  We report that metal-free phthalocyanine (H2Pc) molecules with a central
cavity are able to incorporate Ag atoms from an Ag(110) surface thus creating
silver-phthalocyanine (AgPc). The reaction was investigated by means of
scanning tunneling microscopy (STM) under ultrahigh vacuum, and the metalation
of \ce{H2Pc} at the interface was confirmed with X-ray photoelectron
spectroscopy. Three different kinds of molecules were found on the surface that
are assigned to H2Pc, the corresponding dehydrogenated molecules (Pc) and AgPc.
The relative amounts of Pc and AgPc increase with increasing annealing
temperature. We suggest that the reaction with Ag atoms from the steps of the
surface occurs favorably only for already dehydrogenated molecules; thus, the
metalation of H2Pc is likely limited by the heat-induced dehydrogenation.
Density functional theory simulations of the reaction path are presented to
corroborate this hypothesis.
