Mackinawite-Supported Reduction of C1 Substrates into Prebiotically Relevant Precursors

Abstract

Mackinawite has unique structural properties and reactivities when compared to other iron sulfides. Herein we provide evidence for the mackinawite-supported reduction of KCN into various reduced compounds under primordial conditions. We proposed a reaction mechanism based on the nucleophilic attack by the deprotonated mackinawite -SH surface groups at the carbon atom of HCN. The initial binding of the substrate and the subsequent reduction events are supported by DFT calculations and further experiments using other substrates, such as KSCN, KOCN and CS₂. Until now, conversion of CN⁻ into CH₄ and NH₃ has been limited to nitrogenase cofactors or molecular Fe-CN complexes. Our study provides evidence for mackinawite-supported cleavage of the C−N bond under ambient conditions, which opens new avenues for investigation of other substrates for mackinawite-supported reactions while shedding light on the relevance of this type of reaction to the origin of life on Earth.