title: Modeling Non-Heme Iron Halogenases: High-Spin Oxoiron(IV)-Halide Complexes That Halogenate C-H Bonds.
abstract: The non-heme iron halogenases CytC3 and SyrB2 catalyze C-H bond halogenation in the biosynthesis of some natural products via S = 2 oxoiron(IV)-halide intermediates. These oxidants abstract a hydrogen atom from a substrate C-H bond to generate an alkyl radical that reacts with the bound halide to form a C-X bond chemoselectively. The origin of this selectivity has been explored in biological systems but has not yet been investigated with synthetic models. Here we report the characterization of S = 2 [Fe(IV)(O)(TQA)(Cl/Br)](+) (TQA = tris(quinolyl-2-methyl)amine) complexes that can preferentially halogenate cyclohexane. These are the first synthetic oxoiron(IV)-halide complexes that serve as spectroscopic and functional models for the halogenase intermediates. Interestingly, the nascent substrate radicals generated by these synthetic complexes are not as short-lived as those obtained from heme-based oxidants and can be intercepted by O2 to prevent halogenation, supporting an emerging notion that rapid rebound may not necessarily occur in non-heme oxoiron(IV) oxidations.
authors.affiliation: Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors.forename: Mayank
authors.initials: M
authors.lastname: Puri
authors.affiliation: Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors.forename: Achintesh N
authors.initials: AN
authors.lastname: Biswas
authors.affiliation: Department of Chemistry, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.
authors.forename: Ruixi
authors.initials: R
authors.lastname: Fan
authors.affiliation: Department of Chemistry, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States.
authors.forename: Yisong
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors.forename: Lawrence
authors.initials: L
authors.lastname: Que
mesh_terms: D054879:Halogenation; D058085:Iron Compounds / Q000737:chemistry*; D008958:Models, Molecular; D019159:Nonheme Iron Proteins / Q000737:chemistry*; D010088:Oxidoreductases / Q000737:chemistry*
chemical_list: D058085:Iron Compounds; D019159:Nonheme Iron Proteins; D010088:Oxidoreductases