Nitrogenase cofactor

In the related V clusters a similar core structure is seen but with shorter Fe4S3 bond distances. The ten atom Fe4( 43-S)3( 4-S)3 core is contained in the FeMoco structure, Figure 3, with the same bond connectivity and similar spatial arrangement and, as such, probably provides the best starting point for development of higher nuclearity clusters related to the nitrogenase cofactors. 

Scheme 37 shows a hypothetical cycle for the N2 reduction in the coordination sphere of [Fe(S )] complexes (7e-7g) (47), emphasizing the dominance of iron and sulfur in all nitrogenase cofactors. 

Coucouvanis, D., Han, J., and Moon, N. (2002) Synthesis and characterization of sulfur-voided cubanes. Structural analogues for the MoFe3S3 subunit in the nitrogenase cofactor, 7. Am. Chem. Soc. 124, 216-224. 

T26.2 Consider what is meant by the term efficiency in catalysis (you might want to consult Chapter 25 as well). In terms of mechanistic questions, consider the complexity of the process for production of NH3 from N2 as well as the complexity of the nitrogenase cofactor. For example, can the 3D structure help to decide on the binding site of... 

V) environments of the synthetic clusters showed substantial, quantitative structural agreement with the corresponding sections of the relevant cofactors. A visual and metrical comparison is given in Section 5.5.3.2. This cluster type remains the best synthetic representation of the heterometallic subunits of the nitrogenase cofactors to this day. 

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