Reduction of C1 Substrates to Hydrocarbons by the Homometallic Precursor and Synthetic Mimic of the Nitrogenase Cofactor.

Solvent-extracted nitrogenase cofactors can reduce C1 substrates (CN-, CO and CO2) to hydrocarbons in reactions driven by a strong reductant, SmI2 (E0' = -1.55 V vs SCE). Here we show that a synthetic [Et4N]4[Fe6S9(SEt)2] cluster (designated the Fe6RHH-cluster), which mimics the homometallic [Fe8S9C] core of the nitrogenase cofactor (designated the L-cluster), is capable of conversion of C1 substrates into hydrocarbons in the same reactions. Comparison of the yields and product profiles between these homometallic clusters and their heterometallic counterparts points to possible roles of the heterometal, interstitial carbide and belt sulfur-bridged iron atoms in catalysis. More importantly, the observation that a "simplified", homometallic cofactor mimic can perform Fischer-Tropsch-like hydrocarbon synthesis suggests future biotechnological adaptability of nitrogenase-based biomimetic compounds for recycling C1 substrates into useful chemical and fuel products.