Berg, IrisSchio, LucaReitz, JustusMolteni, ElenaLahav, LinoyBolaños, Carolina GutiérrezGoldoni, AndreaGrazioli, CesareFratesi, GuidoHansmann, Max M.Floreano, LucaGross, Elad2025-04-252025-04-252023-09-24http://hdl.handle.net/2003/4368010.17877/DE290R-25453Self-assembled monolayers (SAMs) of N-heterocyclic olefins (NHOs) have been prepared on Au(111) and their thermal stability, adsorption geometry, and molecular order were characterized by X-ray photoelectron spectroscopy, polarized X-ray absorption spectroscopy, scanning tunneling microscopy (STM), and density functional theory (DFT) calculations. The strong σ-bond character of NHO anchoring to Au induced high geometrical flexibility that enabled a flat-lying adsorption geometry via coordination to a gold adatom. The flat-lying adsorption geometry was utilized to further increase the surface interaction of the NHO monolayer by backbone functionalization with methyl groups that induced high thermal stability and a large impact on work-function values, which outperformed that of N-heterocyclic carbenes. STM measurements, supported by DFT modeling, identified that the NHOs were self-assembled in dimers, trimers, and tetramers constructed of two, three, and four complexes of NHO−Au-adatom. This self-assembly pattern was correlated to strong NHO−Au interactions and steric hindrance between adsorbates, demonstrating the crucial influence of the carbon-metal σ-bond on monolayer properties.enAngewandte Chemie. International edition; 62(46)https://creativecommons.org/licenses/by-nc-nd/4.0/N-Heterocyclic OlefinsScanning Tunneling MicroscopySelf-Assembled MonolayersSurface ChemistryX-Ray Absorption Spectroscopy540ResearchArticle