In Vacuo Porphyrin Metalation on Ag(111) via Chemical Vapor Deposition of Ru₃(CO)₁₂: Mechanistic Insights

Porphyrin molecules offer a very stable molecular environment for the incorporation of numerous metal ions inside their cavity, which enables a plethora of applications. The fabrication and characterization of surface confined metal-organic architectures by employing porphyrins are of particular interest. Here, we report on a comprehensive study of chemical vapor deposition (CVD) of triruthenium dodecacarbonyl as metal precursor for the on-surface metalation of different porphyrin species with Ru under ultrahigh vacuum conditions. By employing synchrotron radiation X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS), and scanning tunneling microscopy (STM), we investigated the metalation process and particularly the role of the support: the close packed Ag(111) surface. It was found that the surface is active in the metalation process under the employed conditions: it decomposes the metal precursor and delivers metal centers to the porphyrin macrocycles. The generality of the metalation process is illustrated for tetraphenylporphyrin, its high temperature derivatives, and porphine.