Synthesis of a Nitrogenase PN‐Cluster Model with [Fe₈S₇(μ‐Sthiolate)₂] Core from the All‐Ferric [Fe₄S₄(Sthiolate)₄] Cubane Synthon

Constructing synthetic models of the nitrogenase P N ‐cluster has been a long‐standing synthetic challenge. Here, we report an optimal nitrogenase P N ‐cluster model [{(TbtS)(OEt 2 )Fe 4 S 3 } 2 (μ‐STbt) 2 (μ 6 ‐S)] ( 2 ) [Tbt=2,4,6‐tris{bis(trimethylsilyl)methyl}phenyl] that is the closest synthetic mimic constructed to date. Of note is that two thiolate ligands and one hexacoordinated sulfide are connecting the two Fe 4 S 3 incomplete cubanes similar to the native P N ‐cluster, which has never been achieved. Cluster 2 has been characterized by X‐ray crystallography and relevant physico‐chemical methods. The variable temperature magnetic moments of 2 indicate a singlet ground state ( S =0). The Mössbauer spectrum of 2 exhibits two doublets with an intensity ratio of 3:1, which suggests the presence of two types of iron sites. The synthetic pathway of the cluster 2 could indicate the native P N ‐cluster maturation process as it has been achieved from the Fe 4 S 4 cubane Fe 4 S 4 (STbt) 4 ( 1 ).