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Title: Equatorial Ligand Perturbations Influence the Reactivity of Manganese(IV)-Oxo Complexes

Authors:
 [1];  [1];  [1];  [1];  [2];  [1];  [2];  [1]
  1. Department of Chemistry, University of Kansas, Lawrence KS USA
  2. Chemical Physics, Department of Chemistry, Lund University, Box 124 22100 Lund Sweden
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1401075
Grant/Contract Number:
SC0016359
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Angewandte Chemie (International Edition)
Additional Journal Information:
Journal Name: Angewandte Chemie (International Edition); Journal Volume: 56; Journal Issue: 15; Related Information: CHORUS Timestamp: 2017-10-20 16:17:05; Journal ID: ISSN 1433-7851
Publisher:
Wiley Blackwell (John Wiley & Sons)
Country of Publication:
Germany
Language:
English

Citation Formats

Massie, Allyssa A., Denler, Melissa C., Cardoso, Luísa Thiara, Walker, Ashlie N., Hossain, M. Kamal, Day, Victor W., Nordlander, Ebbe, and Jackson, Timothy A. Equatorial Ligand Perturbations Influence the Reactivity of Manganese(IV)-Oxo Complexes. Germany: N. p., 2017. Web. doi:10.1002/anie.201612309.
Massie, Allyssa A., Denler, Melissa C., Cardoso, Luísa Thiara, Walker, Ashlie N., Hossain, M. Kamal, Day, Victor W., Nordlander, Ebbe, & Jackson, Timothy A. Equatorial Ligand Perturbations Influence the Reactivity of Manganese(IV)-Oxo Complexes. Germany. doi:10.1002/anie.201612309.
Massie, Allyssa A., Denler, Melissa C., Cardoso, Luísa Thiara, Walker, Ashlie N., Hossain, M. Kamal, Day, Victor W., Nordlander, Ebbe, and Jackson, Timothy A. Thu . "Equatorial Ligand Perturbations Influence the Reactivity of Manganese(IV)-Oxo Complexes". Germany. doi:10.1002/anie.201612309.
@article{osti_1401075,
title = {Equatorial Ligand Perturbations Influence the Reactivity of Manganese(IV)-Oxo Complexes},
author = {Massie, Allyssa A. and Denler, Melissa C. and Cardoso, Luísa Thiara and Walker, Ashlie N. and Hossain, M. Kamal and Day, Victor W. and Nordlander, Ebbe and Jackson, Timothy A.},
abstractNote = {},
doi = {10.1002/anie.201612309},
journal = {Angewandte Chemie (International Edition)},
number = 15,
volume = 56,
place = {Germany},
year = {Thu Mar 16 00:00:00 EDT 2017},
month = {Thu Mar 16 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1002/anie.201612309

Citation Metrics:
Cited by: 2works
Citation information provided by
Web of Science

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  • Triflic acid (HOTf)-bound nonheme Mn( IV)-oxo complexes, [(L)Mn IV(O)] 2+–(HOTf) 2 (L = N4Py and Bn-TPEN; N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine and Bn-TPEN = N-benzyl-N,N',N'-tris(2-pyridylmethyl)ethane-1,2-diamine), were synthesized by adding HOTf to the solutions of the [(L)Mn IV(O)] 2+ complexes and were characterized by various spectroscopies. The one-electron reduction potentials of the Mn IV(O) complexes exhibited a significant positive shift upon binding of HOTf. The driving force dependences of electron transfer (ET) from electron donors to the Mn IV(O) and Mn IV(O)–(HOTf) 2 complexes were examined and evaluated in light of the Marcus theory of ET to determine the reorganization energies of ET.more » The smaller reorganization energies and much more positive reduction potentials of the [(L)Mn IV(O)] 2+–(HOTf) 2 complexes resulted in greatly enhanced oxidation capacity towards one-electron reductants and para-X-substituted-thioanisoles. The reactivities of the Mn(IV)-oxo complexes were markedly enhanced by binding of HOTf, such as a 6.4 × 10 5-fold increase in the oxygen atom transfer (OAT) reaction (i.e., sulfoxidation). Such a remarkable acceleration in the OAT reaction results from the enhancement of ET from para-X-substituted-thioanisoles to the MnIV(O) complexes as revealed by the unified ET driving force dependence of the rate constants of OAT and ET reactions of [(L)Mn IV(O)] 2+–(HOTf) 2. In contrast, deceleration was observed in the rate of H-atom transfer (HAT) reaction of [(L)Mn IV(O)] 2+–(HOTf) 2 complexes with 1,4-cyclohexadiene as compared with those of the [(L)Mn IV(O)] 2+ complexes. Thus, the binding of two HOTf molecules to the Mn IV(O) moiety resulted in remarkable acceleration of the ET rate when the ET is thermodynamically feasible. When the ET reaction is highly endergonic, the rate of the HAT reaction is decelerated due to the steric effect of the counter anion of HOTf.« less
  • The complex ((14-aneN{sub 4})MnO){sub 2}{sup 3+} (14-aneN{sub 4} = 1,4,8,11-tetraazacyclotetradecane) has been prepared and characterized. Results of crystallographic and x-ray band EPR studies used to characterize the complex are reported. The complex was found to be a Robin and Day class II mixed-valence species, and detailed studies of the formation of the binuclear Mn species indicate that the bridging oxygens came from solvent water and that the bridge formation occurs with both manganese ions in the III oxidation state. Cyclic voltmetry exhibits a reversible one-electron oxidation to the IV, IV levels as well as a reversible one-electron reduction to themore » III, III level. Results of spectrochemical experiments performed to help to establish the assignments of the electronic spectrum of the III, IV complex indicate three main absorption maxima in the visible region as well as a tail that extends into the near-infrared region. 25 refs., 6 figs.« less
  • The mononuclear Mn(IV)-oxo complex [Mn IV(O)(N4py)] 2+, where N4py is the pentadentate ligand N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine, we propose to attack C–H bonds by an excited-state reactivity pattern [Cho, K.-B.; Shaik, S.; Nam, W. J. Phys. Chem. Lett. 2012, 3, 2851-2856 (DOI: 10.1021/jz301241z)]. In this model, a 4E excited state is utilized to provide a lower-energy barrier for hydrogen-atom transfer. This proposal is intriguing, as it offers both a rationale for the relatively high hydrogen-atom-transfer reactivity of [Mn IV(O)(N4py)] 2+ and a guideline for creating more reactive complexes through ligand modification. Here we employ a combination of electronic absorption and variable-temperature magnetic circularmore » dichroism (MCD) spectroscopy to experimentally evaluate this excited-state reactivity model. Using these spectroscopic methods, in conjunction with time-dependent density functional theory (TD-DFT) and complete-active space self-consistent-field calculations (CASSCF), we define the ligand-field and charge-transfer excited states of [MnIV(O)(N4py)]2+. Through a graphical analysis of the signs of the experimental C-term MCD signals, we unambiguously assign a low-energy MCD feature of [Mn IV(O)(N4py)] 2+ as the 4E excited state predicted to be involved in hydrogen-atom-transfer reactivity. The CASSCF calculations predict enhanced Mn III-oxyl character on the excited-state 4E surface, consistent with previous DFT calculations. Potential-energy surfaces, developed using the CASSCF methods, are used to determine how the energies and wave functions of the ground and excited states evolved as a function of Mn=O distance. Furthermore, the unique insights into ground- and excited-state electronic structure offered by these spectroscopic and computational studies are harmonized with a thermodynamic model of hydrogen-atom-transfer reactivity, which predicts a correlation between transition-state barriers and driving force« less
    Cited by 4
  • The mononuclear Mn(IV)-oxo complex [Mn IV(O)(N4py)] 2+, where N4py is the pentadentate ligand N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine, we propose to attack C–H bonds by an excited-state reactivity pattern [Cho, K.-B.; Shaik, S.; Nam, W. J. Phys. Chem. Lett. 2012, 3, 2851-2856 (DOI: 10.1021/jz301241z)]. In this model, a 4E excited state is utilized to provide a lower-energy barrier for hydrogen-atom transfer. This proposal is intriguing, as it offers both a rationale for the relatively high hydrogen-atom-transfer reactivity of [Mn IV(O)(N4py)] 2+ and a guideline for creating more reactive complexes through ligand modification. Here we employ a combination of electronic absorption and variable-temperature magnetic circularmore » dichroism (MCD) spectroscopy to experimentally evaluate this excited-state reactivity model. Using these spectroscopic methods, in conjunction with time-dependent density functional theory (TD-DFT) and complete-active space self-consistent-field calculations (CASSCF), we define the ligand-field and charge-transfer excited states of [MnIV(O)(N4py)]2+. Through a graphical analysis of the signs of the experimental C-term MCD signals, we unambiguously assign a low-energy MCD feature of [Mn IV(O)(N4py)] 2+ as the 4E excited state predicted to be involved in hydrogen-atom-transfer reactivity. The CASSCF calculations predict enhanced Mn III-oxyl character on the excited-state 4E surface, consistent with previous DFT calculations. Potential-energy surfaces, developed using the CASSCF methods, are used to determine how the energies and wave functions of the ground and excited states evolved as a function of Mn=O distance. Furthermore, the unique insights into ground- and excited-state electronic structure offered by these spectroscopic and computational studies are harmonized with a thermodynamic model of hydrogen-atom-transfer reactivity, which predicts a correlation between transition-state barriers and driving force« less