Second‐Sphere Aromatic Substitutions That Tune H‐Atom Transfer Reactivity Observed for a Series of S = 1 Nonheme FeIV=O Complexes: An Enthalpy‐Entropy Compensation Effect
4 affiliations
- 1Department of Chemistry University of Minnesota Minneapolis Minnesota USA
- 2Department of Chemistry Carnegie Mellon University Pittsburgh Pennsylvania USA
- 3IQCC and Department of Chemistry University of Girona Girona Spain
- 4ICREA Barcelona Spain
Abstract
Synthetic nonheme FeIV═O complexes reported thus far often have S = 1 ground states, demonstrating markedly lower oxidative reactivity in C─H bond breakage compared to their S = 2 counterparts. Recently, we have identified that incorporating cycloalkyl groups into the second coordination sphere of the nitrilotris(benzimidazole) ligand produce the most reactive FeIV═O complexes within the tripodal ligand family, exhibiting an S = 1 ground state. Here, we have synthesized six S = 1 complexes having the NTB ligand framework with either electron‐rich or electron‐poor aromatic groups in the secondary coordination sphere of the ligand. These complexes have been characterized by Mössbauer data at 4 K and 1H NMR spectra at 193 K with quite similar electronic characteristics despite having distinct electronically tuned ligands. Nevertheless, the complexes show substrate oxidation rates that differ by nearly an order of magnitude from each other, giving rise to a notable linear correlation between activation enthalpies and activation entropies of HAT reactions. These outcomes thus enable further investigation of the Enthalpy‐Entropy Compensation Effect (EECE) in HAT reactions involving these oxoiron(IV) complexes. Finally, the role played by steric attributes of the secondary coordination sphere group in regulating the reactivity of this series of complexes has been explored.
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BibTeX
@article{das2026secondsphere,
title = {{Second‐Sphere Aromatic Substitutions That Tune H‐Atom Transfer Reactivity Observed for a Series of S = 1 Nonheme FeIV=O Complexes: An Enthalpy‐Entropy Compensation Effect}},
author = {Abhishek Das and Jin Xiong and Victor G. Young and Yisong Guo and Marcel Swart and Lawrence Que},
journal = {Angewandte Chemie (International Ed. in English)},
year = {2026},
month = sep,
doi = {10.1002/anie.1885847},
url = {https://doi.org/10.1002/anie.1885847},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Second‐Sphere Aromatic Substitutions That Tune H‐Atom Transfer Reactivity Observed for a Series of S = 1 Nonheme FeIV=O Complexes: An Enthalpy‐Entropy Compensation Effect
AU - Abhishek Das
AU - Jin Xiong
AU - Victor G. Young
AU - Yisong Guo
AU - Marcel Swart
AU - Lawrence Que
PY - 2026
DA - 2026/09/23
JO - Angewandte Chemie (International Ed. in English)
DO - 10.1002/anie.1885847
UR - https://doi.org/10.1002/anie.1885847
AB - Synthetic nonheme FeIV═O complexes reported thus far often have S = 1 ground states, demonstrating markedly lower oxidative reactivity in C─H bond breakage compared to their S = 2 counterparts. Recently, we have identified that incorporating cycloalkyl groups into the second coordination sphere of the nitrilotris(benzimidazole) ligand produce the most reactive FeIV═O complexes within the tripodal ligand family, exhibiting an S = 1 ground state. Here, we have synthesized six S = 1 complexes having the NTB ligand framework with either electron‐rich or electron‐poor aromatic groups in the secondary coordination sphere of the ligand. These complexes have been characterized by Mössbauer data at 4 K and 1H NMR spectra at 193 K with quite similar electronic characteristics despite having distinct electronically tuned ligands. Nevertheless, the complexes show substrate oxidation rates that differ by nearly an order of magnitude from each other, giving rise to a notable linear correlation between activation enthalpies and activation entropies of HAT reactions. These outcomes thus enable further investigation of the Enthalpy‐Entropy Compensation Effect (EECE) in HAT reactions involving these oxoiron(IV) complexes. Finally, the role played by steric attributes of the secondary coordination sphere group in regulating the reactivity of this series of complexes has been explored.
SN - 1433-7851
SN - 1521-3773
ER -