Room Temperature Carbonylation of Iron–Phthalocyanines Adsorbed on a Single Crystal Metal Surface: An in Situ SFG Investigation at Near-Ambient Pressure

We report the experimental spectroscopic evidence for the room temperature carbonylation, at equilibrium with the carbon monoxide gas phase, of iron phthalocyanines adsorbed on the (111) termination of the iridium single crystal. The adsorption process occurs at CO pressures above the mbar yield. Interestingly, heme and heme-like catalytic, carrier, and enzymatic biomolecules interact with the gaseous reactants at partial pressures that are similar to the values that we observed on this model system, a 2D layer of single-atom metallorganic catalysts pre-assembled under ultra-high vacuum conditions. A simple Langmuir description of the adsorption mechanism yields a CO-Fe binding energy of 0.1-0.3 eV, depending on the assumptions about the pre-exponential factor. The internal vibrational structure of the adsorbed iron phthalocyanines is also investigated.