Controlled Incorporation of Nitrides into W‐Fe‐S Clusters

Abstract

AbstractIncorporation of monatomic 2p ligands into the core of iron–sulfur clusters has been researched since the discovery of interstitial carbide in the FeMo cofactor of Mo‐dependent nitrogenase, but has proven to be a synthetic challenge. Herein, two distinct synthetic pathways are rationalized to install nitride ligands into targeted positions of W‐Fe‐S clusters, generating unprecedented nitride‐ligated iron–sulfur clusters, namely [(Tp*)2W2Fe6(μ4‐N)2S6L4]2− (Tp*=tris(3,5‐dimethyl‐1‐pyrazolyl)hydroborate(1−), L=Cl− or Br−). 57Fe Mössbauer study discloses metal oxidation states of WIV2FeII4FeIII2 with localized electron distribution, which is analogous to the mid‐valent iron centres of FeMo cofactor at resting state. Good agreement of Mössbauer data with the empirical linear relationship for Fe–S clusters indicates similar ligand behaviour of nitride and sulfide in such clusters, providing useful reference for reduced nitrogen in a nitrogenase‐like environment.