High-Valent Nonheme Iron. Two Distinct Iron(IV) Species Derived from a Common Iron(II) Precursor

• Published in: Journal of molecular biology 2005-08, Vol.127 (30), p.10512-10525
• Main Authors: Jensen, Michael P, Costas, Miquel, Ho, Raymond Y. N, Kaizer, József, Mairata i Payeras, Antoni, Münck, Eckard, Que, Lawrence, Rohde, Jan-Uwe, Stubna, Audria
• Format: Article
• Language: English
• Subjects: BASIC BIOLOGICAL SCIENCES; Bioinorganic chemistry; Biological and medical sciences; Chemistry; Cold Temperature; Electron Spin Resonance Spectroscopy; Exact sciences and technology; Ferrous Compounds - chemistry; Fundamental and applied biological sciences. Psychology; Heme - chemistry; Inorganic chemistry and origins of life; IRON; Iron Compounds - chemistry; Mechanisms. Catalysis. Electron transfer. Models; MOLECULAR BIOLOGY; Molecular biophysics; national synchrotron light source; Oxidation-Reduction; Physical chemistry in biology; PRECURSOR; Spectroscopy, Mossbauer; Spectrum Analysis, Raman; tert-Butylhydroperoxide - chemistry
• ISSN: 0002-7863; 0022-2836; 1520-5126; 1089-8638
• DOI: 10.1021/ja0438765

The reaction of [FeII(β-BPMCN)(OTf)2] (1, BPMCN = N,N‘-bis(2-pyridylmethyl)-N,N‘-dimethyl-trans-1,2-diaminocyclohexane) with t BuOOH at low-temperature yields alkylperoxoiron(III) intermediates 2 in CH2Cl2 and 2-NCMe in CH3CN. At −45 °C and above, 2-NCMe converts to a pale green species 3 (λmax = 753 nm, ε = 280 M-1 cm-1) in 90% yield, identified as [FeIV(O)(BPMCN)(NCCH3)]2+ by comparison to other nonheme [FeIV(O)(L)]2+ complexes. Below −55 °C in CH2Cl2, 2 decays instead to form deep turquoise 4 (λmax = 656, 845 nm; ε = 4000, 3600 M-1 cm-1), formulated to be an unprecedented alkylperoxoiron(IV) complex [FeIV(BPMCN)(OH)(OO t Bu)]2+ on the basis of Mössbauer, EXAFS, resonance Raman, NMR, and mass spectral evidence. The reactivity of 1 with t BuOOH in the two solvents reveals an unexpectedly rich iron(IV) chemistry that can be supported by the BPMCN ligand.