1
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Haaf S, Engels E, Kaifer E, Himmel HJ. Hexaguanidino-Triptycenes and Triphenylenes: Electronic Coupling in Molecules Containing Three Redox-Active o-Diguanidinobenzene Units Connected either Directly or Interacting Through Homoconjugation. Chemistry 2024; 30:e202301903. [PMID: 37815019 DOI: 10.1002/chem.202301903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 09/22/2023] [Accepted: 10/10/2023] [Indexed: 10/11/2023]
Abstract
Novel redox-active hexaguanidine molecules with multiple redox states were synthesized by connecting three o-diguanidinobenzene units. In 2,3,6,7,14,15-hexaguanidino-triptycenes, the three redox-active o-diguanidinobenzene units are connected through C-C bonds to the sp3 -hybridized bridgehead C atoms, and in 2,3,6,7,10,11-hexaguanidino-triphenylenes they are directly connected. The connectivity difference leads to different electronic coupling between the three redox-active o-diguanidinobenzene units, with homoconjugation being present in the triptycene, but not in the triphenylene compounds. Motivated by the appearance of an intense low-energy electronic transition, we especially analysed the effect of homoconjugation on the electronic structure and charge delocalization in the dicationic redox state of the triptycene derivatives. Then, several trinuclear high-spin cobalt (and copper) complexes were synthesized with the triphenylene and triptycene ligands, and the magnetic coupling and redox properties analysed. By choice of the coligands (hexafluoroacetylacetonate, trifluoroacetylacetonate and acetylacetonate), oxidation could be switched between metal- and ligand-centered redox events, leading to drastic changes in the magnetic or optical properties, especially as a consequence of homoconjugation in the triptycene derivatives.
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Affiliation(s)
- Sebastian Haaf
- Inorganic Chemistry, Ruprecht-Karls University Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Eliane Engels
- Inorganic Chemistry, Ruprecht-Karls University Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Elisabeth Kaifer
- Inorganic Chemistry, Ruprecht-Karls University Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Hans-Jörg Himmel
- Inorganic Chemistry, Ruprecht-Karls University Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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2
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Lohmeyer L, Kaifer E, Himmel HJ. Solvent-Induced Redox Isomerism of Cobalt Complexes with Redox-Active Bisguanidine Ligands. Inorg Chem 2022; 61:8440-8454. [PMID: 35612530 DOI: 10.1021/acs.inorgchem.1c03983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Redox-isomeric coordination compounds, in which the magnetic and optical properties could be varied by a stimulated intramolecular electron transfer between the metal and a redox-active ligand, are of interest for several applications in catalysis and materials science. In this work, the redox chemistry of cobalt complexes with redox-active bisguanidine ligands is studied; systematic modifications at the redox-active bisguanidine and the co-ligand units allow for fine-tuning of the electronic structure, which eventually leads to the first observation of redox isomerism for cobalt complexes with redox-active guanidine ligands. Redox isomerism is triggered by a change in the solvent properties.
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Affiliation(s)
- Lukas Lohmeyer
- Anorganisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
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3
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Wild U, Hübner O, Enders M, Kaifer E, Himmel HJ. Connecting Organic Redox‐Active Building Blocks Through Mild Non‐Catalytic C‐H Activation. European J Org Chem 2022. [DOI: 10.1002/ejoc.202200349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Ute Wild
- Ruprecht Karls Universitat Heidelberg Fakultat fur Chemie und Geowissenschaften Chemistry GERMANY
| | - Olaf Hübner
- Ruprecht Karls Universitat Heidelberg Fakultat fur Chemie und Geowissenschaften Chemistry GERMANY
| | - Markus Enders
- Ruprecht Karls Universitat Heidelberg Fakultat fur Chemie und Geowissenschaften Chemistry GERMANY
| | - Elisabeth Kaifer
- Ruprecht Karls Universitat Heidelberg Fakultat fur Chemie und Geowissenschaften Chemistry GERMANY
| | - Hans-Jörg Himmel
- Ruprecht-Karls-Universität Heidelberg Institut für Anorganische Chemie Im Neuenheimer Feld 270 69120 Heidelberg GERMANY
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4
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Steuer L, Kaifer E, Himmel HJ. Redox‐Active Dendrimer‐Like Oligoguanidines and Their Use in a Proton‐Coupled Electron Transfer Reaction. European J Org Chem 2022. [DOI: 10.1002/ejoc.202101360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Lena Steuer
- Ruprecht Karls Universitat Heidelberg Fakultat fur Chemie und Geowissenschaften Chemistry GERMANY
| | - Elisabeth Kaifer
- Ruprecht Karls Universitat Heidelberg Fakultat fur Chemie und Geowissenschaften Chemistry GERMANY
| | - Hans-Jörg Himmel
- Ruprecht-Karls-Universität Heidelberg Institut für Anorganische Chemie Im Neuenheimer Feld 270 69120 Heidelberg GERMANY
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5
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Role of a Redox-Active Ligand Close to a Dinuclear Activating Framework. TOP ORGANOMETAL CHEM 2022. [DOI: 10.1007/3418_2022_77] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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6
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Steuer L, Kaifer E, Himmel HJ. On the metal-ligand bonding in dinuclear complexes with redox-active guanidine ligands. Dalton Trans 2021; 50:9467-9482. [PMID: 34136887 DOI: 10.1039/d1dt01354h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Coordination compounds with redox-active ligands are currently intensively studied. Within this research theme, redox-active guanidines have been established as a new, eminent class of redox-active ligands. In this work the variation of metal-guanidine bonding in dinuclear transition metal complexes with bridging redox-active tetrakisguanidine ligands is analysed. A series of dinuclear complexes with different metals (Mn, Fe, Co, Ni, Cu and Zn) is synthesized, using either newly prepared redox-active tetrakisguanidino-dioxine or previously reported tetrakisguanidino-benzene ligands. The discussion of the bond properties in this work is predominantly based on the trends of structural parameters, derived from determination of single-crystal structures by X-ray diffraction and quantum chemical calculations. In addition, the trends in the redox potentials and magnetometric (SQUID) measurements on some of the complexes are included. Due to their combined σ- and π-electron donor capability, redox-active guanidine ligands are weak-field ligands; the σ- and π-bonding contributions vary with the metal. The results highlight the peculiarity of copper-guanidine bonding with a high π-bond contribution to metal-guanidine bonding, enabled by structural distortion of the coordination mode from tetrahedral in the direction of square-planar, short copper-guanidine bonds and minor displacement of the copper atoms from the ligand aromatic plane.
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Affiliation(s)
- Lena Steuer
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
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7
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Lohmeyer L, Kaifer E, Enders M, Himmel H. Switching from Metal- to Ligand-Based Oxidation in Cobalt Complexes with Redox-Active Bisguanidine Ligands. Chemistry 2021; 27:11852-11867. [PMID: 34101917 PMCID: PMC8457109 DOI: 10.1002/chem.202101364] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Indexed: 11/19/2022]
Abstract
The control of the redox reactivity, magnetic and optical properties of the different redox states of complexes with redox‐active ligands permits their rational use in catalysis and materials science. The redox‐chemistry of octahedrally coordinated high‐spin CoII complexes (three unpaired electrons) with one redox‐active bisguanidine ligand and two acetylacetonato (acac) co‐ligands is completely changed by replacing the acac by hexafluoro‐acetylacetonato (hfacac) co‐ligands. The first one‐electron oxidation is metal‐centered in the case of the complexes with acac co‐ligands, giving diamagnetic CoIII complexes. By contrast, in the case of the less Lewis‐basic hfacac co‐ligands, the first one‐electron oxidation becomes ligand‐centered, leading to high‐spin CoII complexes with a radical monocationic guanidine ligand unit (four unpaired electrons). Ferromagnetic coupling between the spins on the metal and the organic radical in solution is evidenced by temperature‐dependent paramagnetic NMR studies, allowing to estimate the isotropic exchange coupling constant in solution. Second one‐electron oxidation leads to high‐spin CoII complexes with dicationic guanidine ligand units (three unpaired electrons) in the presence of hfacac co‐ligands, but to low‐spin CoIII complexes with radical monocationic, peralkylated guanidine ligand (one unpaired electron) in the presence of acac co‐ligands. The analysis of the electronic structures is complemented by quantum‐chemical calculations on the spin density distributions and relative energies of the possible redox isomers.
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Affiliation(s)
- Lukas Lohmeyer
- Inorganic ChemistryRuprecht-Karls University of HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Elisabeth Kaifer
- Inorganic ChemistryRuprecht-Karls University of HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Markus Enders
- Inorganic ChemistryRuprecht-Karls University of HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hans‐Jörg Himmel
- Inorganic ChemistryRuprecht-Karls University of HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
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8
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Lohmeyer L, Schön F, Kaifer E, Himmel H. Stimulierung eines redoxinduzierten Elektronentransfers durch Interligand‐Wasserstoffbrücken in einem Cobaltkomplex mit redoxaktivem Guanidin‐Liganden. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202101423] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Lukas Lohmeyer
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Florian Schön
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
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9
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Lohmeyer L, Schön F, Kaifer E, Himmel HJ. Stimulation of Redox-Induced Electron Transfer by Interligand Hydrogen Bonding in a Cobalt Complex with Redox-Active Guanidine Ligand. Angew Chem Int Ed Engl 2021; 60:10415-10422. [PMID: 33616266 PMCID: PMC8252010 DOI: 10.1002/anie.202101423] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Indexed: 12/27/2022]
Abstract
Octahedrally coordinated cobalt(II) complexes with a redox‐active bisguanidine ligand and acac co‐ligands were synthesized and their redox chemistry analysed in detail. The N−H functions in a bisguanidine ligand with partially alkylated guanidino groups form N−H⋅⋅⋅O hydrogen bonds with the acac co‐ligands, thereby massively influencing the redox chemistry. For all complexes, the first one‐electron oxidation is metal‐centred, leading to CoIII complexes with neutral bisguanidine ligand units. Further one‐electron oxidation is ligand‐centred in the case of Co–bisguanidine complexes with fully alkylated guanidino groups, giving CoIII complexes with radical monocationic bisguanidine ligands. On the other hand, the hydrogen‐bond strengthening upon oxidation of the Co–bisguanidine complex with partially alkylated guanidino groups initiates metal reduction (CoIII→CoII) and two‐electron oxidation of the guanidine ligand, providing the first example for the stimulation of redox‐induced electron transfer by interligand hydrogen bonding.
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Affiliation(s)
- Lukas Lohmeyer
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Florian Schön
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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10
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Haaf S, Kaifer E, Wadepohl H, Himmel H. Use of Crown Ether Functions as Secondary Coordination Spheres for the Manipulation of Ligand-Metal Intramolecular Electron Transfer in Copper-Guanidine Complexes. Chemistry 2021; 27:959-970. [PMID: 32833269 PMCID: PMC7839521 DOI: 10.1002/chem.202003469] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Indexed: 01/16/2023]
Abstract
Intramolecular electron transfer (IET) between a redox-active organic ligand and a metal in a complex is of fundamental interest and used in a variety of applications. In this work it is demonstrated that secondary coordination sphere motifs can be applied to trigger a radical change in the electronic structure of copper complexes with a redox-active guanidine ligand through ligand-metal IET. Hence, crown ether functions attached to the ligand allow the manipulation of the degree of IET between the guanidine ligand and the copper atom through metal encapsulation.
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Affiliation(s)
- Sebastian Haaf
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hubert Wadepohl
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
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11
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Wagner C, Kreis F, Popp D, Hübner O, Kaifer E, Himmel H. 1,2,4,5‐Tetrakis(tetramethylguanidino)‐3,6‐diethynyl‐benzenes: Fluorescent Probes, Redox‐Active Ligands and Strong Organic Electron Donors. Chemistry 2020; 26:10336-10347. [PMID: 32368816 PMCID: PMC7497081 DOI: 10.1002/chem.202001557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/30/2020] [Indexed: 11/25/2022]
Abstract
In this work, the change of reactivity induced by the introduction of two para‐ethynyl substituents (CCSi(iPr)3 or CCH) to the organic electron‐donor 1,2,4,5‐tetrakis(tetramethylguanidino)‐benzene is evaluated. The redox‐properties and redox‐state dependent fluorescence are evaluated, and dinuclear CuI and CuII complexes synthesized. The Lewis‐acidic B(C6F5)3 substitutes the proton of the ethynyl −CCH groups to give new anionic −CCB(C6F5)3− substituents, leading eventually to a novel dianionic strong electron donor in its diprotonated form. Its two‐electron oxidation with dioxygen in the presence of a copper catalyst yields the first redox‐active guanidine that is neutral (instead of cationic) in its oxidized form.
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Affiliation(s)
- Conrad Wagner
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Franka Kreis
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Dennis Popp
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Olaf Hübner
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
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12
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Lohmeyer L, Kaifer E, Wadepohl H, Himmel H. 1,2,5,6-Tetrakis(guanidino)-Naphthalenes: Electron Donors, Fluorescent Probes and Redox-Active Ligands. Chemistry 2020; 26:5834-5845. [PMID: 32017282 PMCID: PMC7318682 DOI: 10.1002/chem.201905471] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 01/23/2020] [Indexed: 01/07/2023]
Abstract
New redox-active 1,2,5,6-tetrakis(guanidino)-naphthalene compounds, isolable and storable in the neutral and deep-green dicationic redox states and oxidisable further in two one-electron steps to the tetracations, are reported. Protonation switches on blue fluorescence, with the fluorescence intensity (quantum yield) increasing with the degree of protonation. Reactions with N-halogenosuccinimides or N-halogenophthalimides led to a series of new redox-active halogeno- and succinimido-/phthalimido-substituted derivatives. These highly selective reactions are proposed to proceed via the tri- or tetracationic state as the intermediate. The derivatives are oxidised reversibly at slightly higher potentials than that of the unsubstituted compounds to dications and further to tri- and tetracations. The integration of redox-active ligands in the transition-metal complexes shifts the redox potentials to higher values and also allows reversible oxidation in two potentially separated one-electron steps.
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Affiliation(s)
- Lukas Lohmeyer
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hubert Wadepohl
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
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13
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Wild U, Hübner O, Himmel H. Redox-Active Guanidines in Proton-Coupled Electron-Transfer Reactions: Real Alternatives to Benzoquinones? Chemistry 2019; 25:15988-15992. [PMID: 31535741 PMCID: PMC7065378 DOI: 10.1002/chem.201903438] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Indexed: 01/24/2023]
Abstract
Guanidino-functionalized aromatics (GFAs) are readily available, stable organic redox-active compounds. In this work we apply one particular GFA compound, 1,2,4,5-tetrakis(tetramethylguanidino)benzene, in its oxidized form in a variety of oxidation/oxidative coupling reactions to demonstrate the scope of its proton-coupled electron transfer (PCET) reactivity. Addition of an excess of acid boosts its oxidation power, enabling the oxidative coupling of substrates with redox potentials of at least +0.77 V vs. Fc+ /Fc. The green recyclability by catalytic re-oxidation with dioxygen is also shown. Finally, a direct comparison indicates that GFAs are real alternatives to toxic halo- or cyano-substituted benzoquinones.
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Affiliation(s)
- Ute Wild
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Olaf Hübner
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
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14
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Werr M, Kaifer E, Wadepohl H, Himmel HJ. Tuneable Redox Chemistry and Electrochromism of Persistent Symmetric and Asymmetric Azine Radical Cations. Chemistry 2019; 25:12981-12990. [PMID: 31306523 DOI: 10.1002/chem.201902216] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/21/2019] [Indexed: 12/16/2022]
Abstract
Molecular organic radicals have been intensively studied in the last decades, due to their interesting optical, magnetic and redox properties. Here we report the synthesis and characterisation of persistent organic radicals from one-electron oxidation of redox-active azines (RAAs), composed of two guanidinyl or related groups. By connecting two different groups together, asymmetric compounds result. In this way a series of compounds with varying redox potential is obtained that could be oxidised reversibly to the mono- and the dicationic charge states. The accessible redox states were fully determined by chemical redox reactions. The standard Gibbs free energy change for disproportionation of the radical monocation into the dication and the neutral molecule in solution, estimated from cyclovoltammetric measurements, varies between 43 and 71 kJ mol-1 . While the neutral RAAs absorb predominately UV light, the radical monocations display strong absorptions covering almost the entire visible region and extending for some compounds into the NIR region. A detailed analysis of this highly reversible electrochromism is presented, and the fast switching characteristics are demonstrated in an electrochromic test device.
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Affiliation(s)
- Marco Werr
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Elisabeth Kaifer
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Hubert Wadepohl
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Hans-Jörg Himmel
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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15
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Schön F, Kaifer E, Himmel H. Catalytic Aerobic Phenol Homo‐ and Cross‐Coupling Reactions with Copper Complexes Bearing Redox‐Active Guanidine Ligands. Chemistry 2019; 25:8279-8288. [DOI: 10.1002/chem.201900583] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Indexed: 01/12/2023]
Affiliation(s)
- Florian Schön
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Germany
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16
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Abstract
Bis(guanidine) copper complexes are known for their ability to activate dioxygen. Unfortunately, until now, no bis(guanidine) copper-dioxygen adduct has been able to transfer oxygen to substrates. Using an aromatic backbone, fluorescence properties can be added to the copper(I) complex which renders them useful for later reaction monitoring. The novel bis(guanidine) ligand DMEG2tol stabilizes copper(I) and copper(II) complexes (characterized by single crystal X-ray diffraction, IR spectroscopy, and mass spectrometry) and, after oxygen activation, bis(µ-oxido) dicopper(III) complexes which have been characterized by low-temperature UV/Vis and Raman spectroscopy. These bis(guanidine) stabilized bis(µ-oxido) complexes are able to mediate tyrosinase-like hydroxylation activity as first examples of bis(guanidine) stabilized complexes. The experimental study is accompanied by density functional theory calculations which highlight the special role of the different guanidine donors.
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18
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Schrempp DF, Kaifer E, Himmel HJ. Solvent Control of Ligand-Metal Electron Transfer in Mononuclear Copper Complexes with Redox-Active Bisguanidine Ligands. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800525] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- David F. Schrempp
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Germany
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 270 69120 Heidelberg Germany
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19
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Slusarski T, Kostyrko T, García-Suárez VM. Effects of acceptor doping on a metalorganic switch: DFT vs. model analysis. Phys Chem Chem Phys 2018; 20:13588-13597. [PMID: 29736537 DOI: 10.1039/c8cp01283k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We propose a molecular switch based on copper dioxolene molecules with valence tautomeric properties. We study the system using density functional theory and a model Hamiltonian that can properly account for electronic correlations in these complex molecular systems. We compute the transport properties of the junction with a Cu-dioxolene unit sandwiched between gold electrodes and analyze its dependence on the valence tautomeric state of the molecule. We also study the effects of doping with ICl2 acceptor molecules on the magnetic and electronic features of the device. We find that in the absence of dopants, the Cu-dioxolene unit is weakly charged in a S = 1/2 spin state. However, the acceptors increase the charge state of the molecule and make possible a transition between the high-spin (S = 1) triplet and the low-spin (S = 0) singlet. The I-V dependence shows a manifestation of spin filtering and a voltage-induced multistable behavior that can have several applications in nanoscale electronic devices.
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Affiliation(s)
- Tomasz Slusarski
- Faculty of Chemistry, A. Mickiewicz University, ul. Umultowska 89b, 61-614 Poznań, Poland
| | - Tomasz Kostyrko
- Faculty of Physics, A. Mickiewicz University, ul. Umultowska 85, 61-614 Poznań, Poland.
| | - V M García-Suárez
- Departamento de Física, Universidad de Oviedo, 33007 Oviedo, Spain and Nanomaterials and Nanotechnology Research Center (CINN), Oviedo, Spain
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20
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Lorenz R, Kaifer E, Wadepohl H, Himmel HJ. Di- and tetranuclear transition metal complexes of a tetrakisguanidino-substituted phenazine dye by stepwise coordination. Dalton Trans 2018; 47:11016-11029. [DOI: 10.1039/c8dt02176g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Coordination of a tetrakisguanidino-substituted phenazine dye in two steps provides rational access to tetranuclear homo- and heterobimetallic complexes.
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Affiliation(s)
- Roxana Lorenz
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Hubert Wadepohl
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
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21
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Ziesak A, Steuer L, Kaifer E, Wagner N, Beck J, Wadepohl H, Himmel HJ. Intramolecular metal–ligand electron transfer triggered by co-ligand substitution. Dalton Trans 2018; 47:9430-9441. [DOI: 10.1039/c8dt01234b] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Labile co-ligands are attached to a dinuclear copper(i) complex with a redox-active bridging guanidine ligand. Their substitution triggers electron-transfer from the copper atoms to the guanidine.
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Affiliation(s)
- Alexandra Ziesak
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Lena Steuer
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Norbert Wagner
- Institut für Anorganische Chemie
- Universität Bonn
- 53121 Bonn
- Germany
| | - Johannes Beck
- Institut für Anorganische Chemie
- Universität Bonn
- 53121 Bonn
- Germany
| | - Hubert Wadepohl
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut
- Ruprecht-Karls-Universität Heidelberg
- 69120 Heidelberg
- Germany
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22
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Stanek J, Sackers N, Fink F, Paul M, Peters L, Grunzke R, Hoffmann A, Herres-Pawlis S. Copper Guanidinoquinoline Complexes as Entatic State Models of Electron-Transfer Proteins. Chemistry 2017; 23:15738-15745. [DOI: 10.1002/chem.201703261] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Indexed: 12/17/2022]
Affiliation(s)
- Julia Stanek
- Institut für Anorganische Chemie; RWTH Aachen University; Landoltweg 1 52074 Aachen Germany
| | - Nina Sackers
- Institut für Anorganische Chemie; RWTH Aachen University; Landoltweg 1 52074 Aachen Germany
| | - Fabian Fink
- Institut für Anorganische Chemie; RWTH Aachen University; Landoltweg 1 52074 Aachen Germany
| | - Melanie Paul
- Institut für Anorganische Chemie; RWTH Aachen University; Landoltweg 1 52074 Aachen Germany
| | - Laurens Peters
- Department Chemie; Ludwig-Maximilians Universität München; Butenandtstraße 5-13 81377 München Germany
| | - Richard Grunzke
- Zentrum für Informationsdienste und Hochleistungsrechnen; Technische Universität Dresden; Zellescher Weg 12-14 01062 Dresden Germany
| | - Alexander Hoffmann
- Institut für Anorganische Chemie; RWTH Aachen University; Landoltweg 1 52074 Aachen Germany
| | - Sonja Herres-Pawlis
- Institut für Anorganische Chemie; RWTH Aachen University; Landoltweg 1 52074 Aachen Germany
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23
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Schrempp DF, Leingang S, Schnurr M, Kaifer E, Wadepohl H, Himmel HJ. Inter- and Intramolecular Electron Transfer in Copper Complexes: Electronic Entatic State with Redox-Active Guanidine Ligands. Chemistry 2017; 23:13607-13611. [PMID: 28771843 DOI: 10.1002/chem.201703611] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Indexed: 02/01/2023]
Abstract
Fast and efficient electron transfer in blue copper proteins is realized by a structural harmonization between the CuI and CuII complex pair ("entatic state" model). Herein, we present now a CuI /CuII complex pair with redox-active guanidine ligands showing almost perfect match between both redox states. By modifying the ligand electron donor strength, the redox chemistry of the copper complex can be controlled to be either metal-centered or to cross the borderline to ligand-centered. This work is the first systematic study of complexes with redox-active ligands within the concept of the entatic state.
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Affiliation(s)
- David F Schrempp
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 275, 69120, Heidelberg, Germany
| | - Simone Leingang
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 275, 69120, Heidelberg, Germany
| | - Martin Schnurr
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 275, 69120, Heidelberg, Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 275, 69120, Heidelberg, Germany
| | - Hubert Wadepohl
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 275, 69120, Heidelberg, Germany
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 275, 69120, Heidelberg, Germany
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24
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Schrempp DF, Schneider E, Kaifer E, Wadepohl H, Himmel HJ. Homo- and Heterobinuclear Cu and Pd Complexes with a Bridging Redox-Active Bisguanidino-Substituted Dioxolene Ligand: Electronic Structure and Metal-Ligand Electron-Transfer. Chemistry 2017; 23:11636-11648. [DOI: 10.1002/chem.201702053] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Indexed: 12/17/2022]
Affiliation(s)
- David Fridolin Schrempp
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 275 69120 Heidelberg Germany
| | - Elisa Schneider
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 275 69120 Heidelberg Germany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 275 69120 Heidelberg Germany
| | - Hubert Wadepohl
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 275 69120 Heidelberg Germany
| | - Hans-Jörg Himmel
- Anorganisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; Im Neuenheimer Feld 275 69120 Heidelberg Germany
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25
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Shimizu I, Morimoto Y, Faltermeier D, Kerscher M, Paria S, Abe T, Sugimoto H, Fujieda N, Asano K, Suzuki T, Comba P, Itoh S. Tetrahedral Copper(II) Complexes with a Labile Coordination Site Supported by a Tris-tetramethylguanidinato Ligand. Inorg Chem 2017; 56:9634-9645. [DOI: 10.1021/acs.inorgchem.7b01154] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Ikuma Shimizu
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Yuma Morimoto
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Dieter Faltermeier
- Anorganisch-Chemisches Institut and Interdisciplinary
Center for Scientific Computing, Universität Heidelberg, INF 270, 69120 Heidelberg, Germany
| | - Marion Kerscher
- Anorganisch-Chemisches Institut and Interdisciplinary
Center for Scientific Computing, Universität Heidelberg, INF 270, 69120 Heidelberg, Germany
| | - Sayantan Paria
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Tsukasa Abe
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Hideki Sugimoto
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Nobutaka Fujieda
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Kaori Asano
- Comprehensive Analysis Center, The Institute of Scientific
and Industrial Research (ISIR), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0057, Japan
| | - Takeyuki Suzuki
- Comprehensive Analysis Center, The Institute of Scientific
and Industrial Research (ISIR), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0057, Japan
| | - Peter Comba
- Anorganisch-Chemisches Institut and Interdisciplinary
Center for Scientific Computing, Universität Heidelberg, INF 270, 69120 Heidelberg, Germany
| | - Shinobu Itoh
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
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26
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Strassl F, Grimm-Lebsanft B, Rukser D, Biebl F, Biednov M, Brett C, Timmermann R, Metz F, Hoffmann A, Rübhausen M, Herres-Pawlis S. Oxygen Activation by Copper Complexes with an Aromatic Bis(guanidine) Ligand. Eur J Inorg Chem 2017. [DOI: 10.1002/ejic.201700528] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Florian Strassl
- Institute of Inorganic Chemistry; RWTH Aachen University; Landoltweg 1 52074 Aachen Germany
| | - Benjamin Grimm-Lebsanft
- Institut für Nanostruktur- und Festkörperphysik; Universität Hamburg und Center for Free Electron Laser Science; Notkestraße 85 22607 Hamburg Germany
| | - Dieter Rukser
- Institut für Nanostruktur- und Festkörperphysik; Universität Hamburg und Center for Free Electron Laser Science; Notkestraße 85 22607 Hamburg Germany
| | - Florian Biebl
- Institut für Nanostruktur- und Festkörperphysik; Universität Hamburg und Center for Free Electron Laser Science; Notkestraße 85 22607 Hamburg Germany
| | - Mykola Biednov
- Institut für Nanostruktur- und Festkörperphysik; Universität Hamburg und Center for Free Electron Laser Science; Notkestraße 85 22607 Hamburg Germany
| | - Calvin Brett
- Institut für Nanostruktur- und Festkörperphysik; Universität Hamburg und Center for Free Electron Laser Science; Notkestraße 85 22607 Hamburg Germany
| | - Riccardo Timmermann
- Institute of Inorganic Chemistry; RWTH Aachen University; Landoltweg 1 52074 Aachen Germany
| | - Fabian Metz
- Institute of Inorganic Chemistry; RWTH Aachen University; Landoltweg 1 52074 Aachen Germany
| | - Alexander Hoffmann
- Institute of Inorganic Chemistry; RWTH Aachen University; Landoltweg 1 52074 Aachen Germany
| | - Michael Rübhausen
- Institut für Nanostruktur- und Festkörperphysik; Universität Hamburg und Center for Free Electron Laser Science; Notkestraße 85 22607 Hamburg Germany
| | - Sonja Herres-Pawlis
- Institute of Inorganic Chemistry; RWTH Aachen University; Landoltweg 1 52074 Aachen Germany
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27
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Affiliation(s)
- Arne Wagner
- Institute of Inorganic Chemistry, Ruprecht-Karls University Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Hans-Jörg Himmel
- Institute of Inorganic Chemistry, Ruprecht-Karls University Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
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