title: High-valent nonheme iron. Two distinct iron(IV) species derived from a common iron(II) precursor.
abstract: The reaction of [Fe(II)(beta-BPMCN)(OTf)2] (1, BPMCN = N,N'-bis(2-pyridylmethyl)-N,N'-dimethyl-trans-1,2-diaminocyclohexane) with tBuOOH at low-temperature yields alkylperoxoiron(III) intermediates 2 in CH2Cl2 and 2-NCMe in CH3CN. At -45 degrees C and above, 2-NCMe converts to a pale green species 3 (lambda(max) = 753 nm, epsilon = 280 M(-1) cm(-1)) in 90% yield, identified as [Fe(IV)(O)(BPMCN)(NCCH3)]2+ by comparison to other nonheme [Fe(IV)(O)(L)]2+ complexes. Below -55 degrees C in CH2Cl2, 2 decays instead to form deep turquoise 4 (lambda(max) = 656, 845 nm; epsilon = 4000, 3600 M(-1) cm(-1)), formulated to be an unprecedented alkylperoxoiron(IV) complex [Fe(IV)(BPMCN)(OH)(OOtBu)]2+ on the basis of Mössbauer, EXAFS, resonance Raman, NMR, and mass spectral evidence. The reactivity of 1 with tBuOOH in the two solvents reveals an unexpectedly rich iron(IV) chemistry that can be supported by the BPMCN ligand.
authors.affiliation: Department of Chemistry and the Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Jensen
authors.forename: Miquel
authors.initials: M
authors.lastname: Costas
authors.forename: Raymond Y N
authors.initials: RY
authors.lastname: Ho
authors.forename: József
authors.initials: J
authors.lastname: Kaizer
authors.forename: Antoni
authors.initials: A
authors.lastname: Mairata i Payeras
authors.forename: Eckard
authors.initials: E
authors.lastname: Münck
authors.forename: Lawrence
authors.initials: L
authors.lastname: Que
authors.forename: Jan-Uwe
authors.initials: JU
authors.lastname: Rohde
authors.forename: Audria
authors.initials: A
authors.lastname: Stubna
mesh_terms: D003080:Cold Temperature; D004578:Electron Spin Resonance Spectroscopy; D005296:Ferrous Compounds / Q000737:chemistry*; D006418:Heme / Q000737:chemistry; D058085:Iron Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D015204:Spectroscopy, Mossbauer; D013059:Spectrum Analysis, Raman; D020122:tert-Butylhydroperoxide / Q000737:chemistry
chemical_list: D005296:Ferrous Compounds; D058085:Iron Compounds; D006418:Heme; D020122:tert-Butylhydroperoxide