title: Catalytic reduction of N2 to NH3 by an Fe-N2 complex featuring a C-atom anchor.
abstract: While recent spectroscopic studies have established the presence of an interstitial carbon atom at the center of the iron-molybdenum cofactor (FeMoco) of MoFe-nitrogenase, its role is unknown. We have pursued Fe-N2 model chemistry to explore a hypothesis whereby this C-atom (previously denoted as a light X-atom) may provide a flexible trans interaction with an Fe center to expose an Fe-N2 binding site. In this context, we now report on Fe complexes of a new tris(phosphino)alkyl (CP(iPr)3) ligand featuring an axial carbon donor. It is established that the iron center in this scaffold binds dinitrogen trans to the C(alkyl)-atom anchor in three distinct and structurally characterized oxidation states. Fe-C(alkyl) lengthening is observed upon reduction, reflective of significant ionic character in the Fe-C(alkyl) interaction. The anionic (CP(iPr)3)FeN2(-) species can be functionalized by a silyl electrophile to generate (CP(iPr)3)Fe-N2SiR3. (CP(iPr)3)FeN2(-) also functions as a modest catalyst for the reduction of N2 to NH3 when supplied with electrons and protons at -78 °C under 1 atm N2 (4.6 equiv NH3/Fe).
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91125, United States.
authors.forename: Sidney E
authors.initials: SE
authors.lastname: Creutz
authors.forename: Jonas C
authors.initials: JC
authors.lastname: Peters
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D007501:Iron / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D009584:Nitrogen / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D002244:Carbon; D000641:Ammonia; D007501:Iron; D009584:Nitrogen