In Fig. (b), for CoCp2, the overall reaction energy is negative for the first Cp ligand elimination with H transfer from surface NH2. A moderate energy barrier of 0.73eV is computed for the surface H transfer step. The configuration of transition state is shown in Supporting Information. After CpH formation and elimination, the computed energy gain is -0.21eV. For the second surface H transfer, the computed reaction energy is positive. After the 2 nd CpH desorption, the computed reaction energy is positive at 1.86eV. By contrast, for H transfer from bridge NH, the overall reaction energy is positive for 1 st and 2 nd Cp elimination.