Two-dimensional delocalized states in organometallic bis-acetylide networks on Ag(111)

The electronic structure of surface-supported organometallic networks with Ag-bis-acetylide bonds that are intermediate products in the bottom-up synthesis of graphdiyne and graphdiyne-like networks were studied. Scanning tunneling microscopy (STM) and spectroscopy (STS) reveal a frontier, unoccupied electronic state that is delocalized along the entire organometallic network and proves the covalent nature of the Ag-bis-acetylide bonds. Density-functional theory (DFT) calculations corroborate the spatial distribution of the observed delocalized state and attribute it to band mixing of carbon and silver atoms combined with n-doping of the metal surface. The metal-bis-acetylide bonds are typical metal-organic bonds with mixed character containing covalent and strong ionic contributions. Moreover, the organometallic networks exhibit a characteristic graphene-like band structure with linear band dispersion at each K point.