Computational biomimetic-inspired modifications on the reaction and geometry of the FeNi Hydrogenase active site

We performed a KS-DFT study of the catalytic cycle of FeNi Hydrogenase. We found that the catalytic cycle is dependent on the rigidity of the active site structure which is modulated by the surrounding enzyme, as well as electronic effects on the Fe and Ni atoms. Work has been done to attempt to replicate the activity of this enzyme in the lab to create biomimetic analogues, however the TOFs and overpotentials of these analogues differ significantly from the native enzyme. We performed calculations using biomimetic inspired changes to the computational model to observe effects on catalysis. Common biomimetic changes include replacing the CN ligands on the Fe with cp/cp* ligands, however significant structural changes were found, increasing the energetics and inhibiting the creation of the µ-H bound between Fe and Ni. To further study the ligand environment on Fe, we compared how the electron withdrawing or donating nature of the bound ligands influence the reaction. Results indicate that the electron withdrawing nature of the CN ligands is integral for efficient catalysis. Currently, other active site changes such as the inclusion of pdt ligands are being tested to create a comprehensive picture of how these changes influence the reaction profile and structure of the active site.