1
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Witas K, Nair SS, Maisuradze T, Zedler L, Schmidt H, Garcia-Porta P, Rein ASJ, Bolter T, Rau S, Kupfer S, Dietzek-Ivanšić B, Sorsche DU. Beyond the First Coordination Sphere─Manipulating the Excited-State Landscape in Iron(II) Chromophores with Protons. J Am Chem Soc 2024; 146:19710-19719. [PMID: 38990184 PMCID: PMC11273614 DOI: 10.1021/jacs.4c00552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 06/14/2024] [Accepted: 06/17/2024] [Indexed: 07/12/2024]
Abstract
Molecular transition metal chromophores play a central role in light harvesting and energy conversion. Recently, earth-abundant transition-metal-based chromophores have begun to challenge the dominance of platinum group metal complexes in this area. However, the development of new chromophores with optimized photophysical properties is still limited by a lack of synthetic methods, especially with respect to heteroleptic complexes with functional ligands. Here, we demonstrate a facile and efficient method for the combination of strong-field carbenes with the functional 2,2'-bibenzimidazole ligand in a heteroleptic iron(II) chromophore complex. Our approach yields two isomers that differ predominantly in their excited-state lifetimes based on the symmetry of the ligand field. Deprotonation of both isomers leads to a significant red-shift of the metal-to-ligand charge transfer (MLCT) absorption and a shortening of excited-state lifetimes. Femtosecond transient absorption spectroscopy in combination with quantum chemical simulations and resonance Raman spectroscopy reveals the complex relationship between protonation and photophysical properties. Protonation is found to tip the balance between MLCT and metal-centered (MC) excited states in favor of the former. This study showcases the first example of fine-tuning of the excited-state landscape in an iron(II) chromophore through second-sphere manipulations and provides a new perspective to the challenge of excited-state optimizations in 3d transition metal chromophores.
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Affiliation(s)
- Kamil Witas
- Institute
for Inorganic Chemistry 1, Ulm University
(UUlm), Albert-Einstein-Allee 11, Ulm 89081, Germany
| | - Shruthi Santhosh Nair
- Research
Department Functional Interfaces, Leibniz
Institute of Photonic Technology (Leibniz-IPHT), Albert-Einstein-Straße 9, Jena 07745, Germany
- Institute
for Physical Chemistry, Friedrich-Schiller-Universität
Jena (FSU Jena), Lessingstraße 4, Jena 07743, Germany
| | - Tamar Maisuradze
- Institute
for Physical Chemistry, Friedrich-Schiller-Universität
Jena (FSU Jena), Lessingstraße 4, Jena 07743, Germany
| | - Linda Zedler
- Research
Department Functional Interfaces, Leibniz
Institute of Photonic Technology (Leibniz-IPHT), Albert-Einstein-Straße 9, Jena 07745, Germany
- Institute
for Physical Chemistry, Friedrich-Schiller-Universität
Jena (FSU Jena), Lessingstraße 4, Jena 07743, Germany
| | - Heiner Schmidt
- Research
Department Functional Interfaces, Leibniz
Institute of Photonic Technology (Leibniz-IPHT), Albert-Einstein-Straße 9, Jena 07745, Germany
- Institute
for Physical Chemistry, Friedrich-Schiller-Universität
Jena (FSU Jena), Lessingstraße 4, Jena 07743, Germany
| | - Pablo Garcia-Porta
- Institute
for Inorganic Chemistry 1, Ulm University
(UUlm), Albert-Einstein-Allee 11, Ulm 89081, Germany
| | | | - Tim Bolter
- Institute
for Inorganic Chemistry 1, Ulm University
(UUlm), Albert-Einstein-Allee 11, Ulm 89081, Germany
| | - Sven Rau
- Institute
for Inorganic Chemistry 1, Ulm University
(UUlm), Albert-Einstein-Allee 11, Ulm 89081, Germany
| | - Stephan Kupfer
- Institute
for Physical Chemistry, Friedrich-Schiller-Universität
Jena (FSU Jena), Lessingstraße 4, Jena 07743, Germany
| | - Benjamin Dietzek-Ivanšić
- Research
Department Functional Interfaces, Leibniz
Institute of Photonic Technology (Leibniz-IPHT), Albert-Einstein-Straße 9, Jena 07745, Germany
- Institute
for Physical Chemistry, Friedrich-Schiller-Universität
Jena (FSU Jena), Lessingstraße 4, Jena 07743, Germany
| | - Dieter U. Sorsche
- Institute
for Inorganic Chemistry 1, Ulm University
(UUlm), Albert-Einstein-Allee 11, Ulm 89081, Germany
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2
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Rudolf R, Batman D, Mehner N, Walter RRM, Sarkar B. Redox-Active Triazole-Derived Mesoionic Imines with Ferrocenyl Substituents and their Metal Complexes: Directed Hydrogen-Bonding, Unusual C-H Activation and Ion-Pair Formation. Chemistry 2024; 30:e202400730. [PMID: 38634285 DOI: 10.1002/chem.202400730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/17/2024] [Accepted: 04/17/2024] [Indexed: 04/19/2024]
Abstract
We present herein the synthesis, characterization and complexation of ferrocenyl-substituted MIIs (mesoionic imines) and their metal complexes. In the free MIIs, strong hydrogen bonding interactions are observed between the imine-N and the C-H bonds of the ferrocenyl substituents both in the solid state and in solution. The influence of this hydrogen bonding is so strong that complexation of the MIIs with [IrCp*Cl2]2 yields unique six-membered iridacycles via C-H-activation of the corresponding C-H-site at the Fc-substituent and not the Ph-substituent. This result is in contrast to previous reports in which always a preferential C-H activation at the phenyl substituent is observed in competitive reactions in the presence of ferrocenyl substituents. The corresponding Ir complexes formed after in-situ halide exchange reaction exist in either [Ir-I] contact or as [Ir]+I- solvent separated ion-pairs depending on the solvent polarity. The iodide coordinated and solvent separated ion-pairs display drastically different physical properties. The TEP (Tolman-electronic-parameter) of these ligands was determined and lines up with previously reported MII-ligands. The redox properties were investigated by a combination of electrochemical and spectroelectrochemical methods. We show here how non-covalent interactions can have a drastic influence on the physical and chemical properties of these new class of compounds.
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Affiliation(s)
- Richard Rudolf
- Universität Stuttgart, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569, Stuttgart
| | - Derman Batman
- Universität Stuttgart, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569, Stuttgart
| | - Niklas Mehner
- Universität Stuttgart, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569, Stuttgart
| | - Robert R M Walter
- Universität Stuttgart, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569, Stuttgart
| | - Biprajit Sarkar
- Universität Stuttgart, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569, Stuttgart
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3
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Chen LX, Yano J. Deciphering Photoinduced Catalytic Reaction Mechanisms in Natural and Artificial Photosynthetic Systems on Multiple Temporal and Spatial Scales Using X-ray Probes. Chem Rev 2024; 124:5421-5469. [PMID: 38663009 DOI: 10.1021/acs.chemrev.3c00560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2024]
Abstract
Utilization of renewable energies for catalytically generating value-added chemicals is highly desirable in this era of rising energy demands and climate change impacts. Artificial photosynthetic systems or photocatalysts utilize light to convert abundant CO2, H2O, and O2 to fuels, such as carbohydrates and hydrogen, thus converting light energy to storable chemical resources. The emergence of intense X-ray pulses from synchrotrons, ultrafast X-ray pulses from X-ray free electron lasers, and table-top laser-driven sources over the past decades opens new frontiers in deciphering photoinduced catalytic reaction mechanisms on the multiple temporal and spatial scales. Operando X-ray spectroscopic methods offer a new set of electronic transitions in probing the oxidation states, coordinating geometry, and spin states of the metal catalytic center and photosensitizers with unprecedented energy and time resolution. Operando X-ray scattering methods enable previously elusive reaction steps to be characterized on different length scales and time scales. The methodological progress and their application examples collected in this review will offer a glimpse into the accomplishments and current state in deciphering reaction mechanisms for both natural and synthetic systems. Looking forward, there are still many challenges and opportunities at the frontier of catalytic research that will require further advancement of the characterization techniques.
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Affiliation(s)
- Lin X Chen
- Chemical Science and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Junko Yano
- Molecular Biophysics & Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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4
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Prakash O, Chábera P, Kaul N, Hlynsson VF, Rosemann NW, Losada IB, Hoang Hai YT, Huang P, Bendix J, Ericsson T, Häggström L, Gupta AK, Strand D, Yartsev A, Lomoth R, Persson P, Wärnmark K. How Rigidity and Conjugation of Bidentate Ligands Affect the Geometry and Photophysics of Iron N-Heterocyclic Complexes: A Comparative Study. Inorg Chem 2024; 63:4461-4473. [PMID: 38421802 PMCID: PMC10934811 DOI: 10.1021/acs.inorgchem.3c03972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 02/07/2024] [Accepted: 02/08/2024] [Indexed: 03/02/2024]
Abstract
Two iron complexes featuring the bidentate, nonconjugated N-heterocyclic carbene (NHC) 1,1'-methylenebis(3-methylimidazol-2-ylidene) (mbmi) ligand, where the two NHC moieties are separated by a methylene bridge, have been synthesized to exploit the combined influence of geometric and electronic effects on the ground- and excited-state properties of homoleptic FeIII-hexa-NHC [Fe(mbmi)3](PF6)3 and heteroleptic FeII-tetra-NHC [Fe(mbmi)2(bpy)](PF6)2 (bpy = 2,2'-bipyridine) complexes. They are compared to the reported FeIII-hexa-NHC [Fe(btz)3](PF6)3 and FeII-tetra-NHC [Fe(btz)2(bpy)](PF6)2 complexes containing the conjugated, bidentate mesoionic NHC ligand 3,3'-dimethyl-1,1'-bis(p-tolyl)-4,4'-bis(1,2,3-triazol-5-ylidene) (btz). The observed geometries of [Fe(mbmi)3](PF6)3 and [Fe(mbmi)2(bpy)](PF6)2 are evaluated through L-Fe-L bond angles and ligand planarity and compared to those of [Fe(btz)3](PF6)3 and [Fe(btz)2(bpy)](PF6)2. The FeII/FeIII redox couples of [Fe(mbmi)3](PF6)3 (-0.38 V) and [Fe(mbmi)2(bpy)](PF6)2 (-0.057 V, both vs Fc+/0) are less reducing than [Fe(btz)3](PF6)3 and [Fe(btz)2(bpy)](PF6)2. The two complexes show intense absorption bands in the visible region: [Fe(mbmi)3](PF6)3 at 502 nm (ligand-to-metal charge transfer, 2LMCT) and [Fe(mbmi)2(bpy)](PF6)2 at 410 and 616 nm (metal-to-ligand charge transfer, 3MLCT). Lifetimes of 57.3 ps (2LMCT) for [Fe(mbmi)3](PF6)3 and 7.6 ps (3MLCT) for [Fe(mbmi)2(bpy)](PF6)2 were probed and are somewhat shorter than those for [Fe(btz)3](PF6)3 and [Fe(btz)2(bpy)](PF6)2. [Fe(mbmi)3](PF6)3 exhibits photoluminescence at 686 nm (2LMCT) in acetonitrile at room temperature with a quantum yield of (1.2 ± 0.1) × 10-4, compared to (3 ± 0.5) × 10-4 for [Fe(btz)3](PF6)3.
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Affiliation(s)
- Om Prakash
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Pavel Chábera
- Chemical
Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Nidhi Kaul
- Department
of Chemistry − Ångström Laboratory, Uppsala University, Box
523, SE-751 20 Uppsala, Sweden
| | - Valtýr F. Hlynsson
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Nils W. Rosemann
- Chemical
Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Iria Bolaño Losada
- Theoretical
Chemistry Division, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Yen Tran Hoang Hai
- Theoretical
Chemistry Division, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Ping Huang
- Department
of Chemistry − Ångström Laboratory, Uppsala University, Box
523, SE-751 20 Uppsala, Sweden
| | - Jesper Bendix
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Tore Ericsson
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Lennart Häggström
- Department
of Physics − Ångström Laboratory, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden
| | - Arvind Kumar Gupta
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Daniel Strand
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Arkady Yartsev
- Chemical
Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Reiner Lomoth
- Department
of Chemistry − Ångström Laboratory, Uppsala University, Box
523, SE-751 20 Uppsala, Sweden
| | - Petter Persson
- Theoretical
Chemistry Division, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Kenneth Wärnmark
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
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5
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Putra MH, Bagemihl B, Rau S, Groß A. Prediction of Strong Solvatochromism in a Molecular Photocatalyst. Chemistry 2024; 30:e202302643. [PMID: 37754665 DOI: 10.1002/chem.202302643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 09/25/2023] [Accepted: 09/25/2023] [Indexed: 09/28/2023]
Abstract
Based on quantum chemical calculations, we predict strong solvatochromism in a light-driven molecular photocatalyst for hydrogen generation, that is we show that the electronic and optical properties of the photocatalyst strongly depend on the solvent it is dissolved in. Our calculations in particular indicate a solvent-dependent relocation of the highest occupied molecular orbital (HOMO). Ground-state density functional theory and linear response time-dependent density functional theory calculations were applied in order to investigate the influence of implicit solvents on the structural, electronic and optical properties of a molecular photocatalyst. Only at high dielectric constants of the solvent, is the HOMO located at the metal center of the photosensitizer, whereas at low dielectric constants the HOMO is centered at the metal atom of the catalytically active complex. We elucidate the electronic origins of this strong solvatochromic effect and sketch the consequences of these insights for the use of photocatalysts in different environments.
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Affiliation(s)
| | - Benedikt Bagemihl
- Institute of Inorganic Chemistry I, Materials and Catalysis, Ulm University, 89069, Ulm, Germany
| | - Sven Rau
- Institute of Inorganic Chemistry I, Materials and Catalysis, Ulm University, 89069, Ulm, Germany
| | - Axel Groß
- Institute of Theoretical Chemistry, Ulm University, 89069, Ulm, Germany
- Helmholtz Institute Ulm (HIU), Electrochemical Energy Storage, 89069, Ulm, Germany
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6
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Bens T, Marhöfer D, Boden P, Steiger ST, Suntrup L, Niedner-Schatteburg G, Sarkar B. A Different Perspective on Tuning the Photophysical and Photochemical Properties: The Influence of Constitutional Isomers in Group 6 Carbonyl Complexes with Pyridyl-Mesoionic Carbenes. Inorg Chem 2023; 62:16182-16195. [PMID: 37721537 DOI: 10.1021/acs.inorgchem.3c02478] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
Exploring novel and existing design principles to tune the photochemical and photophysical properties of transition-metal complexes is an important goal in contemporary research. Here, we highlight the influence of constitutional isomers of pyridyl-1,2,3-triazolylidene mesoionic carbene (MIC) ligands on the photophysical and photochemical properties of the corresponding tetracarbonyl group 6 metal complexes (M = Cr, Mo, W). All new complexes [M(C-C)] presented herein incorporate a C-C linked pyridyl-MIC ligand and were fully characterized by X-ray diffraction analysis, elemental analysis, and 1H NMR and IR spectroscopy. Detailed photophysical investigations reveal a single emission in the VIS region, which extends into the NIR with lifetimes of up to 3.5 μs in the solid state at lower temperatures. The quantum yields were determined for all three complexes, and, in particular, the W0 complex shows an unusually high quantum yield of 29% compared to the values of 0.02% obtained for the [M(C-N)] isomers investigated in earlier works. Beyond this, the investigated W0 complex also exhibits an emission at 717 nm in a fluid solution. The combination of luminescence and FTIR-step scan spectroscopy with theoretical calculations reveals an emissive 3MLCT state. Irradiation of the presented complexes leads to a clean cleavage of one axial CO ligand. A metastable 16 VE species with a vacant axial coordination site was detected in the solid state at low temperatures. In solution, the respective solvato complexes are formed. A dark reverse reaction is observed, as previously described for the [M(C-N)] analogues. The increased electron density induced by the C-C linked pyridyl-MIC ligand leads to an increased kinetic rate constant for the reformation of the starting species and is also reflected in the lower photodissociation quantum yields.
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Affiliation(s)
- Tobias Bens
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, Stuttgart D-70569, Germany
- Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße 34-36, Berlin 14195, Germany
| | - Daniel Marhöfer
- Department of Chemistry and Research Center Optimas, TU Kaiserslautern, Erwin-Schrödinger-Straße, Kaiserslautern 67663, Germany
| | - Pit Boden
- Department of Chemistry and Research Center Optimas, TU Kaiserslautern, Erwin-Schrödinger-Straße, Kaiserslautern 67663, Germany
| | - Sophie T Steiger
- Department of Chemistry and Research Center Optimas, TU Kaiserslautern, Erwin-Schrödinger-Straße, Kaiserslautern 67663, Germany
| | - Lisa Suntrup
- Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße 34-36, Berlin 14195, Germany
| | - Gereon Niedner-Schatteburg
- Department of Chemistry and Research Center Optimas, TU Kaiserslautern, Erwin-Schrödinger-Straße, Kaiserslautern 67663, Germany
| | - Biprajit Sarkar
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, Stuttgart D-70569, Germany
- Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße 34-36, Berlin 14195, Germany
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7
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Sinha N, Wenger OS. Photoactive Metal-to-Ligand Charge Transfer Excited States in 3d 6 Complexes with Cr 0, Mn I, Fe II, and Co III. J Am Chem Soc 2023; 145:4903-4920. [PMID: 36808978 PMCID: PMC9999427 DOI: 10.1021/jacs.2c13432] [Citation(s) in RCA: 40] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Many coordination complexes and organometallic compounds with the 4d6 and 5d6 valence electron configurations have outstanding photophysical and photochemical properties, which stem from metal-to-ligand charge transfer (MLCT) excited states. This substance class makes extensive use of the most precious and least abundant metal elements, and consequently there has been a long-standing interest in first-row transition metal compounds with photoactive MLCT states. Semiprecious copper(I) with its completely filled 3d subshell is a relatively straightforward and well explored case, but in 3d6 complexes the partially filled d-orbitals lead to energetically low-lying metal-centered (MC) states that can cause undesirably fast MLCT excited state deactivation. Herein, we discuss recent advances made with isoelectronic Cr0, MnI, FeII, and CoIII compounds, for which long-lived MLCT states have become accessible over the past five years. Furthermore, we discuss possible future developments in the search for new first-row transition metal complexes with partially filled 3d subshells and photoactive MLCT states for next-generation applications in photophysics and photochemistry.
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Affiliation(s)
- Narayan Sinha
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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8
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Matsubara K, Yamada Y, Iwasaki H, Ikeda H, Kanetsugu Y, Kawata S, Koga Y. A 1,2,3-triazole-derived pincer-type mesoionic carbene complex of iron(II): carbonyl elimination and hydrosilylation of aromatic aldehydes via the concerted reaction with hydrosilane and a base. Dalton Trans 2023; 52:572-582. [PMID: 36537300 DOI: 10.1039/d2dt03617g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Iron complexes bearing 1,2,3-triazol-5-ylidene were synthesized and applied to the reaction with hydrosilane and homogeneous catalytic hydrosilylation of aromatic ketones and aldehydes. Addition of a free carbene to a solution of Fe(CO)4Br2 yielded an octahedral, diamagnetic and cationic iron(II) complex [Fe(1,2,3-triazolylidene)(CO)2Br]+. Pyrolysis of the dicarbonyl complex eliminated the two CO ligands to form a paramagnetic four-coordinate complex. A theoretical study using DFT calculations indicated that the spin state changed from singlet to quintet during ligand elimination. Investigations of the successful hydrosilylation of acetophenone and benzaldehyde derivatives using MIC-iron(II) bromide suggested the importance of the base for efficient conversion in the catalytic process. The bromide-to-hydride exchange reaction, transmetallation, of MIC-iron(II) bromide in the presence of KOtBu and HSi(OEt)3 which could occur in the initial process of hydrosilylation was proposed, and supported by a theoretical study.
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Affiliation(s)
- Kouki Matsubara
- Department of Chemistry, Fukuoka University, 8-19-1 Nanakuma, Fukuoka 814-0180, Japan.
| | - Yuji Yamada
- Department of Chemistry, Fukuoka University, 8-19-1 Nanakuma, Fukuoka 814-0180, Japan.
| | - Haruka Iwasaki
- Department of Chemistry, Fukuoka University, 8-19-1 Nanakuma, Fukuoka 814-0180, Japan.
| | - Hayao Ikeda
- Department of Chemistry, Fukuoka University, 8-19-1 Nanakuma, Fukuoka 814-0180, Japan.
| | - Yuki Kanetsugu
- Department of Chemistry, Fukuoka University, 8-19-1 Nanakuma, Fukuoka 814-0180, Japan.
| | - Satoshi Kawata
- Department of Chemistry, Fukuoka University, 8-19-1 Nanakuma, Fukuoka 814-0180, Japan.
| | - Yuji Koga
- Department of Chemistry, Fukuoka University, 8-19-1 Nanakuma, Fukuoka 814-0180, Japan.
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9
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Prakash O, Lindh L, Kaul N, Rosemann NW, Losada IB, Johnson C, Chábera P, Ilic A, Schwarz J, Gupta AK, Uhlig J, Ericsson T, Häggström L, Huang P, Bendix J, Strand D, Yartsev A, Lomoth R, Persson P, Wärnmark K. Photophysical Integrity of the Iron(III) Scorpionate Framework in Iron(III)-NHC Complexes with Long-Lived 2LMCT Excited States. Inorg Chem 2022; 61:17515-17526. [PMID: 36279568 PMCID: PMC9644379 DOI: 10.1021/acs.inorgchem.2c02410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Indexed: 11/30/2022]
Abstract
Fe(III) complexes with N-heterocyclic carbene (NHC) ligands belong to the rare examples of Earth-abundant transition metal complexes with long-lived luminescent charge-transfer excited states that enable applications as photosensitizers for charge separation reactions. We report three new hexa-NHC complexes of this class: [Fe(brphtmeimb)2]PF6 (brphtmeimb = [(4-bromophenyl)tris(3-methylimidazol-2-ylidene)borate]-, [Fe(meophtmeimb)2]PF6 (meophtmeimb = [(4-methoxyphenyl)tris(3-methylimidazol-2-ylidene)borate]-, and [Fe(coohphtmeimb)2]PF6 (coohphtmeimb = [(4-carboxyphenyl)tris(3-methylimidazol-2-ylidene)borate]-. These were derived from the parent complex [Fe(phtmeimb)2]PF6 (phtmeimb = [phenyltris(3-methylimidazol-2-ylidene)borate]- by modification with electron-withdrawing and electron-donating substituents, respectively, at the 4-phenyl position of the ligand framework. All three Fe(III) hexa-NHC complexes were characterized by NMR spectroscopy, high-resolution mass spectroscopy, elemental analysis, single crystal X-ray diffraction analysis, electrochemistry, Mößbauer spectroscopy, electronic spectroscopy, magnetic susceptibility measurements, and quantum chemical calculations. Their ligand-to-metal charge-transfer (2LMCT) excited states feature nanosecond lifetimes (1.6-1.7 ns) and sizable emission quantum yields (1.7-1.9%) through spin-allowed transition to the doublet ground state (2GS), completely in line with the parent complex [Fe(phtmeimb)2]PF6 (2.0 ns and 2.1%). The integrity of the favorable excited state characteristics upon substitution of the ligand framework demonstrates the robustness of the scorpionate motif that tolerates modifications in the 4-phenyl position for applications such as the attachment in molecular or hybrid assemblies.
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Affiliation(s)
- Om Prakash
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Linnea Lindh
- Chemical
Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
- Theoretical
Chemistry Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Nidhi Kaul
- Department
of Chemistry − Ångström Laboratory, Uppsala University, Box 523, SE-75120Uppsala, Sweden
| | - Nils W. Rosemann
- Chemical
Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Iria Bolaño Losada
- Theoretical
Chemistry Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Catherine Johnson
- Department
of Chemistry − Ångström Laboratory, Uppsala University, Box 523, SE-75120Uppsala, Sweden
| | - Pavel Chábera
- Chemical
Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Aleksandra Ilic
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Jesper Schwarz
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Arvind Kumar Gupta
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Jens Uhlig
- Chemical
Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Tore Ericsson
- Department
of Physics − Ångström Laboratory, Uppsala University, Box 523, SE-75120Uppsala, Sweden
| | - Lennart Häggström
- Department
of Physics − Ångström Laboratory, Uppsala University, Box 523, SE-75120Uppsala, Sweden
| | - Ping Huang
- Department
of Chemistry − Ångström Laboratory, Uppsala University, Box 523, SE-75120Uppsala, Sweden
| | - Jesper Bendix
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100Copenhagen, Denmark
| | - Daniel Strand
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Arkady Yartsev
- Chemical
Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Reiner Lomoth
- Department
of Chemistry − Ångström Laboratory, Uppsala University, Box 523, SE-75120Uppsala, Sweden
| | - Petter Persson
- Theoretical
Chemistry Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Kenneth Wärnmark
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
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10
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Boden PJ, Di Martino‐Fumo P, Bens T, Steiger ST, Marhöfer D, Niedner‐Schatteburg G, Sarkar B. Mechanistic and Kinetic Investigations of ON/OFF (Photo)Switchable Binding of Carbon Monoxide by Chromium(0), Molybdenum(0) and Tungsten(0) Carbonyl Complexes with a Pyridyl‐Mesoionic Carbene Ligand. Chemistry 2022; 28:e202201038. [PMID: 35705508 PMCID: PMC9542575 DOI: 10.1002/chem.202201038] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Indexed: 11/30/2022]
Abstract
This work tackles the photochemistry of a series of mononuclear Cr0, Mo0 and W0 carbonyl complexes containing a bidentate mesoionic carbene ligand of the 1,2,3‐triazol‐5‐ylidene type. FTIR spectroscopy, combined with density functional theory calculations, revealed a clean photo‐induced reaction in organic solvents (acetonitrile, pyridine, valeronitrile) to give mainly one photoproduct with monosubstitution of a carbonyl ligand for a solvent molecule. The highest photodissociation quantum yields were reached for the Cr0 complex under UV irradiation (266 nm). Based on previous investigations, the kinetics of the dark reverse reactions have now been determined, with reaction times of up to several hours in pyridine. Photochemical studies in the solid state (KBr matrix, frozen solution) also showed light‐induced reactivity with stabilization of the metastable intermediate with a free coordination site at very low temperature. The identified reactive species emphasizes a mechanism without ligand–sphere reorganization.
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Affiliation(s)
- Pit J. Boden
- Department of Chemistry and State Research Center Optimas TU Kaiserslautern Erwin-Schrödinger-Straße 52 67663 Kaiserslautern Germany
| | - Patrick Di Martino‐Fumo
- Department of Chemistry and State Research Center Optimas TU Kaiserslautern Erwin-Schrödinger-Straße 52 67663 Kaiserslautern Germany
| | - Tobias Bens
- Chair of Inorganic Coordination Chemistry Institute of Inorganic Chemistry University of Stuttgart Pfaffenwaldring 55 70569 Stuttgart Germany
| | - Sophie T. Steiger
- Department of Chemistry and State Research Center Optimas TU Kaiserslautern Erwin-Schrödinger-Straße 52 67663 Kaiserslautern Germany
| | - Daniel Marhöfer
- Department of Chemistry and State Research Center Optimas TU Kaiserslautern Erwin-Schrödinger-Straße 52 67663 Kaiserslautern Germany
| | - Gereon Niedner‐Schatteburg
- Department of Chemistry and State Research Center Optimas TU Kaiserslautern Erwin-Schrödinger-Straße 52 67663 Kaiserslautern Germany
| | - Biprajit Sarkar
- Chair of Inorganic Coordination Chemistry Institute of Inorganic Chemistry University of Stuttgart Pfaffenwaldring 55 70569 Stuttgart Germany
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11
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Bysewski O, Winter A, Liebing P, Schubert US. Noble Metal Complexes of a Bis-Caffeine Containing NHC Ligand. Molecules 2022; 27:molecules27134316. [PMID: 35807559 PMCID: PMC9268361 DOI: 10.3390/molecules27134316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 06/26/2022] [Accepted: 06/28/2022] [Indexed: 12/04/2022] Open
Abstract
N-Heterocyclic carbenes (NHCs) have seen more and more use over the years. The go-to systems that are usually considered are derivatives of benzimidazole or imidazole. Caffeine possesses an imidazole unit and was already utilized as a carbene-type ligand; however, its use within a tridentate bis-NHC system has—to the best of our knowledge—not been reported so far. The synthesis of the ligand is straightforward and metal complexes are readily available via silver-salt metathesis. A platinum(II) and a palladium(II) complex were isolated and a crystal structure of the former was examined. For the Pt(II) complex, luminescence is observed in solid state as well as in solution.
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Affiliation(s)
- Oliver Bysewski
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstr. 10, 07743 Jena, Germany; (O.B.); (A.W.)
- Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, 07743 Jena, Germany
| | - Andreas Winter
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstr. 10, 07743 Jena, Germany; (O.B.); (A.W.)
- Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, 07743 Jena, Germany
| | - Phil Liebing
- Institute for Inorganic and Analytical Chemistry (IAAC), Friedrich Schiller University Jena, Humboldtstr. 8, 07743 Jena, Germany;
| | - Ulrich S. Schubert
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstr. 10, 07743 Jena, Germany; (O.B.); (A.W.)
- Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, 07743 Jena, Germany
- Correspondence:
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12
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Rudolf R, Neuman NI, Walter RRM, Ringenberg MR, Sarkar B. Mesoionic Imines (MIIs): Strong Donors and Versatile Ligands for Transition Metals and Main Group Substrates. Angew Chem Int Ed Engl 2022; 61:e202200653. [PMID: 35286004 PMCID: PMC9322014 DOI: 10.1002/anie.202200653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Indexed: 11/08/2022]
Abstract
We report the synthesis and the reactivity of 1,2,3-triazolin-5-imine type mesoionic imines (MIIs). The MIIs are accessible by a base-mediated cycloaddition between a substituted acetonitrile and an aromatic azide, methylation by established routes and subsequent deprotonation. C=O-stretching frequencies in MII-CO2 and -Rh(CO)2 Cl complexes were used to determine the overall donor strength. The MIIs are stronger donors than the N-heterocyclic imines (NHIs). MIIs are excellent ligands for main group elements and transition metals in which they display substituent-induced fluorine-specific interactions and undergo C-H activation. DFT calculations gave insights into the frontier orbitals of the MIIs. The calculations predict a relatively small HOMO-LUMO gap compared to other related ligands. MIIs are potentially able to act as both π-donor and π-acceptor ligands. This report highlights the potential of MIIs to display exciting properties with a huge potential for future development.
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Affiliation(s)
- Richard Rudolf
- Lehrstuhl für Anorganische KoordinationschemieInstitut für Anorganische ChemieUniversity of StuttgartPfaffenwaldring 5570569StuttgartGermany
| | - Nicolás I. Neuman
- Lehrstuhl für Anorganische KoordinationschemieInstitut für Anorganische ChemieUniversity of StuttgartPfaffenwaldring 5570569StuttgartGermany
- Instituto de Desarrollo Tecnológico para la Industria QuímicaINTEC, UNL-CONICET Predio CONICET Santa Fe “Dr. Alberto Cassano”Colectora Ruta Nacional 168, Km 0Paraje El PozoS3000ZAA) Santa FeArgentina
| | - Robert R. M. Walter
- Lehrstuhl für Anorganische KoordinationschemieInstitut für Anorganische ChemieUniversity of StuttgartPfaffenwaldring 5570569StuttgartGermany
| | - Mark. R. Ringenberg
- Lehrstuhl für Anorganische KoordinationschemieInstitut für Anorganische ChemieUniversity of StuttgartPfaffenwaldring 5570569StuttgartGermany
| | - Biprajit Sarkar
- Lehrstuhl für Anorganische KoordinationschemieInstitut für Anorganische ChemieUniversity of StuttgartPfaffenwaldring 5570569StuttgartGermany
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13
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Herr P, Schwab A, Kupfer S, Wenger OS. Deep‐Red Luminescent Molybdenum(0) Complexes with Bi‐ and Tridentate Isocyanide Chelate Ligands. CHEMPHOTOCHEM 2022. [DOI: 10.1002/cptc.202200052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Patrick Herr
- University of Basel: Universitat Basel Department of Chemistry SWITZERLAND
| | - Alexander Schwab
- Friedrich-Schiller-Universität Jena: Friedrich-Schiller-Universitat Jena Institute of Physical Chemistry GERMANY
| | - Stephan Kupfer
- Friedrich-Schiller-Universität Jena: Friedrich-Schiller-Universitat Jena Institute of Physical Chemistry GERMANY
| | - Oliver S. Wenger
- Universität Basel Departement für Chemie St. Johanns-Ring 19 4056 Basel SWITZERLAND
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14
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Rudolf R, Neuman NI, Walter RRM, Ringenberg MR, Sarkar B. Mesoionische Imine (MIIs): Starke Donoren und vielseitige Liganden für Übergangsmetalle und Hauptgruppensubstrate. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202200653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Richard Rudolf
- Lehrstuhl für Anorganische Koordinationschemie Institut für Anorganische Chemie Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Deutschland
| | - Nicolás I. Neuman
- Lehrstuhl für Anorganische Koordinationschemie Institut für Anorganische Chemie Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Deutschland
- Instituto de Desarrollo Tecnológico para la Industria Química CINTEC, VUNL-CONICET VPredio CONICET Santa Fe “Dr. Alberto Cassano“ Colectora Ruta Nacional 168, Km 0 Paraje El Pozo S3000ZAA) Santa Fe Argentinien
| | - Robert R. M. Walter
- Lehrstuhl für Anorganische Koordinationschemie Institut für Anorganische Chemie Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Deutschland
| | - Mark. R. Ringenberg
- Lehrstuhl für Anorganische Koordinationschemie Institut für Anorganische Chemie Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Deutschland
| | - Biprajit Sarkar
- Lehrstuhl für Anorganische Koordinationschemie Institut für Anorganische Chemie Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Deutschland
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15
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Cebrían C, Pastore M, Monari A, Assfeld X, Gros PC, Haacke S. Ultrafast Spectroscopy of Fe(II) Complexes Designed for Solar Energy Conversion: Current Status and Open Questions. Chemphyschem 2022; 23:e202100659. [DOI: 10.1002/cphc.202100659] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 01/22/2022] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | | | - Stefan Haacke
- University of Strasbourg: Universite de Strasbourg IPCMS 23, rue du Loess 67034 Strasbourg FRANCE
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16
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Maity R, Sarkar B. Chemistry of Compounds Based on 1,2,3-Triazolylidene-Type Mesoionic Carbenes. JACS AU 2022; 2:22-57. [PMID: 35098220 PMCID: PMC8790748 DOI: 10.1021/jacsau.1c00338] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Indexed: 05/04/2023]
Abstract
Mesoionic carbenes (MICs) of the 1,2,3-triazolylidene type have established themselves as a popular class of compounds over the past decade. Primary reasons for this popularity are their modular synthesis and their strong donor properties. While such MICs have mostly been used in combination with transition metals, the past few years have also seen their utility together with main group elements. In this paper, we present an overview of the recent developments on this class of compounds that include, among others, (i) cationic and anionic MIC ligands, (ii) the donor/acceptor properties of these ligands with a focus on the several methods that are known for estimating such donor/acceptor properties, (iii) a detailed overview of 3d metal complexes and main group compounds with these MIC ligands, (iv) results on the redox and photophysical properties of compounds based on MIC ligands, and (v) an overview on electrocatalysis, redox-switchable catalysis, and small-molecule activation to highlight the applications of compounds based on MIC ligands in contemporary chemistry. By discussing several aspects from the synthetic, spectroscopic, and application point of view of these classes of compounds, we highlight the state of the art of compounds containing MICs and present a perspective for future research in this field.
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Affiliation(s)
- Ramananda Maity
- Dr.
R. Maity Department of Chemistry, University
of Calcutta, 92, A. P.
C. Road, Kolkata 700009, India
| | - Biprajit Sarkar
- Prof.
Dr. B. Sarkar Lehrstuhl für Anorganische Koordinationschemie,
Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
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17
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Neururer F, Liu S, Leitner D, Baltrun M, Fisher KR, Kopacka H, Wurst K, Daumann LJ, Munz D, Hohloch S. Mesoionic Carbenes in Low- to High-Valent Vanadium Chemistry. Inorg Chem 2021; 60:15421-15434. [PMID: 34590834 PMCID: PMC8527456 DOI: 10.1021/acs.inorgchem.1c02087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Indexed: 12/12/2022]
Abstract
We report the synthesis of vanadium(V) oxo complex 1 with a pincer-type dianionic mesoionic carbene (MIC) ligand L1 and the general formula [VOCl(L1)]. A comparison of the structural (SC-XRD), electronic (UV-vis), and electrochemical (cyclic voltammetry) properties of 1 with the benzimidazolinylidene congener 2 (general formula [VOCl(L2)]) shows that the MIC is a stronger donor also for early transition metals with low d-electron population. Since electrochemical studies revealed both complexes to be reversibly reduced, the stronger donor character of MICs was not only demonstrated for the vanadium(V) but also for the vanadium(IV) oxidation state by isolating the reduced vanadium(IV) complexes [Co(Cp*)2][1] and [Co(Cp*)2][2] ([Co(Cp*)2] = decamethylcobaltocenium). The electronic structures of the compounds were investigated by computational methods. Complex 1 was found to be a moderate precursor for salt metathesis reactions, showing selective reactivity toward phenolates or secondary amides, but not toward primary amides and phosphides, thiophenols, or aryls/alkyls donors. Deoxygenation with electron-rich phosphines failed to give the desired vanadium(III) complex. However, treatment of the deprotonated ligand precursor with vanadium(III) trichloride resulted in the clean formation of the corresponding MIC vanadium(III) complex 6, which undergoes a clean two-electron oxidation with organic azides yielding the corresponding imido complexes. The reaction with TMS-N3 did not afford a nitrido complex, but instead the imido complex 10. This study reveals that, contrary to popular belief, MICs are capable of supporting early transition-metal complexes in a variety of oxidation states, thus making them promising candidates for the activation of small molecules and redox catalysis.
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Affiliation(s)
- Florian
R. Neururer
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Shenyu Liu
- Faculty
of Science, Department of Chemistry, University
of Paderborn, Warburger Straße 100, 33098 Paderborn, Germany
| | - Daniel Leitner
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Marc Baltrun
- Faculty
of Science, Department of Chemistry, University
of Paderborn, Warburger Straße 100, 33098 Paderborn, Germany
| | - Katherine R. Fisher
- Department
Chemie, Ludwigs-Maximilians-University Munich, Butenandtstraße 5-13 Haus D, 81377 Munich, Germany
| | - Holger Kopacka
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Klaus Wurst
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Lena J. Daumann
- Department
Chemie, Ludwigs-Maximilians-University Munich, Butenandtstraße 5-13 Haus D, 81377 Munich, Germany
| | - Dominik Munz
- Fakultät
NT, Inorganic Chemistry: Coordination Chemistry, Saarland University, Campus C4.1, 66123 Saarbrücken, Germany
| | - Stephan Hohloch
- Institute
of Inorganic, General and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
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