The results of DFT calculations have been used to define the trends in the interactions of H2, N2, C2H4, C2H2, and C2Me2 with the bivalent lanthanide metallocenes Cp2M (Cp = η5-C5H5) and Cp*2M (Cp* = η5-C5Me5), where M = Sm, Eu, Yb. These results, together with those previously published for the bonding of CO to Cp2M (M = Ca, Eu, Yb), suggest that the interaction of these ligands with the lanthanide metallocenes results from a subtle balance between attractive (dipole−dipole or dipole−induced dipole) and repulsive (electron−electron repulsion within the f shell) forces. The balance between the attractive and repulsive forces, and therefore the net bond energy, depends on the f-electron count in these bivalent lanthanide metallocenes. The computational results are compared with experimental observations on paramagnetic Cp*2Eu and diamagnetic ytterbocene, Cp*2Yb.