N -Heterocyclic carbenes on close-packed coinage metal surfaces: bis-carbene metal adatom bonding scheme of monolayer films on Au, Ag and Cu

Li Jiang (1) , Bodong Zhang (1) , Guillaume Médard (2) , Ari Paavo Seitsonen (3) , Felix Haag (1) , Francesco Allegretti (1) , Joachim Reichert (1) , Bernhard Kuster (2) , Johannes Barth (1) , Anthoula Papageorgiou (1)

1 E20 - Chair of Molecular Nanoscience and Chemical Physics of Interfaces
2 Chair of Proteomics and Bioanalytics
3 Département de Chimie - ENS Paris

By means of scanning tunnelling microscopy (STM), complementary density functional theory (DFT) and X-ray photoelectron spectroscopy (XPS) we investigate the binding and self-assembly of a saturated molecular layer of model N-heterocyclic carbene (NHC) on Cu(111), Ag(111) and Au(111) surfaces under ultra-high vacuum (UHV) conditions. XPS reveals that at room temperature, coverages up to a monolayer exist, with the molecules engaged in metal carbene bonds. On all three surfaces, we resolve similar arrangements, which can be interpreted only in terms of mononuclear M(NHC)2 (M = Cu, Ag, Au) complexes, reminiscent of the paired bonding of thiols to surface gold adatoms. Theoretical investigations for the case of Au unravel the charge distribution of a Au(111) surface covered by Au(NHC)2 and reveal that this is the energetically preferential adsorption configuration.

Domaines: Physique [physics]

Li Jiang, Bodong Zhang, Guillaume Médard, Ari Paavo Seitsonen, Felix Haag, et al.. N -Heterocyclic carbenes on close-packed coinage metal surfaces: bis-carbene metal adatom bonding scheme of monolayer films on Au, Ag and Cu. Chemical Science, 2017, 8 (12), pp.8301-8308. ⟨10.1039/C7SC03777E⟩. ⟨cea-04075498⟩