TY - JOUR
T1 - Generation of [(N4Py)Fe(IV)═O]2+ through Heterolytic O-O Bond Cleavage in [(N4Py)Fe(II)(OOH)]+
AU - Chen, Juan
AU - Sardjan, Andy S.
AU - de Roo, C. Maurits
AU - Di Berto Mancini, Marika
AU - Draksharapu, Apparao
AU - Angelone, Davide
AU - Hage, Ronald
AU - Swart, Marcel
AU - Browne, Wesley R.
N1 - Publisher Copyright:
© 2025 The Authors. Published by American Chemical Society.
PY - 2025/5/19
Y1 - 2025/5/19
N2 - High-valent Fe(IV) oxido species are important intermediates in the catalyzed oxidation of organic compounds by nonheme iron enzymes. These species can be generated in biomimetic model complexes directly using oxygen atom transfer oxidants, e.g., PhIO and ClO-. Their formation by heterolysis of the O-O bond of putative Fe(II)-OOH species (formed from Fe(II) precursors and H2O2) has scarcely been observed. Reaction with near-stoichiometric H2O2 typically shows initial formation of Fe(III)-OH and Fe(III)-OOH species, with homolytic O-O bond cleavage thereafter proposed to generate the Fe(IV)═O state. Here, we show that [(N4Py)Fe(IV)═O]2+ (where N4Py = 1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)methanamine) is formed with substoichiometric H2O2 in methanol through heterolytic cleavage of the O-O bond of an Fe(II)-OOH intermediate. Temperature-dependent studies show that the ligand exchange reactions preceding formation of the Fe(II)-OOH species and subsequent comproportionations limit the yield of the Fe(IV)═O species. Furthermore, comproportionation proceeds through hydrogen atom transfer from [(N4Py)Fe(II)(OH2)]2+ to [(N4Py)Fe(IV)═O]2+. These data rationalize the extent of the initial conversion of [(N4Py)Fe(II)(CH3CN)]2+ to [(N4Py)Fe(IV)═O]2+ under conditions relevant to catalytic oxidations. The heterolytic pathway to formation of [(N4Py)Fe(IV)═O]2+ is a key step in the development of iron(II) oxidation catalysts that can cycle between the Fe(II) and Fe(IV)═O states, avoiding nonselective reactive oxygen species.
AB - High-valent Fe(IV) oxido species are important intermediates in the catalyzed oxidation of organic compounds by nonheme iron enzymes. These species can be generated in biomimetic model complexes directly using oxygen atom transfer oxidants, e.g., PhIO and ClO-. Their formation by heterolysis of the O-O bond of putative Fe(II)-OOH species (formed from Fe(II) precursors and H2O2) has scarcely been observed. Reaction with near-stoichiometric H2O2 typically shows initial formation of Fe(III)-OH and Fe(III)-OOH species, with homolytic O-O bond cleavage thereafter proposed to generate the Fe(IV)═O state. Here, we show that [(N4Py)Fe(IV)═O]2+ (where N4Py = 1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)methanamine) is formed with substoichiometric H2O2 in methanol through heterolytic cleavage of the O-O bond of an Fe(II)-OOH intermediate. Temperature-dependent studies show that the ligand exchange reactions preceding formation of the Fe(II)-OOH species and subsequent comproportionations limit the yield of the Fe(IV)═O species. Furthermore, comproportionation proceeds through hydrogen atom transfer from [(N4Py)Fe(II)(OH2)]2+ to [(N4Py)Fe(IV)═O]2+. These data rationalize the extent of the initial conversion of [(N4Py)Fe(II)(CH3CN)]2+ to [(N4Py)Fe(IV)═O]2+ under conditions relevant to catalytic oxidations. The heterolytic pathway to formation of [(N4Py)Fe(IV)═O]2+ is a key step in the development of iron(II) oxidation catalysts that can cycle between the Fe(II) and Fe(IV)═O states, avoiding nonselective reactive oxygen species.
UR - http://www.scopus.com/inward/record.url?scp=105004279124&partnerID=8YFLogxK
U2 - 10.1021/acs.inorgchem.4c05172
DO - 10.1021/acs.inorgchem.4c05172
M3 - Article
AN - SCOPUS:105004279124
SN - 0020-1669
VL - 64
SP - 9408
EP - 9417
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 19
M1 - 4c05172
ER -