Biologically inspired 3Fe4S cluster as structural mimics of FeMoco M‐cluster

Abstract A 3Fe4S cluster related to M‐cluster of Mo‐nitrogenase is reported. [K(THF) 5 ][Fe 3 (μ‐bdt) 2 (μ‐PPh 2 )(CO) 5 ] ( 1 ) is synthesized from photo‐assisted structural rearrangement of [K(THF) 2 ][(μ,κ 2 ‐bdt)Fe 2 (μ‐PPh 2 )(CO) 5 ] under visible light irradiation. The molecular structure of 1 consists of a Fe 3 core bearing one dithiolate bridge and the second dithiolate group capping onto the metallic plane. The structural motif of 1 is analogous to that of Mo‐participated 3Fe4S unit in M‐cluster of Mo‐nitrogenase, with the similar Fe‐Fe and Fe‐S bond distances. Upon protonation in 193 K, a Fe‐hydride species ( 1H ) is generated and characterized to possess the bridging hydride group (δ = −12.57 ppm) by 1 H‐NMR spectroscopy and DFT calculation. In CH 3 CN solution, complex 1 exhibits a reversible reduction and oxidation process at = −1.94 V and = −0.18 V, respectively, at 273 K. The reduction behavior of 1 in CH 2 Cl 2 solution at 243 K displays a slight modification in the presence of trifluoroacetic acid, revealing a moderate anodic potential shift (~50 mV). The current amplitude of the reduction wave is linearly increased with the increasement of acid added, indicative of the catalytic event.