Spin-State-Selective Secondary-Sphere Control in Hemicryptophane Cages Enables Tunable Reactivity of Iron-Oxo Centers
- 1Northeast Normal University , , ,
Abstract
High-valent iron-oxo species are key intermediates in oxidation catalysis, yet modulating their electronic structures via the secondary coordination sphere remains challenging. Here, we designed a hemicryptophane-encapsulated iron-oxo complex (FeO-TPA@Hm2) and elucidate how the cage modulates methane C–H activation. Our calculations indicate that the Hm2 framework stabilizes the quintet state as the global minimum, potentially increasing the accessibility of the low-barrier quintet pathway. Crucially, we further uncover a spin-gated regulatory mechanism: on the triplet manifold, the cage exhibits pronounced redox noninnocence, acting as a tunable electron reservoir where remote substituents ″switch″ the electronic topology among Fe(III)–O2–, Fe(III)–O–•, Fe(IV)═O, and Fe(II)–O•• regimes. In contrast, the quintet state displays remarkable electronic rigidity due to exchange stabilization, rendering the cage effectively redox-innocent. Consequently, although the triplet surface is highly sensitive to substituent-induced polarization, the quintet pathway remains robust and dominant. This work establishes a synergy between spin-selective reactivity and spin-differentiated substituent sensitivity, providing a programmable strategy for orchestrating electron-transfer pathways in supramolecular catalysis.
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BibTeX
@article{mao2026spinstateselective,
title = {{Spin-State-Selective Secondary-Sphere Control in Hemicryptophane Cages Enables Tunable Reactivity of Iron-Oxo Centers}},
author = {Xin-Rui Mao and Chao-Yu Zhao and Ying Lu and Cai-Yun Geng},
journal = {ACS Central Science},
year = {2026},
month = nov,
doi = {10.1021/acscentsci.6c01540},
url = {https://pubs.acs.org/acscii/article/doi/10.1021/acscentsci.6c01540/5466429/Spin-State-Selective-Secondary-Sphere-Control-in},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Spin-State-Selective Secondary-Sphere Control in Hemicryptophane Cages Enables Tunable Reactivity of Iron-Oxo Centers
AU - Xin-Rui Mao
AU - Chao-Yu Zhao
AU - Ying Lu
AU - Cai-Yun Geng
PY - 2026
DA - 2026/11/09
JO - ACS Central Science
DO - 10.1021/acscentsci.6c01540
UR - https://pubs.acs.org/acscii/article/doi/10.1021/acscentsci.6c01540/5466429/Spin-State-Selective-Secondary-Sphere-Control-in
AB - High-valent iron-oxo species are key intermediates in oxidation catalysis, yet modulating their electronic structures via the secondary coordination sphere remains challenging. Here, we designed a hemicryptophane-encapsulated iron-oxo complex (FeO-TPA@Hm2) and elucidate how the cage modulates methane C–H activation. Our calculations indicate that the Hm2 framework stabilizes the quintet state as the global minimum, potentially increasing the accessibility of the low-barrier quintet pathway. Crucially, we further uncover a spin-gated regulatory mechanism: on the triplet manifold, the cage exhibits pronounced redox noninnocence, acting as a tunable electron reservoir where remote substituents ″switch″ the electronic topology among Fe(III)–O2–, Fe(III)–O–•, Fe(IV)═O, and Fe(II)–O•• regimes. In contrast, the quintet state displays remarkable electronic rigidity due to exchange stabilization, rendering the cage effectively redox-innocent. Consequently, although the triplet surface is highly sensitive to substituent-induced polarization, the quintet pathway remains robust and dominant. This work establishes a synergy between spin-selective reactivity and spin-differentiated substituent sensitivity, providing a programmable strategy for orchestrating electron-transfer pathways in supramolecular catalysis.
SN - 2374-7943
SN - 2374-7951
ER -