Academic Journal
Axial Ligation Impedes Proton-Coupled Electron-Transfer Reactivity of a Synthetic Compound I Analog
| العنوان: | Axial Ligation Impedes Proton-Coupled Electron-Transfer Reactivity of a Synthetic Compound I Analog |
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| المؤلفون: | Thomas, Jithin, Mokkawes, Thirakorn, Senft, Laura, Dey, Aniruddha, Gordon, Jesse B., Ivanovic-Burmazovic, Ivana, De Visser, Samuel, Goldberg, David P. |
| المصدر: | Thomas , J , Mokkawes , T , Senft , L , Dey , A , Gordon , J B , Ivanovic-Burmazovic , I , De Visser , S & Goldberg , D P 2024 , ' Axial Ligation Impedes Proton-Coupled Electron-Transfer Reactivity of a Synthetic Compound I Analog ' , Journal of the American Chemical Society|J Am Chem Soc . https://doi.org/10.1021/jacs.3c08950 |
| سنة النشر: | 2024 |
| المجموعة: | The University of Manchester: Research Explorer - Publications |
| الوصف: | The nature of the axial ligand in high-valent iron-oxo heme enzyme intermediates and related synthetic catalysts is a critical structural element for controlling the proton-coupled electron-transfer (PCET) reactivity of these species. Herein we describe the generation and characterization of three new 6-coordinate, iron(IV)-oxo porphyrinoid-π-cation-radical complexes, and report their PCET reactivity together with a previously published 5-coordinate analog, FeIV(O)(TBP 8 Cz +• ) (TBP 8 Cz = octakis(p-tert-butylphenyl)corrolazinato 3– ), (2) (J. Am. Chem. Soc., 2012, 134, 7392–7399). The new complexes Fe IV (O)(TBP 8 Cz +• )(L) (L = 1-methylimidazole (1-MeIm) (4a), 4-dimethylaminopyridine (DMAP) (4b), cyanide (CN - ) (4c)), can be generated from either oxidation of the ferric precursors or by addition of L to the Compound-I (Cpd-I) analog at low temperatures. These complexes were characterized by UV-vis, EPR, and Mössbauer spectroscopies, and cryospray ionization mass spectrometry (CSIMS). The PCET reactivity of these complexes was examined with the OH bond donor 4-OMe-TEMPOH as a test substrate. Kinetic studies indicate that coordination of a 6 th axial ligand dramatically lowers the PCET reactivity of the Cpd-I analog (rates up to 7000 times slower). Extensive DFT calculations together with the experimental data show that the trend in reactivity with the axial ligands does not correlate with the thermodynamic driving force for these reactions, or the calculated strengths of the O-H bonds being formed in the Fe IV (O-H) products, pointing to non-Bell-Evans-Polanyi behavior. However, the PCET reactivity does follow a trend with the bracketed reduction potential of Cpd-I analogs and calculated electron affinities. The combined data suggest a concerted mechanism (a concerted proton electron transfer (CPET)), and an asynchronous movement of the electron/proton pair in the transition state. |
| نوع الوثيقة: | article in journal/newspaper |
| وصف الملف: | application/pdf |
| اللغة: | English |
| Relation: | https://research.manchester.ac.uk/en/publications/26f6b0fb-ae59-4502-af2f-e2f81444d028 |
| DOI: | 10.1021/jacs.3c08950 |
| الاتاحة: | https://research.manchester.ac.uk/en/publications/26f6b0fb-ae59-4502-af2f-e2f81444d028 https://doi.org/10.1021/jacs.3c08950 https://pure.manchester.ac.uk/ws/files/298544650/Goldberg_Fe_O_Cz_axial_ligands_ms_4th_revision_Final.pdf |
| Rights: | info:eu-repo/semantics/openAccess |
| رقم الانضمام: | edsbas.D6D03DC4 |
| قاعدة البيانات: | BASE |
| DOI: | 10.1021/jacs.3c08950 |
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