On‐Surface Friedel–Crafts Alkylation Through a Stabilized Intermediate Complex

ABSTRACT The incorporation of ‐hybridized carbon centers into planar carbon nanostructures is a powerful strategy in solution chemistry for tuning their electronic and structural properties. While on‐surface synthesis has demonstrated efficient coupling strategies for systems, ─ bond formation on surfaces remains largely unexplored. Here, we report the on‐surface analogue of Friedel–Crafts alkylation on a metal surface: an intramolecular ─ coupling reaction based on a specifically designed fluorinated aromatic reactant, with the metal surface itself acting as catalyst. Our reactant‐catalyst design stabilizes the key intermediate; allowing for direct real‐space imaging at the single‐molecule level. By integrating high‐resolution scanning tunneling microscopy, x‐ray photoelectron spectroscopy, and first‐principles computations, we elucidate each elementary step of the on‐surface Friedel–Crafts alkylation pathway. These results open a new route toward the controlled integration of centers into hybrid ─ carbon nanostructures, expanding the synthetic toolbox of on‐surface chemistry.