuC bonds.