The organometallic active site of [Fe]hydrogenase: Models and entatic states

The simple organometallic, (mu-S-2)Fe-2(CO)(6), serves as a precursor to synthetic analogues of the chemically rudimentary iron-only hydrogenase enzyme active site. The fundamental properties of the (mu-SCH2CH2CH2S)[Fe(CO)(3)](2) compound, including structural mobility and regioselectivity in cyanide/carbon monoxide substitution reactions, relate to the enzyme active site in the form of transition-state structures along reaction paths rather than ground-state structures. Even in the absence of protein-based active-site organization, the ground-state structural model complexes are shown to serve as hydrogenase enzyme reaction models, H-2 uptake and H-2 production, with the input of photo- or electrochemical energy, respectively.