High-valent nonheme iron. Two distinct iron(IV) species derived from a common iron(II) precursor.
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.
Jensen
Michael P
MP
Department of Chemistry and the Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Costas
Miquel
M
Ho
Raymond Y N
RY
Kaizer
József
J
Mairata i Payeras
Antoni
A
Münck
Eckard
E
Que
Lawrence
L
Rohde
Jan-Uwe
JU
Stubna
Audria
A
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
D005296:Ferrous Compounds; D058085:Iron Compounds; D006418:Heme; D020122:tert-Butylhydroperoxide