Electronic Elements Governing the Binding of Small Molecules to a [Fe]-hydrogenase Mimic

[Fe]-hydrogenase, one of three types of hydrogenases, activates molecular hydrogen. Here, using DFT computations, we examine the electronic elements governing the binding of small ligands to a recently synthesized [Fe]-hydrogenase biomimic. Computed reaction free energies indicate that anionic species, such as CN- and H-, and acceptors, such as CO, bind favourably with the Fe centre. Ligands such as H2O, CH3CN, and H-2, however, do not bind iron. Protonation of an adjacent thiolate ligand on the mimic significantly increases the energies of ligand binding. Additional computational analysis reveals that the degree of electron donation from the ligand to the mimic correlates strongly with overall binding ability. The results give insights into the electronic elements of iron-small-molecule interaction in these model complexes.