1
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Kass D, Larson VA, Corona T, Kuhlmann U, Hildebrandt P, Lohmiller T, Bill E, Lehnert N, Ray K. Trapping of a phenoxyl radical at a non-haem high-spin iron(II) centre. Nat Chem 2024; 16:658-665. [PMID: 38216752 DOI: 10.1038/s41557-023-01405-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 11/17/2023] [Indexed: 01/14/2024]
Abstract
The activation of dioxygen at haem and non-haem metal centres, and subsequent functionalization of unactivated C‒H bonds, has been a focal point of much research. In iron-mediated oxidation reactions, O2 binding at an iron(II) centre is often accompanied by an oxidation of the iron centre. Here we demonstrate dioxygen activation by sodium tetraphenylborate and protons in the presence of an iron(II) complex to form a reactive radical species, whereby the iron oxidation state remains unaltered in the presence of a highly oxidizing phenoxyl radical and O2. This complex, containing an unusual iron(II)-phenoxyl radical motif, represents an elusive example of a spectroscopically characterized oxygen-derived iron(II)-reactive intermediate during chemical and biological dioxygen activation at haem and non-haem iron active centres. The present report opens up strategies for the stabilization of a phenoxyl radical cofactor, with its full oxidizing capabilities, to act as an independent redox centre next to an iron(II) site during substrate oxidation reactions.
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Affiliation(s)
- Dustin Kass
- Department of Chemistry, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Virginia A Larson
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, MI, USA
| | - Teresa Corona
- Department of Chemistry, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Uwe Kuhlmann
- Department of Chemistry, Technische Universität Berlin, Berlin, Germany
| | - Peter Hildebrandt
- Department of Chemistry, Technische Universität Berlin, Berlin, Germany
| | - Thomas Lohmiller
- Department of Chemistry, Humboldt-Universität zu Berlin, Berlin, Germany
- EPR4Energy Joint Lab, Department Spins in Energy Conversion and Quantum Information Science, Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Mülheim an der Ruhr, Germany
| | - Nicolai Lehnert
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, MI, USA.
| | - Kallol Ray
- Department of Chemistry, Humboldt-Universität zu Berlin, Berlin, Germany.
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2
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Sharma A, Mejia K, Ueno H, Zhou W, Chiang L. Copper complexes of strongly electron rich and deficient salen ligands. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2022.121106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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3
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Pentacoordinated Fe(III) complex containing the cis-N2O2 asymmetrical tetradentate Schiff base and p-Br-C6H4O- as ligands. Promising building block for the construction of dipolar D–π–A architectures: Synthesis, characterization, spectroscopic, electrochemical and structural studies. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2020.129709] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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4
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Al‐Azzani MA, Al‐Mjeni F, Mitsuhashi R, Mikuriya M, Al‐Omari IA, Robertson CC, Bill E, Shongwe MS. Unusual Magneto‐Structural Features of the Halo‐Substituted Materials [Fe
III
(5‐X‐salMeen)
2
]Y: a Cooperative [HS‐HS]↔[HS‐LS] Spin Transition. Chemistry 2020; 26:4766-4779. [DOI: 10.1002/chem.201904744] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Indexed: 01/21/2023]
Affiliation(s)
- Mariam A. Al‐Azzani
- Department of ChemistryCollege of ScienceSultan Qaboos University Private Bag 36, Al-Khod 123 Muscat Sultanate of Oman
| | - Faizah Al‐Mjeni
- Department of ChemistryCollege of ScienceSultan Qaboos University Private Bag 36, Al-Khod 123 Muscat Sultanate of Oman
| | - Ryoji Mitsuhashi
- School of Science and TechnologyKwansei Gakuin University 2-1 Gakuen Sanda 669-1337 Japan
| | - Masahiro Mikuriya
- School of Science and TechnologyKwansei Gakuin University 2-1 Gakuen Sanda 669-1337 Japan
| | - Imaddin A. Al‐Omari
- Department of PhysicsCollege of ScienceSultan Qaboos University Private Bag 36, Al-Khod 123 Muscat Sultanate of Oman
| | | | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion Stiftstrasse 34–36 45470 Mülheim an der Ruhr Germany
| | - Musa S. Shongwe
- Department of ChemistryCollege of ScienceSultan Qaboos University Private Bag 36, Al-Khod 123 Muscat Sultanate of Oman
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5
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Basu D, Mazumder S, Kpogo KK, Verani CN. Influence of nitro substituents on the redox, electronic, and proton reduction catalytic behavior of phenolate-based [N 2O 3]-type cobalt(iii) complexes. Dalton Trans 2019; 48:14669-14677. [PMID: 31536091 DOI: 10.1039/c9dt03158h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We report on the synthesis, redox, electronic, and catalytic behavior of two new cobalt(iii) complexes, namely [CoIII(L1)MeOH] (1) and [CoIII(L2)MeOH] (2). These species contain nitro-rich, phenolate-based pentadentate ligands and present dramatically distinct properties associated with the position in which the -NO2 substituents are installed. Species 1 displays nitro-substituted phenolates, and exhibits irreversible redox response and negligible catalytic activity, whereas 2 has fuctionalized phenylene moieties, shows much improved redox reversibility and catalytic proton reduction activity at low overpotentials. A concerted experimental and theoretical approach sheds some light on these drastic differences.
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Affiliation(s)
- Debashis Basu
- Department of Chemistry, Wayne State University, Detroit, MI-48202, USA.
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6
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Safaei E, Balaghi SE, Chiang L, Clarke RM, Martelino D, Webb MI, Wong EWY, Savard D, Walsby CJ, Storr T. Stabilization of different redox levels of a tridentate benzoxazole amidophenoxide ligand when bound to Co(iii) or V(v). Dalton Trans 2019; 48:13326-13336. [DOI: 10.1039/c9dt02865j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The electronic structure of Co and V complexes of a tridentate benzoxazole-containing aminophenol ligand NNOH2 were characterized by both experimental and theoretical methods.
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Affiliation(s)
- Elham Safaei
- Department of Chemistry
- College of Science
- Shiraz University
- Shiraz
- Iran
| | | | - Linus Chiang
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Ryan M. Clarke
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Diego Martelino
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Michael I. Webb
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Edwin W. Y. Wong
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Didier Savard
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Charles J. Walsby
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Tim Storr
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
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7
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Brand I, Juhaniewicz-Debinska J, Wickramasinghe L, Verani CN. An in situ spectroelectrochemical study on the orientation changes of an [Fe iiiL N2O3] metallosurfactant deposited as LB Films on gold electrode surfaces. Dalton Trans 2018; 47:14218-14226. [PMID: 29589614 DOI: 10.1039/c8dt00333e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In this paper we analyze the changes in molecular orientation triggered by electrochemical reduction of an iron-containing surfactant in Langmuir-Blodgett films deposited onto gold electrodes. The metallosurfactant [Feiii(LN2O3)] (1) is an established molecular rectifier capable of unidirectional electron transfer between two electrodes. A gradual decrease in the activity is observed in sequential current vs. potential curves upon repeated cycles. Here we evaluate the redox response associated with the reduction of the Feiii/Feii couple in a single monolayer, as well as in a 5-layer LB film of 1. We use polarization modulation infrared reflection absorption spectroscopy (PM IRRAS) to follow structural and orientation changes associated with such applied potential scans. We observe that the reduction of the Fe center becomes increasingly irreversible because an Fe-Ophenolate bond is cleaved. This transformation is accompanied by an almost vertical change in the orientation of metallosurfactant molecules in LB films.
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Affiliation(s)
- Izabella Brand
- Department of Chemistry, Carl von Ossietzky University of Oldenburg, 26111 Oldenburg, Germany.
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8
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Weeraratne ADKI, Baydoun H, Shakya R, Niklas J, Xie L, Mao G, Stoian SA, Poluektov OG, Verani CN. Observation of current rectification by the new bimetallic iron(iii) hydrophobe [Fe(L N4O6)] on Au|LB-molecule|Au devices. Dalton Trans 2018; 47:14352-14361. [PMID: 30215065 DOI: 10.1039/c8dt03158d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Targeting the development of stimulus-responsive molecular materials with electronic functionality, we have synthesized and studied the redox and electronic properties of a new bimetallic iron hydrophobe [FeIII2(LN4O6)] (1). The new H6LN4O6 ligand displays bicompartmental topology capable of accomodating two five-coordinate HSFeIII ions bridged by tetraaminobenzene at a close distance of ca. 8 Å. We show that the metal-based reduction processes in (1) proceed sequentially, as observed for electronically coupled metal centers. This species forms a well-defined Pockels-Langmuir film at the air-water interface, with collapse pressure of 32 mN m-1. Langmuir-Blodgett monolayers were deposited on gold substrates and used to investigate current-voltage (I-V) measurements. This unprecedented bimetallic hydrophobe [FeIII2(LN4O6)] (1) shows unquestionable molecular rectification and displays a rectification ratio RR between 2 and 15.
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9
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Johnson MS, Horton CL, Gonawala S, Verani CN, Metzger RM. Observation of current rectification by a new asymmetric iron(iii) surfactant in a eutectic GaIn|LB monolayer|Au sandwich. Dalton Trans 2018; 47:6344-6350. [PMID: 29633775 DOI: 10.1039/c8dt00562a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
In this paper we expand on the search for molecular rectifiers of electrical current and report on a hexacoordinate metallosurfactant [FeIII(LN3O)(OMe)2], where (LN3O)- is the deprotonated form of the new asymmetric ligand 2-((E)-((4,5-bis(2-methoxyethoxy)-2-(((E)-pyridin-2-ylmethylene)amino)phenyl)imino)methyl)-4,6-di-tert-butyl-phenol. This species rectifies current when deposited as a Langmuir-Blodget film in a "EGaIn/Ga2O3|LB|Au" sandwich with rectification ratios ranging from 25 to 300 at 1 Volt.
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Affiliation(s)
- Marcus S Johnson
- Laboratory for Molecular Electronics, Department of Chemistry and Biochemistry, University of Alabama, Box 870336, Tuscaloosa, AL 35487, USA.
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10
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Leconte N, Moutet J, Constantin T, Molton F, Philouze C, Thomas F. Coordination Chemistry of the Redox Non-Innocent Ligand Bis(2-amino-3,5-di-tert
-butylphenyl)amine with Group 10 Metal Ions (Ni, Pd, Pt). Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201701448] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Nicolas Leconte
- Département de Chimie Moléculaire, UMR-5250; Université Grenoble Alpes; BP 53 38041 Grenoble Cedex 9 France
| | - Jules Moutet
- Département de Chimie Moléculaire, UMR-5250; Université Grenoble Alpes; BP 53 38041 Grenoble Cedex 9 France
| | - Thibaut Constantin
- Département de Chimie Moléculaire, UMR-5250; Université Grenoble Alpes; BP 53 38041 Grenoble Cedex 9 France
| | - Florian Molton
- Département de Chimie Moléculaire, UMR-5250; Université Grenoble Alpes; BP 53 38041 Grenoble Cedex 9 France
| | - Christian Philouze
- Département de Chimie Moléculaire, UMR-5250; Université Grenoble Alpes; BP 53 38041 Grenoble Cedex 9 France
| | - Fabrice Thomas
- Département de Chimie Moléculaire, UMR-5250; Université Grenoble Alpes; BP 53 38041 Grenoble Cedex 9 France
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11
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Erxleben A. Transition metal salen complexes in bioinorganic and medicinal chemistry. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2017.06.060] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Xing Y, Liu Y, Xue X, Wang X, Li W. Copper and manganese complexes based on 1,4-naphthalene dicarboxylic acid ligand and its derivative: Syntheses, crystal structures, and magnetic properties. J Mol Struct 2018. [DOI: 10.1016/j.molstruc.2017.09.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Lecarme L, Chiang L, Moutet J, Leconte N, Philouze C, Jarjayes O, Storr T, Thomas F. The structure of a one-electron oxidized Mn(iii)-bis(phenolate)dipyrrin radical complex and oxidation catalysis control via ligand-centered redox activity. Dalton Trans 2018; 45:16325-16334. [PMID: 27711805 DOI: 10.1039/c6dt02163h] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The tetradentate ligand dppH3, which features a half-porphyrin and two electron-rich phenol moieties, was prepared and chelated to manganese. The mononuclear Mn(iii)-dipyrrophenolate complex 1 was structurally characterized. The metal ion lies in a square pyramidal environment, the apical position being occupied by a methanol molecule. Complex 1 displays two reversible oxidation waves at 0.00 V and 0.47 V vs. Fc+/Fc, which are assigned to ligand-centered processes. The one-electron oxidized species 1+ SbF6- was crystallized, showing an octahedral Mn(iii) center with two water molecules coordinated at both apical positions. The bond distance analysis and DFT calculations disclose that the radical is delocalized over the whole aromatic framework. Complex 1+ SbF6- exhibits an Stot = 3/2 spin state due to the antiferromagnetic coupling between Mn(iii) and the ligand radical. The zero field splitting parameters are D = 1.6 cm-1, E/D = 0.18(1), g⊥ = 1.99 and g∥ = 1.98. The dication 12+ is an integer spin system, which is assigned to a doubly oxidized ligand coordinated to a Mn(iii) metal center. Both 1 and 1+ SbF6- catalyze styrene oxidation in the presence of PhIO, but the nature of the main reaction product is different. Styrene oxide is the main reaction product when using 1, but phenylacetaldehyde is formed predominantly when using 1+ SbF6-. We examined the ability of complex 1+ SbF6- to catalyze the isomerization of styrene oxide and found that it is an efficient catalyst for the anti-Markovnikov opening of styrene oxide. The formation of phenylacetaldehyde from styrene therefore proceeds in a tandem E-I (epoxidation-isomerization) mechanism in the case of 1+ SbF6-. This is the first evidence of control of the reactivity for styrene oxidation by changing the oxidation state of a catalyst based on a redox-active ligand.
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Affiliation(s)
- Laureline Lecarme
- Département de Chimie Moléculaire - Chimie Inorganique Redox (CIRE) - UMR CNRS 5250, Université Grenoble Alpes, B. P. 53, 38041 Grenoble cedex 9, France.
| | - Linus Chiang
- Simon Fraser University, Department of Chemistry, 8888 University Drive, Burnaby, British Columbia V5A-1S4, Canada
| | - Jules Moutet
- Département de Chimie Moléculaire - Chimie Inorganique Redox (CIRE) - UMR CNRS 5250, Université Grenoble Alpes, B. P. 53, 38041 Grenoble cedex 9, France.
| | - Nicolas Leconte
- Département de Chimie Moléculaire - Chimie Inorganique Redox (CIRE) - UMR CNRS 5250, Université Grenoble Alpes, B. P. 53, 38041 Grenoble cedex 9, France.
| | - Christian Philouze
- Département de Chimie Moléculaire - Chimie Inorganique Redox (CIRE) - UMR CNRS 5250, Université Grenoble Alpes, B. P. 53, 38041 Grenoble cedex 9, France.
| | - Olivier Jarjayes
- Département de Chimie Moléculaire - Chimie Inorganique Redox (CIRE) - UMR CNRS 5250, Université Grenoble Alpes, B. P. 53, 38041 Grenoble cedex 9, France.
| | - Tim Storr
- Simon Fraser University, Department of Chemistry, 8888 University Drive, Burnaby, British Columbia V5A-1S4, Canada
| | - Fabrice Thomas
- Département de Chimie Moléculaire - Chimie Inorganique Redox (CIRE) - UMR CNRS 5250, Université Grenoble Alpes, B. P. 53, 38041 Grenoble cedex 9, France.
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14
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Safaei E, Alaji Z, Panahi F, Wojtczak A, Jagličić JZ. Synthesis and characterization of a novel oxo-bridged binuclear iron( iii) complex: its catalytic application in the synthesis of benzoxazoles using benzyl alcohol in water. NEW J CHEM 2018. [DOI: 10.1039/c8nj00921j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A novel oxo-bridged binuclear iron(iii) complex was found to be an efficient catalyst in the synthesis of benzoxazoles from benzyl alcohols.
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Affiliation(s)
- Elham Safaei
- Department of Chemistry
- College of Sciences
- Shiraz University
- Shiraz
- Iran
| | - Zahra Alaji
- Institute for Advanced Studies in Basic Sciences (IASBS)
- Zanjan
- Iran
| | - Farhad Panahi
- Department of Chemistry
- College of Sciences
- Shiraz University
- Shiraz
- Iran
| | | | - Janez Zvonko Jagličić
- Institute of Mathematics
- Physics and Mechanics & Faculty of Civil and Geodetic Engineering
- University of Ljubljana
- Ljubljana
- Slovenia
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15
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Verani CN. Molecular rectifiers based on five-coordinate iron(iii)-containing surfactants. Dalton Trans 2018; 47:14153-14168. [DOI: 10.1039/c8dt02891e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The state-of-the-art of metallorganic-based molecular rectification is reviewed with an emphasis on asymmetric five-coordinate FeIII-containing surfactants in electrode|LB film|electrode assemblies.
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16
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Baydoun H, Mazumder S, Schlegel HB, Verani CN. Deactivation of a Cobalt Catalyst for Water Reduction through Valence Tautomerism. Chemistry 2017; 23:9266-9271. [DOI: 10.1002/chem.201701783] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Indexed: 11/12/2022]
Affiliation(s)
- Habib Baydoun
- Department of Chemistry Wayne State University 5101 Cass Ave Detroit MI 48202 USA
| | - Shivnath Mazumder
- Department of Chemistry Wayne State University 5101 Cass Ave Detroit MI 48202 USA
- Current address: Department of Chemistry Hofstra University Berliner Hall Hempstead NY 11549 USA
| | - H. Bernhard Schlegel
- Department of Chemistry Wayne State University 5101 Cass Ave Detroit MI 48202 USA
| | - Cláudio N. Verani
- Department of Chemistry Wayne State University 5101 Cass Ave Detroit MI 48202 USA
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17
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Wickramasinghe LD, Mazumder S, Kpogo KK, Staples RJ, Schlegel HB, Verani CN. Electronic Modulation of the SOMO–HOMO Energy Gap in Iron(III) Complexes towards Unimolecular Current Rectification. Chemistry 2016; 22:10786-90. [DOI: 10.1002/chem.201602444] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Indexed: 11/08/2022]
Affiliation(s)
| | - Shivnath Mazumder
- Department of Chemistry Wayne State University 5101 Cass Ave Detroit MI 48202 USA
| | - Kenneth K. Kpogo
- Department of Chemistry Wayne State University 5101 Cass Ave Detroit MI 48202 USA
| | | | - H. Bernhard Schlegel
- Department of Chemistry Wayne State University 5101 Cass Ave Detroit MI 48202 USA
| | - Cláudio N. Verani
- Department of Chemistry Wayne State University 5101 Cass Ave Detroit MI 48202 USA
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18
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Schlimgen AW, Heaps CW, Mazziotti DA. Entangled Electrons Foil Synthesis of Elusive Low-Valent Vanadium Oxo Complex. J Phys Chem Lett 2016; 7:627-31. [PMID: 26824140 DOI: 10.1021/acs.jpclett.5b02547] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We examine the recently reported first synthesis of the elusive low-valent vanadium(III) in a vanadium oxo complex with a computation representing 10(21) quantum degrees of freedom. While this computation is intractable with a conventionally constructed wave function, it is performed here by a direct calculation of the system's two-electron reduced density matrix (2-RDM), where the 2-RDM is constrained by nontrivial conditions, known as N-representability conditions, that restrict the 2-RDM to represent an N electron quantum system. We show that the added (reducing) electron becomes entangled among the five pyridine ligands. While smaller calculations predict a metal-centered addition, large-scale 2-RDM calculations show that quantum entanglement redirects the electron transfer to the pyridine ligands, resulting in a ligand-centered addition. Beyond its implications for the synthesis of low-valent vanadium oxo complexes, the result suggests new possibilities for using quantum entanglement to predict and control electron transfer in chemical and biological materials.
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Affiliation(s)
- Anthony W Schlimgen
- The Department of Chemistry and The James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
| | - Charles W Heaps
- The Department of Chemistry and The James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
| | - David A Mazziotti
- The Department of Chemistry and The James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
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19
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Ciccione J, Leconte N, Luneau D, Philouze C, Thomas F. Geometric and Electronic Structures of Nickel(II) Complexes of Redox Noninnocent Tetradentate Phenylenediamine Ligands. Inorg Chem 2016; 55:649-65. [PMID: 26689346 DOI: 10.1021/acs.inorgchem.5b01947] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Five tetradentate ligands based on the N,N'-bis(2-amino-3,5-di-tert-butylphenyl)-o-phenylenediamine backbone were prepared, with different substituents at positions 4 and 5 (CH3 (3a), p-CH3O-C6H4 (3b), H (3c), Cl (3d), F (3e)). Their reaction with a nickel(II) salt in air affords the neutral species 4(a-e), which were isolated as single crystals. 4(a-e) feature two antiferromagnetically exchange-coupled diiminosemiquinonate moieties, both located on peripheral rings, and a diamidobenzene bridging unit. Oxidation of 4(a-e) with 1 equiv of AgSbF6 yields the cations 4(a-e)(+), which harbor a single diiminosemiquinonate radical. Significant structural differences were observed within the series. 4b(+) is mononuclear and contains a localized diiminosemiquinonate moiety. In contrast, 4c(+) is a dimer wherein the diiminosemiquinonate radical is rather delocalized over both peripheral rings. 4d(+) represents an intermediate case where the complex is mononuclear, but the radical is fully delocalized. Oxidation of 4(a-e) with 2 equiv of AgSbF6 produces the corresponding mononuclear dications. X-ray diffraction data on 4(b-d)(2+) reveals that the bridging ring retains its diamidobenzene character, whereas both peripheral rings have been oxidized into diiminobenzoquinone moieties. All the complexes were characterized by electrochemistry, EPR, and UV-vis-NIR spectroscopy. Remarkably, the electronic structures of the complexes differ from those reported by Wieghardt et al. for copper and zinc complexes of a related ligand involving a mixed N2O2 donor set (J. Am. Chem. Soc. 1999, 121, 9599). The easier oxidation of phenylenediamine moieties in comparison to aminophenols is proposed to account for the difference.
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Affiliation(s)
- Jérémie Ciccione
- Chimie Inorganique Redox, Département de Chimie Moléculaire (UMR CNRS 5250), Université Grenoble Alpes, UMR-5250 , 38041 Grenoble Cedex 9, France
| | - Nicolas Leconte
- Chimie Inorganique Redox, Département de Chimie Moléculaire (UMR CNRS 5250), Université Grenoble Alpes, UMR-5250 , 38041 Grenoble Cedex 9, France
| | - Dominique Luneau
- Laboratoire des Multimatériaux et Interfaces (UMR CNRS 5615), Université Claude Bernard Lyon 1 , 69622 Villeurbanne cedex, France
| | - Christian Philouze
- Chimie Inorganique Redox, Département de Chimie Moléculaire (UMR CNRS 5250), Université Grenoble Alpes, UMR-5250 , 38041 Grenoble Cedex 9, France
| | - Fabrice Thomas
- Chimie Inorganique Redox, Département de Chimie Moléculaire (UMR CNRS 5250), Université Grenoble Alpes, UMR-5250 , 38041 Grenoble Cedex 9, France
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20
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Gonawala S, Baydoun H, Wickramasinghe L, Verani CN. Efficient water oxidation with electromodified Langmuir–Blodgett films of procatalytic [CoIII(N2O3)] metallosurfactants on electrodes. Chem Commun (Camb) 2016; 52:8440-3. [DOI: 10.1039/c6cc03263j] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Electromodified Langmuir–Blodgett films of a cobalt-based metallosurfactant support water oxidation at turnover numbers of up to 54 000 h−1.
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21
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Davila R, Farias N, Carolina Sañudo E, Vega A, Escuer A, Soler M, Manzur J. Dinuclear cobalt(iii) and mixed valence trinuclear MnIII–MnII–MnIII complexes with a tripodal bridging pyridylaminophenol ligand. NEW J CHEM 2016. [DOI: 10.1039/c5nj03670d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Two new complexes with the tripodal N-(2-pyridyl-methyl)-N,N-bis-[2′-hydroxy-5′-methyl-benzyl]-amine, one CoIII dimer and a linear mixed valence MnIII–MnII–MnIII have been synthesized and characterized.
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Affiliation(s)
- Ruben Davila
- Deapartamento de Ciencia de los Materiales
- Facultad de Ciencias Físicas y Matemáticas
- Universidad de Chile
- Santiago
- Chile
| | - Nicolas Farias
- Deapartamento de Ciencia de los Materiales
- Facultad de Ciencias Físicas y Matemáticas
- Universidad de Chile
- Santiago
- Chile
| | - E. Carolina Sañudo
- Departament de Química Inorgánica
- Universitat de Barcelona
- 08028-Barcelona
- Spain
| | - Andrés Vega
- Departamento de Ciencias Químicas
- Facultad de Ciencias Exactas
- Universidad Andres Bello
- Viña del Mar
- Chile
| | - Albert Escuer
- Departament de Química Inorgánica
- Universitat de Barcelona
- 08028-Barcelona
- Spain
| | - Mónica Soler
- Deapartamento de Ciencia de los Materiales
- Facultad de Ciencias Físicas y Matemáticas
- Universidad de Chile
- Santiago
- Chile
| | - Jorge Manzur
- Deapartamento de Ciencia de los Materiales
- Facultad de Ciencias Físicas y Matemáticas
- Universidad de Chile
- Santiago
- Chile
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22
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de Bellefeuille D, Orio M, Barra AL, Aukauloo A, Journaux Y, Philouze C, Ottenwaelder X, Thomas F. Redox Noninnocence of the Bridge in Copper(II) Salophen and Bis(oxamato) Complexes. Inorg Chem 2015; 54:9013-26. [DOI: 10.1021/acs.inorgchem.5b01285] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- David de Bellefeuille
- Department
of Chemistry and Biochemistry, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | - Maylis Orio
- Laboratoire
de Spectrochimie Infrarouge et Raman, Université des Sciences et Technologies de Lille, UMR CNRS 8516, 59655 Villeneuve
d’Ascq Cedex, France
| | - Anne-Laure Barra
- Laboratoire National des Champs Magnétiques Intenses, CNRS, 25 rue des Martyrs, 38042 Grenoble, France
| | - Ally Aukauloo
- Institut
de Chimie Moléculaire et des Matériaux d’Orsay,
UMR CNRS 8182, Université Paris-Sud XI, 91405 Orsay, France
- Service de Bioénergétique,
Biologie Structurale et Mécanismes (SB2SM), CEA, iBiTec-S;
Biochimie Biophysique et Biologie Structurale (B3S),
I2BC, UMR 9198, 91191 Gif-sur-Yvette, France
| | - Yves Journaux
- Institut
de Chimie Moléculaire et des Matériaux d’Orsay,
UMR CNRS 8182, Université Paris-Sud XI, 91405 Orsay, France
- Sorbonne Universités,
UPMC Université Paris 06, UMR CNRS 8232, Institut
Parisien de Chimie Moléculaire, France
| | - Christian Philouze
- Equipe
CIRE, Département de Chimie Moléculaire, UMR CNRS 5250, Université Grenoble-Alpes, 38041 Grenoble Cedex 9, France
| | - Xavier Ottenwaelder
- Department
of Chemistry and Biochemistry, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | - Fabrice Thomas
- Equipe
CIRE, Département de Chimie Moléculaire, UMR CNRS 5250, Université Grenoble-Alpes, 38041 Grenoble Cedex 9, France
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23
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Wang D, Lindeman SV, Fiedler AT. Bimetallic Complexes Supported by a Redox-Active Ligand with Fused Pincer-Type Coordination Sites. Inorg Chem 2015; 54:8744-54. [PMID: 26280846 DOI: 10.1021/acs.inorgchem.5b01380] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The remarkable chemistry of mononuclear complexes featuring tridentate, meridionally chelating "pincer" ligands has stimulated the development of ligand frameworks containing multiple pincer sites. Here, the coordination chemistry of a novel pentadentate ligand (L(N3O2)) that provides two closely spaced NNO pincer-type compartments fused together at a central diarylamido unit is described. The trianionic L(N3O2) chelate supports homobimetallic structures in which each M(II) ion (M = Co, Cu, Zn) is bound in a meridional fashion by the bridging diarylamido N atom and O,N-donors of the salicyaldimine arms. The metal centers are also coordinated by a mono- or bidentate auxiliary ligand (L(aux)), resulting in complexes with the general form [M2(L(N3O2))(L(aux))2](+) (where L(aux) = 1-methyl-benzimidazole (1MeBI), 2,2'-bipyridine (bpy), 4,4'-dibromo-2,2'-bipyridine (bpy(Br2)), or (S)-2-(4-isopropyl-4,5-dihydrooxazolyl)pyridine (S-(iPr)OxPy)). The fused nature of the NNO pincer sites results in short metal-metal distances ranging from 2.70 Å for [Co2(L(N3O2)) (bpy)2](+) to 3.28 Å for [Zn2(L(N3O2)) (bpy)2](+), as revealed by X-ray crystallography. The complexes possess C2 symmetry due to the twisting of the aryl rings of the μ-NAr2 core; spectroscopic studies indicate that chiral L(aux) ligands, such as S-(iPr)OxPy, are capable of controlling the helical sense of the L(N3O2) scaffold. Since the four- or five-coordinate M(II) centers are linked solely by the amido moiety, each features an open coordination site in the intermetallic region, allowing for the possibility of metal-metal cooperativity in small-molecule activation. Indeed, the dicobalt(II) complex [Co2(L(N3O2)) (bpy(Br2))2](+) reacts with O2 to yield a dicobalt(III) species with a μ-1,2-peroxo ligand. The bpy-containing complexes exhibit rich electrochemical properties due to multiple metal- and ligand-based redox events across a wide (3.0 V) potential window. Using electron paramagnetic resonance (EPR) spectroscopy and density functional theory (DFT), it was determined that one-electron oxidation of [Co2(L(N3O2)) (bpy)2](+) results in formation of a S = 1/2 species with a L(N3O2)-based radical coupled to low-spin Co(II) centers.
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Affiliation(s)
- Denan Wang
- Department of Chemistry, Marquette University , Milwaukee, Wisconsin 53201, United States
| | - Sergey V Lindeman
- Department of Chemistry, Marquette University , Milwaukee, Wisconsin 53201, United States
| | - Adam T Fiedler
- Department of Chemistry, Marquette University , Milwaukee, Wisconsin 53201, United States
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24
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Chiang L, Herasymchuk K, Thomas F, Storr T. Influence of Electron-Withdrawing Substituents on the Electronic Structure of Oxidized Ni and Cu Salen Complexes. Inorg Chem 2015; 54:5970-80. [DOI: 10.1021/acs.inorgchem.5b00783] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Linus Chiang
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Khrystyna Herasymchuk
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Fabrice Thomas
- Département de Chimie Moléculaire,
Chimie Inorganique Redox (CIRE), UMR-5250, Université Grenoble Alpes, BP 53, 38041 Grenoble
Cedex 9, France
| | - Tim Storr
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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25
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Badetti E, Gjoka B, Nagy EM, Bernardinelli G, Kündig PE, Zonta C, Licini G. Mononuclear Iron(III) Complexes as Functional Models of Catechol Oxidases and Catalases. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201403225] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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26
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Basu D, Allard MM, Xavier FR, Heeg MJ, Schlegel HB, Verani CN. Modulation of electronic and redox properties in phenolate-rich cobalt(iii) complexes and their implications for catalytic proton reduction. Dalton Trans 2015; 44:3454-66. [DOI: 10.1039/c4dt03337j] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The redox, spectroscopic and catalytic activity of a series of cobalt complexes with phenolate-rich environments was investigated. The complex [CoIII(LCl)MeOH] shows considerable proton reduction in MeCN:HOAc with TON = 10.8.
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Affiliation(s)
- Debashis Basu
- Department of Chemistry
- Wayne State University
- Detroit
- USA
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27
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Basu D, Mazumder S, Shi X, Baydoun H, Niklas J, Poluektov O, Schlegel HB, Verani CN. Ligand Transformations and Efficient Proton/Water Reduction with Cobalt Catalysts Based on Pentadentate Pyridine‐Rich Environments. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201409813] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Debashis Basu
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202 (USA) http://chem.wayne.edu/veranigroup/
| | - Shivnath Mazumder
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202 (USA) http://chem.wayne.edu/veranigroup/
| | - Xuetao Shi
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202 (USA) http://chem.wayne.edu/veranigroup/
| | - Habib Baydoun
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202 (USA) http://chem.wayne.edu/veranigroup/
| | - Jens Niklas
- Argonne National Laboratory, Chemistry Division, E117, 9700 South Cass Ave. Argonne, IL 60439 (USA)
| | - Oleg Poluektov
- Argonne National Laboratory, Chemistry Division, E117, 9700 South Cass Ave. Argonne, IL 60439 (USA)
| | - H. Bernhard Schlegel
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202 (USA) http://chem.wayne.edu/veranigroup/
| | - Cláudio N. Verani
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202 (USA) http://chem.wayne.edu/veranigroup/
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28
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Basu D, Mazumder S, Shi X, Baydoun H, Niklas J, Poluektov O, Schlegel HB, Verani CN. Ligand transformations and efficient proton/water reduction with cobalt catalysts based on pentadentate pyridine-rich environments. Angew Chem Int Ed Engl 2014; 54:2105-10. [PMID: 25533319 DOI: 10.1002/anie.201409813] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 11/25/2014] [Indexed: 11/10/2022]
Abstract
A series of cobalt complexes with pentadentate pyridine-rich ligands is studied. An initial Co(II) amine complex 1 is prone to aerial oxidation yielding a Co(III) imine complex 2 that is further converted into an amide complex 4 in presence of adventitious water. Introduction of an N-methyl protecting group to the ligand inhibits this oxidation and gives rise to the Co(II) species 5. Both the Co(III) 4 and Co(II) 5 show electrocatalytic H2 generation in weakly acidic media as well as in water. Mechanisms of catalysis seem to involve the protonation of a Co(II)-H species generated in situ.
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Affiliation(s)
- Debashis Basu
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202 (USA) http://chem.wayne.edu/veranigroup/
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29
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Pascualini ME, Di Russo NV, Quintero PA, Thuijs AE, Pinkowicz D, Abboud KA, Dunbar KR, Christou G, Meisel MW, Veige AS. Synthesis, Characterization, and Reactivity of Iron(III) Complexes Supported by a Trianionic ONO3– Pincer Ligand. Inorg Chem 2014; 53:13078-88. [DOI: 10.1021/ic502251p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | | | - Dawid Pinkowicz
- Department of Chemistry, Texas A&M University, College Station, Texas 77842-3012, United States
- Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland
| | | | - Kim R. Dunbar
- Department of Chemistry, Texas A&M University, College Station, Texas 77842-3012, United States
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30
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Wickramasinghe LD, Mazumder S, Gonawala S, Perera MM, Baydoun H, Thapa B, Li L, Xie L, Mao G, Zhou Z, Schlegel HB, Verani CN. The Mechanisms of Rectification in Au|Molecule|Au Devices Based on Langmuir-Blodgett Monolayers of Iron(III) and Copper(II) Surfactants. Angew Chem Int Ed Engl 2014; 53:14462-7. [DOI: 10.1002/anie.201408649] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 09/18/2014] [Indexed: 11/08/2022]
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31
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Wickramasinghe LD, Mazumder S, Gonawala S, Perera MM, Baydoun H, Thapa B, Li L, Xie L, Mao G, Zhou Z, Schlegel HB, Verani CN. The Mechanisms of Rectification in Au|Molecule|Au Devices Based on Langmuir-Blodgett Monolayers of Iron(III) and Copper(II) Surfactants. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201408649] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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32
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Synthesis of homo- and heterobimetallic Ni II –M II (M = Fe, Co, Ni, Zn) complexes based on an unsymmetric ligand framework: Structures, spectroscopic features, and redox properties. Inorganica Chim Acta 2014. [DOI: 10.1016/j.ica.2014.07.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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34
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Chiang L, Savard D, Shimazaki Y, Thomas F, Storr T. FeIII Bipyrrolidine Phenoxide Complexes and Their Oxidized Analogues. Inorg Chem 2014; 53:5810-9. [DOI: 10.1021/ic500663x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Linus Chiang
- Department of Chemistry, Simon Fraser University , Burnaby, British Columbia V5A 1S6, Canada
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35
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Metzinger R, Demeshko S, Limberg C. A Novel Pentadentate Redox-Active Ligand and Its Iron(III) Complexes: Electronic Structures and O2Reactivity. Chemistry 2014; 20:4721-35. [DOI: 10.1002/chem.201304535] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 01/15/2014] [Indexed: 11/11/2022]
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36
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Wickramasinghe LD, Perera MM, Li L, Mao G, Zhou Z, Verani CN. Rectification in Nanoscale Devices Based on an Asymmetric Five-Coordinate Iron(III) Phenolate Complex. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201306765] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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37
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Wickramasinghe LD, Perera MM, Li L, Mao G, Zhou Z, Verani CN. Rectification in Nanoscale Devices Based on an Asymmetric Five-Coordinate Iron(III) Phenolate Complex. Angew Chem Int Ed Engl 2013; 52:13346-50. [DOI: 10.1002/anie.201306765] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Indexed: 11/12/2022]
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38
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Baum AE, Lindeman SV, Fiedler AT. Preparation of a semiquinonate-bridged diiron(II) complex and elucidation of its geometric and electronic structures. Chem Commun (Camb) 2013; 49:6531-3. [PMID: 23765069 DOI: 10.1039/c3cc42980f] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The synthesis and crystal structure of a diiron(II) complex containing a bridging semiquinonate radical are presented. The unique electronic structure of this S = 7/2 complex is examined with spectroscopic (absorption, EPR, resonance Raman) and computational methods.
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Affiliation(s)
- Amanda E Baum
- Department of Chemistry, Marquette University, 535 N. 14th St., Milwaukee, WI 53233, USA
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39
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Lyons CT, Stack TDP. Recent advances in phenoxyl radical complexes of salen-type ligands as mixed-valent galactose oxidase models. Coord Chem Rev 2013; 257:528-540. [PMID: 23264696 PMCID: PMC3524984 DOI: 10.1016/j.ccr.2012.06.003] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The interplay between redox-active transition metal ions and redox-active ligands in metalloenzyme sites is an area of considerable research interest. Galactose oxidase (GO) is the archetypical example, catalyzing the aerobic oxidation of primary alcohols to aldehydes via two one-electron cofactors: a copper atom and a cysteine-modified tyrosine residue. The electronic structure of the oxidized form of the enzyme (GO(ox)) has been investigated extensively through small molecule analogues including metal-salen phenoxyl radical complexes. Similar to GO(ox), one-electron oxidized metal-salen complexes are mixed-valent species, in which molecular orbitals (MOs) with predominantly phenolate and phenoxyl π-character act as redox-active centers bridged by mixing with metal d-orbitals. A detailed evaluation of the electronic distribution in these odd electron species using a variety of spectroscopic, electrochemical, and theoretical techniques has led to keen insights into the electronic structure of GO(ox).
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Affiliation(s)
| | - T. Daniel P. Stack
- Department of Chemistry, Stanford University, Sanford, CA 94305, United States
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40
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Verani CN, Shanmugam R, Xavier FR, Allard MM, Kpogo KK. Electronic and interfacial behavior of gemini metallosurfactants with copper(ii)/pseudohalide cascade cores. Dalton Trans 2013; 42:15296-306. [DOI: 10.1039/c3dt50788b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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41
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Tomco D, Xavier FR, Allard MM, Verani CN. Probing chemical reduction in a cobalt(III) complex as a viable route for the inhibition of the 20S proteasome. Inorganica Chim Acta 2012. [DOI: 10.1016/j.ica.2012.06.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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42
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Allard MM, Xavier FR, Heeg MJ, Schlegel HB, Verani CN. Sequential Phenolate Oxidations in Octahedral Cobalt(III) Complexes with [N2O3] Ligands. Eur J Inorg Chem 2012. [DOI: 10.1002/ejic.201200171] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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43
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Chiang L, Kochem A, Jarjayes O, Dunn TJ, Vezin H, Sakaguchi M, Ogura T, Orio M, Shimazaki Y, Thomas F, Storr T. Radical Localization in a Series of Symmetric NiIIComplexes with Oxidized Salen Ligands. Chemistry 2012; 18:14117-27. [DOI: 10.1002/chem.201201410] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Indexed: 11/12/2022]
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44
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Shongwe MS, Al-Zaabi UA, Al-Mjeni F, Eribal CS, Sinn E, Al-Omari IA, Hamdeh HH, Matoga D, Adams H, Morris MJ, Rheingold AL, Bill E, Sellmyer DJ. Accessibility and selective stabilization of the principal spin states of iron by pyridyl versus phenolic ketimines: modulation of the 6A1 ↔ 2T2 ground-state transformation of the [FeN4O2]+ chromophore. Inorg Chem 2012; 51:8241-53. [PMID: 22808945 DOI: 10.1021/ic300732r] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Several potentially tridentate pyridyl and phenolic Schiff bases (apRen and HhapRen, respectively) were derived from the condensation reactions of 2-acetylpyridine (ap) and 2'-hydroxyacetophenone (Hhap), respectively, with N-R-ethylenediamine (RNHCH(2)CH(2)NH(2), Ren; R = H, Me or Et) and complexed in situ with iron(II) or iron(III), as dictated by the nature of the ligand donor set, to generate the six-coordinate iron compounds [Fe(II)(apRen)(2)]X(2) (R = H, Me; X(-) = ClO(4)(-), BPh(4)(-), PF(6)(-)) and [Fe(III)(hapRen)(2)]X (R = Me, Et; X(-) = ClO(4)(-), BPh(4)(-)). Single-crystal X-ray analyses of [Fe(II)(apRen)(2)](ClO(4))(2) (R = H, Me) revealed a pseudo-octahedral geometry about the ferrous ion with the Fe(II)-N bond distances (1.896-2.041 Å) pointing to the (1)A(1) (d(π)(6)) ground state; the existence of this spin state was corroborated by magnetic susceptibility measurements and Mössbauer spectroscopy. In contrast, the X-ray structure of the phenolate complex [Fe(III)(hapMen)(2)]ClO(4), determined at 100 K, demonstrated stabilization of the ferric state; the compression of the coordinate bonds at the metal center is in accord with the (2)T(2) (d(π)(5)) ground state. Magnetic susceptibility measurements along with EPR and Mössbauer spectroscopic techniques have shown that the iron(III) complexes are spin-crossover (SCO) materials. The spin transition within the [Fe(III)N(4)O(2)](+) chromophore was modulated with alkyl substituents to afford two-step and one-step (6)A(1) ↔ (2)T(2) transformations in [Fe(III)(hapMen)(2)]ClO(4) and [Fe(III)(hapEen)(2)]ClO(4), respectively. Previously, none of the X-salRen- and X-sal(2)trien-based ferric spin-crossover compounds exhibited a stepwise transition. The optical spectra of the LS iron(II) and SCO iron(III) complexes display intense d(π) → p(π)* and p(π) → d(π) CT visible absorptions, respectively, which account for the spectacular color differences. All the complexes are redox-active; as expected, the one-electron oxidative process in the divalent compounds occurs at higher redox potentials than does the reverse process in the trivalent compounds. The cyclic voltammograms of the latter compounds reveal irreversible electrochemical generation of the phenoxyl radical. Finally, the H(2)salen-type quadridentate ketimine H(2)hapen complexed with an equivalent amount of iron(III) to afford the μ-oxo-monobridged dinuclear complex [{Fe(III)(hapen)}(2)(μ-O)] exhibiting a distorted square-pyramidal geometry at the metal centers and considerable antiferromagnetic coupling of spins (J ≈ -99 cm(-1)).
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Affiliation(s)
- Musa S Shongwe
- Department of Chemistry, College of Science, Sultan Qaboos University, PO Box 36, Al-Khod 123, Muscat, Sultanate of Oman.
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45
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Dunn TJ, Chiang L, Ramogida CF, Webb MI, Savard D, Sakaguchi M, Ogura T, Shimazaki Y, Storr T. Non-innocent ligand behaviour of a bimetallic Cu complex employing a bridging catecholate. Dalton Trans 2012; 41:7905-14. [DOI: 10.1039/c2dt30444a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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