Redox and structural properties of mixed-valence models for the active site of the [FeFe]-hydrogenase: progress and challenges

A study was conducted to examine the oxidations of [Fe.sub.2]([S.sub.2][C.sub.3][H.sub.6])[(CO).sub.3](L)(dppv) (L = CO, P[Me.sub.3], Pi-[Pr.sub.3]) as models for the [H.sub.ox] state of the [FeFe]-hydrogenases. The results for studied diiron(I) dithiolato carbonyls provide insights into the factors that affect the oxidation state assignments, structures, and reactivity of these low-molecular weight models for the [H.sub.ox] state of the [FeFe]-hydrogenases.