Model Study of CO Inhibition of [NiFe]hydrogenase

We propose a modified mechanism for the inhibition of [NiFe]hydrogenase ([NiFe]H2ase) by CO. We present a model study, using a NiRu H2ase mimic, that demonstrates that (i) CO completely inhibits the catalytic cycle of the model compound, (ii) CO prefers to coordinate to the RuII center rather than taking an axial position on the NiII center, and (iii) CO is unable to displace a hydrido ligand from the NiRu center. We combine these studies with a reevaluation of previous studies to propose that, under normal circumstances, CO inhibits [NiFe]H2ase by complexing to the FeII center.