In general, three fundamental steps are pivotal in assessing the catalytic activity of the trimetallic MOF nodes for propylene oligomerization which are hydride insertion (BC TS1 ), olefin insertion i.e., C-C coupling (DE TS2 ) and β-hydride elimination (EF TS3 ). We have considered the reaction mechanism shown in Figure for the propylene oligomerization on the trimetallic MOF nodes, Fe 2 M by varying the active metal Ni with other 3dtransition metals i.e., from Sc to Cu. Here, the two Fe atoms are in +3 oxidation state and the active metals are in +2 oxidation state. Further, we also explored the impact of varying spectator atoms on the energy barriers of three crucial steps. Specifically, we examined how substituting Fe in Fe 2 Ni with other 3d transition metals, ranging from Sc to Cu, affects these energy barriers. All the possible spin-states were considered as listed in Table . The Gibbs free energies of the most stable spin-state are chosen to obtain the reaction pathway and are provided in Table . The data shows that the hydride insertion step exhibits lower activation energies than the C-C coupling barriers across all the transition metals (Figure ). Between the C-C coupling and β-hydride elimination steps, C-C coupling generally exhibits higher activation energies (Figure ). However, there are four exceptions where β-hydride elimination has higher activation energies. These include two cases where the gies compared to the hydride insertion step (Figure ). However, there are three outliers where hydride insertion requires more energy than β-hydride elimination, and they are dominated by variations in the spectator atoms. Specifically, spectator atoms with early transition metals i.e., Sc 2 Ni, Ti 2 Ni, and Cr 2 Ni exhibits higher barrier for hydride insertion than β-hydride elimination. Among variations in active metals i.e., Fe 2 M trimetallic MOF nodes, the early transition metals i.e., M ranging from Sc to Co, manifest C-C coupling as the step with the highest energy barrier. In contrast, late transition metals, i.e., Ni and Cu display the highest energy barrier for β-hydride elimination. Additionally, we observed a substantially higher energy barrier (40 kJ/mol higher) for the Fe 3 trimetallic MOF nodes compared to the Fe 2 Ni node, which resonates with the findings reported by Yeh et al. They observed a three-order-of-magnitude lower rate of oligomerization on the pure iron analog MIL-127 compared to Ni-MIL-127. These findings offer reassurance when assessing energy barriers for other transition metal catalysts, thus facilitating initial predictions about potential transition metal catalyst candidates for propylene oligomerization. Further, we plotted the correlation diagram between hydride insertion and β-hydride elimination barriers, considering the two steps are reverse processes of each other. To systematically study the impact of variations, we focused on changing the spectator atoms, thereby understanding the effects of the second coordination sphere while keeping the active metal constant (Figure ). We obtained a strong inverse relationship with R 2 = 0.84 between the two processes, whereby an increase in the energy barrier for hydride insertion is accompanied by a decrease in the energy barrier for β-hydride elimination, and vice versa. This strong correlation highlights the interdependent nature of these steps in catalytic cycles. By systematically varying the spectator atoms in the second coordination sphere, we can fine-tune the catalytic activity and selectivity to optimize the reaction products. This understanding is crucial in catalyst design where the hydride insertion barrier facilitates chain growth if the hydride insertion barrier is lowered and β-hydride lowering is more beneficial for terminating the growth of the polymer chain.