title: Fe-N2/CO complexes that model a possible role for the interstitial C atom of FeMo-cofactor (FeMoco).
abstract: We report here a series of four- and five-coordinate Fe model complexes that feature an axial tri(silyl)methyl ligand positioned trans to a substrate-binding site. This arrangement is used to crudely model a single-belt Fe site of the FeMo-cofactor that might bind N2 at a position trans to the interstitial C atom. Reduction of a trigonal pyramidal Fe(I) complex leads to uptake of N2 and subsequent functionalization furnishes an open-shell Fe-diazenido complex. A related series of five-coordinate Fe-CO complexes stable across three redox states is also described. Spectroscopic, crystallographic, and Density Functional Theory (DFT) studies of these complexes suggest that a decrease in the covalency of the Fe-C(alkyl) interaction occurs upon reduction and substrate binding. This leads to unusually long Fe-C(alkyl) bond distances that reflect an ionic Fe-C bond. The data presented are contextualized in support of a hypothesis wherein modulation of a belt Fe-C interaction in the FeMo-cofactor facilitates substrate binding and reduction.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Rittle
authors.forename: Jonas C
authors.initials: JC
authors.lastname: Peters
mesh_terms: D002244:Carbon / Q000737:chemistry*; D018360:Crystallography, X-Ray; D055664:Electrochemical Techniques; D058085:Iron Compounds / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D008983:Molybdoferredoxin / Q000737:chemistry* / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D010084:Oxidation-Reduction; D015204:Spectroscopy, Mossbauer
chemical_list: D058085:Iron Compounds; D008983:Molybdoferredoxin; D002244:Carbon; D009584:Nitrogen
keywords: Fe–N2 complexes; ammonia production; nitrogen fixation; nitrogenase; small molecule activation
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