Recently, N-heterocyclic carbenes (NHCs) were introduced as alternative anchors for surface modifications and so offered many attractive features, which might render them superior to thiol-based systems. However, little effort has been made to investigate the self-organization process of NHCs on surfaces, an important aspect for the formation of self-assembled monolayers (SAMs), which requires molecular mobility. Based on investigations with scanning tunnelling microscopy and first-principles calculations, we provide an understanding of the microscopic mechanism behind the high mobility observed for NHCs. These NHCs extract a gold atom from the surface, which leads to the formation of an NHC-gold adatom complex that displays a high surface mobility by a ballbot-type motion. Together with their high desorption barrier this enables the formation of ordered and strongly bound SAMs. In addition, this mechanism allows a complementary surface-assisted synthesis of dimeric and hitherto unknown trimeric NHC gold complexes on the surface.

Metal-catalyzed polymerization of 2,6-naphthalenedicarboxylic acid (NDCA) to form poly-2,6-naphthalenes at various surfaces is reported. Polymerizations occur via initial formal dehydrogenation of self-assembled diacids with subsequent decarboxylation to give polymeric bisnaphthyl-Cu species at elevated temperature as intermediate structures (<160 °C). Further temperature increase eventually leads to poly-naphthalenes via reductive elimination. It is demonstrated that the Cu(111) surface works most efficiently to conduct such polymerizations as compared to the Au(111), Ag(111), Cu(100), and Cu(110) surfaces. Poly-2,6-naphthalene with a chain length of over 50 nm is obtained by using this approach. The decarboxylative coupling of aromatic diacids is a very promising tool which further enlarges the portfolio of reactions allowing for on-surface polymerizations and novel organometallic systems preparations.

Polymerization of 1,4-diaminonaphthalene on various Cu substrates resulting in stereoselectively well-defined metal-organic coordination polymers is reported. By using different crystallographic planes (111), (110) and (100) of a Cu substrate the structure of the resulting coordination polymer was controlled.