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Chang X, Arnold ME, Blinder R, Zolg J, Wischnat J, van Slageren J, Jelezko F, Kuehne AJC, von Delius M. A Stable Chichibabin Diradicaloid with Near-Infrared Emission. Angew Chem Int Ed Engl 2024; 63:e202404853. [PMID: 38695271 DOI: 10.1002/anie.202404853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Indexed: 06/21/2024]
Abstract
Conjugated molecules with multiple radical centers such as the iconic Chichibabin diradicaloid hold promise as building blocks in materials for quantum sensing and quantum information processing. However, it is a considerable challenge to design simple analogues of the Chichibabin hydrocarbon that are chemically inert, exhibit high diradical character and emit light at a distinct wavelength that may offer an optical readout of the spin state in functional ensembles. Here we describe the serendipitous discovery of the stable TTM-TTM diradicaloid, which exhibits high diradical character, a striking sky-blue color and near-infrared (NIR) emission (in solution). This combination of properties is unique among related diradicaloids and is due to the presence of hydrogen and chlorine atoms in "just the right positions", allowing a perfectly planar, yet predominantly benzenoid bridge to connect the two sterically stabilized radical centers. In-depth studies of the optical and magnetic properties suggest that this structural motif could become a mainstay building block of organic spin materials.
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Affiliation(s)
- Xingmao Chang
- Institute of Organic Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Mona E Arnold
- Institute of Macromolecular and Organic Chemistry and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Rémi Blinder
- Institute of Quantum Optics and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Julia Zolg
- Institute of Macromolecular and Organic Chemistry and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Jonathan Wischnat
- Institut für Physikalische Chemie and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Joris van Slageren
- Institut für Physikalische Chemie and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Fedor Jelezko
- Institute of Quantum Optics and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Alexander J C Kuehne
- Institute of Macromolecular and Organic Chemistry and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Max von Delius
- Institute of Organic Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
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2
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Steffenfauseweh H, Vishnevskiy YV, Neumann B, Stammler HG, de Bruin B, Ghadwal RS. N-Heterocyclic Carbene Analogues of Wittig Hydrocarbon. Chemistry 2024; 30:e202400879. [PMID: 38437163 DOI: 10.1002/chem.202400879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Accepted: 03/04/2024] [Indexed: 03/06/2024]
Abstract
N-Heterocyclic carbene (NHC) analogues of Wittig hydrocarbon, [(NHC)(Stil)(NHC)] (3a-c) (NHC = SIPr (1a) = C[N(Dipp)CH2]2, Dipp = 2,6-iPr2C6H3; IPr (1b) = C[N(Dipp)CH]2; Me-IPr (1c) = C[N(Dipp)CMe]2 and Stil = C6H4CHCHC6H4) have been reported as crystalline solids. 3a-c are prepared by two-electron reductions of the corresponding bis-1,3-imidazoli(ni)um bromides [(NHC)(Stil)NHC)](Br)2 (2a-c) with KC8 in >94 % yields. 2a-c are accessible by the nickel catalyzed direct C-C coupling of NHCs (1a-c) with (E)-4,4'-dibromostilbene. One-electron oxidation of 3a,b yields the corresponding radical cations [(NHC)(Stil)NHC)]B(C6F5)4 4a,b. All compounds have been characterized by UV-Vis/NMR/EPR spectroscopy as well as 2a, 3a, and 3b by single crystal X-ray diffraction. The electronic structures of representative systems have been analyzed by quantum chemical calculations.
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Affiliation(s)
- Henric Steffenfauseweh
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Yury V Vishnevskiy
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Hans-Georg Stammler
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
| | - Bas de Bruin
- University of Amsterdam (UvA), Faculty of Science, Van 't Hoff Institute for Molecular Sciences (HIMS), Homogeneous and Supramolecular Catalysis Group, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Rajendra S Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615, Bielefeld, Germany
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3
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Hou P, Peschtrich S, Feuerstein W, Schoch R, Hohloch S, Breher F, Paradies J. Imidazolyl-Substituted Benzo- and Naphthodithiophenes as Precursors for the Synthesis of Transient Open-Shell Quinoids. ChemistryOpen 2023; 12:e202300003. [PMID: 36703547 PMCID: PMC10661821 DOI: 10.1002/open.202300003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 01/09/2023] [Indexed: 01/28/2023] Open
Abstract
The synthesis of three novel imidazolyl-substituted sulfur-containing heteroacenes is reported. These heteroacenes consisting of annelated benzo- and naphthothiophenes serve as precursors for the generation of open-shell quinoid heteroacenes by oxidation with alkaline ferric cyanide. Spectroscopic and computational experiments support the formation of reactive open-shell quinoids, which, however, quickly produce paramagnetic polymeric material.
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Affiliation(s)
- Peng Hou
- Chemistry DepartmentPaderborn UniversityWarburger Strasse 10033098PaderbornGermany
| | - Sebastian Peschtrich
- Chemistry DepartmentPaderborn UniversityWarburger Strasse 10033098PaderbornGermany
| | - Wolfram Feuerstein
- Institute of Inorganic ChemistryKarlsruhe Institute of Technology (KIT)Engesserstraße 1576131KarlsruheGermany
| | - Roland Schoch
- Chemistry DepartmentPaderborn UniversityWarburger Strasse 10033098PaderbornGermany
| | - Stephan Hohloch
- Department of General, Inorganic and Theoretical ChemistryUniversity of InnsbruckInnrain 80–826020InnsbruckAustria
| | - Frank Breher
- Institute of Inorganic ChemistryKarlsruhe Institute of Technology (KIT)Engesserstraße 1576131KarlsruheGermany
| | - Jan Paradies
- Chemistry DepartmentPaderborn UniversityWarburger Strasse 10033098PaderbornGermany
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4
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Ghadwal RS. 1,3-Imidazole-Based Mesoionic Carbenes and Anionic Dicarbenes: Pushing the Limit of Classical N-Heterocyclic Carbenes. Angew Chem Int Ed Engl 2023; 62:e202304665. [PMID: 37132480 DOI: 10.1002/anie.202304665] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 05/02/2023] [Accepted: 05/03/2023] [Indexed: 05/04/2023]
Abstract
Classical N-heterocyclic carbenes (NHCs) featuring the carbene center at the C2-position of 1,3-imidazole framework (i.e. C2-carbenes) are well acknowledged as very versatile neutral ligands in molecular as well as in materials sciences. The efficiency and success of NHCs in diverse areas is essentially attributed to their persuasive stereoelectronics, in particular the potent σ-donor property. The NHCs with the carbene center at the unusual C4 (or C5) position, the so-called abnormal NHCs (aNHCs) or mesoionic carbenes (iMICs), are however superior σ-donors than C2-carbenes. Hence, iMICs have substantial potential in sustainable synthesis and catalysis. The main obstacle in this direction is rather demanding synthetic accessibility of iMICs. The aim of this review article is to highlight recent advances, particularly by the author's research group, in accessing stable iMICs, quantifying their properties, and exploring their applications in synthesis and catalysis. In addition, the synthetic viability and use of vicinal C4,C5-anionic dicarbenes (ADCs), also based on an 1,3-imidazole framework, are presented. As will be apparent on following pages, iMICs and ADCs hold potentials in pushing the limit of classical NHCs by enabling access to conceptually new main-group heterocycles, radicals, molecular catalysts, ligands sets, and more.
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Affiliation(s)
- Rajendra S Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, 33615, Bielefeld, Germany
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5
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Abstract
Heteroatom-centered diradical(oid)s have been in the focus of molecular main group chemistry for nearly 30 years. During this time, the diradical concept has evolved and the focus has shifted to the rational design of diradical(oid)s for specific applications. This review article begins with some important theoretical considerations of the diradical and tetraradical concept. Based on these theoretical considerations, the design of diradical(oid)s in terms of ligand choice, steric, symmetry, electronic situation, element choice, and reactivity is highlighted with examples. In particular, heteroatom-centered diradical reactions are discussed and compared with closed-shell reactions such as pericyclic additions. The comparison between closed-shell reactivity, which proceeds in a concerted manner, and open-shell reactivity, which proceeds in a stepwise fashion, along with considerations of diradical(oid) design, provides a rational understanding of this interesting and unusual class of compounds. The application of diradical(oid)s, for example in small molecule activation or as molecular switches, is also highlighted. The final part of this review begins with application-related details of the spectroscopy of diradical(oid)s, followed by an update of the heteroatom-centered diradical(oid)s and tetraradical(oid)s published in the last 10 years since 2013.
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Affiliation(s)
- Alexander Hinz
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Jonas Bresien
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
| | - Frank Breher
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Axel Schulz
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
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6
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Kundu G, Dash SR, Kumar R, Vanka K, Ghosh A, Sen SS. Enhancing Diradical Character of Chichibabin's Hydrocarbon through Fluoride Substitution. Chempluschem 2023; 88:e202300273. [PMID: 37409641 DOI: 10.1002/cplu.202300273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 07/04/2023] [Accepted: 07/06/2023] [Indexed: 07/07/2023]
Abstract
In this work, 5-SIDipp [SIDipp=1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene] (1) derived Chichibabin's hydrocarbon with an octafluorobiphenylene spacer (3) has been reported. The addition of two equivalents of 5-SIDipp with decafluorobiphenyl in presence of BF3 gives the double C-F bond activated imidazolium salt with two tetrafluoroborate anions, 2. Further reduction of 2 gives the fluorine substituted 5-SIDipp based Chichibabin's hydrocarbon, 3. Quantum chemical calculations suggested a singlet state of 3 with a singlet-triplet energy gap (ΔES-T ) of 3.7 kcal mol-1 , which is substantially lower with respect to the hydrogen substituted NHC-based Chichibabin's hydrocarbons (10.7 kcal mol-1 , B3LYP). As a result, the diradical character (y) of 3 (y=0.62) is also noticeably higher than the hydrogen substituted CHs (y=0.41-0.43). The ▵ES-T was found to be higher in CASSCF (22.24 kcal mol-1 ) and CASPT2 (11.17 kcal mol-1 ) for 3 and the diradical character (d) is 44.6 %.
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Affiliation(s)
- Gargi Kundu
- Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road Pashan, Pune, 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Soumya Ranjan Dash
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road Pashan, Pune, 411008, India
| | - Ravi Kumar
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road Pashan, Pune, 411008, India
| | - Kumar Vanka
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road Pashan, Pune, 411008, India
| | - Aryya Ghosh
- Department of Chemistry, Ashoka University, Sonipat, Haryana, 131029, India
| | - Sakya S Sen
- Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road Pashan, Pune, 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
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7
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Karak P, Mandal SK, Choudhury J. Bis-Imidazolium-Embedded Heterohelicene: A Regenerable NADP + Cofactor Analogue for Electrocatalytic CO 2 Reduction. J Am Chem Soc 2023; 145:7230-7241. [PMID: 36944228 DOI: 10.1021/jacs.2c12883] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
Biomimetic NAD(P)H-type organic hydride donors have recently been advocated as potential candidates to act as metal-free catalysts for fuel-forming reactions such as the reduction of CO2 to formic acid and methanol, similar to the natural photosynthesis process of fixing CO2 into carbohydrates. Although these artificial synthetic organic hydrides are extensively used in organic reduction chemistry in a stoichiometric manner, translating them into catalysts has been challenging due to problems associated with the regeneration of these hydride species under applied reaction conditions. A recent discovery of the possibility of their regeneration under electrochemical conditions via a proton-coupled electron-transfer pathway triggered intense research to accomplish their catalytic use in electrochemical CO2 reduction reactions (eCO2RR). However, success is yet to be realized to term them as "true" catalysts, as the typical turnover numbers (TONs) of the eCO2RR processes on inert electrodes for the production of formic acid and/or methanol reported so far are still in the order of 10-3-10-2; thus, sub-stoichiometric only! Herein, we report a novel class of structurally engineered heterohelicene-based organic hydride donor with a proof-of-principle demonstration of catalytic electrochemical CO2 reduction reaction showing a significantly improved activity with more than stoichiometric turnover featuring a 100-1000-fold enhancement of the existing TON values. Mechanistic investigations suggested the critical role of the two cationic imidazolium motifs along with the extensive π-conjugation present in the backbone of the heterohelicene molecules in accessing and stabilizing various radical species involved in the generation and transfer of hydride, via multielectron-transfer steps in the electrochemical process.
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Affiliation(s)
- Pirudhan Karak
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal 462 066, India
| | - Sanajit Kumar Mandal
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal 462 066, India
| | - Joyanta Choudhury
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal 462 066, India
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8
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Song H, Lee E. Revisiting the Reaction of IPr with Tritylium: An Alternative Mechanistic Pathway. Chemistry 2023; 29:e202203364. [PMID: 36445754 DOI: 10.1002/chem.202203364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 11/29/2022] [Accepted: 11/29/2022] [Indexed: 11/30/2022]
Abstract
Despite a recent proposal on the mechanism of a single-electron transfer (SET) process between tritylium and 2,6-bis(diisopropylphenyl)imidazol-2-ylidene (IPr) based on evidence of transient IPr radical cation intermediate ([IPr]⋅+ ) formation, such oxidation is still contentious because of the high oxidation potential of N-heterocyclic carbenes. Our experimental analysis indicates that the appearance of deep purple color, previously considered to be from transient [IPr]⋅+ , originates from a zwitterionic intermediate (3 a), not a radical cation. Here, we propose an alternative mechanism for the reaction involving tritylium and IPr. This mechanism is noteworthy for explaining how [NHC-H]+ can be generated without the formation of transient [NHC]⋅+ , which has been frequently proposed as an intermediate for the reaction between NHC and oxidants. These results also show that a transient strong single-electron donor (3 a) could be generated by the alternative mechanism for oxidants using NHCs, which is a more feasible explanation for the reactivity of NHCs with oxidants.
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Affiliation(s)
- Hayoung Song
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Eunsung Lee
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea.,Division of Advanced Materials Science, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
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9
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Weiser J, Cui J, Dewhurst RD, Braunschweig H, Engels B, Fantuzzi F. Structure and bonding of proximity-enforced main-group dimers stabilized by a rigid naphthyridine diimine ligand. J Comput Chem 2023; 44:456-467. [PMID: 36054757 DOI: 10.1002/jcc.26994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 08/01/2022] [Accepted: 08/03/2022] [Indexed: 12/31/2022]
Abstract
The development of ligands capable of effectively stabilizing highly reactive main-group species has led to the experimental realization of a variety of systems with fascinating properties. In this work, we computationally investigate the electronic, structural, energetic, and bonding features of proximity-enforced group 13-15 homodimers stabilized by a rigid expanded pincer ligand based on the 1,8-naphthyridine (napy) core. We show that the redox-active naphthyridine diimine (NDI) ligand enables a wide variety of structural motifs and element-element interaction modes, the latter ranging from isolated, element-centered lone pairs (e.g., E = Si, Ge) to cases where through-space π bonds (E = Pb), element-element multiple bonds (E = P, As) and biradical ground states (E = N) are observed. Our results hint at the feasibility of NDI-E2 species as viable synthetic targets, highlighting the versatility and potential applications of napy-based ligands in main-group chemistry.
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Affiliation(s)
- Jonas Weiser
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Physical and Theoretical Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Jingjing Cui
- School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan, People's Republic of China
| | - Rian D Dewhurst
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Holger Braunschweig
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Bernd Engels
- Institute for Physical and Theoretical Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Felipe Fantuzzi
- Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.,School of Chemistry and Forensic Science, University of Kent, Canterbury, UK
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10
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Dai Y, Xie Z, Bao M, Liu C, Su Y. Multiple stable redox states and tunable ground states via the marriage of viologens and Chichibabin's hydrocarbon †. Chem Sci 2023; 14:3548-3553. [PMID: 37006684 PMCID: PMC10056129 DOI: 10.1039/d3sc00102d] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 02/28/2023] [Indexed: 03/30/2023] Open
Abstract
Chichibabin's hydrocarbon and viologens are among the most famous diradicaloids and organic redox systems, respectively. However, each has its own disadvantages: the instability of the former and its charged species, and the closed-shell nature of the neutral species derived from the latter, respectively. Herein, we report that terminal borylation and central distortion of 4,4′-bipyridine allow us to readily isolate the first bis-BN-based analogues (1 and 2) of Chichibabin's hydrocarbon with three stable redox states and tunable ground states. Electrochemically, both compounds exhibit two reversible oxidation processes with wide redox ranges. One- and two-electron chemical oxidations of 1 afford the crystalline radical cation 1˙+ and dication 12+, respectively. Moreover, the ground states of 1 and 2 are tunable with 1 as a closed-shell singlet and the tetramethyl-substituted 2 as an open-shell singlet, the latter of which could be thermally excited to its triplet state because of the small singlet-triplet gap. Herein, we report the isolation of bis-BN-based species 1 and 2 with multiple stable redox states. Their ground states are tunable with 1 as a closed-shell singlet and 2 as an open-shell singlet with a small singlet-triplet gap.![]()
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Affiliation(s)
- Yuyang Dai
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow UniversitySuzhou 215123China
| | - Zhuofeng Xie
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow UniversitySuzhou 215123China
| | - Manling Bao
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow UniversitySuzhou 215123China
| | - Chunmeng Liu
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow UniversitySuzhou 215123China
| | - Yuanting Su
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow UniversitySuzhou 215123China
- State Key Laboratory of Coordination Chemistry, Nanjing UniversityNanjing 210023China
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11
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Steffenfauseweh H, Vishnevskiy YV, Neumann B, Stammler H, Andrada DM, Ghadwal RS. Isolation of an Arsenic Diradicaloid with a Cyclic C 2 As 2 -Core. Angew Chem Int Ed Engl 2022; 61:e202207415. [PMID: 35652361 PMCID: PMC9545666 DOI: 10.1002/anie.202207415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Indexed: 01/08/2023]
Abstract
Herein, we report on the synthesis, characterization, and reactivity studies of the first cyclic C2 As2 -diradicaloid {(IPr)CAs}2 (6) (IPr = C{N(Dipp)CH}2 ; Dipp = 2,6-iPr2 C6 H3 ). Treatment of (IPr)CH2 (1) with AsCl3 affords the Lewis adduct {(IPr)CH2 }AsCl3 (2). Compound 2 undergoes stepwise dehydrochlorination to yield {(IPr)CH}AsCl2 (3) and {(IPr)CAsCl}2 (5 a) or [{(IPr)CAs}2 Cl]OTf (5 b). Reduction of 5 a (or 5 b) with magnesium turnings gives 6 as a red crystalline solid in 90% yield. Compound 6 featuring a planar C2 As2 ring is diamagnetic and exhibits well resolved NMR signals. DFT calculations reveal a singlet ground state for 6 with a small singlet-triplet energy gap of 8.7 kcal mol-1 . The diradical character of 6 amounts to 20% (CASSCF, complete active space self consistent field) and 28% (DFT). Treatments of 6 with (PhSe)2 and Fe2 (CO)9 give rise to {(IPr)CAs(SePh)}2 (7) and {(IPr)CAs}2 Fe(CO)4 (8), respectively.
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Affiliation(s)
- Henric Steffenfauseweh
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstr. 2533615BielefeldGermany
| | - Yury V. Vishnevskiy
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstr. 2533615BielefeldGermany
| | - Beate Neumann
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstr. 2533615BielefeldGermany
| | - Hans‐Georg Stammler
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstr. 2533615BielefeldGermany
| | - Diego M. Andrada
- Faculty of Natural Sciences and TechnologyDepartment of ChemistrySaarland UniversityCampus C4.166123SaarbrückenGermany
| | - Rajendra S. Ghadwal
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstr. 2533615BielefeldGermany
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12
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Steffenfauseweh H, Vishnevskiy YV, Neumann B, Stammler HG, Andrada DM, Ghadwal R. Isolation of an Arsenic Diradicaloid with a Cyclic C2As2‐Core. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202207415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
| | | | - Beate Neumann
- Bielefeld University: Universitat Bielefeld Chemistry GERMANY
| | | | - Diego M. Andrada
- Saarland University: Universitat des Saarlandes Chemistry GERMANY
| | - Rajendra Ghadwal
- Universitat Bielefeld Institut für Anorganische Chemie Universitätstrasse 25 33615 Bielefeld GERMANY
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13
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Maiti A, Elvers BJ, Bera S, Lindl F, Krummenacher I, Ghosh P, Braunschweig H, Yildiz CB, Schulzke C, Jana A. Disclosing Cyclic(Alkyl)(Amino)Carbenes as One-Electron Reductants: Synthesis of Acyclic(Amino)(Aryl)Carbene-Based Kekulé Diradicaloids. Chemistry 2022; 28:e202104567. [PMID: 35262232 PMCID: PMC9321839 DOI: 10.1002/chem.202104567] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Indexed: 11/10/2022]
Abstract
Herein, we disclose cyclic(alkyl)(amino)carbenes (CAACs) to be one-electron reductants under the formation of a transient radical cation as indicated by EPR spectroscopy. The disclosed CAAC reducing reactivity was used to synthesize acyclic(amino)(aryl)carbene-based Thiele and Chichibabin hydrocarbons, a new class of Kekulé diradicaloids. The results demonstrate CAACs to be potent organic reductants. Notably, the acyclic(amino)(aryl)carbene-based Chichibabin's hydrocarbon shows an appreciable population of the triplet state at room temperature, as evidenced by both variable-temperature NMR and EPR spectroscopy.
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Affiliation(s)
- Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046, TelanganaIndia
| | - Benedict J. Elvers
- Institut für BiochemieUniversität GreifswaldFelix-Hausdorff-Straße 417489GreifswaldGermany
| | - Sachinath Bera
- Department of ChemistryRamakrishna Mission Residential College NarendrapurKolkata700103India
- Shahid Matangini Hazra Govt General Degree College for Women TamlukPurba Medinipur721649India
| | - Felix Lindl
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB)Julius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB)Julius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Prasanta Ghosh
- Department of ChemistryRamakrishna Mission Residential College NarendrapurKolkata700103India
| | - Holger Braunschweig
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB)Julius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Cem B. Yildiz
- Department of Aromatic and Medicinal PlantsAksaray UniversityAksaray68100Turkey
| | - Carola Schulzke
- Institut für BiochemieUniversität GreifswaldFelix-Hausdorff-Straße 417489GreifswaldGermany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad GopanpallyHyderabad500046, TelanganaIndia
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14
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Xie Z, Dai Y, Bao M, Feng Z, Wang W, Liu C, Wang X, Su Y. Crystalline radical cations of bis-BN-based analogues of Thiele's hydrocarbon. Chem Commun (Camb) 2022; 58:5391-5394. [PMID: 35412540 DOI: 10.1039/d2cc01254e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two radical cations of bis-BN-based analogues of Thiele's hydrocarbons were facilely synthesized, fully characterized, and theoretically investigated. One-electron oxidation leads to the reduced bond length alternation and NICS values of the central C4N2 rings, suggesting the decreasing antiaromatic character. The spin density of the radical cations is significantly delocalized over the central linkers with a small contribution from two terminal N-heterocyclic boryl units.
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Affiliation(s)
- Zhuofeng Xie
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, China.
| | - Yuyang Dai
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, China.
| | - Manling Bao
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, China.
| | - Zhongtao Feng
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210023, China.
| | - Wenjuan Wang
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, China.
| | - Chunmeng Liu
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, China.
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210023, China.
| | - Yuanting Su
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection, Soochow University, Suzhou 215123, China. .,State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210023, China.
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15
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Hou P, Peschtrich S, Huber N, Feuerstein W, Bihlmeier A, Krummenacher I, Schoch R, Klopper W, Breher F, Paradies J. Impact of Heterocycle Annulation on NIR Absorbance in Quinoid Thioacene Derivatives. Chemistry 2022; 28:e202200478. [PMID: 35254693 PMCID: PMC9314731 DOI: 10.1002/chem.202200478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Indexed: 11/30/2022]
Abstract
The synthesis and characterisation of a homologous series of quinoid sulfur-containing imidazolyl-substituted heteroacenes is described. The optoelectronic and magnetic properties were investigated by UV/vis, fluorescence and EPR spectroscopy as well as quantum-chemical calculations, and were compared to those of the corresponding benzo congener. The room-temperature and atmospherically stable quinoids display strong absorption in the NIR region between 678 and 819 nm. The dithieno[3,2-b:2',3'-d]thiophene and the thieno[2',3':4,5]thieno[3,2-b]thieno[2,3-d]thiophene derivatives were EPR active at room temperature. For the latter, variable-temperature EPR spectroscopy revealed the presence of a thermally accessible triplet state, with a singlet-triplet separation of 14.1 kJ mol-1 .
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Affiliation(s)
- Peng Hou
- Chemistry DepartmentPaderborn UniversityWarburger Straße 10033098PaderbornGermany
| | - Sebastian Peschtrich
- Chemistry DepartmentPaderborn UniversityWarburger Straße 10033098PaderbornGermany
| | - Nils Huber
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Kaiserstraße 1276131KarlsruheGermany
| | - Wolfram Feuerstein
- Institute of Inorganic ChemistryKarlsruhe Institute of Technology (KIT)Engesserstraße 1576131KarlsruheGermany
| | - Angela Bihlmeier
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Kaiserstraße 1276131KarlsruheGermany
| | - Ivo Krummenacher
- Institute of Inorganic ChemistryUniversity of WürzburgAm Hubland97074WürzburgGermany
| | - Roland Schoch
- Chemistry DepartmentPaderborn UniversityWarburger Straße 10033098PaderbornGermany
| | - Wim Klopper
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Kaiserstraße 1276131KarlsruheGermany
| | - Frank Breher
- Institute of Inorganic ChemistryKarlsruhe Institute of Technology (KIT)Engesserstraße 1576131KarlsruheGermany
| | - Jan Paradies
- Chemistry DepartmentPaderborn UniversityWarburger Straße 10033098PaderbornGermany
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16
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Maiti A, Sobottka S, Chandra S, Jana D, Ravat P, Sarkar B, Jana A. Diamidocarbene-Based Thiele and Tschitschibabin Hydrocarbons: Carbonyl Functionalized Kekulé Diradicaloids. J Org Chem 2021; 86:16464-16472. [PMID: 34780693 DOI: 10.1021/acs.joc.1c01827] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Herein, we report diamidocarbene (DAC)-based Thiele and Tschitschibabin hydrocarbons, diradicaloids that contain four carbonyl/amido functional groups. The impact of two different π-conjugated spacers, p-phenylene vs p,p'-biphenylene, has been realized. The quantum chemical calculations suggest diamidocarbene (DAC)-based Thiele hydrocarbon (p-phenylene bridged) closed-shell singlet is the ground state, whereas for the diamidocarbene (DAC)-based Tschitschibabin hydrocarbon (p,p'-biphenylene bridged), open-shell singlet is the ground state. The influence of two different π-conjugated spacers also has been reflected in their UV-vis spectra. To gain more information on the diamidocarbene (DAC)-based Thiele and Tschitschibabin hydrocarbons, we have also carried out cyclic voltammetry investigations along with UV-vis-NIR-spectroelectrochemical studies of their corresponding 2-e oxidized product.
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Affiliation(s)
- Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, Telangana, India
| | - Sebastian Sobottka
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195 Berlin, Germany
| | - Shubhadeep Chandra
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195 Berlin, Germany.,Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Debayan Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, Telangana, India
| | - Prince Ravat
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Biprajit Sarkar
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195 Berlin, Germany.,Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, Telangana, India
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17
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A crystalline radical cation derived from Thiele's hydrocarbon with redox range beyond 1 V. Nat Commun 2021; 12:7052. [PMID: 34862371 PMCID: PMC8642399 DOI: 10.1038/s41467-021-27104-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 11/03/2021] [Indexed: 02/07/2023] Open
Abstract
Thiele’s hydrocarbon occupies a central role as an open-shell platform for new organic materials, however little is known about its redox behaviour. While recent synthetic approaches involving symmetrical carbene substitution of the CPh2 termini yield isolable neutral/dicationic analogues, the intervening radical cations are much more difficult to isolate, due to narrow compatible redox ranges (typically < 0.25 V). Here we show that a hybrid BN/carbene approach allows access to an unsymmetrical analogue of Thiele’s hydrocarbon 1, and that this strategy confers markedly enhanced stability on the radical cation. 1•+ is stable across an exceptionally wide redox range (> 1 V), permitting its isolation in crystalline form. Further single-electron oxidation affords borenium dication 12+, thereby establishing an organoboron redox system fully characterized in all three redox states. We perceive that this strategy can be extended to other transient organic radicals to widen their redox stability window and facilitate their isolation. Organic molecules that can access various redox states have potential applications in electronics, batteries, catalysis, among others. Here the authors report the preparation of an unsymmetrical organoboron analogue of Thiele’s hydrocarbon and study its one- and two-electron oxidation reactions; remarkably, the radical cation is stable over a redox range of > 1 V and can also be isolated.
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18
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Zhao J, Li X, Han YF. Air-/Heat-Stable Crystalline Carbon-Centered Radicals Derived from an Annelated N-Heterocyclic Carbene. J Am Chem Soc 2021; 143:14428-14432. [PMID: 34469133 DOI: 10.1021/jacs.1c06464] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Organic radicals are open-shell species and have been extensively applied to functional materials due to their unique physicochemical properties with unpaired electrons; however, most of them are highly reactive and short-lived. Herein, a series of stable radicals were readily accessed in two steps from a bis(imino)acenaphthene-supported N-heterocyclic carbene (IPr(BIAN)) through enhancing the delocalization of spin density. The IPr(BIAN)-based radicals 3a-c, obtained by reduction of the corresponding iminium salts 2a-c with KC8, have been spectroscopically and crystallographically (3a,c) characterized. DFT calculations indicate that increasing the electron-withdrawing properties of the para substituent on the carbene carbon atom results in the spin density evolving from the acenaphthene ring to the phenyl ring. The IPr(BIAN)-based radicals 3a-c show excellent stability: they have half-lives of 1 week in well-aerated solutions and feature a high thermal decomposition temperature up to 200 °C.
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Affiliation(s)
- Jing Zhao
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, People's Republic of China
| | - Xin Li
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, People's Republic of China
| | - Ying-Feng Han
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, People's Republic of China
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19
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Mahata A, Chrysochos N, Krummenacher I, Chandra S, Braunschweig H, Schulzke C, Sarkar B, Yildiz CB, Jana A. α,α'-Diamino- p-tetrafluoroquinodimethane: Stability of One- and Two-Electron Oxidized Species and Fixation of Molecular Oxygen. J Org Chem 2021; 86:10467-10473. [PMID: 34269573 DOI: 10.1021/acs.joc.1c01120] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Herein, we report the synthesis, characterization, and reactivity of α,α'-diamino-p-tetrafluoroquinodimethane, a p-tetrafluorophenylene-bridged monosubstituted carbene-based Thiele's hydrocarbon A. The compound exhibits a reversible two-step one-electron oxidation with a marginally stable radical cation state B. The in situ formation of the radical cation could be confirmed by electron paramagnetic resonance spectroscopy. Interestingly, α,α'-diamino-p-tetrafluoroquinodimethane fixates atmospheric oxygen to form a 16-membered peroxide-bridged macrocyclic compound C.
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Affiliation(s)
- Alok Mahata
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, Telangana, India
| | - Nicolas Chrysochos
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, D-17489 Greifswald, Germany
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry and Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Shubhadeep Chandra
- Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Holger Braunschweig
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry and Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, D-17489 Greifswald, Germany
| | - Biprajit Sarkar
- Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
| | - Cem B Yildiz
- Department of Medicinal and Aromatic Plants, University of Aksaray, 68100 Aksaray, Turkey
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, Telangana, India
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20
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Maiti A, Zhang F, Krummenacher I, Bhattacharyya M, Mehta S, Moos M, Lambert C, Engels B, Mondal A, Braunschweig H, Ravat P, Jana A. Anionic Boron- and Carbon-Based Hetero-Diradicaloids Spanned by a p-Phenylene Bridge. J Am Chem Soc 2021; 143:3687-3692. [PMID: 33651600 DOI: 10.1021/jacs.0c12624] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Herein we report the synthesis and characterization of anionic boron- and carbon-based Kekulé diradicaloids spanned by a p-phenylene bridge. In contrast to Thiele's hydrocarbon, a closed-shell singlet system, they show an appreciable population of the triplet state at room temperature, as evidenced by both NMR and EPR spectroscopy. Moreover, en route to these anionic boron- and carbon-based hetero-diradicaloids, the formation of an isolable diamino(4-diarylboryl-phenyl)methyl radical was observed.
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Affiliation(s)
- Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, India
| | - Fangyuan Zhang
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ivo Krummenacher
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Moulika Bhattacharyya
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, India
| | - Sakshi Mehta
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Michael Moos
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Christoph Lambert
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Bernd Engels
- Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität Würzburg, Emil-Fischer-Strasse 42, 97074 Würzburg, Germany
| | - Abhishake Mondal
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Holger Braunschweig
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Prince Ravat
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, India
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21
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Sharma MK, Rottschäfer D, Glodde T, Neumann B, Stammler H, Ghadwal RS. Ein offenschaliges Singulett‐Sn
I
‐Diradikal und H
2
‐Spaltung. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202017078] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Mahendra K. Sharma
- Anorganische Molekülchemie und Katalyse Anorganische Chemie und Strukturchemie Zentrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Dennis Rottschäfer
- Anorganische Molekülchemie und Katalyse Anorganische Chemie und Strukturchemie Zentrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Timo Glodde
- Anorganische Molekülchemie und Katalyse Anorganische Chemie und Strukturchemie Zentrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Beate Neumann
- Anorganische Molekülchemie und Katalyse Anorganische Chemie und Strukturchemie Zentrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Hans‐Georg Stammler
- Anorganische Molekülchemie und Katalyse Anorganische Chemie und Strukturchemie Zentrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Rajendra S. Ghadwal
- Anorganische Molekülchemie und Katalyse Anorganische Chemie und Strukturchemie Zentrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
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22
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Sharma MK, Rottschäfer D, Glodde T, Neumann B, Stammler H, Ghadwal RS. An Open-Shell Singlet Sn I Diradical and H 2 Splitting. Angew Chem Int Ed Engl 2021; 60:6414-6418. [PMID: 33460280 PMCID: PMC7986611 DOI: 10.1002/anie.202017078] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Indexed: 11/17/2022]
Abstract
The first SnI diradical [(ADCPh )Sn]2 (4) based on an anionic dicarbene (ADCPh ={CN(Dipp)}2 CPh; Dipp=2,6-iPr2 C6 H3 ) scaffold has been isolated as a green crystalline solid by KC8 reduction of the corresponding bis-chlorostannylene [(ADCPh )SnCl]2 (3). The six-membered C4 Sn2 -ring of 4 containing six π-electrons shows a diatropic ring current, thus 4 may also be regarded as the first 1,4-distannabenzene derivative. DFT calculations suggest an open-shell singlet (OS) ground state of 4 with a remarkably small singlet-triplet energy gap (ΔEOS-T =4.4 kcal mol-1 ), which is consistent with CASSCF (ΔES-T =6.6 kcal mol-1 and diradical character y=37 %) calculations. The diradical 4 splits H2 at room temperature to yield the bis-hydridostannylene [(ADCPh )SnH]2 (5). Further reactivity of 4 has been studied with PhSeSePh and MeOTf.
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Affiliation(s)
- Mahendra K. Sharma
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Dennis Rottschäfer
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Timo Glodde
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Beate Neumann
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Hans‐Georg Stammler
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Rajendra S. Ghadwal
- Molecular Inorganic Chemistry and CatalysisInorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
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23
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Merschel A, Glodde T, Neumann B, Stammler H, Ghadwal RS. Nickel-Catalyzed Intramolecular 1,2-Aryl Migration of Mesoionic Carbenes (iMICs). Angew Chem Int Ed Engl 2021; 60:2969-2973. [PMID: 33155756 PMCID: PMC7898293 DOI: 10.1002/anie.202014328] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Indexed: 12/26/2022]
Abstract
Intramolecular 1,2-Dipp migration of seven mesoionic carbenes (iMICAr ) 2 a-g (iMICAr =ArC{N(Dipp)}2 CHC; Ar=aryl; Dipp=2,6-iPr2 C6 H3 ) under nickel catalysis to give 1,3-imidazoles (IMDAr ) 3 a-g (IMDAr =ArC{N(Dipp)CHC(Dipp)N}) has been reported. The formation of 3 indicates the cleavage of an N-CDipp bond and the subsequent formation of a C-CDipp bond in 2, which is unprecedented in NHC chemistry. The use of 3 in accessing super-iMICs (5) (S-iMIC=ArC{N(Dipp)N(Me)C(Dipp)}C) has been shown with selenium (6), gold (7), and palladium (8) compounds. The quantification of the stereoelectronic properties reveals the superior σ-donor strength of 5 compared to that of classical NHCs. Remarkably, the percentage buried volume of 5 (%Vbur =45) is the largest known amongst thus far reported iMICs. Catalytic studies show a remarkable activity of 5, which is consistent with their auspicious stereoelectronic features.
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Affiliation(s)
- Arne Merschel
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Timo Glodde
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Hans‐Georg Stammler
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
| | - Rajendra S. Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural ChemistryCenter for Molecular MaterialsFaculty of ChemistryUniversität BielefeldUniversitätsstrasse 2533615BielefeldGermany
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24
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Abstract
Singlet fission (SF) is a photophysical downconversion pathway, in which a singlet excitation transforms into two triplet excited states. As such, it constitutes an exciton multiplication generation process, which is currently at the focal point for future integration into solar energy conversion devices. Beyond this, various other exciting applications were proposed, including quantum cryptography or organic light emitting diodes. Also, the mechanistic understanding evolved rapidly during the last year. Unfortunately, the number of suitable SF-chromophores is still limited. This is per se problematic, considering the wide range of envisaged applicability. With that in mind, we emphasize uncommon SF-scaffolds and outline requirements as well as strategies to expand the chromophore pool of SF-materials.
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Affiliation(s)
- Tobias Ullrich
- Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Department für Chemie und Pharmazie, Egerlandstr. 1-3, 91058 Erlangen, Germany.
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25
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Das A, Ahmed J, Rajendran NM, Adhikari D, Mandal SK. A Bottleable Imidazole-Based Radical as a Single Electron Transfer Reagent. J Org Chem 2021; 86:1246-1252. [PMID: 33280378 DOI: 10.1021/acs.joc.0c02465] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Reduction of 1,3-bis(2,6-diisopropylphenyl)-2,4-diphenyl-1H-imidazol-3-ium chloride (1) resulted in the formation of the first structurally characterized imidazole-based radical 2. 2 was established as a single electron transfer reagent by treating it with an acceptor molecule tetracyanoethylene. Moreover, radical 2 was utilized as an organic electron donor in a number of organic transformations such as in activation of an aryl-halide bond, alkene hydrosilylation, and in catalytic reduction of CO2 to methoxyborane, all under ambient temperature and pressure.
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Affiliation(s)
- Arpan Das
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Jasimuddin Ahmed
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - N M Rajendran
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Debashis Adhikari
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, SAS Nagar, 140306, India
| | - Swadhin K Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
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26
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Sharma MK, Ebeler F, Glodde T, Neumann B, Stammler HG, Ghadwal RS. Isolation of a Ge(I) Diradicaloid and Dihydrogen Splitting. J Am Chem Soc 2020; 143:121-125. [DOI: 10.1021/jacs.0c11828] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Mahendra K. Sharma
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany
| | - Falk Ebeler
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany
| | - Timo Glodde
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany
| | - Hans-Georg Stammler
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany
| | - Rajendra S. Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany
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27
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Merschel A, Glodde T, Neumann B, Stammler H, Ghadwal RS. Nickel‐katalysierte intramolekulare 1,2‐Aryl‐Wanderung von mesoionischen Carbenen (iMICs). Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202014328] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Arne Merschel
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Centrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Timo Glodde
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Centrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Beate Neumann
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Centrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Hans‐Georg Stammler
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Centrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Rajendra S. Ghadwal
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Centrum für Molekulare Materialien Fakultät für Chemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Deutschland
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28
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Wang Z, Akisaka R, Yabumoto S, Nakagawa T, Hatano S, Abe M. Impact of the macrocyclic structure and dynamic solvent effect on the reactivity of a localised singlet diradicaloid with π-single bonding character. Chem Sci 2020; 12:613-625. [PMID: 34163792 PMCID: PMC8179019 DOI: 10.1039/d0sc05311b] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Localised singlet diradicals are key intermediates in bond homolysis processes. Generally, these highly reactive species undergo radical–radical coupling reaction immediately after their generation. Therefore, their short-lived character hampers experimental investigations of their nature. In this study, we implemented the new concept of “stretch effect” to access a kinetically stabilised singlet diradicaloid. To this end, a macrocyclic structure was computationally designed to enable the experimental examination of a singlet diradicaloid with π-single bonding character. The kinetically stabilised diradicaloid exhibited a low carbon–carbon coupling reaction rate of 6.4 × 103 s−1 (155.9 μs), approximately 11 and 1000 times slower than those of the first generation of macrocyclic system (7.0 × 104 s−1, 14.2 μs) and the parent system lacking the macrocycle (5 × 106 s−1, 200 ns) at 293 K in benzene, respectively. In addition, a significant dynamic solvent effect was observed for the first time in intramolecular radical–radical coupling reactions in viscous solvents such as glycerin triacetate. This theoretical and experimental study demonstrates that the stretch effect and solvent viscosity play important roles in retarding the σ-bond formation process, thus enabling a thorough examination of the nature of the singlet diradicaloid and paving the way toward a deeper understanding of reactive intermediates. An extremely long-lived localised singlet diradical with π-single bonding character is found in a macrocyclic structure that retards the radical–radical coupling reaction by the “stretch and solvent-dynamic effects”.![]()
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Affiliation(s)
- Zhe Wang
- Department of Chemistry, Graduate School of Science, Hiroshima University 1-3-1 Kagamiyama, Higashi-Hiroshima Hiroshima 739-8526 Japan
| | - Rikuo Akisaka
- Department of Chemistry, Graduate School of Science, Hiroshima University 1-3-1 Kagamiyama, Higashi-Hiroshima Hiroshima 739-8526 Japan
| | - Sohshi Yabumoto
- Unisoku Co., Ltd. 2-4-3 Kasugano, Hirakata Osaka 573-0131 Japan
| | - Tatsuo Nakagawa
- Unisoku Co., Ltd. 2-4-3 Kasugano, Hirakata Osaka 573-0131 Japan
| | - Sayaka Hatano
- Department of Chemistry, Graduate School of Science, Hiroshima University 1-3-1 Kagamiyama, Higashi-Hiroshima Hiroshima 739-8526 Japan
| | - Manabu Abe
- Department of Chemistry, Graduate School of Science, Hiroshima University 1-3-1 Kagamiyama, Higashi-Hiroshima Hiroshima 739-8526 Japan .,Hiroshima University Research Centre for Photo-Drug-Delivery-Systems (HiU-P-DDS), Hiroshima University 1-3-1 Kagamiyama, Higashi-Hiroshima Hiroshima 739-8526 Japan
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29
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Jiménez VG, Mayorga-Burrezo P, Blanco V, Lloveras V, Gómez-García CJ, Šolomek T, Cuerva JM, Veciana J, Campaña AG. Dibenzocycloheptatriene as end-group of Thiele and tetrabenzo-Chichibabin hydrocarbons. Chem Commun (Camb) 2020; 56:12813-12816. [PMID: 32966400 DOI: 10.1039/d0cc04489j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Thiele (Th) and tetrabenzo-Chichibabin (TBC) derivatives with terminal dibenzocycloheptatriene (DBHept) units were prepared. A clear correlation between their electronic and molecular structures was stablished. Insights into their closed- or open-shell ground states were gained, where particular contribution of the heptagonal carbocycles as end-groups was proved. Remarkably, a thermally accessible triplet diradical configuration was confirmed for the DBHept-TBC compound.
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Affiliation(s)
- Vicente G Jiménez
- Department of Organic Chemistry, Unidad de Excelencia de Química aplicada a Biomedicina y Medio Ambiente, University of Granada (UGR), C. U. Fuentenueva, Granada 18071, Spain.
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30
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Mahata A, Chandra S, Maiti A, Rao DK, Yildiz CB, Sarkar B, Jana A. α,α′-Diamino-p-quinodimethanes with Three Stable Oxidation States. Org Lett 2020; 22:8332-8336. [DOI: 10.1021/acs.orglett.0c02964] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alok Mahata
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, India
| | - Shubhadeep Chandra
- Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie, Universität Stuttgart, Fakultät Chemie, Pfaffenwaldring 55, D-70569, Stuttgart, Germany
| | - Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, India
| | - D. Krishna Rao
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, India
| | - Cem B. Yildiz
- Department of Aromatic and Medicinal Plants, University of Aksaray, Aksaray-68100, Turkey
| | - Biprajit Sarkar
- Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie, Universität Stuttgart, Fakultät Chemie, Pfaffenwaldring 55, D-70569, Stuttgart, Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad-500046, India
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31
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Maiti A, Chandra S, Sarkar B, Jana A. Acyclic diaminocarbene-based Thiele, Chichibabin, and Müller hydrocarbons. Chem Sci 2020; 11:11827-11833. [PMID: 34123209 PMCID: PMC8162802 DOI: 10.1039/d0sc03622f] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Thiele, Chichibabin and Müller hydrocarbons are considered as classical Kekulé diradicaloids. Herein we report the synthesis and characterization of acyclic diaminocarbene (ADC)-based Thiele, Chichibabin, and Müller hydrocarbons. The calculated singlet–triplet energy gaps are ΔES–T = −27.96, −3.70, −0.37 kcal mol−1, respectively, and gradually decrease with the increasing length of the π-conjugated spacer (p-phenylene vs. p,p′-biphenylene vs. p,p′′-terphenylene) between the two ADC-scaffolds. In agreement with the calculations, we also experimentally observed the enhancement of paramagnetic diradical character as a function of the length of the π-conjugated spacer. ADC-based Thiele's hydrocarbon is EPR silent and exhibits very well resolved NMR spectra, whereas ADC-based Müller's hydrocarbon displays EPR signals and featureless NMR spectra at room temperature. The spacer also has a strong influence on the UV-Vis-NIR spectra of these compounds. Considering that our methodology is modular, these results provide a convenient platform for the synthesis of an electronically modified new class of carbon-centered Kekulé diradicaloids. We report the synthesis of acyclic diaminocarbene (ADC)-scaffold based Thiele, Chichibabin, and Müller hydrocarbons. Studies support that the singlet-triplet energy gap depends on the π-conjugated spacer between the ADC scaffolds.![]()
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Affiliation(s)
- Avijit Maiti
- Tata Institute of Fundamental Research Hyderabad Gopanpally Hyderabad-500046 Telangana India
| | - Shubhadeep Chandra
- Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie Pfaffenwaldring 55 D-70569 Stuttgart Germany
| | - Biprajit Sarkar
- Universität Stuttgart, Fakultät Chemie, Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie Pfaffenwaldring 55 D-70569 Stuttgart Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research Hyderabad Gopanpally Hyderabad-500046 Telangana India
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32
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Rottschäfer D, Fuhs DE, Neumann B, Stammler H, Ghadwal RS. Saturated NHC Derived Dichalcogen Dications. Z Anorg Allg Chem 2020. [DOI: 10.1002/zaac.202000189] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Dennis Rottschäfer
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| | - Désirée E. Fuhs
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| | - Beate Neumann
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| | - Hans‐Georg Stammler
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
| | - Rajendra S. Ghadwal
- Anorganische Molekülchemie und Katalyse Lehrstuhl für Anorganische Chemie und Strukturchemie Universität Bielefeld Universitätsstraße 25 33615 Bielefeld Germany
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33
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Maiti A, Stubbe J, Neuman NI, Kalita P, Duari P, Schulzke C, Chandrasekhar V, Sarkar B, Jana A. CAAC‐Based Thiele and Schlenk Hydrocarbons. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201915802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Avijit Maiti
- Tata Institute of Fundamental Research (TIFR) Hyderabad Gopanpally Hyderabad-500107 Telangana India
| | - Jessica Stubbe
- Institut für Chemie und BiochemieAnorganische ChemieFreie Universität Berlin Fabeckstraße 34–36 14195 Berlin Germany
| | - Nicolás I. Neuman
- Institut für Chemie und BiochemieAnorganische ChemieFreie Universität Berlin Fabeckstraße 34–36 14195 Berlin Germany
- Instituto de Desarrollo Tecnológico para laIndustria Química, CCT Santa Fe CONICET-UNL Colectora Ruta Nacional 168, Km 472, Paraje El Pozo 3000 Santa Fe Argentina
| | - Pankaj Kalita
- Tata Institute of Fundamental Research (TIFR) Hyderabad Gopanpally Hyderabad-500107 Telangana India
| | - Prakash Duari
- Tata Institute of Fundamental Research (TIFR) Hyderabad Gopanpally Hyderabad-500107 Telangana India
| | - Carola Schulzke
- Institut für BiochemieUniversität Greifswald Felix-Hausdorff-Straße 4 17487 Greifswald Germany
| | - Vadapalli Chandrasekhar
- Tata Institute of Fundamental Research (TIFR) Hyderabad Gopanpally Hyderabad-500107 Telangana India
- Department of ChemistryIndian Institute of Technology Kanpur Kanpur 208016 India
| | - Biprajit Sarkar
- Institut für Chemie und BiochemieAnorganische ChemieFreie Universität Berlin Fabeckstraße 34–36 14195 Berlin Germany
- Institut für Anorganische ChemieUniversität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research (TIFR) Hyderabad Gopanpally Hyderabad-500107 Telangana India
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34
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Maiti A, Stubbe J, Neuman NI, Kalita P, Duari P, Schulzke C, Chandrasekhar V, Sarkar B, Jana A. CAAC-Based Thiele and Schlenk Hydrocarbons. Angew Chem Int Ed Engl 2020; 59:6729-6734. [PMID: 31960562 PMCID: PMC7187164 DOI: 10.1002/anie.201915802] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Indexed: 01/17/2023]
Abstract
Diradicals have been of tremendous interest for over a century ever since the first reports of p- and m-phenylene-bridged diphenylmethylradicals in 1904 by Thiele and 1915 by Schlenk. Reported here are the first examples of cyclic(alkyl)(amino)carbene (CAAC) analogues of Thiele's hydrocarbon, a Kekulé diradical, and Schlenk's hydrocarbon, a non-Kekulé diradical, without using CAAC as a precursor. The CAAC analogue of Thiele's hydrocarbon has a singlet ground state, whereas the CAAC analogue of Schlenk's hydrocarbon contains two unpaired electrons. The latter forms a dimer, by an intermolecular double head-to-tail dimerization. This straightforward synthetic methodology is modular and can be extended for the generation of redox-active organic compounds.
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Affiliation(s)
- Avijit Maiti
- Tata Institute of Fundamental Research (TIFR) Hyderabad, Gopanpally, Hyderabad-500107, Telangana, India
| | - Jessica Stubbe
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany
| | - Nicolás I Neuman
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany.,Instituto de Desarrollo Tecnológico para la, Industria Química, CCT Santa Fe CONICET-UNL, Colectora Ruta Nacional 168, Km 472, Paraje El Pozo, 3000, Santa Fe, Argentina
| | - Pankaj Kalita
- Tata Institute of Fundamental Research (TIFR) Hyderabad, Gopanpally, Hyderabad-500107, Telangana, India
| | - Prakash Duari
- Tata Institute of Fundamental Research (TIFR) Hyderabad, Gopanpally, Hyderabad-500107, Telangana, India
| | - Carola Schulzke
- Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Straße 4, 17487, Greifswald, Germany
| | - Vadapalli Chandrasekhar
- Tata Institute of Fundamental Research (TIFR) Hyderabad, Gopanpally, Hyderabad-500107, Telangana, India.,Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Biprajit Sarkar
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34-36, 14195, Berlin, Germany.,Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Anukul Jana
- Tata Institute of Fundamental Research (TIFR) Hyderabad, Gopanpally, Hyderabad-500107, Telangana, India
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35
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Rottschäfer D, Glodde T, Neumann B, Stammler HG, Ghadwal RS. A crystalline C5-protonated 1,3-imidazol-4-ylidene. Chem Commun (Camb) 2020; 56:2027-2030. [DOI: 10.1039/c9cc09428h] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The first C5-protonated 1,3-imidazole-based mesoionic carbene (iMICBp) has been isolated and characterized by single-crystal X-ray diffraction.
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Affiliation(s)
- Dennis Rottschäfer
- Molecular Inorganic Chemistry and Catalysis
- Inorganic and Structural Chemistry
- Center for Molecular Materials
- Faculty of Chemistry
- Universität Bielefeld
| | - Timo Glodde
- Molecular Inorganic Chemistry and Catalysis
- Inorganic and Structural Chemistry
- Center for Molecular Materials
- Faculty of Chemistry
- Universität Bielefeld
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis
- Inorganic and Structural Chemistry
- Center for Molecular Materials
- Faculty of Chemistry
- Universität Bielefeld
| | - Hans-Georg Stammler
- Molecular Inorganic Chemistry and Catalysis
- Inorganic and Structural Chemistry
- Center for Molecular Materials
- Faculty of Chemistry
- Universität Bielefeld
| | - Rajendra S. Ghadwal
- Molecular Inorganic Chemistry and Catalysis
- Inorganic and Structural Chemistry
- Center for Molecular Materials
- Faculty of Chemistry
- Universität Bielefeld
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36
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Sharma MK, Blomeyer S, Neumann B, Stammler HG, Hinz A, van Gastel M, Ghadwal RS. Isolation of singlet carbene derived 2-arsa-1,3-butadiene radical cations and dications. Chem Commun (Camb) 2020; 56:3575-3578. [PMID: 32104835 DOI: 10.1039/d0cc00624f] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
2-Arsa-1,3-butadienes (L)As(cAACR) (L = PhC[double bond, length as m-dash]C{(NDipp)CH}2, Dipp = 2,6-iPr2C6H3; cAACR = C{(NDipp)CMe2CH2C(R)}, R = Me22a, R = cyclohexyl (Cy) 2b) and the corresponding radical cations [(L)As(cAACR)]GaCl4 (R = Me23a, Cy 3b) and dications [(L)As(cAACR)](GaCl4)2 (R = Me 4a, Cy 4b) featuring a C[double bond, length as m-dash]C-As[double bond, length as m-dash]C π-conjugated framework are reported.
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Affiliation(s)
- Mahendra K Sharma
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
| | - Sebastian Blomeyer
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
| | - Beate Neumann
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
| | - Hans-Georg Stammler
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
| | - Alexander Hinz
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstr. 15, 76131 Karlsruhe, Germany
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung, Molecular Theory and Spectroscopy, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr, D-45470, Germany
| | - Rajendra S Ghadwal
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
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Kundu G, De S, Tothadi S, Das A, Koley D, Sen SS. Saturated N-Heterocyclic Carbene Based Thiele's Hydrocarbon with a Tetrafluorophenylene Linker. Chemistry 2019; 25:16533-16537. [PMID: 31609519 DOI: 10.1002/chem.201904421] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/06/2019] [Indexed: 01/24/2023]
Abstract
The synthesis of a SIPr [1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene] derived Kekulé diradicaloid with a tetrafluorophenylene spacer (3) has been described. Two synthetic routes have been reported to access 3. The cleavage of C-F bond of C6 F6 by SIPr in the presence of BF3 led to double C-F activated compound with two tetrafluoro borate counter anions (2), which upon reduction by lithium metal afforded 3. Alternatively, 3 can be directly accessed in one step by reacting SIPr with C6 F6 in presence of Mg metal. Compounds 2 and 3 were well characterized spectroscopically and by single-crystal X-ray diffraction studies. Experimental and computational studies support the cumulenic closed-shell singlet state of 3 with a singlet-triplet energy gap (ΔES-T ) of 23.7 kcal mol-1 .
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Affiliation(s)
- Gargi Kundu
- Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), New Ghaziabad, 201002, India
| | - Sriman De
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, 741246, India
| | - Srinu Tothadi
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India
| | - Abhishek Das
- Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata, 700032, India
| | - Debasis Koley
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, 741246, India
| | - Sakya S Sen
- Inorganic Chemistry and Catalysis Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), New Ghaziabad, 201002, India
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Werr M, Kaifer E, Wadepohl H, Himmel HJ. Tuneable Redox Chemistry and Electrochromism of Persistent Symmetric and Asymmetric Azine Radical Cations. Chemistry 2019; 25:12981-12990. [PMID: 31306523 DOI: 10.1002/chem.201902216] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/21/2019] [Indexed: 12/16/2022]
Abstract
Molecular organic radicals have been intensively studied in the last decades, due to their interesting optical, magnetic and redox properties. Here we report the synthesis and characterisation of persistent organic radicals from one-electron oxidation of redox-active azines (RAAs), composed of two guanidinyl or related groups. By connecting two different groups together, asymmetric compounds result. In this way a series of compounds with varying redox potential is obtained that could be oxidised reversibly to the mono- and the dicationic charge states. The accessible redox states were fully determined by chemical redox reactions. The standard Gibbs free energy change for disproportionation of the radical monocation into the dication and the neutral molecule in solution, estimated from cyclovoltammetric measurements, varies between 43 and 71 kJ mol-1 . While the neutral RAAs absorb predominately UV light, the radical monocations display strong absorptions covering almost the entire visible region and extending for some compounds into the NIR region. A detailed analysis of this highly reversible electrochromism is presented, and the fast switching characteristics are demonstrated in an electrochromic test device.
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Affiliation(s)
- Marco Werr
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Elisabeth Kaifer
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Hubert Wadepohl
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Hans-Jörg Himmel
- Anorganisch Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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Escayola S, Callís M, Poater A, Solà M. Effect of Exocyclic Substituents and π-System Length on the Electronic Structure of Chichibabin Diradical(oid)s. ACS OMEGA 2019; 4:10845-10853. [PMID: 31460182 PMCID: PMC6648453 DOI: 10.1021/acsomega.9b00916] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 06/03/2019] [Indexed: 06/10/2023]
Abstract
The ground state (GS) of Chichibabin's polycyclic hydrocarbons (CPHs) can be singlet [open- or closed-shell (OSS or CS)] or triplet (T), depending on the elongation of the π-system and the exocyclic substituents. CPHs with either a small singlet-triplet energy gap (ΔE ST) or even a triplet GS have potential applications in optoelectronics. To analyze the effect of the size and exocyclic substituents on the nature of the GS of CPHs, we have selected a number of them with different substituents in the exocyclic carbon atoms and different ring chain lengths. The OPBE/cc-pVTZ level of theory was used for the optimization of the systems. The aromaticity of the resulting electronic structures was evaluated with HOMA, NICS, FLU, PDI, Iring, and MCI aromaticity indices. Our results show that the shortest π-systems (one or two rings) have a singlet GS. However, systems with three to five rings favor OSS GSs. Electron-withdrawing groups (EWGs) and aromatic substituents in the exocyclic carbons tend to stabilize the OSS and T states, whereas electron-donating groups slightly destabilize them. For CS, OSS, and T states, aromaticity measures indicate a gain of aromaticity of the 6-membered rings of the CPHs with the increase in their size and when CPHs incorporate EWGs or aromatic substituents. In general, the CPHs analyzed present small singlet-triplet energy gaps, and in particular, the ones containing EWGs or aromatic substituents present the smallest singlet-triplet energy gaps.
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Affiliation(s)
- Sílvia Escayola
- Institut de Química
Computacional i Catàlisi and Departament de Química, Universitat de Girona, C/Maria Aurèlia Capmany, 69, 17003 Girona, Catalonia, Spain
| | - Marc Callís
- Institut de Química
Computacional i Catàlisi and Departament de Química, Universitat de Girona, C/Maria Aurèlia Capmany, 69, 17003 Girona, Catalonia, Spain
| | - Albert Poater
- Institut de Química
Computacional i Catàlisi and Departament de Química, Universitat de Girona, C/Maria Aurèlia Capmany, 69, 17003 Girona, Catalonia, Spain
| | - Miquel Solà
- Institut de Química
Computacional i Catàlisi and Departament de Química, Universitat de Girona, C/Maria Aurèlia Capmany, 69, 17003 Girona, Catalonia, Spain
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40
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Antoni PW, Bruckhoff T, Hansmann MM. Organic Redox Systems Based on Pyridinium–Carbene Hybrids. J Am Chem Soc 2019; 141:9701-9711. [DOI: 10.1021/jacs.9b04249] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Patrick W. Antoni
- Georg-August Universität Göttingen, Tammannstraße 2, 37077 Göttingen, Germany
| | - Tim Bruckhoff
- Georg-August Universität Göttingen, Tammannstraße 2, 37077 Göttingen, Germany
| | - Max M. Hansmann
- Georg-August Universität Göttingen, Tammannstraße 2, 37077 Göttingen, Germany
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41
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Transmetalation from Magnesium–NHCs—Convenient Synthesis of Chelating π-Acidic NHC Complexes. INORGANICS 2019. [DOI: 10.3390/inorganics7050065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The synthesis of chelating N-heterocyclic carbene (NHC) complexes with considerable π-acceptor properties can be a challenging task. This is due to the dimerization of free carbene ligands, the moisture sensitivity of reaction intermediates or reagents, and challenges associated with the workup procedure. Herein, we report a general route using transmetalation from magnesium–NHCs. Notably, this route gives access to transition-metal complexes in quantitative conversion without the formation of byproducts. It therefore produces transition-metal complexes outperforming the conventional routes based on free or lithium-coordinated carbene, silver complexes, or in situ metalation in dimethyl sulfoxide (DMSO). We therefore propose transmetalation from magnesium–NHCs as a convenient and general route to obtain NHC complexes.
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42
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Sinhababu S, Kundu S, Siddiqui MM, Paesch AN, Herbst-Irmer R, Schwederski B, Saha P, Zhao L, Frenking G, Kaim W, Stalke D, Roesky HW. Synthesis of cAAC stabilized biradical of "Me 2Si" and "Me 2SiCl" monoradical from Me 2SiCl 2 - an important feedstock material. Chem Commun (Camb) 2019; 55:4534-4537. [PMID: 30924826 DOI: 10.1039/c9cc01448a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The cyclic alkyl(amino) carbene (cAAC) coordinated biradical of dimethylsilicon was isolated as (cAAC)2Me2Si (1), (cAAC = C(CH2)(CMe2)2N-2,6-i-Pr2C6H3), synthesized from the reduction of Me2SiCl2 using two equivalents of KC8 in the presence of two equivalents of cAAC. The reduction of Me2SiCl2 by one equivalent of KC8 in the presence of one equivalent of cAAC resulted in the stable dimethylsiliconchloride monoradical (cAAC)Me2SiCl (2).
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Affiliation(s)
- Soumen Sinhababu
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany.
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Kundu S, Sinhababu S, Chandrasekhar V, Roesky HW. Stable cyclic (alkyl)(amino)carbene (cAAC) radicals with main group substituents. Chem Sci 2019; 10:4727-4741. [PMID: 31160949 PMCID: PMC6510188 DOI: 10.1039/c9sc01351b] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 04/06/2019] [Indexed: 11/21/2022] Open
Abstract
Recent attempts to isolate cyclic (alkyl)(amino)carbene stabilized radicals of p-block elements have been described here.
Isolation and characterization of stable radicals has been a long-pursued quest. While there has been some progress in this field particularly with respect to carbon, radicals involving heavier p-block elements are still considerably sparse. In this review we describe our recent successful efforts on the isolation of stable p-block element radicals particularly those involving aluminum, silicon, and phosphorus.
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Affiliation(s)
- Subrata Kundu
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstrasse 4 , D-37077 , Göttingen , Germany .
| | - Soumen Sinhababu
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstrasse 4 , D-37077 , Göttingen , Germany .
| | - Vadapalli Chandrasekhar
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstrasse 4 , D-37077 , Göttingen , Germany . .,Tata Institute of Fundamental Research Hyderabad , Hyderabad 500107 , India.,Department of Chemistry , Indian Institute of Technology Kanpur , Kanpur 208016 , India .
| | - Herbert W Roesky
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstrasse 4 , D-37077 , Göttingen , Germany .
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Rottschäfer D, Neumann B, Stammler H, Kishi R, Nakano M, Ghadwal RS. A Phosphorus Analogue ofp‐Quinodimethane with a Planar P4Ring: A Metal‐Free Diphosphorus Source. Chemistry 2019; 25:3244-3247. [PMID: 30716177 DOI: 10.1002/chem.201805932] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/03/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Dennis Rottschäfer
- Anorganische Molekülchemie und Katalyse, Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für ChemieUniversität Bielefeld Universitätsstrasse 25 33615 Bielefeld Germany
| | - Beate Neumann
- Anorganische Molekülchemie und Katalyse, Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für ChemieUniversität Bielefeld Universitätsstrasse 25 33615 Bielefeld Germany
| | - Hans‐Georg Stammler
- Anorganische Molekülchemie und Katalyse, Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für ChemieUniversität Bielefeld Universitätsstrasse 25 33615 Bielefeld Germany
| | - Ryohei Kishi
- Department of Materials Engineering Science, Graduate School of, Engineering ScienceOsaka University Toyonaka Osaka 560-8531 Japan
| | - Masayoshi Nakano
- Department of Materials Engineering Science, Graduate School of, Engineering ScienceOsaka University Toyonaka Osaka 560-8531 Japan
- Institute for Molecular Science 38 Nishigo-Naka, Myodaiji Okazaki 444-8585 Japan
| | - Rajendra S. Ghadwal
- Anorganische Molekülchemie und Katalyse, Anorganische Chemie und Strukturchemie, Centrum für Molekulare Materialien, Fakultät für ChemieUniversität Bielefeld Universitätsstrasse 25 33615 Bielefeld Germany
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45
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Sharma MK, Rottschäfer D, Blomeyer S, Neumann B, Stammler HG, van Gastel M, Hinz A, Ghadwal RS. Diphosphene radical cations and dications with a π-conjugated C 2P 2C 2-framework. Chem Commun (Camb) 2019; 55:10408-10411. [PMID: 31403648 DOI: 10.1039/c9cc04701h] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis and characterization of the crystalline diphosphene radical cations [{(NHC)C(Ph)}P]2(GaCl4) (NHC = IPr = C{(NDipp)CH}23, SIPr = C{(NDipp)CH2}24; Dipp = 2,6-iPr2C6H3) and dications [{(NHC)C(Ph)}P]2(GaCl4)2 (NHC = IPr 5, SIPr 6) featuring a π-conjugated C2P2C2-framework has been reported.
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Affiliation(s)
- Mahendra K Sharma
- Molecular Inorganic Chemistry and Catalysis, Inorganic and Structural Chemistry, Center for Molecular Materials, Faculty of Chemistry, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
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46
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Rottschäfer D, Busch J, Neumann B, Stammler HG, van Gastel M, Kishi R, Nakano M, Ghadwal RS. Diradical Character Enhancement by Spacing: N-Heterocyclic Carbene Analogues of Müller's Hydrocarbon. Chemistry 2018; 24:16537-16542. [DOI: 10.1002/chem.201804524] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Indexed: 11/11/2022]
Affiliation(s)
- Dennis Rottschäfer
- Anorganische Molekülchemie und Katalyse; Lehrstuhl für Anorganische Chemie und Strukturchemie; Centrum für Molekulare Materialien; Fakultät für Chemie; Universität Bielefeld; Universitätsstrasse 25 33615 Bielefeld Germany
| | - Jasmin Busch
- Anorganische Molekülchemie und Katalyse; Lehrstuhl für Anorganische Chemie und Strukturchemie; Centrum für Molekulare Materialien; Fakultät für Chemie; Universität Bielefeld; Universitätsstrasse 25 33615 Bielefeld Germany
| | - Beate Neumann
- Anorganische Molekülchemie und Katalyse; Lehrstuhl für Anorganische Chemie und Strukturchemie; Centrum für Molekulare Materialien; Fakultät für Chemie; Universität Bielefeld; Universitätsstrasse 25 33615 Bielefeld Germany
| | - Hans-Georg Stammler
- Anorganische Molekülchemie und Katalyse; Lehrstuhl für Anorganische Chemie und Strukturchemie; Centrum für Molekulare Materialien; Fakultät für Chemie; Universität Bielefeld; Universitätsstrasse 25 33615 Bielefeld Germany
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung; Kaiser-Wilhelm-Platz 1 45470 Mülheim an der Ruhr Germany
| | - Ryohei Kishi
- Department of Materials Engineering Science; Graduate School of Engineering Science; Osaka University; Toyonaka Osaka 560-8531 Japan
| | - Masayoshi Nakano
- Department of Materials Engineering Science; Graduate School of Engineering Science; Osaka University; Toyonaka Osaka 560-8531 Japan
- Institute for Molecular Science; 38 Nishigo-Naka Myodaiji, Okazaki 444-8585 Japan
| | - Rajendra S. Ghadwal
- Anorganische Molekülchemie und Katalyse; Lehrstuhl für Anorganische Chemie und Strukturchemie; Centrum für Molekulare Materialien; Fakultät für Chemie; Universität Bielefeld; Universitätsstrasse 25 33615 Bielefeld Germany
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47
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Antoni PW, Hansmann MM. Pyrylenes: A New Class of Tunable, Redox-Switchable, Photoexcitable Pyrylium–Carbene Hybrids with Three Stable Redox-States. J Am Chem Soc 2018; 140:14823-14835. [DOI: 10.1021/jacs.8b08545] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Patrick W. Antoni
- Georg-August Universität Göttingen, Tammannstraße 2, 37077 Göttingen, Germany
| | - Max M. Hansmann
- Georg-August Universität Göttingen, Tammannstraße 2, 37077 Göttingen, Germany
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48
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Messelberger J, Grünwald A, Pinter P, Hansmann MM, Munz D. Carbene derived diradicaloids - building blocks for singlet fission? Chem Sci 2018; 9:6107-6117. [PMID: 30090299 PMCID: PMC6053972 DOI: 10.1039/c8sc01999a] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 06/25/2018] [Indexed: 12/13/2022] Open
Abstract
Organic singlet diradicaloids promise application in non-linear optics, electronic devices and singlet fission. The stabilization of carbon allotropes/cumulenes (C1, C2, C4) by carbenes has been equally an area of high activity. Combining these fields, we showed recently that carbene scaffolds allow as well for the design of diradicaloids. Herein, we report a comprehensive computational investigation (CASSCF/NEVPT2; fractional occupation DFT) on the electronic properties of carbene-bridge-carbene type diradicaloids. We delineate how to adjust the properties of these ensembles through the choice of carbene and bridge and show that already a short C2 bridge results in remarkable diradicaloid character. The choice of the carbene separately tunes the energies of the S1 and T1 excited states, whereas the bridge adjusts the overall energy level of the excited states. Accordingly, we develop guidelines on how to tailor the electronic properties of these molecules. Of particular note, fractional occupation DFT is an excellent tool to predict singlet-triplet gaps.
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Affiliation(s)
- Julian Messelberger
- Friedrich-Alexander Universität Erlangen-Nürnberg , Anorganische und Allgemeine Chemie , Egerlandstr. 1 , 91058 Erlangen , Germany .
| | - Annette Grünwald
- Friedrich-Alexander Universität Erlangen-Nürnberg , Anorganische und Allgemeine Chemie , Egerlandstr. 1 , 91058 Erlangen , Germany .
| | - Piermaria Pinter
- Technische Universität Dresden, Physikalische Organische Chemie , Bergstr. 66 , 01069 Dresden , Germany
| | - Max M Hansmann
- Georg-August Universität Göttingen , Institut für Organische und Biomolekulare Chemie , Tammannstraße 2 , 37073 Göttingen , Germany
| | - Dominik Munz
- Friedrich-Alexander Universität Erlangen-Nürnberg , Anorganische und Allgemeine Chemie , Egerlandstr. 1 , 91058 Erlangen , Germany .
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49
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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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