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O: Fachverband Oberflächenphysik
O 25: Organic Molecules on Inorganic Substrates III: Adsorption & Growth
O 25.6: Vortrag
Dienstag, 19. März 2024, 11:45–12:00, MA 043
Adsorption and Orientation of N-heterocyclic Carbenes and Olefines on Metallic Surfaces — •Felix Landwehr1, Mowpriya Das2, Sergio Tosoni3, Juan Navarro1, Ankita Das2, Maximilian Koy2, Markus Heyde1, Gianfranco Pacchioni3, Frank Glorius2, and Beatriz Roldan Cuenya1 — 1Fritz-Haber Institute of the MPG, Berlin, Germany — 2Westfälische Wilhelms-Universität, Münster, Germany — 3Università di Milano-Bicocca, Milano, Italy
N-Heterocyclic carbenes (NHCs) have attracted scientific interest in recent years due to their excellent properties as surface modifiers with applications in materials science and catalysis. Structurally similar to NHCs are N-heterocyclic olefins (NHOs), comprising of an additional terminal alkylidene moiety (CH2) at the carbene position. NHOs possess highly polarizable and remarkably electron-rich double bonds and have been effectively utilized as exceptional anchors for surface modifications. We investigated the adsorption, orientation and electronic properties of the sterically low-demanding IMe-NHO compared to its analogous IMe-NHC counterpart on a Cu(111) surface. High-resolution electron energy-loss spectroscopy (HREELS) measurements show a flat-lying ring adsorption configuration for both molecules. While the NHC adopts a dimer configuration including a Cu adatom, the NHO chemisorbs over a C-Cu bond perpendicular to the surface. This distinct difference leads for the NHOs to a higher net electron transfer from the surface compared to the NHCs. These results highlight the role of NHOs in surface science as they extend the functionalization capabilities of NHCs into stronger electronic modification.
Keywords: N-Heterocyclic Olefins; N-Heterocyclic Carbenes; High-Resolution Electron Energy-Loss Spectroscopy; Scanning Tunneling Microscopy; X-ray Photoemission Spectroscopy