On‐Surface Debromination of 2,3‐Bis(dibromomethyl)‐ and 2,3‐Bis(bromomethyl)naphthalene: Dimerization or Polymerization?

We describe the on‐surface dehalogenative homocoupling of benzylic bromides, namely bis‐bromomethyl‐ and bis‐gem‐(dibromomethyl) naphthalene as a potential route to either hydrocarbon dimers or conjugated polymers on Au(111). While bis‐gem‐(dibromomethyl) naphthalene affords different dimers with naphthocyclobutadiene as the key intermediate, bis‐bromomethyl naphthalene furnishes a poly(o‐naphthylene vinylidene) as a non‐conjugated polymer which undergoes dehydrogenation toward its conjugated derivative poly(o‐naphthylene vinylene) upon mild annealing. A combination of scanning tunneling microscopy, non‐contact atomic force microscopy and density functional theory calculations provides deep insights into the prevailing mechanisms.