TY - JOUR
T1 - Protonation of a peroxodiiron(III) complex and conversion to a diiron(III/IV) intermediate
T2 - Implications for proton-assisted O-O bond cleavage in nonheme diiron enzymes
AU - Cranswick, Matthew A.
AU - Meier, Katlyn K.
AU - Shan, Xiaopeng
AU - Stubna, Audria
AU - Kaizer, Jószef
AU - Mehn, Mark P.
AU - Münck, Eckard
AU - Que, Lawrence
PY - 2012/10/1
Y1 - 2012/10/1
N2 - Oxygenation of a diiron (II) complex, [FeII 2 ( μ - OH)2(BnBQA)2(NCMe)2]2+ [2, where BnBQA is N-benzyl-N,N-bis(2-quinolinylmethyl)amine], results in the formation of a metastable peroxodiferric intermediate, 3. The treatment of 3 with strong acid affords its conjugate acid, 4, in which the (μ-oxo)(μ-1,2-peroxo) diiron(III) core of 3 is protonated at the oxo bridge. The core structures of 3 and 4 are characterized in detail by UV-vis, Mössbauer, resonance Raman, and X-ray absorption spectroscopies. Complex 4 is shorter-lived than 3 and decays to generate in ∼20% yield of a diiron(III/IV) species 5, which can be identified by electron paramagnetic resonance and Mössbauer spectroscopies. This reaction sequence demonstrates for the first time that protonation of the oxo bridge of a (μ-oxo)(μ-1,2-peroxo)diiron(III) complex leads to cleavage of the peroxo O-O bond and formation of a high-valent diiron complex, thereby mimicking the steps involved in the formation of intermediate X in the activation cycle of ribonucleotide reductase.
AB - Oxygenation of a diiron (II) complex, [FeII 2 ( μ - OH)2(BnBQA)2(NCMe)2]2+ [2, where BnBQA is N-benzyl-N,N-bis(2-quinolinylmethyl)amine], results in the formation of a metastable peroxodiferric intermediate, 3. The treatment of 3 with strong acid affords its conjugate acid, 4, in which the (μ-oxo)(μ-1,2-peroxo) diiron(III) core of 3 is protonated at the oxo bridge. The core structures of 3 and 4 are characterized in detail by UV-vis, Mössbauer, resonance Raman, and X-ray absorption spectroscopies. Complex 4 is shorter-lived than 3 and decays to generate in ∼20% yield of a diiron(III/IV) species 5, which can be identified by electron paramagnetic resonance and Mössbauer spectroscopies. This reaction sequence demonstrates for the first time that protonation of the oxo bridge of a (μ-oxo)(μ-1,2-peroxo)diiron(III) complex leads to cleavage of the peroxo O-O bond and formation of a high-valent diiron complex, thereby mimicking the steps involved in the formation of intermediate X in the activation cycle of ribonucleotide reductase.
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U2 - 10.1021/ic301642w
DO - 10.1021/ic301642w
M3 - Article
C2 - 22971084
AN - SCOPUS:84868149420
SN - 0020-1669
VL - 51
SP - 10417
EP - 10426
JO - Inorganic chemistry
JF - Inorganic chemistry
IS - 19
ER -