Fig. 6: Free energy profile of the selective hydrogenation of the alkyne.

All energies were calculated at the ωB97XD/6-311 + G(d,p)-SDD/SMD(Water)//B3LYP-D3(BJ)/6-31 G(d)-LANL2DZ level of theory. The catalyst employed in DFT calculations is a single-atom Pd(II)-N4 site. See SI for computational details and disfavored pathways.