On-Surface Synthesis and Intermolecular Cycloadditions of Indacenoditetracenes, Antiaromatic Analogues of Undecacene.

The formation of -indaceno[1,2-:5,6-']ditetracene and -indaceno[2,3-:6,7-']ditetracene containing indenofluorene cores from a common precursor has been achieved by a dehydrogenative surface-assisted cyclization on Au(111) and confirmed by bond-resolved non-contact atomic force microscopy. On-surface generated -indaceno[2,3-:6,7-']ditetracenes undergo fusion, which leads to T-shaped adducts by an intermolecular cycloaddition. The same type of cycloaddition, which has no parallel in solution chemistry, has been observed between -indaceno[2,3-:6,7-']ditetracene and pentacene or octacene. These examples of surface-assisted cycloaddition provide perspectives for the rational design and synthesis of molecular nanostructures.