TY - JOUR
T1 - Crystallographic Evidence for a Sterically Induced Ferryl Tilt in a Non-Heme Oxoiron(IV) Complex that Makes it a Better Oxidant
AU - Rasheed, Waqas
AU - Draksharapu, Apparao
AU - Banerjee, Saikat
AU - Young, Victor G
AU - Fan, Ruixi
AU - Guo, Yisong
AU - Ozerov, M.
AU - Nehrkorn, Joscha
AU - Krzystek, J.
AU - Telser, Joshua
AU - Que, Larry
N1 - Publisher Copyright:
© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2018/7/20
Y1 - 2018/7/20
N2 - Oxoiron(IV) units are often implicated as intermediates in the catalytic cycles of non-heme iron oxygenases and oxidases. The most reactive synthetic analogues of these intermediates are supported by tetradentate tripodal ligands with N-methylbenzimidazole or quinoline donors, but their instability precludes structural characterization. Herein we report crystal structures of two [FeIV(O)(L)]2+ complexes supported by pentadentate ligands incorporating these heterocycles, which show longer average Fe–N distances than the complex with only pyridine donors. These longer distances correlate linearly with log k2′ values for O- and H-atom transfer rates, suggesting that weakening the ligand field increases the electrophilicity of the Fe=O center. The sterically bulkier quinoline donors are also found to tilt the Fe=O unit away from a linear N-Fe=O arrangement by 10°.
AB - Oxoiron(IV) units are often implicated as intermediates in the catalytic cycles of non-heme iron oxygenases and oxidases. The most reactive synthetic analogues of these intermediates are supported by tetradentate tripodal ligands with N-methylbenzimidazole or quinoline donors, but their instability precludes structural characterization. Herein we report crystal structures of two [FeIV(O)(L)]2+ complexes supported by pentadentate ligands incorporating these heterocycles, which show longer average Fe–N distances than the complex with only pyridine donors. These longer distances correlate linearly with log k2′ values for O- and H-atom transfer rates, suggesting that weakening the ligand field increases the electrophilicity of the Fe=O center. The sterically bulkier quinoline donors are also found to tilt the Fe=O unit away from a linear N-Fe=O arrangement by 10°.
KW - hydrogen atom transfer (HAT)
KW - non-heme iron complexes
KW - oxoiron(IV) complexes
KW - two-state reactivity
UR - http://www.scopus.com/inward/record.url?scp=85050025845&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85050025845&partnerID=8YFLogxK
U2 - 10.1002/anie.201804836
DO - 10.1002/anie.201804836
M3 - Article
C2 - 29882390
AN - SCOPUS:85050025845
SN - 1433-7851
VL - 57
SP - 9387
EP - 9391
JO - Angewandte Chemie - International Edition
JF - Angewandte Chemie - International Edition
IS - 30
ER -