Scheme 1. Schematic representation of H-cluster assembly. The transfer of the pre-catalyst ([2Fe]adt) from HydF results in the release of a CO ligand and oxidation of the dinuclear complex to give Hox ([FeIIFeI]-[4Fe4S]2+-HydA), with concomitant reduction of the [4Fe4S] cluster on HydF ([4Fe4S]+-HydF). Note that the model for [2Fe]adt binding to HydF is based on ref. 5. An alternative model, with a reversed μ-CN– bond is proposed in ref. 27.
