Nitride‐Bridged Mo−Fe−S Double‐Cubanes: Syntheses, Redox Behaviors and Comparison with their W Analogs

Abstract

The FeMo cofactor (FeMoco) of the Mo‐dependent nitrogenase was identified as a Mo‐Fe‐S cluster incorporating a 2p atom in the core. The edge‐bridged double‐cubane (EBDC, [M2Fe6(µ3‐S)6(µ4‐S)2]z (M = Mo/V; z denotes charge)) clusters were demonstrated to undergo rearrangement reactions to generate the apex‐fused double‐cubane clusters ([M2Fe6(μ2‐S)2(μ3‐S)6(μ6‐S)]z) as mimics of the PN‐clusters. The introduction of 2p atoms into the core of EBDC clusters will furnish the possibility of mimicking the FeMoco structure through rearrangement. In this work, an EBDC Mo‐Fe‐S cluster with core nitrides, namely [(Tp*)2Mo2Fe6(μ4‐N)2S6Cl4]2− (Tp* = tris(3,5‐dimethyl‐1‐pyrazolyl)hydroborate), has been synthesized. Subsequent terminal ligand substitution has produced a series of EBDC clusters with isostructural cores. Further studies of the series of nitride‐containing EBDC clusters are focused on their structures and redox properties, as well as comparisons with their W analogs. The results indicate that the core structures of these clusters are affected by distinct hetero‐metal centers and different terminal ligands to a limited extent, but the redox behavior and redox potentials of these clusters differ significantly. This work provides us with a viable method for regulating the properties of the nitride‐containing EBDC clusters, which may be enlightening for further studies of the rearrangement reactions towards mimicking the FeMoco structure.