Bond Energies of Molecular Fragments to Metal Surfaces Track Their Bond Energies to H Atoms

The bond energy of molecular fragments to metal surfaces is of great fundamental importance, especially for understanding catalytic reactivity. Thus, the energies of adsorbed intermediates are routinely calculated to understand and even predict the activity of catalytic materials. By correlating our recent calorimetry measurements of the adiabatic bond dissociation enthalpies of three oxygen-bound molecular fragments [-OH, -OCH3, and -O(O)CH] to the Pt(111) surface, it is found that these RO-Pt(111) bond enthalpies vary linearly with the RO-H bond enthalpies in the corresponding gas-phase molecules (water, methanol, and formic acid), with a slope of 1.00. This parallels the known trend for organometallic complexes, thus highlighting the local character of chemical bonding, even on extended metal surfaces. This allows prediction of bond enthalpies for many other molecular fragments to metal surfaces, and the energetics of important catalytic reactions.