1
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Stroek W, Albrecht M. Application of first-row transition metal complexes bearing 1,2,3-triazolylidene ligands in catalysis and beyond. Chem Soc Rev 2024; 53:6322-6344. [PMID: 38726664 PMCID: PMC11181992 DOI: 10.1039/d4cs00021h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Indexed: 06/18/2024]
Abstract
Triazole-derived N-heterocyclic carbenes, triazolylidenes (trz) have become an interesting alternative to the ubiquitous Arduengo-type imidazole-derived carbenes, in part because they are stronger donors, and in other parts due to their versatile synthesis through different types of click reactions. While the use of trz ligands has initially focused on their coordination to precious metals for catalytic applications, the recent past has seen a growing interest in their impact on first-row transition metals. Coordination of trz ligands to such 3d metals is more challenging due to the orbital mismatch between the carbene and the 3d metal center, which also affects the stability of such complexes. Here we summarize the strategies that have been employed so far to overcome these challenges and to prepare first-row transition metal complexes containing at least one trz ligand. Both properties and reactivities of these trz complexes are comprehensively compiled, with a focus on photophysical properties and, in particular, on the application of these complexes in homogeneous catalysis. The diversity of catalytic transformations entailed with these trz 3d metal complexes as well as the record-high performance in some of the reactions underpins the benefits imparted by trz ligands.
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Affiliation(s)
- Wowa Stroek
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
| | - Martin Albrecht
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
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2
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Neshat A, Mousavizadeh Mobarakeh A, Yousefshahi MR, Varmaghani F, Dusek M, Eigner V, Kucerakova M. Introducing Novel Redox-Active Bis(phenolate) N-Heterocyclic Carbene Proligands: Investigation of Their Coordination to Fe(II)/Fe(III) and Their Catalytic Activity in Transfer Hydrogenation of Carbonyl Compounds. ACS OMEGA 2024; 9:25135-25145. [PMID: 38882110 PMCID: PMC11170717 DOI: 10.1021/acsomega.4c02602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 05/19/2024] [Accepted: 05/23/2024] [Indexed: 06/18/2024]
Abstract
A simple and efficient procedure for synthesizing novel pincer-type tridentate N-heterocyclic carbene bisphenolate ligands is reported. The synthesis of pincer proligands with N,N'-disubstituted imidazoline core, 5 and 6, was carried out via triethylorthoformate-promoted cyclization of either N,N'-bis(2-hydroxy-3,5-di-tert-butylphenyl)cyclohexanediamine, 3, or N,N'-bis(2-hydroxyphenyl)cyclohexanediamine, 4, in the presence of concentrated hydrochloric acid. Cyclic voltammograms of the ligands revealed ligand-centered redox activity, indicating the noninnocent nature of the ligands. The voltammograms of the ligands exhibit two successive one-electron oxidations and two consecutive one-electron reductions. In contrast to previous reports, the redox-active ligands in this study exhibit one-electron oxidation and reduction processes. All products were thoroughly characterized by using 1H and 13C NMR spectroscopy. The base-promoted deprotonation of the proligands and subsequent reaction with iron(II) and iron(III) chlorides yielded compounds 7 and 8. These compounds are binuclear and tetranuclear iron(III) complexes that do not contain carbene functional groups. Complexes 7 and 8 were characterized by using elemental analysis and single-crystal X-ray crystallography. At low catalyst loadings, both 7 and 8 exhibited high catalytic activity in the transfer hydrogenation of selected aldehydes and ketones.
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Affiliation(s)
- Abdollah Neshat
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), 444 Prof. Sobouti Blvd., Gava Zang, Zanjan 45137-66731, Iran
| | - Ali Mousavizadeh Mobarakeh
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), 444 Prof. Sobouti Blvd., Gava Zang, Zanjan 45137-66731, Iran
| | - Mohammad Reza Yousefshahi
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), 444 Prof. Sobouti Blvd., Gava Zang, Zanjan 45137-66731, Iran
| | - Fahimeh Varmaghani
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), 444 Prof. Sobouti Blvd., Gava Zang, Zanjan 45137-66731, Iran
| | - Michal Dusek
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221 Prague 8, The Czech Republic
| | - Vaclav Eigner
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221 Prague 8, The Czech Republic
| | - Monika Kucerakova
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221 Prague 8, The Czech Republic
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3
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Zhang Y, Lee TS, Petersen JL, Milsmann C. Photophysical Studies of a Zr(IV) Complex with Two Pyrrolide-Based Tetradentate Schiff Base Ligands. Inorg Chem 2024; 63:9002-9013. [PMID: 38700497 PMCID: PMC11110004 DOI: 10.1021/acs.inorgchem.4c00365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/05/2024] [Accepted: 04/23/2024] [Indexed: 05/05/2024]
Abstract
The reaction of two equivalents of N,N'-bis(2-pyrrolylmethylidene)-1,2-phenylenediamine (H2bppda) with tetrabenzylzirconium provided the air- and moisture-stable eight-coordinate complex Zr(bppda)2. Temperature-dependent steady-state and time-resolved emission spectroscopy established weak photoluminescence (ΦPL = 0.4% at 293 K) by a combination of prompt fluorescence and thermally activated delayed fluorescence (TADF) upon visible light excitation at and around room temperature. TADF emission is strongly quenched by 3O2 and shows highly temperature-sensitive emission lifetimes of hundreds of microseconds. The lifetime of the lowest energy singlet excited state, S1, was established by transient absorption spectroscopy and shows rapid deactivation (τ = 142 ps) by prompt fluorescence and intersystem crossing to the triplet state, T1. Time-dependent density functional theory (TD-DFT) calculations predict moderate ligand-to-metal charge transfer (LMCT) contributions of 25-30% for the S1 and T1 states. A comparison of Zr(bppda)2 to related zirconium pyridine dipyrrolide complexes, Zr(PDP)2, revealed important electronic structure changes due to the eight-coordinate ligand environment in Zr(bppda)2, which were correlated to differences in the photophysical properties between the two compound classes.
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Affiliation(s)
- Yu Zhang
- C.
Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
- Department
of Chemistry, Tufts University, Medford, Massachusetts 02144, United States
| | - Tia S. Lee
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Jeffrey L. Petersen
- C.
Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Carsten Milsmann
- C.
Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
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4
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May AM, Dempsey JL. A new era of LMCT: leveraging ligand-to-metal charge transfer excited states for photochemical reactions. Chem Sci 2024; 15:6661-6678. [PMID: 38725519 PMCID: PMC11079626 DOI: 10.1039/d3sc05268k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 04/02/2024] [Indexed: 05/12/2024] Open
Abstract
Ligand-to-metal charge transfer (LMCT) excited states are capable of undergoing a wide array of photochemical reactions, yet receive minimal attention compared to other charge transfer excited states. This work provides general criteria for designing transition metal complexes that exhibit low energy LMCT excited states and routes to drive photochemistry from these excited states. General design principles regarding metal identity, oxidation state, geometry, and ligand sets are summarized. Fundamental photoreactions from these states including visible light-induced homolysis, excited state electron transfer, and other photoinduced chemical transformations are discussed and key design principles for enabling these photochemical reactions are further highlighted. Guided by these fundamentals, this review outlines critical considerations for the future design and application of coordination complexes with LMCT excited states.
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Affiliation(s)
- Ann Marie May
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
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5
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Thierry T, Giuso V, Polo F, Mercandelli P, Chen YT, Chang CH, Mauro M, Bellemin-Laponnaz S. A stable and true-blue emissive hexacoordinate Si(IV) N-heterocyclic carbene complex and its use in organic light-emitting diodes. Dalton Trans 2024; 53:6445-6450. [PMID: 38511259 DOI: 10.1039/d4dt00420e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
A neutral hexacoordinate Si(IV) complex containing two tridentate N-heterocyclic carbene ligands is synthesised and characterized by X-ray crystallography, optical spectroscopy, electrochemistry and computational methods. The stable compound exhibits remarkable deep-blue photoluminescence particularly in the solid state, which enables its use as an electroluminescent material in organic light-emitting diodes.
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Affiliation(s)
- Thibault Thierry
- Institut de Physique et Chimie des Matériaux de Strasbourg UMR 7504 - Université de Strasbourg & CNRS, 23 rue du Loess, 67034 Strasbourg, France.
| | - Valerio Giuso
- Institut de Physique et Chimie des Matériaux de Strasbourg UMR 7504 - Université de Strasbourg & CNRS, 23 rue du Loess, 67034 Strasbourg, France.
| | - Federico Polo
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Via Torino 155, 30172 Venice, Italy
- European Centre for Living Technology (ECLT), Ca' Foscari University of Venice, Ca' Bottacin, 30124, Venice, Italy
| | | | - Yi-Ting Chen
- Department of Electrical Engineering, Yuan Ze University, 32003 Taoyuan, Taiwan
| | - Chih-Hao Chang
- Department of Electrical Engineering, Yuan Ze University, 32003 Taoyuan, Taiwan
| | - Matteo Mauro
- Institut de Physique et Chimie des Matériaux de Strasbourg UMR 7504 - Université de Strasbourg & CNRS, 23 rue du Loess, 67034 Strasbourg, France.
| | - Stéphane Bellemin-Laponnaz
- Institut de Physique et Chimie des Matériaux de Strasbourg UMR 7504 - Université de Strasbourg & CNRS, 23 rue du Loess, 67034 Strasbourg, France.
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6
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Barker M, Whittemore TJ, London HC, Sledesky JM, Harris EA, Smith Pellizzeri TM, McMillen CD, Wagenknecht PS. Design Strategies for Luminescent Titanocenes: Improving the Photoluminescence and Photostability of Arylethynyltitanocenes. Inorg Chem 2023; 62:17870-17882. [PMID: 37831503 PMCID: PMC10618925 DOI: 10.1021/acs.inorgchem.3c02712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Indexed: 10/14/2023]
Abstract
Complexes that undergo ligand-to-metal charge transfer (LMCT) to d0 metals are of interest as possible photocatalysts. Cp2Ti(C2Ph)2 (where C2Ph = phenylethynyl) was reported to be weakly emissive in room-temperature (RT) fluid solution from its phenylethynyl-to-Ti 3LMCT state but readily photodecomposes. Coordination of CuX between the alkyne ligands to give Cp2Ti(C2Ph)2CuX (X = Cl, Br) has been shown to significantly increase the photostability, but such complexes are not emissive in RT solution. Herein, we investigate whether inhibition of alkyne-Ti-alkyne bond compression might be responsible for the increased photostability of the CuX complexes by investigating the decomposition of a structurally constrained analogue, Cp2Ti(OBET) (OBET = o-bis(ethynyl)tolane). To investigate the mechanism of nonradiative decay from the 3LMCT states in Cp2Ti(C2Ph)2CuX, the photophysical properties were investigated both upon deuteration and upon rigidifying in a poly(methyl methacrylate) film. These investigations suggested that inhibition of structural rearrangement may play a dominant role in increasing emission lifetimes and quantum yields. The bulkier Cp*2Ti(C2Ph)2CuBr was prepared and is emissive at 693 nm in RT THF solution with a photoluminescent quantum yield of 1.3 × 10-3 (τ = 0.18 μs). Time-dependent density functional theory (TDDFT) calculations suggest that emission occurs from a 3LMCT state dominated by Cp*-to-Ti charge transfer.
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Affiliation(s)
- Matilda Barker
- Department
of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Thomas J. Whittemore
- Department
of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Henry C. London
- Department
of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Jack M. Sledesky
- Department
of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Elizabeth A. Harris
- Department
of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Tiffany M. Smith Pellizzeri
- Department
of Chemistry and Biochemistry, Eastern Illinois
University, Charleston, Illinois 61920, United States
| | - Colin D. McMillen
- Department
of Chemistry, Clemson University, Clemson, South Carolina 29634, United States
| | - Paul S. Wagenknecht
- Department
of Chemistry, Furman University, Greenville, South Carolina 29609, United States
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7
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Leary D, Zhang Y, Rodriguez JG, Akhmedov NG, Petersen JL, Dolinar BS, Milsmann C. Organometallic Intermediates in the Synthesis of Photoluminescent Zirconium and Hafnium Complexes with Pyridine Dipyrrolide Ligands. Organometallics 2023; 42:1220-1231. [PMID: 37324448 PMCID: PMC10266360 DOI: 10.1021/acs.organomet.3c00058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Indexed: 03/12/2023]
Abstract
The two commercially available zirconium complexes tetrakis(dimethylamido)zirconium, Zr(NMe2)4, and tetrabenzylzirconium, ZrBn4, were investigated for their utility as starting materials in the synthesis of bis(pyridine dipyrrolide)zirconium photosensitizers, Zr(PDP)2. Reaction with one equivalent of the ligand precursor 2,6-bis(5-methyl-3-phenyl-1H-pyrrol-2-yl)pyridine, H2MePDPPh, resulted in the isolation and structural characterization of the complexes (MePDPPh)Zr(NMe2)2thf and (MePDPPh)ZrBn2, which could be converted to the desired photosensitizer Zr(MePDPPh)2 upon addition of a second equivalent of H2MePDPPh. Using the more sterically encumbered ligand precursor 2,6-bis(5-(2,4,6-trimethylphenyl)-3-phenyl-1H-pyrrol-2-yl)pyridine, H2MesPDPPh, only ZrBn4 yielded the desired bis-ligand complex Zr(MesPDPPh)2. Careful monitoring of the reaction at different temperatures revealed the importance of the organometallic intermediate (cyclo-MesPDPPh)ZrBn, which was characterized by X-ray diffraction analysis and 1H NMR spectroscopy and shown to contain a cyclometalated MesPDPPh unit. Taking inspiration from the results for zirconium, syntheses for two hafnium photosensitizers, Hf(MePDPPh)2 and Hf(MesPDPPh)2, were established and shown to proceed through similar intermediates starting from tetrabenzylhafnium, HfBn4. Initial studies of the photophysical properties of the photoluminescent hafnium complexes indicate similar optical properties compared to their zirconium analogues.
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Affiliation(s)
- Dylan
C. Leary
- C. Eugene Bennett Department
of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | | | - Jose G. Rodriguez
- C. Eugene Bennett Department
of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Novruz G. Akhmedov
- C. Eugene Bennett Department
of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Jeffrey L. Petersen
- C. Eugene Bennett Department
of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Brian S. Dolinar
- C. Eugene Bennett Department
of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Carsten Milsmann
- C. Eugene Bennett Department
of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
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8
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Horrer G, Krummenacher I, Mann S, Braunschweig H, Radius U. N-Heterocyclic carbene and cyclic (alkyl)(amino)carbene complexes of vanadium(III) and vanadium(V). Dalton Trans 2022; 51:11054-11071. [PMID: 35796195 DOI: 10.1039/d2dt01250b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
[VCl3(THF)3] offers a convenient entrance point into the chemistry of carbene stabilized V(III) complexes. Herein we report the paramagnetic mono- and biscarbene complexes [VCl3(cAACMe)] 1, [VCl3(cAACMe)(THF)] 1(thf), [VCl3(IMes)] 2, [{VCl2(IiPrMe)(μ-Cl)}2] 3, [VCl3(IDipp)] 4, [VCl3(SIDipp)] 5, [VCl3(SIDipp)(THF)] 5(thf), [VCl3(ItBu)] 6, [VCl3(cAACMe)2] 7 and [VCl3(IiPrMe)2] 8. Reaction of 1 with MesMgCl, MesLi and LiNPh2 afforded the complexes [VCl2(Mes)(cAACMe)] 9, [cAACMeH]+[VCl2Mes2]-10 and [VCl2(NPh2)(cAACMe)] 11. The V(V) complexes [V(O)Cl3(IDipp)] 12 and [V(O)Cl3(SIDipp)] 13 were selectively prepared from oxygen oxidation of 4 and 5. [V(O)Cl3(IDipp)] 12 and [V(O)Cl3(IMes)] react with isocyanates to yield the NHC-ligated imido complexes [V(N-p-CH3C6H4)Cl3(IDipp)] 14, [V(N-p-FC6H4)Cl3(IDipp)] 15, [V(N-p-CH3C6H4)Cl3(SIDipp)] 16, [V(N-p-FC6H4)Cl3(SIDipp)] 17, [V(N-p-CH3C6H4)Cl3(IMes)] 18 and [V(N-p-FC6H4)Cl3(IMes)] 19.
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Affiliation(s)
- Günther Horrer
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Ivo Krummenacher
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany. .,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Sophie Mann
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Holger Braunschweig
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany. .,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Udo Radius
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
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9
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London HC, Pritchett DY, Pienkos JA, McMillen CD, Whittemore TJ, Bready CJ, Myers AR, Vieira NC, Harold S, Shields GC, Wagenknecht PS. Photochemistry and Photophysics of Charge-Transfer Excited States in Emissive d10/ d0 Heterobimetallic Titanocene Tweezer Complexes. Inorg Chem 2022; 61:10986-10998. [PMID: 35786924 DOI: 10.1021/acs.inorgchem.2c01746] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Transition-metal complexes that undergo ligand-to-metal charge transfer (LMCT) to d0 metals are of interest as possible photocatalysts due to the lack of deactivating d-d states. Herein, the synthesis and characterization of nine titanocene complexes of the formula Cp2Ti(C2Ar)2·MX (where Ar = phenyl, dimethylaniline, or triphenylamine; and MX = CuCl, CuBr, or AgCl) are presented. Solid-state structural characterization demonstrates that MX coordinates to the alkyne tweezers and CuX coordination has a greater structural impact than AgCl. All complexes, including the parent complexes without coordinated MX, are brightly emissive at 77 K (emission max between 575 and 767 nm), with the coordination of MX redshifting the emission in all cases except for the coordination of AgCl into Cp2Ti(C2Ph)2. TDDFT investigations suggest that emission is dominated by arylalkynyl-to-titanium 3LMCT in all cases except Cp2Ti(C2Ph)2·CuBr, which is dominated by CuBr-to-Ti charge transfer. In room-temperature fluid solution, only Cp2Ti(C2Ph)2 and Cp2Ti(C2Ph)2·AgCl are emissive, albeit with photoluminescent quantum yields ≤2 × 10-4. The parent complexes photodecompose in room-temperature solution with quantum yields, Φrxn, between 0.25 and 0.99. The coordination of MX decreases Φrxn by two to three orders of magnitude. There is a clear trend that Φrxn increases as the emission energy increases. This trend is consistent with a competition between energy-gap-law controlled nonradiative decay and thermally activated intersystem crossing between the 3LMCT state and the singlet transition state for decomposition.
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Affiliation(s)
- Henry C London
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - David Y Pritchett
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Jared A Pienkos
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Colin D McMillen
- Department of Chemistry, Clemson University, Clemson, South Carolina 29634, United States
| | - Thomas J Whittemore
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Conor J Bready
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Alexis R Myers
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Noah C Vieira
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Shannon Harold
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - George C Shields
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Paul S Wagenknecht
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
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10
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Stipurin S, Strassner T. Phosphorescent Cyclometalated Platinum(
ii
) Hexahydroimidazo[1,5‐
a
]pyridinylidene Complexes. Eur J Inorg Chem 2022. [DOI: 10.1002/ejic.202200295] [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)
- Sergej Stipurin
- Physikalische Organische Chemie Technische Universität Dresden 01069 Dresden Germany
| | - Thomas Strassner
- Physikalische Organische Chemie Technische Universität Dresden 01069 Dresden Germany
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11
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Ruamps M, Bastin S, Rechignat L, Sournia-Saquet A, Vendier L, Lugan N, Mouesca JM, Valyaev DA, Maurel V, César V. Redox-Switchable Behavior of Transition-Metal Complexes Supported by Amino-Decorated N-Heterocyclic Carbenes. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27123776. [PMID: 35744903 PMCID: PMC9227367 DOI: 10.3390/molecules27123776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/07/2022] [Accepted: 06/08/2022] [Indexed: 11/16/2022]
Abstract
The coordination chemistry of the N-heterocyclic carbene ligand IMes(NMe2)2, derived from the well-known IMes ligand by substitution of the carbenic heterocycle with two dimethylamino groups, was investigated with d6 [Mn(I), Fe(II)], d8 [Rh(I)], and d10 [Cu(I)] transition-metal centers. The redox behavior of the resulting organometallic complexes was studied through a combined experimental/theoretical study, involving electrochemistry, EPR spectroscopy, and DFT calculations. While the complexes [CuCl(IMes(NMe2)2)], [RhCl(COD)(IMes(NMe2)2)], and [FeCp(CO)2 (IMes(NMe2)2)](BF4) exhibit two oxidation waves, the first oxidation wave is fully reversible but only for the first complex the second oxidation wave is reversible. The mono-oxidation event for these complexes occurs on the NHC ligand, with a spin density mainly located on the diaminoethylene NHC-backbone, and has a dramatic effect on the donating properties of the NHC ligand. Conversely, as the Mn(I) center in the complex [MnCp(CO)2 ((IMes(NMe2)2)] is easily oxidizable, the latter complex is first oxidized on the metal center to form the corresponding cationic Mn(II) complex, and the NHC ligand is oxidized in a second reversible oxidation wave.
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Affiliation(s)
- Mirko Ruamps
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
| | - Stéphanie Bastin
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
| | - Lionel Rechignat
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
| | - Alix Sournia-Saquet
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
| | - Laure Vendier
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
| | - Noël Lugan
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
| | - Jean-Marie Mouesca
- Université Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, France;
| | - Dmitry A. Valyaev
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
- Correspondence: (D.A.V.); (V.M.); (V.C.)
| | - Vincent Maurel
- Université Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, France;
- Correspondence: (D.A.V.); (V.M.); (V.C.)
| | - Vincent César
- LCC-CNRS, Université de Toulouse, CNRS, 31077 Toulouse, France; (M.R.); (S.B.); (L.R.); (A.S.-S.); (L.V.); (N.L.)
- Correspondence: (D.A.V.); (V.M.); (V.C.)
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12
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Poland EM, Ho CC. Photoactive N‐Heterocyclic Carbene Transition Metal Complexes in Bond‐Forming Photocatalysis: State‐of‐the‐Art and Opportunities. Appl Organomet Chem 2022. [DOI: 10.1002/aoc.6746] [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)
- Eve M. Poland
- School of Natural Sciences – Chemistry University of Tasmania Hobart Tasmania Australia
| | - Curtis C. Ho
- School of Natural Sciences – Chemistry University of Tasmania Hobart Tasmania Australia
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13
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Rodriguez TM, Deegbey M, Jakubikova E, Dempsey JL. The ligand-to-metal charge transfer excited state of [Re(dmpe) 3] 2. PHOTOSYNTHESIS RESEARCH 2022; 151:155-161. [PMID: 34258679 DOI: 10.1007/s11120-021-00859-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 06/24/2021] [Indexed: 06/13/2023]
Abstract
The ligand-to-metal charge transfer (LMCT) transitions of [Re(dmpe)3]2+ (dmpe = bis-1,2-(dimethylphosphino)ethane) were interrogated using UV/Vis absorbance spectroscopy, photoluminescence spectroscopy, and time-dependent density functional theory. The solvent dependence of the lowest energy charge transfer transition was quantified; no solvatochromism was observed. TD-DFT calculations reveal the dominant LMCT transition is highly symmetric and delocalized involving all phopshine ligand donors in the charge transfer, providing an understanding for the absence of solvatochromism of [Re(dmpe)3]2+.
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Affiliation(s)
- Tayliz M Rodriguez
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA
| | - Mawuli Deegbey
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, 27695, USA
| | - Elena Jakubikova
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, 27695, USA
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA.
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14
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Watt FA, Sieland B, Dickmann N, Schoch R, Herbst-Irmer R, Ott H, Paradies J, Kuckling D, Hohloch S. Coupling of CO 2 and epoxides catalysed by novel N-fused mesoionic carbene complexes of nickel(II). Dalton Trans 2021; 50:17361-17371. [PMID: 34788774 DOI: 10.1039/d1dt03311e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the syntheses of two rigid mesoionic carbene (MIC) ligands with a carbazole backbone via an intramolecular Finkelstein-cyclisation cascade and investigate their coordination behavior towards nickel(II) acetate. Despite the nickel(II) carbene complexes 4a,b showing only minor differences in their chemical composition, they display curious differences in their chemical properties, e.g. solubility. Furthermore, the potential of these novel MIC complexes in the coupling of carbon dioxide and epoxides as well as the differences in reactivity compared to classical NHC-derived complexes are evaluated.
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Affiliation(s)
- Fabian A Watt
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Benedikt Sieland
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Nicole Dickmann
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Roland Schoch
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Regine Herbst-Irmer
- University of Göttingen, Institute of Inorganic Chemistry, Tammannstraße 4, 37077 Göttingen, Germany
| | - Holger Ott
- Bruker AXS GmbH, Östliche Rheinbrückenstraße 49, 76187 Karlsruhe, Germany
| | - Jan Paradies
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Dirk Kuckling
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Stephan Hohloch
- University of Innsbruck, Faculty of Chemistry and Pharmacy, Institute of General, Inorganic and Theoretical Chemistry, Innrain 80-82, 6020 Innsbruck, Austria.
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15
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Wegeberg C, Wenger OS. Luminescent First-Row Transition Metal Complexes. JACS AU 2021; 1:1860-1876. [PMID: 34841405 PMCID: PMC8611671 DOI: 10.1021/jacsau.1c00353] [Citation(s) in RCA: 114] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Indexed: 05/25/2023]
Abstract
Precious and rare elements have traditionally dominated inorganic photophysics and photochemistry, but now we are witnessing a paradigm shift toward cheaper and more abundant metals. Even though emissive complexes based on selected first-row transition metals have long been known, recent conceptual breakthroughs revealed that a much broader range of elements in different oxidation states are useable for this purpose. Coordination compounds of V, Cr, Mn, Fe, Co, Ni, and Cu now show electronically excited states with unexpected reactivity and photoluminescence behavior. Aside from providing a compact survey of the recent conceptual key advances in this dynamic field, our Perspective identifies the main design strategies that enabled the discovery of fundamentally new types of 3d-metal-based luminophores and photosensitizers operating in solution at room temperature.
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16
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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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17
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Roux SL, Ori G, Bellemin-Laponnaz S, Boero M. Tridentate complexes of group 4 bearing bis-aryloxide N-heterocyclic carbene ligand: Structure, spin density and charge states. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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18
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London HC, Whittemore TJ, Gale AG, McMillen CD, Pritchett DY, Myers AR, Thomas HD, Shields GC, Wagenknecht PS. Ligand-to-Metal Charge-Transfer Photophysics and Photochemistry of Emissive d 0 Titanocenes: A Spectroscopic and Computational Investigation. Inorg Chem 2021; 60:14399-14409. [PMID: 34495657 DOI: 10.1021/acs.inorgchem.1c02182] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Complexes with ligand-to-metal charge-transfer (LMCT) excited states involving d0 metals represent a new design for photocatalysts. Herein, the photochemistry and photophysics of d0 titanocenes of the type Cp2Ti(C2R)2, where C2R = ethynylphenyl (C2Ph), 4-ethynyldimethylaniline (C2DMA), or 4-ethynyltriphenylamine (C2TPA), have been investigated. Cp2Ti(C2Ph)2 and Cp2Ti(C2DMA)2 have also been characterized by single-crystal X-ray diffraction. The two aryl rings in Cp2Ti(C2DMA)2 are nearly face-to-face in the solid state, whereas they are mutually perpendicular for Cp2Ti(C2Ph)2. All three complexes are brightly emissive at 77 K but photodecompose at room temperature when irradiated into their lowest-energy absorption band. The emission wavelengths and photodecomposition quantum yields are as follows: Cp2Ti(C2Ph)2, 575 nm and 0.65; Cp2Ti(C2TPA)2, 642 nm and 0.42; Cp2Ti(C2DMA)2, 672 nm and 0.25. Extensive benchmarking of the density functional theory (DFT) model against the structural data and of the time-dependent DFT (TDDFT) model against the absorption and emission data was performed using combinations of 13 different functionals and 4 basis sets. The model that predicted the absorption and emission data with the greatest fidelity utilized MN15/LANL2DZ for both the DFT optimization and the TDDFT. Computational analysis shows that absorption involves a transition to a 1LMCT state. Whereas the spectroscopic data for Cp2Ti(C2TPA)2 and Cp2Ti(C2DMA)2 are well modeled using the optimized structure of these complexes, Cp2Ti(C2Ph)2 required averaging of the spectra from multiple rotamers involving rotation of the Ph rings. Consistent with this finding, an energy scan of all rotamers showed a very flat energetic surface, with less than 1.3 kcal/mol separating the minimum and maximum. The computational data suggest that emission occurs from a 3LMCT state. Optimization of the 3LMCT state demonstrates compression of the C-Ti-C bond angle, consistent with the known products of photodecomposition.
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Affiliation(s)
- Henry C London
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Thomas J Whittemore
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Ariel G Gale
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Colin D McMillen
- Department of Chemistry, Clemson University, Clemson, South Carolina 29634, United States
| | - David Y Pritchett
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Alexis R Myers
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Hannah D Thomas
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - George C Shields
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Paul S Wagenknecht
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
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19
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Dunlop D, Večeřa M, Gyepes R, Kubát P, Lang K, Horáček M, Pinkas J, Šimková L, Liška A, Lamač M. Luminescent Cationic Group 4 Metallocene Complexes Stabilized by Pendant N-Donor Groups. Inorg Chem 2021; 60:7315-7328. [PMID: 33945274 DOI: 10.1021/acs.inorgchem.1c00461] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Cationic group 4 metallocene complexes with pendant imine and pyridine donor groups were prepared as stable crystalline [B(C6F5)4]- salts either by protonation of the intramolecularly bound ketimide moiety in neutral complexes [(η5-C5Me5){η5-C5H4CMe2CMe2C(R)═N-κN}MCl] (M = Ti, Zr, Hf; R = t-Bu, Ph) by PhNMe2H+[B(C6F5)4]- to give [(η5-C5Me5){η5-C5H4CMe2CMe2C(R)═NH-κN}MCl]+[B(C6F5)4]- or by chloride ligand abstraction from the complexes [(η5-C5Me5)(η5-C5H4CMe2CH2C5H4N)MCl2] (M = Ti, Zr) by Li[B(C6F5)4]·2.5Et2O to give [(η5-C5Me5)(η5-C5H4CMe2CH2C5H4N-κN)MCl]+[B(C6F5)4]-. Solid state structures of the new compounds were established by X-ray diffraction analysis, and their electrochemical behavior was studied by cyclic voltammetry. The cationic complexes of Zr and Hf, compared to the corresponding neutral species, exhibited significantly enhanced luminescence predominantly from triplet ligand-to-metal (3LMCT) excited states with lifetimes up to 62 μs and quantum yields up to 58% in the solid state. DFT calculations were performed to explain the structural features and optical and electrochemical properties of the complexes.
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Affiliation(s)
- David Dunlop
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic.,Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, 128 40 Praha 2, Czech Republic
| | - Miloš Večeřa
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
| | - Róbert Gyepes
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic.,Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, 128 40 Praha 2, Czech Republic
| | - Pavel Kubát
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
| | - Kamil Lang
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, 250 68 Husinec-Řež, Czech Republic
| | - Michal Horáček
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
| | - Jiří Pinkas
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
| | - Ludmila Šimková
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
| | - Alan Liška
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
| | - Martin Lamač
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
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20
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Tukhbatullin AA, Kovyazin PV, Sharipov GL, Parfenova LV, Ivchenko PV, Nifant'ev IE. Photoluminescence and mechanoluminescence of solid-state zirconocene dichlorides. LUMINESCENCE 2021; 36:943-950. [PMID: 33522099 DOI: 10.1002/bio.4020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/27/2021] [Accepted: 01/28/2021] [Indexed: 12/13/2022]
Abstract
Spectral-luminescence properties of 23 samples of zirconium complexes were studied. Mechanoluminescence spectra of 10 complexes were obtained. The solid-state component of the mechanoluminescence spectrum, that is the luminescence of the crystal itself, coincided with the photoluminescence spectra of these complexes, which indicated identical emission from the same excited states in mechanoluminescence and photoluminescence, despite the different ways of excitation. The luminescence maximum was red shifted as substituents appeared in the ligand, in particular in the presence of a bridging group connecting π-ligands (ansa-complexes) and also for a substituted bis-indenyl complex rac-Me2 Si(2-Me-4-Ph-5-OMe-6-But -Ind)2 ZrCl2 ). It was found that mechanical destruction of the rac-isomer of complex Mе2 С(2-Me-4-But -C5 H2 )2 ZrCl2 , unlike that of the meso-isomer, was accompanied by a more than a 10-fold increase in intensity and by a shift in the mechanoluminescence spectrum to longer wavelengths.
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Affiliation(s)
- Adis A Tukhbatullin
- Russian Academy of Sciences, Institute of Petrochemistry and Catalysis, 141, Oktyabrya Prosp., Ufa, Russian Federation
| | - Pavel V Kovyazin
- Russian Academy of Sciences, Institute of Petrochemistry and Catalysis, 141, Oktyabrya Prosp., Ufa, Russian Federation
| | - Glyus L Sharipov
- Russian Academy of Sciences, Institute of Petrochemistry and Catalysis, 141, Oktyabrya Prosp., Ufa, Russian Federation
| | - Lyudmila V Parfenova
- Russian Academy of Sciences, Institute of Petrochemistry and Catalysis, 141, Oktyabrya Prosp., Ufa, Russian Federation
| | - Pavel V Ivchenko
- Department of Chemistry, Lomonosov Moscow State University, 1-3 Leninskiye Gory, Moscow, Russian Federation.,Russian Academy of Sciences, A.V. Topchiev Institute of Petrochemical Synthesis, 29, Leninsky Prosp., Moscow, Russian Federation
| | - Ilya E Nifant'ev
- Department of Chemistry, Lomonosov Moscow State University, 1-3 Leninskiye Gory, Moscow, Russian Federation.,Russian Academy of Sciences, A.V. Topchiev Institute of Petrochemical Synthesis, 29, Leninsky Prosp., Moscow, Russian Federation
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21
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Romain C, Bellemin-Laponnaz S, Dagorne S. Recent progress on NHC-stabilized early transition metal (group 3–7) complexes: Synthesis and applications. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213411] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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22
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Zhang Y, Leary DC, Belldina AM, Petersen JL, Milsmann C. Effects of Ligand Substitution on the Optical and Electrochemical Properties of (Pyridinedipyrrolide)zirconium Photosensitizers. Inorg Chem 2020; 59:14716-14730. [PMID: 32975946 DOI: 10.1021/acs.inorgchem.0c02343] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of seven bis(pyridinedipyrrolide)zirconium complexes, Zr(R1PDPR2)2, where [R1PDPR2]2- is the doubly deprotonated form of [2,6-bis(5-R1-3-R2-1H-pyrrol-2-yl)pyridine], were prepared and characterized in solution by NMR, UV/vis absorption, and emission spectroscopy and cyclic voltammetry. The molecular structures were determined by single-crystal X-ray crystallography. All complexes exhibit remarkably long emission lifetimes (τ = 190-576 μs) with high quantum efficiencies (ΦPL = 0.10-0.38) upon excitation with visible light in a benzene solution. The substituents on the pyrrolide rings were shown to have significant effects on the photoluminescence and electrochemical properties of these compounds. The R2 substituents (R2 = H, Me, Ph, or C6F5) show only limited effects on the absorption and emission profiles of the complexes but allow systematic tuning of the ground- and excited-state redox potentials over a range of almost 600 mV. The R1 substituents (R1 = H, Me, Ph, or 2,4,6-Me3Ph) influence both the optical and electrochemical properties through electronic effects. Additionally, the R1 substituents have profound consequences for the structural flexibility and overall stability of the compounds. Distortions of the Zr(PDP)2 core from idealized D2d symmetry in the solid state can be traced to the steric profiles of the R1 substituents and correlate with the observed Stokes shifts for each compound. The complex with the smallest ligand system, Zr(HPDPH)2, coordinates two additional solvent molecules in a tetrahydrofuran (THF) solution, which allowed the isolation of photoluminescent, eight-coordinate Zr(HPDPH)2(THF)2. The photoredox catalytic dehalogenation of aryl iodides and aryl chlorides using the most reducing derivative, Zr(MePDPMe)2, highlights the potential of Zr(PDP)2 photosensitizers to promote challenging reductive transformations under mild conditions upon excitation with green light.
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Affiliation(s)
- Yu Zhang
- C. Eugene Bennett Department of Chemistry, West Virginia University (WVU), 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Dylan C Leary
- C. Eugene Bennett Department of Chemistry, West Virginia University (WVU), 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Anne M Belldina
- C. Eugene Bennett Department of Chemistry, West Virginia University (WVU), 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Jeffrey L Petersen
- C. Eugene Bennett Department of Chemistry, West Virginia University (WVU), 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Carsten Milsmann
- C. Eugene Bennett Department of Chemistry, West Virginia University (WVU), 100 Prospect Street, Morgantown, West Virginia 26506, United States
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23
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Meshcheryakova IN, Arsenyeva KV, Fukin GK, Cherkasov VK, Piskunov AV. Stable N-heterocyclic carbene derivatives of copper(i) and silver(i) containing radical anion redox active ligands. MENDELEEV COMMUNICATIONS 2020. [DOI: 10.1016/j.mencom.2020.09.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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24
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Taakili R, Canac Y. NHC Core Pincer Ligands Exhibiting Two Anionic Coordinating Extremities. Molecules 2020; 25:molecules25092231. [PMID: 32397416 PMCID: PMC7248942 DOI: 10.3390/molecules25092231] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/04/2020] [Accepted: 05/06/2020] [Indexed: 01/01/2023] Open
Abstract
The chemistry of NHCcore pincer ligands of LX2 type bearing two pending arms, identical or not, whose coordinating center is anionic in nature, is here reviewed. In this family, the negative charge of the coordinating atoms can be brought either by a carbon atom via a phosphonium ylide (R3P+-CR2-) or by a heteroatom through amide (R2N-), oxide (RO-), or thio(seleno)oxide (RS-, RSe-) donor functionalities. Through selected examples, the synthetic methods, coordination properties, and applications of such tridentate systems are described. Particular emphasis is placed on the role of the donor ends in the chemical behavior of these species.
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25
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Abstract
The synthesis and characterization of a series of homoleptic iron complexes [Fe(benzNHCOCO)2]2-/1-/0/1+ supported by the tridentate bis-aryloxide benzimidazolin-2-ylidene pincer ligand benzNHCOCO2- (II) is presented. While the reaction of 2 equiv of free ligand II with a ferrous iron precursor leads to the isolation of the coordination polymer [Fe(benzNHCOCOK)2]n (1), treatment of II with ferric iron salts allows for the synthesis and isolation of the mononuclear, octahedral bis-pincer compound K[Fe(benzNHCOCO)2] (2) and its crown-ether derivative [K(18c6)(THF)2][Fe(benzNHCOCO)2] (3). Electrochemical studies of 2 suggested stable products upon further one- and two-electron oxidation. Hence, treatment of 2 with 1 equiv of AgPF6 yields the charge-neutral species [Fe(benzNHCOCO)2] (4). Similarly, the cationic complex [Fe(benzNHCOCO)2]PF6 (5) is obtained by addition of 2 equiv of AgPF6. The characterization of complexes 1, 3, and 4 reveals iron-centered reduction and oxidation processes; thus, preserving the dianionic, closed-shell structure of both coordinated benzNHCOCO pincer chelates, II. This implies a stabilization of a highly Lewis acidic iron(IV) center by four phenolate anions rather than charge distribution across the ligand framework with a lower formal oxidation state at iron. Notably, the overall charge-neutral iron(IV) complex undergoes reductive elimination of the pincer ligand, providing a metal-free compound that can be described as a spirocyclic imidazolone ketal (6). In contrast, the ligand-metal bonds in 5, formally an iron(V) complex, are considerably covalent, rendering the assignment of its oxidation state challenging, if not impossible. All compounds are fully characterized, and the complexes' electronic structures were studied with a variety of spectroscopic and computational methods, including single-crystal X-ray diffraction (SC-XRD), X-band electron paramagnetic resonance (EPR), and zero-field 57Fe Mössbauer spectroscopy, variable-field and variable-temperature superconducting quantum interference device (SQUID) magnetization measurements, and multi-reference ab initio (NEVPT2/CASSCF) as well as density functional theory (DFT) studies. Taken altogether, the electronic structure of 5 is best described as an iron(IV) center antiferromagnetically coupled to a ligand-centered radical.
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Affiliation(s)
- Lisa Gravogl
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany
| | - Frank W Heinemann
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany
| | - Dominik Munz
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany
| | - Karsten Meyer
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany
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Delayed fluorescence from a zirconium(IV) photosensitizer with ligand-to-metal charge-transfer excited states. Nat Chem 2020; 12:345-352. [PMID: 32203439 DOI: 10.1038/s41557-020-0430-7] [Citation(s) in RCA: 113] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 01/24/2020] [Indexed: 11/08/2022]
Abstract
Advances in chemical control of the photophysical properties of transition-metal complexes are revolutionizing a wide range of technologies, particularly photocatalysis and light-emitting diodes, but they rely heavily on molecules containing precious metals such as ruthenium and iridium. Although the application of earth-abundant 'early' transition metals in photosensitizers is clearly advantageous, a detailed understanding of excited states with ligand-to-metal charge transfer (LMCT) character is paramount to account for their distinct electron configurations. Here we report an air- and moisture-stable, visible light-absorbing Zr(IV) photosensitizer, Zr(MesPDPPh)2, where [MesPDPPh]2- is the doubly deprotonated form of [2,6-bis(5-(2,4,6-trimethylphenyl)-3-phenyl-1H-pyrrol-2-yl)pyridine]. This molecule has an exceptionally long-lived triplet LMCT excited state (τ = 350 μs), featuring highly efficient photoluminescence emission (Ф = 0.45) due to thermally activated delayed fluorescence emanating from the higher-lying singlet configuration with significant LMCT contributions. Zr(MesPDPPh)2 engages in numerous photoredox catalytic processes and triplet energy transfer. Our investigation provides a blueprint for future photosensitizer development featuring early transition metals and excited states with significant LMCT contributions.
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27
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van der Vlugt JI. Redox-Active Pincer Ligands. TOP ORGANOMETAL CHEM 2020. [DOI: 10.1007/3418_2020_68] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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28
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Baltrun M, Watt FA, Schoch R, Hohloch S. Dioxo-, Oxo-imido-, and Bis-imido-Molybdenum(VI) Complexes with a Bis-phenolate-NHC Ligand. Organometallics 2019. [DOI: 10.1021/acs.organomet.9b00472] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Marc Baltrun
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Fabian A. Watt
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Roland Schoch
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
| | - Stephan Hohloch
- Paderborn University, Faculty of Science, Department of Chemistry, Warburger Straße 100, 33098 Paderborn, Germany
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29
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Kunert R, Philouze C, Jarjayes O, Thomas F. Stable M(II)-Radicals and Nickel(III) Complexes of a Bis(phenol) N-Heterocyclic Carbene Chelated to Group 10 Metal Ions. Inorg Chem 2019; 58:8030-8044. [PMID: 31185559 DOI: 10.1021/acs.inorgchem.9b00784] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The tetradentate ligand based on (1-imidazolium-3,5-di tert-butylphenol) units was prepared and chelated to group 10 metal ions (Ni(II), Pd(II), and Pt(II)), affording complexes 1, 2, and 3, respectively. The X-ray crystal structures of 1-3 show a square planar metal ion coordinated to two N-heterocyclic carbenes and two phenolate moieties. The cyclic voltammetry curves of complexes 1-3 show two reversible oxidation waves in the range 0.11-0.21 V ( E1/21) and 0.55-0.65 V ( E1/22) vs Fc+/Fc, which are assigned to the successive oxidations of the phenolate moieties. One-electron oxidation affords mononuclear ( S = 1/2) systems. Complex 1+·SbF6- was remarkably stable, and its structure was characterized. The coordination sphere is slightly dissymmetric, while the typical patterns of phenoxyl radicals were observed within the ligand framework. Complex 1+ exhibits a rhombic signal at g = 2.087, 2.016, and 1.992, confirming its predominant phenoxyl radical character. The g-values are slightly smaller for 2+ (2.021, 2.008, and 1.983) and larger for 3+ (2.140, 1.999, and 1.885) yet consistent with phenoxyl radical species. The electronic spectra of 1+-3+ display an intervalence charge-transfer (IVCT) transition at 2396, 2600, and 2294 nm, respectively. Its intensity supports the description of cations 1+ and 3+ as mixed-valent (Class II/III) compounds according to the Robin Day classification. Complex 2+ behaves as a mixed-valent class II radical compound. In the presence of pyridine, radical species 1+ is successively converted into stable mono and bis(adducts), which are both Ni(III) complexes. Dications 1+2-3+2 were prepared electrochemically. They are electron paramagnetic resonance (EPR)-silent and do not show IVCT transition in their NIR spectra, consistent with a bis(radical) formulation. The proposed electronic structures are fully supported by density functional theory calculations.
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Affiliation(s)
- Romain Kunert
- Université Grenoble Alpes , UMR CNRS-5250, Département de Chimie Moléculaire , Grenoble F-38000 , France
| | - Christian Philouze
- Université Grenoble Alpes , UMR CNRS-5250, Département de Chimie Moléculaire , Grenoble F-38000 , France
| | - Olivier Jarjayes
- Université Grenoble Alpes , UMR CNRS-5250, Département de Chimie Moléculaire , Grenoble F-38000 , France
| | - Fabrice Thomas
- Université Grenoble Alpes , UMR CNRS-5250, Département de Chimie Moléculaire , Grenoble F-38000 , France
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30
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van der Vlugt JI. Radical-Type Reactivity and Catalysis by Single-Electron Transfer to or from Redox-Active Ligands. Chemistry 2019; 25:2651-2662. [PMID: 30084211 PMCID: PMC6471147 DOI: 10.1002/chem.201802606] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Indexed: 12/12/2022]
Abstract
Controlled ligand-based redox-activity and chemical non-innocence are rapidly gaining importance for selective (catalytic) processes. This Concept aims to provide an overview of the progress regarding ligand-to-substrate single-electron transfer as a relatively new mode of operation to exploit ligand-centered reactivity and catalysis based thereon.
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Affiliation(s)
- Jarl Ivar van der Vlugt
- Bio-Inspired Homogeneous and Supramolecular Catalysis Groupvan ‘t Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 9041098 XHAmsterdamNetherlands
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31
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Baltrun M, Watt FA, Schoch R, Wölper C, Neuba AG, Hohloch S. A new bis-phenolate mesoionic carbene ligand for early transition metal chemistry. Dalton Trans 2019; 48:14611-14625. [DOI: 10.1039/c9dt03099a] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A new chelating mesoionic carbene ligand, derived from 1,2,3-triazoles, with two redox-active tert-butyl-phenolate linkers has been synthesized and explored towards its reactivity and electrochemical properties in early transition metal chemistry.
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Affiliation(s)
- Marc Baltrun
- Universität Paderborn
- Fakultät für Naturwissenschaften
- Department Chemie Warburger Straße 100
- 33098 Paderborn
- Germany
| | - Fabian A. Watt
- Universität Paderborn
- Fakultät für Naturwissenschaften
- Department Chemie Warburger Straße 100
- 33098 Paderborn
- Germany
| | - Roland Schoch
- Universität Paderborn
- Fakultät für Naturwissenschaften
- Department Chemie Warburger Straße 100
- 33098 Paderborn
- Germany
| | | | - Adam G. Neuba
- Universität Paderborn
- Fakultät für Naturwissenschaften
- Department Chemie Warburger Straße 100
- 33098 Paderborn
- Germany
| | - Stephan Hohloch
- Universität Paderborn
- Fakultät für Naturwissenschaften
- Department Chemie Warburger Straße 100
- 33098 Paderborn
- Germany
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32
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Abstract
In this invited Perspective, recent developments and possible future directions of research on photoactive coordination compounds made from nonprecious transition metal elements will be discussed. The focus is on conceptually new, structurally well-characterized complexes with excited-state lifetimes between 10 ps and 1 ms in fluid solution for possible applications in photosensitizing, light-harvesting, luminescence and catalysis. The key metal elements considered herein are Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, W and Ce in various oxidation states equipped with diverse ligands, giving access to long-lived excited states via a range of fundamentally different types of electronic transitions. Research performed in this area over the past five years demonstrated that a much broader spectrum of metal complexes than what was long considered relevant exhibits useful photophysics and photochemistry.
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Affiliation(s)
- Oliver S Wenger
- Department of Chemistry , University of Basel , St. Johanns-Ring 19 , 4056 Basel , Switzerland
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33
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Kuhlmann L, Methling R, Simon J, Neumann B, Stammler HG, Strassert CA, Mitzel NW. Fluorescent phenoxy benzoxazole complexes of zirconium and hafnium: synthesis, structure and photo-physical behaviour. Dalton Trans 2018; 47:11245-11252. [PMID: 30058654 DOI: 10.1039/c8dt01757c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A series of ten heteroleptic and homoleptic mononuclear Zr(iv) and Hf(iv) complexes bearing differently substituted phenoxy-benzoxazole ligands was synthesised. The complexes were characterised by 1H and 13C{1H} NMR spectroscopy as well as by elemental analyses and X-ray diffraction experiments. The molecular structures show octahedral or tetragonal-antiprismatic coordination motifs at the metal atom. The crystal packing patterns depend on the substitution of the ligands. The intermolecular interactions in the solid state are governed by weak π-π interactions, and are also dependent on the ligand structure. Photo-physical investigations reveal that all ten complexes show a ligand-centered fluorescence with emission maxima in the blue region of the electromagnetic spectrum.
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Affiliation(s)
- Lisa Kuhlmann
- Fakultät für Chemie, Lehrstuhl für Anorganische Chemie und Strukturchemie (ACS), Centrum für molekulare Materialien CM2, Universität Bielefeld, Universitätsstraße 25, D-33615 Bielefeld, Germany.
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34
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Zhang Y, Lee TS, Petersen JL, Milsmann C. A Zirconium Photosensitizer with a Long-Lived Excited State: Mechanistic Insight into Photoinduced Single-Electron Transfer. J Am Chem Soc 2018; 140:5934-5947. [PMID: 29671586 DOI: 10.1021/jacs.8b00742] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Time-resolved emission spectroscopy for the luminescent zirconium complex Zr(MePDP)2 (MePDP = 2,6-bis(5-methyl-3-phenyl-1 H-pyrrol-2-yl)pyridine) revealed a long-lived excited state with a lifetime τ = 325 ± 10 μs. Computational studies using time-dependent density functional theory were conducted to identify the nature of the luminescent excited state as a mixed triplet intraligand/ligand-to-metal charge-transfer state. Stern-Volmer experiments showed a strong dependence of the quenching rate on the redox potential of the quencher indicating photoinduced single-electron transfer (SET) as the quenching pathway. Mechanistic investigations of the photocatalytic homocoupling of benzyl bromide allowed the detection of organic radical intermediates during turnover and provided further evidence for SET mediated by Zr(MePDP)2. Isolation of the one-electron-reduced form of the photosensitizer, [Zr(MePDP)2]-, enabled studies of its electronic structure by a combination of experimental and computational techniques and confirmed its role as a strong reductant. Additionally, the role of the benzimidazolium hydride derivatives as two-electron sacrificial reductants during photoredox catalysis was investigated. In combination, the results presented in this report establish a detailed mechanistic picture of a photoredox catalytic reaction promoted by an earth-abundant early transition metal photosensitizer.
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Affiliation(s)
- Yu Zhang
- C. Eugene Bennett Department of Chemistry , West Virginia University , Morgantown , West Virginia 26506 , United States
| | - Tia S Lee
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , United States
| | - Jeffrey L Petersen
- C. Eugene Bennett Department of Chemistry , West Virginia University , Morgantown , West Virginia 26506 , United States
| | - Carsten Milsmann
- C. Eugene Bennett Department of Chemistry , West Virginia University , Morgantown , West Virginia 26506 , United States
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35
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Li M, Shu X, Cai Z, Eisen MS. Synthesis, Structures, and Norbornene Polymerization Behavior of Neutral Nickel(II) and Palladium(II) Complexes Bearing Aryloxide Imidazolidin-2-imine Ligands. Organometallics 2018. [DOI: 10.1021/acs.organomet.8b00059] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Mingyuan Li
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, People’s Republic of China
| | - Xin Shu
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, People’s Republic of China
| | - Zhengguo Cai
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, People’s Republic of China
| | - Moris S. Eisen
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa, 32000, Israel
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36
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Hameury S, de Frémont P, Braunstein P. Metal complexes with oxygen-functionalized NHC ligands: synthesis and applications. Chem Soc Rev 2018; 46:632-733. [PMID: 28083579 DOI: 10.1039/c6cs00499g] [Citation(s) in RCA: 150] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Ligand design has met with considerable success with both categories of hybrid ligands, which are characterized by chemically different donor groups, and of N-heterocyclic carbenes (NHCs). Their spectacular development and diversity are attracting worldwide interest and offers almost unlimited diversity and potential in e.g. coordination/organometallic main group and transition metal chemistry, catalysis, medicinal chemistry and materials science. This review aims at providing a comprehensive update on a specific class of ligands that has enjoyed much attention in the past few years, at the intersection between the two categories mentioned above, that of hybrid NHC ligands in which the functionality associated with the carbene donor is of the oxygen-donor type. For each type of oxygen-donor present in such chelating (Section 1) or bridging (Section 2) hybrid ligands, we will examine the synthesis, structures and reactivity of their metal complexes and their applications, with a special focus on homogeneous catalysis (Section 3). Thus, hydrogenation, C-H bond activation, C-C, C-N, C-O bond formation, hydrolysis of silanes, oligomerization, polymerization, metathesis, hydrosilylation, C-C bond cleavage, acceptorless dehydrogenation, dehalogenation/hydrogen transfer, oxidation and reduction reactions will be successively presented in a tabular manner, to facilitate an overview and a rapid identification of the relevant publications describing which metals associated with a given oxygen functionality are most suitable. The literature coverage includes the year 2015.
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Affiliation(s)
- Sophie Hameury
- Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Chimie de Coordination, 4 rue Blaise Pascal, 67081 Strasbourg, France. and Universität Freiburg, Makromolekulare Chemie, Stefan-Meier-Str. 31, 79104 Freiburg, Germany
| | - Pierre de Frémont
- Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Chimie de Coordination, 4 rue Blaise Pascal, 67081 Strasbourg, France. and Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Synthèse, Réactivité et Catalyse Organométalliques, 4 rue Blaise Pascal, 67081 Strasbourg, France
| | - Pierre Braunstein
- Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Chimie de Coordination, 4 rue Blaise Pascal, 67081 Strasbourg, France.
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37
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Garden JA, White AJP, Williams CK. Heterodinuclear titanium/zinc catalysis: synthesis, characterization and activity for CO 2/epoxide copolymerization and cyclic ester polymerization. Dalton Trans 2018; 46:2532-2541. [PMID: 28154848 DOI: 10.1039/c6dt04193k] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The preparation of heterodinuclear complexes, especially those comprising early-late transition metals coordinated by a simple or symmetrical ancillary ligand, represents a fundamental challenge and an opportunity to prepare catalysts benefitting from synergic properties. Here, two new mixed titanium(iv)-zinc(ii) complexes, [LTi(OiPr)2ZnEt] and [LTi(OiPr)2ZnPh], both coordinated by a diphenolate tetra(amine) macrocyclic ligand (L), are prepared. The synthesis benefits from the discovery that reaction of the ligand with a single equivalent of titanium tetrakis(iso-propoxide) allows the efficient formation of a mono-Ti(iv) complex, [LTi(OiPr)2]. All new complexes are characterized by a combination of single crystal X-ray diffraction, multinuclear NMR spectroscopy and mass spectrometry techniques. The two heterobimetallic complexes, [LTi(OiPr)2ZnEt] and [LTi(OiPr)2ZnPh], feature trianionic coordination by the macrocyclic ligand and bridging alkoxide groups coordinate to both the different metal centres. The heterodinuclear catalysts are compared to the mono-titanium analogue, [LTi(OiPr)2], in various polymerization reactions. In the alternating copolymerizations of carbon dioxide and cyclohexene oxide, the mono-titanium complex is totally inactive whilst the heterodinuclear complexes show moderate activity (TOF = 3 h-1); it should be noted the activity is measured using just 1 bar pressure of carbon dioxide. In the ring opening polymerization of lactide and ε-caprolactone, the mono-Ti(iv) complex is totally inactive whilst the heterodinuclear complexes show moderate-high activities, qualified by comparison to other known titanium polymerization catalysts (l-lactide, kobs = 11 × 10-4 s-1 at 70 °C, 1 M in [lactide]) and ε-caprolactone (kobs = 5 × 10-4 s-1 at 70 °C, 0.9 M in [ε-caprolactone]).
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Affiliation(s)
- Jennifer A Garden
- EastCHEM School of Chemistry, Joseph Black Building, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, UK
| | - Andrew J P White
- Department of Chemistry, Imperial College London, London, SW7 2AZ, UK
| | - Charlotte K Williams
- Chemistry Research Laboratory, 12 Mansfield Road, University of Oxford, Oxford, OX1 3TA, UK.
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38
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Lalrempuia R, Breivik F, Törnroos KW, Le Roux E. Coordination behavior of bis-phenolate saturated and unsaturated N-heterocyclic carbene ligands to zirconium: reactivity and activity in the copolymerization of cyclohexene oxide with CO 2. Dalton Trans 2018; 46:8065-8076. [PMID: 28604887 DOI: 10.1039/c7dt01117b] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Tetravalent zirconium complexes supported by tridentate bis-phenolate imidazolidin-2-ylidene (L1), imidazol-2-ylidene (L2) and benzimidazol-2-ylidene (L3) NHC ligands were synthesized and evaluated as precursors for the copolymerization of cyclohexene oxide (CHO) with CO2. While the reactivity of the imidazolidinium [H3L1] chloride salt with Zr(OiPr)4(HOiPr), and subsequent ligand exchanges with either (CH3)3SiCl or LiOiPr lead to a series of heteroleptic compounds (κ3-O,C,O-L1)Zr(X)2(THF) (X = Cl, OiPr), both imidazolium [H3L2] and benzimidazolium [H3L3] chloride salts give a mixture of homoleptic (κ3-O,C,O-NHC)2Zr and zwitterionic (κ2-O,O-HL)ZrCl2(OiPr) compounds along with traces or the absence of the heteroleptic intermediate (κ3-O,C,O-NHC)Zr(Cl)(OiPr)(THF). Such dissimilar reactivity between the unsaturated and saturated NHC ligands is predominantly ascribed to the increased acidity of azolium salts along with the π-donor strength of the Ccarbene in L2 and L3-Zr moieties. The reactivity with the more acidic azolium salts (H3L2/3) and the destabilized Zr-Xtrans to NHCcarbene bond results in a significant increase in the amount of homoleptic compounds generating HCl. The released HCl reacts preferentially with the heteroleptic intermediates having non-planar NHC ligands (i.e. L2/3) promoting the formation of zwitterionic complexes. The in situ deprotonation of the isolated zwitterionic (κ2-O,O-HL3)ZrCl2(OiPr) compound by using Ag2O gives the homoleptic complex as the major component along with a bimetallic hydroxo-bridged [(κ3-O,C,O-L3)Zr(μ-OH)(OiPr)]2 compound. Of particular interest is that only the heteroleptic NHC-Zr(iv) complexes were identified to be active and highly selective towards the copolymerization of CHO with CO2 independently of the co-catalysts used (both anionic and neutral) under mild conditions (PCO2 < 1 bar, T = 60 °C), and gave atactic and completely alternating copolymers in a controlled manner (Mw/Mn ≈ 1.3-1.8). In contrast, the isolated homoleptic, zwitterionic and bimetallic zirconium species were found to be inactive under similar reaction conditions. Although the activity found for NHC-Zr(iv) complexes is nearly of the same order of magnitude as that of the NHC-Ti(iv) analogues, these results are the first examples of tetravalent zirconium complexes achieving high selectivity (99% in PCHC) in the catalyzed copolymerization of CHO with CO2.
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Affiliation(s)
- Ralte Lalrempuia
- University of Bergen, Department of Chemistry, Allégaten 41, N-5007, Bergen, Norway.
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39
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Ruamps M, Bastin S, Rechignat L, Sournia-Saquet A, Valyaev DA, Mouesca JM, Lugan N, Maurel V, César V. Unveiling the redox-active character of imidazolin-2-thiones derived from amino-substituted N-heterocyclic carbenes. Chem Commun (Camb) 2018; 54:7653-7656. [DOI: 10.1039/c8cc03934h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Spectroscopic, structural and computational studies on the amino-substituted imidazolin-2-thiones reveal the imidazolyl ring to be redox active.
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Affiliation(s)
- Mirko Ruamps
- LCC-CNRS, Université de Toulouse
- INPT
- UPS
- 31077 Toulouse cedex 4
- France
| | - Stéphanie Bastin
- LCC-CNRS, Université de Toulouse
- INPT
- UPS
- 31077 Toulouse cedex 4
- France
| | - Lionel Rechignat
- LCC-CNRS, Université de Toulouse
- INPT
- UPS
- 31077 Toulouse cedex 4
- France
| | | | | | | | - Noël Lugan
- LCC-CNRS, Université de Toulouse
- INPT
- UPS
- 31077 Toulouse cedex 4
- France
| | | | - Vincent César
- LCC-CNRS, Université de Toulouse
- INPT
- UPS
- 31077 Toulouse cedex 4
- France
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40
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Harris CF, Bayless MB, van Leest NP, Bruch QJ, Livesay BN, Bacsa J, Hardcastle KI, Shores MP, de Bruin B, Soper JD. Redox-Active Bis(phenolate) N-Heterocyclic Carbene [OCO] Pincer Ligands Support Cobalt Electron Transfer Series Spanning Four Oxidation States. Inorg Chem 2017; 56:12421-12435. [DOI: 10.1021/acs.inorgchem.7b01906] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Caleb F. Harris
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Michael B. Bayless
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Nicolaas P. van Leest
- Van ’t Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam (UvA), Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Quinton J. Bruch
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Brooke N. Livesay
- Department of Chemistry, Colorado State University, Fort
Collins, Colorado 80523-1872, United States
| | - John Bacsa
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
- X-ray Crystallography Center, Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - Kenneth I. Hardcastle
- X-ray Crystallography Center, Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - Matthew P. Shores
- Department of Chemistry, Colorado State University, Fort
Collins, Colorado 80523-1872, United States
| | - Bas de Bruin
- Van ’t Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam (UvA), Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Jake D. Soper
- School of Chemistry
and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
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41
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Khalil G, Orvain C, Fang L, Barloy L, Chaumont A, Gaiddon C, Henry M, Kyritsakas N, Mobian P. Monomeric Ti(iv)-based complexes incorporating luminescent nitrogen ligands: synthesis, structural characterization, emission spectroscopy and cytotoxic activities. Dalton Trans 2016; 45:19072-19085. [DOI: 10.1039/c6dt03477b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Novel photoluminescent 2,2′-bipyrimidine ligands and their titanium(iv) complexes are cytotoxic.
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Affiliation(s)
- Georges Khalil
- Laboratoire de Chimie Moléculaire de l'Etat Solide
- UMR 7140 UDS-CNRS
- Université de Strasbourg
- F-67000 Strasbourg
- France
| | - Christophe Orvain
- Laboratoire des “Mécanismes moléculaires de la réponse au stress et pathologies”
- Strasbourg
- France
- Département Cancer
- Fédération de Médecine Translationnelle de Strasbourg
| | - Lu Fang
- Laboratoire de Chimie Moléculaire de l'Etat Solide
- UMR 7140 UDS-CNRS
- Université de Strasbourg
- F-67000 Strasbourg
- France
| | - Laurent Barloy
- Laboratoire de Chimie Moléculaire de l'Etat Solide
- UMR 7140 UDS-CNRS
- Université de Strasbourg
- F-67000 Strasbourg
- France
| | - Alain Chaumont
- Laboratoire de Chimie Moléculaire de l'Etat Solide
- UMR 7140 UDS-CNRS
- Université de Strasbourg
- F-67000 Strasbourg
- France
| | - Christian Gaiddon
- Laboratoire des “Mécanismes moléculaires de la réponse au stress et pathologies”
- Strasbourg
- France
- Département Cancer
- Fédération de Médecine Translationnelle de Strasbourg
| | - Marc Henry
- Laboratoire de Chimie Moléculaire de l'Etat Solide
- UMR 7140 UDS-CNRS
- Université de Strasbourg
- F-67000 Strasbourg
- France
| | - Nathalie Kyritsakas
- Laboratoire de Tectonique Moléculaire
- UMR 7140 UDS-CNRS
- Université de Strasbourg
- F-67000 Strasbourg
- France
| | - Pierre Mobian
- Laboratoire de Chimie Moléculaire de l'Etat Solide
- UMR 7140 UDS-CNRS
- Université de Strasbourg
- F-67000 Strasbourg
- France
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42
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Loukova GV, Milov AA, Vasiliev VP, Minkin VI. Dipole moments and solvatochromism of metal complexes: principle photophysical and theoretical approach. Phys Chem Chem Phys 2016; 18:17822-6. [DOI: 10.1039/c6cp03348b] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
For metal-based compounds, the ground- and excited-state dipole moments and the difference thereof are obtained both experimentally and theoretically.
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Affiliation(s)
- Galina V. Loukova
- Institute of Problems of Chemical Physics
- Russian Academy of Sciences
- Chernogolovka
- Russian Federation
| | - Alexey A. Milov
- Southern Scientific Center
- Russian Academy of Sciences
- Rostov-on-Don
- Russian Federation
| | - Vladimir P. Vasiliev
- Institute of Problems of Chemical Physics
- Russian Academy of Sciences
- Chernogolovka
- Russian Federation
| | - Vladimir I. Minkin
- Southern Scientific Center
- Russian Academy of Sciences
- Rostov-on-Don
- Russian Federation
- Southern Federal University
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43
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Romain C, Specklin D, Miqueu K, Sotiropoulos JM, Fliedel C, Bellemin-Laponnaz S, Dagorne S. Unusual Benzyl Migration Reactivity in NHC-Bearing Group 4 Metal Chelates: Synthesis, Characterization, and Mechanistic Investigations. Organometallics 2015. [DOI: 10.1021/om501143t] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Charles Romain
- Institut
de chimie de Strasbourg, UMR 7177, CNRS-Université de Strasbourg, 1 rue
Blaise Pascal, F-67000 Strasbourg, France
| | - David Specklin
- Institut
de chimie de Strasbourg, UMR 7177, CNRS-Université de Strasbourg, 1 rue
Blaise Pascal, F-67000 Strasbourg, France
| | - Karinne Miqueu
- Institut
des Sciences Analytiques et de Physico-Chimie pour l’Environnement
et les Matériaux, UMR 5254, Université de Pau et des Pays de l’Adour, Technopôle Hélioparc, 2 avenue du Président Angot, F-64053 Pau cedex 09, France
| | - Jean-Marc Sotiropoulos
- Institut
des Sciences Analytiques et de Physico-Chimie pour l’Environnement
et les Matériaux, UMR 5254, Université de Pau et des Pays de l’Adour, Technopôle Hélioparc, 2 avenue du Président Angot, F-64053 Pau cedex 09, France
| | - Christophe Fliedel
- Institut
de chimie de Strasbourg, UMR 7177, CNRS-Université de Strasbourg, 1 rue
Blaise Pascal, F-67000 Strasbourg, France
| | - Stéphane Bellemin-Laponnaz
- Institut
de Physique et Chimie des Matériaux de Strasbourg UMR 7504, CNRS-Université de Strasbourg, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex
2, France and
| | - Samuel Dagorne
- Institut
de chimie de Strasbourg, UMR 7177, CNRS-Université de Strasbourg, 1 rue
Blaise Pascal, F-67000 Strasbourg, France
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44
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Barbante GJ, Doeven EH, Francis PS, Stringer BD, Hogan CF, Kheradmand PR, Wilson DJD, Barnard PJ. Iridium(iii) N-heterocyclic carbene complexes: an experimental and theoretical study of structural, spectroscopic, electrochemical and electrogenerated chemiluminescence properties. Dalton Trans 2015; 44:8564-76. [DOI: 10.1039/c4dt03378g] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Theoretical and experimental studies of a series of iridium N-heterocyclic carbene complexes.
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Affiliation(s)
- Gregory J. Barbante
- Centre for Chemistry and Biotechnology
- School of Life and Environmental Sciences
- Faculty of Science
- Engineering and Built Environment
- Deakin University
| | - Egan H. Doeven
- Centre for Chemistry and Biotechnology
- School of Life and Environmental Sciences
- Faculty of Science
- Engineering and Built Environment
- Deakin University
| | - Paul S. Francis
- Centre for Chemistry and Biotechnology
- School of Life and Environmental Sciences
- Faculty of Science
- Engineering and Built Environment
- Deakin University
| | - Bradley D. Stringer
- Department of Chemistry
- La Trobe Institute for Molecular Science
- La Trobe University
- Melbourne
- Australia
| | - Conor F. Hogan
- Department of Chemistry
- La Trobe Institute for Molecular Science
- La Trobe University
- Melbourne
- Australia
| | - Peyman R. Kheradmand
- Department of Chemistry
- La Trobe Institute for Molecular Science
- La Trobe University
- Melbourne
- Australia
| | - David J. D. Wilson
- Department of Chemistry
- La Trobe Institute for Molecular Science
- La Trobe University
- Melbourne
- Australia
| | - Peter J. Barnard
- Department of Chemistry
- La Trobe Institute for Molecular Science
- La Trobe University
- Melbourne
- Australia
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45
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Zhang M, Zhang J, Ni X, Shen Z. Bis(phenolate) N-heterocyclic carbene rare earth metal complexes: synthesis, characterization and applications in the polymerization of n-hexyl isocyanate. RSC Adv 2015. [DOI: 10.1039/c5ra16447h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Polyhexyl isocyanantes catalyzed by N-heterocyclic carbene rare earth metal complexes show high molecular weight with narrow molecular weight distribution.
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Affiliation(s)
- Min Zhang
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization
- Department of Polymer Science and Engineering
- Zhejiang University
- Hangzhou 310027
- China
| | - Jingjing Zhang
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization
- Department of Polymer Science and Engineering
- Zhejiang University
- Hangzhou 310027
- China
| | - Xufeng Ni
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization
- Department of Polymer Science and Engineering
- Zhejiang University
- Hangzhou 310027
- China
| | - Zhiquan Shen
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization
- Department of Polymer Science and Engineering
- Zhejiang University
- Hangzhou 310027
- China
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46
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Zhang D, Zi G. N-heterocyclic carbene (NHC) complexes of group 4 transition metals. Chem Soc Rev 2015; 44:1898-921. [DOI: 10.1039/c4cs00441h] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This review summarizes the progress in the synthesis and catalytic activity of group 4 NHC–metal complexes.
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Affiliation(s)
- Dao Zhang
- Department of Chemistry
- Fudan University
- Shanghai 200433
- China
| | - Guofu Zi
- Department of Chemistry
- Beijing Normal University
- Beijing 100875
- China
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47
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Bellemin-Laponnaz S, Dagorne S. Group 1 and 2 and early transition metal complexes bearing N-heterocyclic carbene ligands: coordination chemistry, reactivity, and applications. Chem Rev 2014; 114:8747-74. [PMID: 25144918 DOI: 10.1021/cr500227y] [Citation(s) in RCA: 251] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Stéphane Bellemin-Laponnaz
- IPCMS (Institut de Physique et Chimie des Matériaux de Strasbourg), CNRS-Université de Strasbourg , 23 rue du Loess BP 43, F-67034 Strasbourg, France
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