Parallel computational modeling of both enzyme active sites and biomimetic complexes provides closer coupling of these two areas and a better understanding of their similarities and differences. Our work has developed along several lines: (1) determinations of thermodynamic properties such as acidity constants (pKa) and redox potentials (E0) of both enzyme active sites and model complexes; (2) predictions of electronic structures and rearrangement mechanisms of oxidized, reduced, and protonated model complexes and enzyme active sites; (3) correlation spectroscopy properties, especially IR frequencies, as a means of identifying the structure and state of active sites and intermediates in model chemistries. This presentation will concentrate on the mechanism of hydrogen evolution from bimetallic complexes that have structural similarities to NiFe hydrogenase. In particular, a series of MN2S2-M’ complexes (M = Ni or Fe(NO); M’ = Fe(CO)Cp or Fe(NO)2) show a range of mechanisms for hydrogen evolution from heterolytic to homolytic coupling where the breaking and reforming of the metal-sulfur bonds play an unexpectedly important role.

Unmasking the interplay of redox-active and hemi-labile ligands in proton reduction electrocatalysis: Computationally derived mechanisms

254th National Meeting (2017)

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