The second and third H2 molecules to bind at a cluster are calculated to be slightly weaker than the first binding event by 1-2 kJ/mol, which is minor and can be considered negligible, especially when compared to the differences in the calculated adsorption enthalpies among the Cu I M4 clusters. This illustrates the significance of the identity of the central metal of the secondary building unit in controlling H2 binding at peripheral Cu I sites. Additionally, H2 binding for the Cu I sites in the same cluster have minimal cooperativity. Indeed, the plot of ∆Hads against H2 loading in Figure We employed an energy decomposition analysis based on absolutely localized molecular orbitals (ALMO-EDA) to understand the nature of the binding interaction between Cu I and H2