Biomimetic [MFe<sub>3</sub>S<sub>4</sub>]<sup>3+</sup> Cubanes (M = V/Mo) as Catalysts for a Fischer–Tropsch-like\nHydrocarbon SynthesisA Computational Study

Nitrogenase is the enzyme primarily responsible for reducing atmospheric\nnitrogen to ammonia. There are three general forms of nitrogenase\nbased on the metal ion present in the cofactor binding site, namely,\nmolybdenum-dependent nitrogenases with the iron–molybdenum\ncofactor (FeMoco), the vanadium-dependent nitrogenases with FeVco,\nand the iron-only nitrogenases. It has been shown that the vanadium-dependent\nnitrogenases tend to have a lesser efficacy in reducing dinitrogen\nbut a higher efficacy in binding and reducing carbon monoxide. In\nbiomimetic chemistry, [MFe<sub>3</sub>S<sub>4</sub>] (M = Mo/V) cubanes\nhave been synthesized, studied, and shown to be promising mimics of\nsome of the geometric and electronic properties of the nitrogenase\ncofactors. In this work, a density functional theory (DFT) study is\npresented on Fischer–Tropsch catalysis by these cubane complexes\nby studying CO binding and reduction to hydrocarbons. Our work implies\nthat molybdenum has stronger binding interactions with the iron–sulfur\nframework of the cubane, which results in easier reduction of substrates\nlike N<sub>2</sub>H<sub>4</sub>. However, this inhibits the binding\nand activation of CO, and hence, the molybdenum-containing complexes\nare less suitable for Fischer–Tropsch catalysis than vanadium-containing\ncomplexes.