Basicity of MnIII-Hydroxo Complexes Controls the Thermodynamics of Proton-Coupled Electron Transfer Reactions
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388955%3A_____%2F24%3A00600567" target="_blank" >RIV/61388955:_____/24:00600567 - isvavai.cz</a>
Result on the web
<a href="https://pubs.acs.org/doi/10.1021/acs.inorgchem.4c03254" target="_blank" >https://pubs.acs.org/doi/10.1021/acs.inorgchem.4c03254</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1021/acs.inorgchem.4c03254" target="_blank" >10.1021/acs.inorgchem.4c03254</a>
Alternative languages
Result language
angličtina
Original language name
Basicity of MnIII-Hydroxo Complexes Controls the Thermodynamics of Proton-Coupled Electron Transfer Reactions
Original language description
Several manganese-dependent enzymes utilize MnIII-hydroxo units in concerted proton-electron transfer (CPET) reactions. We recently demonstrated that hydrogen bonding to the hydroxo ligand in the synthetic [MnIII(OH)(PaPy2N)]+ complex increased rates of CPET reactions compared to the [MnIII(OH)(PaPy2Q)]+ complex that lacks a hydrogen bond. In this work, we determine the effect of hydrogen bonding on the basicity of the hydroxo ligand and evaluate the corresponding effect on CPET reactions. Both [MnIII(OH)(PaPy2Q)]+ and [MnIII(OH)(PaPy2N)]+ react with strong acids to yield MnIII-aqua complexes [MnIII(OH2)(PaPy2Q)]2+ and [MnIII(OH2)(PaPy2N)]2+, for which we determined pKa values of 7.6 and 13.1, respectively. Reactions of the MnIII-aqua complexes with one-electron reductants yielded estimates of reduction potentials, which were combined with pKa values to give O-H bond dissociation free energies (BDFEs) of 77 and 85 kcal mol-1 for the MnII-aqua complexes [MnII(OH2)(PaPy2Q)]+ and [MnII(OH2)(PaPy2N)]+. Using these BDFEs, we performed an analysis of the thermodynamic driving force for phenol oxidation by these complexes and observed the unexpected result that slower rates are associated with more asynchronous CPET. In addition, reactions of acidic phenols with the MnIII-hydroxo complexes show rates that deviate from the thermodynamic trends, consistent with a change in mechanism from CPET to proton transfer.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10403 - Physical chemistry
Result continuities
Project
<a href="/en/project/GA24-11247S" target="_blank" >GA24-11247S: Off-diagonal thermodynamics and its connection with other factors as a route to predictable selectivity in C-H bond cleavage</a><br>
Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2024
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Inorganic Chemistry
ISSN
0020-1669
e-ISSN
1520-510X
Volume of the periodical
63
Issue of the periodical within the volume
46
Country of publishing house
US - UNITED STATES
Number of pages
13
Pages from-to
21941-21953
UT code for WoS article
001349186700001
EID of the result in the Scopus database
2-s2.0-85208174129