On the Variability of Ligand pKa during Homogeneously Catalyzed Aqueous Methanol Dehydrogenation

Using DFT based molecular dynamics simulations

incorporating explicit water solvent, we elucidate the varying behaviour of the ligand pKa of a molecular catalyst for methanol dehydrogenation, using the Ru(PNP) catalytic system

as a case study. The pKa of the amido ligand moiety in this catalytic system is highly sensitive to the species adsorbed on the metal

center, resulting in a substantial variation of the ligand pKa along the catalytic cycle. Since the ligand pKa is an important characteristic that determines the exact role of the ligand during aqueous methanol dehydrogenation, this characteristic has important implications on metal ligand cooperative pathways.