Dithiolato-Bridged Dinuclear Iron−Nickel Complexes [Fe(CO)₂(CN)₂(μ-SCH₂CH₂CH₂S)Ni(S₂CNR₂)]⁻Modeling the Active Site of [NiFe] Hydrogenase

[NiFe] hydrogenase, the enzyme of which catalyzes the reversible oxidation of molecular hydrogen to protons and electrons, contains a unique heterodinuclear thiolate-bridged Ni-Fe complex in which the iron center is coordinated by CO and CN. We have synthesized dithiolate-bridged Ni-Fe complexes bearing CO and CN ligands to model the active center of [NiFe] hydrogenase. The Ni-Fe complexes containing a [(CN)2(CO)2Fe(mu-S2)NiS2] framework are the closest yet structural models of [NiFe] hydrogenase.