On‐Surface Synthesis of Unsaturated Hydrocarbon Chains through C−S Activation

We use an on‐surface synthesis approach to drive the homocoupling reaction of a simple dithiophenyl‐functionalized precursor on Cu(111). The C−S activation reaction is initiated at low annealing temperature and yields unsaturated hydrocarbon chains interconnected in a fully conjugated reticulated network. High‐resolution atomic force microscopy imaging reveals the opening of the thiophenyl rings and the presence of trans‐ and cis‐oligoacetylene chains as well as pentalene units. The chemical transformations were studied by C 1s and S 2p core level photoemission spectroscopy and supported by theoretical calculations. At higher annealing temperature, additional cyclization reactions take place, leading to the formation of small graphene flakes.