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Prieto-Pascual U, Bustos I, Salcedo-Abraira P, Vitorica-Yrezabal IJ, Landa A, Freixa Z, Huertos MA. Unsaturated chiral-only-at-metal rhodium(III) complexes bearing SiN-type ligands. Chem Commun (Camb) 2024; 60:11299-11302. [PMID: 39292191 DOI: 10.1039/d4cc03665d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2024]
Abstract
Enantiopure chiral-at-metal rhodium(III) unsaturated 16e complexes have been obtained from racemic [Rh(SiN)2Cl] (SiN= 8-(dimethylsilyl)quinoline) using a readily accessible chiral spiroborate as chiral resolution agent. This strategy allows an easy access to enantiopure neutral Δ/Λ-Rh(SiN)2Cl and cationic Δ/Λ-Rh(SiN)2[BAr4F] unsaturated complexes, wherein rhodium(III) is coordinated to two inert silylquinoline ligands in a propeller-like arrangement.
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Affiliation(s)
- Unai Prieto-Pascual
- Facultad de Química de San Sebastián, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20080, San Sebastián, Spain.
| | - Itxaso Bustos
- Facultad de Química de San Sebastián, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20080, San Sebastián, Spain.
| | - Pablo Salcedo-Abraira
- Departamento de Química Inorgánica, Universidad de Granada, Avenida Fuentenueva s/n, 18071 Granada, Spain
| | - Iñigo J Vitorica-Yrezabal
- Departamento de Química Inorgánica, Universidad de Granada, Avenida Fuentenueva s/n, 18071 Granada, Spain
| | - Aitor Landa
- Facultad de Química de San Sebastián, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20080, San Sebastián, Spain.
| | - Zoraida Freixa
- Facultad de Química de San Sebastián, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20080, San Sebastián, Spain.
- IKERBASQUE, Basque Fundation for Science, 48011, Bilbao, Spain
| | - Miguel A Huertos
- Facultad de Química de San Sebastián, Universidad del País Vasco (UPV/EHU), Apartado 1072, 20080, San Sebastián, Spain.
- IKERBASQUE, Basque Fundation for Science, 48011, Bilbao, Spain
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2
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Bens T, Kübler JA, Walter RRM, Beerhues J, Wenger OS, Sarkar B. Impact of Bidentate Pyridyl-Mesoionic Carbene Ligands: Structural, (Spectro)Electrochemical, Photophysical, and Theoretical Investigations on Ruthenium(II) Complexes. ACS ORGANIC & INORGANIC AU 2023; 3:184-198. [PMID: 37545659 PMCID: PMC10401885 DOI: 10.1021/acsorginorgau.3c00005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 04/19/2023] [Accepted: 04/19/2023] [Indexed: 08/08/2023]
Abstract
We present here new synthetic strategies for the isolation of a series of Ru(II) complexes with pyridyl-mesoionic carbene ligands (MIC) of the 1,2,3-triazole-5-ylidene type, in which the bpy ligands (bpy = 2,2'-bipyridine) of the archetypical [Ru(bpy)3]2+ have been successively replaced by one, two, or three pyridyl-MIC ligands. Three new complexes have been isolated and investigated via NMR spectroscopy and single-crystal X-ray diffraction analysis. The incorporation of one MIC unit shifts the potential of the metal-centered oxidation about 160 mV to more cathodic potential in cyclic voltammetry, demonstrating the extraordinary σ-donor ability of the pyridyl-MIC ligand, while the π-acceptor capacities are dominated by the bpy ligand, as indicated by electron paramagnetic resonance spectroelectrochemistry (EPR-SEC). The replacement of all bpy ligands by the pyridyl-MIC ligand results in an anoidic shift of the ligand-centered reduction by 390 mV compared to the well-established [Ru(bpy)3]2+ complex. In addition, UV/vis/NIR-SEC in combination with theoretical calculations provided detailed insights into the electronic structures of the respective redox states, taking into account the total number of pyridyl-MIC ligands incorporated in the Ru(II) complexes. The luminescence quantum yield and lifetimes were determined by time-resolved absorption and emission spectroscopy. An estimation of the excited state redox potentials conclusively showed that the pyridyl-MIC ligand can tune the photoredox activity of the isolated complexes to stronger photoreductants. These observations can provide new strategies for the design of photocatalysts and photosensitizers based on MICs.
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Affiliation(s)
- Tobias Bens
- Institut
für Anorganische Chemie, Universität
Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
- Institut
für Chemie und Biochemie, Freie Universität
Berlin, Fabeckstraße
34-36, 14195 Berlin, Germany
| | - Jasmin A. Kübler
- Department
of Chemistry, University of Basel, 4056 Basel, Switzerland
| | - Robert R. M. Walter
- Institut
für Anorganische Chemie, Universität
Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Julia Beerhues
- Institut
für Anorganische Chemie, Universität
Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
- Institut
für Chemie und Biochemie, Freie Universität
Berlin, Fabeckstraße
34-36, 14195 Berlin, Germany
| | - Oliver S. Wenger
- Department
of Chemistry, University of Basel, 4056 Basel, Switzerland
| | - Biprajit Sarkar
- Institut
für Anorganische Chemie, Universität
Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
- Institut
für Chemie und Biochemie, Freie Universität
Berlin, Fabeckstraße
34-36, 14195 Berlin, Germany
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3
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Ye CX, Meggers E. Chiral-at-Ruthenium Catalysts for Nitrene-Mediated Asymmetric C-H Functionalizations. Acc Chem Res 2023; 56:1128-1141. [PMID: 37071874 DOI: 10.1021/acs.accounts.3c00081] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
ConspectusAsymmetric transition metal catalysis is an indispensable tool used both in academia and industry for forging chiral molecules in an enantioselective fashion. Its advancement relies in large part on the design and discovery of new chiral catalysts. In contrast to conventional endeavors of generating chiral transition metal catalysts from carefully tailored chiral ligands, the development of chiral transition metal catalysts containing solely achiral ligands (chiral-at-metal catalysts) has been neglected. This Account presents our recent work on the synthesis and catalytic applications of a new class of C2-symmetric chiral-at-ruthenium catalysts. These octahedral ruthenium(II) complexes are constructed from two achiral bidentate N-(2-pyridyl)-substituted N-heterocyclic carbene (PyNHC) ligands and two monodentate acetonitriles, and the dicationic complexes are typically complemented with two hexafluorophosphate anions. The chirality of these complexes originates from the helical cis-arrangement of the bidentate ligands, thereby generating a stereogenic metal center as the exclusive stereocenter in these complexes. The strong σ donor and π acceptor properties of the PyNHC ligands provide a strong ligand field that ensures a high constitutional and configurational inertness of the helical Ru(PyNHC)2 core, while at the same time, the trans-effect exerted by the σ-donating NHC ligands results in high lability of the MeCN ligands and, therefore, provides high catalytic activity. As a result, this chiral-at-ruthenium catalyst scaffold combines formidable structural robustness with high catalytic activity in a unique fashion. Asymmetric nitrene C-H insertion constitutes an efficient strategy for accessing chiral amines. The direct conversion of C(sp3)-H bonds into amine functionality circumvents the need for using functionalized starting materials. Our C2-symmetric chiral-at-ruthenium complexes display exceptionally high catalytic activity and excellent stereocontrol for various asymmetric nitrene C(sp3)-H insertion reactions. The ruthenium nitrene species can be generated from nitrene precursors, such as organic azides and hydroxylamine derivatives, which undergo ring-closing C-H aminations to afford chiral cyclic pyrrolidines, ureas, and carbamates in high yields and with excellent enantioselectivities at low catalyst loadings. Mechanistically, the turnover-determining C-H insertion is proposed to proceed in a concerted or stepwise fashion, depending on the nature of intermediate ruthenium nitrenes (singlet or triplet). Computational studies revealed that the stereocontrol originates from a better steric fit in combination with favorable catalyst/substrate π-π stacking effects for aminations at benzylic C-H bonds. In addition, we also present our research for exploring novel reaction patterns and reactivities of intermediate transition metal nitrenes. First, we discovered a novel chiral-at-ruthenium-catalyzed 1,3-migratory nitrene C(sp3)-H insertion to convert azanyl esters into nonracemic α-amino acids. Second, we found a chiral-at-ruthenium-catalyzed intramolecular C(sp3)-H oxygenation, thereby allowing for the construction of chiral cyclic carbonates and lactones via nitrene chemistry. We expect that our research program on catalyst development and reaction discovery will inspire the creation of novel types of chiral-at-metal catalysts and drive the development of new applications for nitrene-mediated asymmetric C-H functionalization reactions.
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Affiliation(s)
- Chen-Xi Ye
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein Straße 4, 35043 Marburg, Germany
| | - Eric Meggers
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein Straße 4, 35043 Marburg, Germany
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Findlay MT, Domingo-Legarda P, McArthur G, Yen A, Larrosa I. Catalysis with cycloruthenated complexes. Chem Sci 2022; 13:3335-3362. [PMID: 35432864 PMCID: PMC8943884 DOI: 10.1039/d1sc06355c] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 02/08/2022] [Indexed: 12/03/2022] Open
Abstract
Cycloruthenated complexes have been studied extensively over the last few decades. Many accounts of their synthesis, characterisation, and catalytic activity in a wide variety of transformations have been reported to date. Compared with their non-cyclometallated analogues, cycloruthenated complexes may display enhanced catalytic activities in known transformations or possess entirely new reactivity. In other instances, these complexes can be chiral, and capable of catalysing stereoselective reactions. In this review, we aim to highlight the catalytic applications of cycloruthenated complexes in organic synthesis, emphasising the recent advancements in this field. We discuss recent advances in the applications of cycloruthenated complexes in organic synthesis, comprising C–H activation, chiral-at-metal catalysis, Z-selective olefin metathesis, transfer hydrogenation, enantioselective cyclopropanations and cycloadditions.![]()
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Affiliation(s)
- Michael T Findlay
- School of Chemistry, University of Manchester Oxford Road Manchester M13 9PL UK
| | | | - Gillian McArthur
- School of Chemistry, University of Manchester Oxford Road Manchester M13 9PL UK
| | - Andy Yen
- School of Chemistry, University of Manchester Oxford Road Manchester M13 9PL UK
| | - Igor Larrosa
- School of Chemistry, University of Manchester Oxford Road Manchester M13 9PL UK
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5
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Jerwood K, Lowy P, Deeming L, Kariuki BM, Newman PD. Remote control: stereoselective coordination of electron-deficient 2,2'-bipyridine ligands to Re(I) and Ir(III) cores. Dalton Trans 2021; 50:16459-16463. [PMID: 34668511 DOI: 10.1039/d1dt02928b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Highly diastereoselective coordination of unsymmetrical cationic 2,2'-bipyridine ligands bearing a chiral amidinium substituent to [Re(CO)3Cl] and [Ir(PhPy)2]+ cores is reported. Binding strength and stereoselectivity have been correlated with the position of the amidinium group on the bipy. The 4-, 5- and 6-substituted ligands all produce C-[Re(CO)3(LH)Cl]X selectively, while only the 4-derivative gives preferred formation of Δ-[Ir(Phpy)2(4-LH)](BF4)2.
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Affiliation(s)
- Kimberley Jerwood
- School of Chemistry, Cardiff University, Cardiff, Wales, CF10 3AT, UK
| | - Phoebe Lowy
- School of Chemistry, Cardiff University, Cardiff, Wales, CF10 3AT, UK
| | - Laura Deeming
- School of Chemistry, Cardiff University, Cardiff, Wales, CF10 3AT, UK
| | - Benson M Kariuki
- School of Chemistry, Cardiff University, Cardiff, Wales, CF10 3AT, UK
| | - Paul D Newman
- Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff, Wales, CF10 3AT, UK.
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