The third hydrogenase: More natural organometallics

The [Fe]-hydrogenase, also known as “H₂-forming methylenetetrahydromethanopterin dehydrogenase” (Hmd) or “iron-sulfur cluster-free hydrogenase”, is the third distinct class of hydrogenase enzyme to be discovered. In the presence of its carbocation substrate, it catalyzes the reversible cleavage of dihydrogen into H⁺ and H^-, placing the later concomitantly onto the substrate molecule. This review describes the emerging chemistry behind this fascinating enzyme.