After adsorption of metal precursors, we explore the ligand exchange reaction to eliminate Cp ligand through H transfer, CpH formation and CpH desorption, which is the same as the NHx-terminated Co and Ru surfaces. The computed reaction energies along the pathway for Cp ligand elimination on the Hterminated Si(100) surface for RuCp2 and CoCp2 are shown in Figure . We see that one Cp ligand could be eliminated for both precursors with the computed reaction energies for the elimination of the first CpH being 0.05eV for RuCp2 and 0.12eV for CoCp2. The overall reaction energy for elimination of two Cp ligands is endothermic for both precursors. The computed energy cost for elimination of two Cp ligands are 2.83eV for CoCp2 and 2.09eV for RuCp2.