Biological systems employ polynuclear clusters for the biological activation of small molecule substrates in a way to promote multi-electron redox reactions. For instance, biological N2 fixation is a process that involves a six-electron reduction and it is catalyzed by a family of metalloenzymes called nitrogenases. The most abundant nitrogenase is the molybdenum-dependent nitrogenase found in diazotrophs that contains the iron-molybdenum cofactor (FeMoco) in its active site – a cluster composed of seven Fe and one Mo atoms bound through bridging sulfides. There are evidences for the presence of hydride bridges in the FeMoco during the N2 reduction and such ligands are believed to act as sites for storage of electron and proton equivalents, having an essential role in the N2-binding and reduction. For these reasons, we are investigating the synthesis and reactivity of bromide- and sulfide-bridged triiron clusters and specifically, that of mixed sulfide-hydride systems. In this work, we will discuss our ongoing efforts to synthesize and examine the reactivity of such clusters using a multinucleating ligand scaffold containing β-diketiminate coordination sites.

Triiron clusters containing mixed bridging ligands for the study of dinitrogen reduction

254th National Meeting (2017)

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