6. The iron-molybdenum cofactor of nitrogenase

A New Nitrogenase Mechanism Using a CFe8S9 Model: Does H2 Elimination Activate the Complex to N2 Addition to the Central Carbon Atom?

“…Some microorganisms are able to use the nitrogenase enzyme to convert N 2 to ammonia at 1 atm and room temperature. − By contrast, humans use the Haber–Bosch process, which requires high temperatures and pressures. Much effort has been spent to understand the nitrogenase mechanism in order to develop a bioinspired catalyst. − Dance has been a major contributor to the exploration of the nitrogenase mechanism. − …”

“…The oxidation states of the Fe/Mo atoms in the cluster have been the subject of much debate. , The situation has become even more uncertain with the recent discovery that the Mo oxidation state is +3 rather than +4 as previously assumed. , The spin state of the resting cofactor is S = 3/2, and it is known that at least three protonation/reduction (PR) steps are required before turnover begins. − In a previous study of the nitrogenase mechanism, , a high-spin model NFe 8 S 9 with a plus one charge was used. While a broken-symmetry solution was computed to be lower in energy, the high-spin solution was easier to calculate.…”