1
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Russell JJ, DeJesus JF, Smith BA, Nalaoh P, Vogiatzis KD, Jenkins DM. Disparate reactivity of a chiral iron(II) tetracarbene complex with organic azides. Dalton Trans 2024; 53:10819-10823. [PMID: 38864554 DOI: 10.1039/d4dt01422g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
A chiral tetra-NHC iron(II) complex and its disparate reactivity with multiple organic azides is reported. Both aryl and alkyl azides react with the iron(II) complex yielding three distinct products: an iron(IV) imide, an iron(IV) tetrazene, and a surprising and unprecedented double imide insertion complex.
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Affiliation(s)
- Jerred J Russell
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996, USA.
| | - Joseph F DeJesus
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996, USA.
| | - Brett A Smith
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996, USA.
| | - Phattananawee Nalaoh
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996, USA.
| | | | - David M Jenkins
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996, USA.
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2
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Inglis CM, Manzano RA, Kirk RM, Sharma M, Stewart MD, Watson LJ, Hill AF. Poly(imidazolyliden-yl)borato Complexes of Tungsten: Mapping Steric vs. Electronic Features of Facially Coordinating Ligands. Molecules 2023; 28:7761. [PMID: 38067496 PMCID: PMC10798377 DOI: 10.3390/molecules28237761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 11/21/2023] [Accepted: 11/21/2023] [Indexed: 01/22/2024] Open
Abstract
A convenient synthesis of [HB(HImMe)3](PF6)2 (ImMe = N-methylimidazolyl) is decribed. This salt serves in situ as a precursor to the tris(imidazolylidenyl)borate Li[HB(ImMe)3] pro-ligand upon deprotonation with nBuLi. Reaction with [W(≡CC6H4Me-4)(CO)2(pic)2(Br)] (pic = 4-picoline) affords the carbyne complex [W(≡CC6H4Me-4)(CO)2{HB(ImMe)3}]. Interrogation of experimental and computational data for this compound allow a ranking of familiar tripodal and facially coordinating ligands according to steric (percentage buried volume) and electronic (νCO) properties. The reaction of [W(≡CC6H4Me-4)(CO)2{HB(ImMe)3}] with [AuCl(SMe2)] affords the heterobimetallic semi-bridging carbyne complex [WAu(μ-CC6H4Me-4)(CO)2(Cl){HB(ImMe)3}].
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Affiliation(s)
| | | | | | | | | | | | - Anthony F. Hill
- Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
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3
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Epping RF, Vesseur D, Zhou M, de Bruin B. Carbene Radicals in Transition-Metal-Catalyzed Reactions. ACS Catal 2023; 13:5428-5448. [PMID: 37123600 PMCID: PMC10127290 DOI: 10.1021/acscatal.3c00591] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/21/2023] [Indexed: 04/08/2023]
Abstract
Discovered as organometallic curiosities in the 1970s, carbene radicals have become a staple in modern-day homogeneous catalysis. Carbene radicals exhibit nucleophilic radical-type reactivity orthogonal to classical electrophilic diamagnetic Fischer carbenes. Their successful catalytic application has led to the synthesis of a myriad of carbo- and heterocycles, ranging from simple cyclopropanes to more challenging eight-membered rings. The field has matured to employ densely functionalized chiral porphyrin-based platforms that exhibit high enantio-, regio-, and stereoselectivity. Thus far the focus has largely been on cobalt-based systems, but interest has been growing for the past few years to expand the application of carbene radicals to other transition metals. This Perspective covers the advances made since 2011 and gives an overview on the coordination chemistry, reactivity, and catalytic application of carbene radical species using transition metal complexes and catalysts.
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Affiliation(s)
- Roel F.J. Epping
- Homogeneous, Supramolecular and Bio-Inspired Catalysis Group, van ‘t Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - David Vesseur
- Homogeneous, Supramolecular and Bio-Inspired Catalysis Group, van ‘t Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Minghui Zhou
- Homogeneous, Supramolecular and Bio-Inspired Catalysis Group, van ‘t Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Bas de Bruin
- Homogeneous, Supramolecular and Bio-Inspired Catalysis Group, van ‘t Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
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4
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Schlachta TP, Kühn FE. Cyclic iron tetra N-heterocyclic carbenes: synthesis, properties, reactivity, and catalysis. Chem Soc Rev 2023; 52:2238-2277. [PMID: 36852959 DOI: 10.1039/d2cs01064j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Cyclic iron tetracarbenes are an emerging class of macrocyclic iron N-heterocyclic carbene (NHC) complexes. They can be considered as an organometallic compound class inspired by their heme analogs, however, their electronic properties differ, e.g. due to the very strong σ-donation of the four combined NHCs in equatorial coordination. The ligand framework of iron tetracarbenes can be readily modified, allowing fine-tuning of the structural and electronic properties of the complexes. The properties of iron tetracarbene complexes are discussed quantitatively and correlations are established. The electronic nature of the tetracarbene ligand allows the isolation of uncommon iron(III) and iron(IV) species and reveals a unique reactivity. Iron tetracarbenes are successfully applied in C-H activation, CO2 reduction, aziridination and epoxidation catalysis and mechanisms as well as decomposition pathways are described. This review will help researchers evaluate the structural and electronic properties of their complexes and target their catalyst properties through ligand design.
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Affiliation(s)
- Tim P Schlachta
- Technical University of Munich, School of Natural Sciences, Department of Chemistry and Catalysis Research Center, Molecular Catalysis, Lichtenbergstraße 4, 85748 Garching, Germany.
| | - Fritz E Kühn
- Technical University of Munich, School of Natural Sciences, Department of Chemistry and Catalysis Research Center, Molecular Catalysis, Lichtenbergstraße 4, 85748 Garching, Germany.
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5
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Wentz KE, Molino A, Freeman LA, Dickie DA, Wilson DJD, Gilliard RJ. Approaching Dianionic Tetraoxadiborecine Macrocycles: 10-Membered Bora-Crown Ethers Incorporating Borafluorenate Units. Angew Chem Int Ed Engl 2023; 62:e202215772. [PMID: 36437238 DOI: 10.1002/anie.202215772] [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: 10/26/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022]
Abstract
The addition of non-benzenoid quinones, acenapthenequinone or aceanthrenequinone, to the 9-carbene-9-borafluorene monoanion (1) affords the first examples of dianionic 10-membered bora-crown ethers (2-5), which are characterized by multi-nuclear NMR spectroscopy (1 H, 13 C, 11 B), X-ray crystallography, elemental analysis, and UV/Vis spectroscopy. These tetraoxadiborecines have distinct absorption profiles based on the positioning of the alkali metal cations. When compound 4, which has a vacant C4 B2 O4 cavity, is reacted with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, a color change from purple to orange serves as a visual indicator of metal binding to the central ring, whereby the Na+ ion coordinates to four oxygen atoms. A detailed theoretical analysis of the calculated reaction energetics is provided to gain insight into the reaction mechanism for the formation of 2-5. These data, and the electronic structures of proposed intermediates, indicate that the reaction proceeds via a boron enolate intermediate.
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Affiliation(s)
- Kelsie E Wentz
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, 22904, Charlottesville, VA, USA
| | - Andrew Molino
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, 3086, Melbourne, Victoria, Australia
| | - Lucas A Freeman
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, 22904, Charlottesville, VA, USA
| | - Diane A Dickie
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, 22904, Charlottesville, VA, USA
| | - David J D Wilson
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, 3086, Melbourne, Victoria, Australia
| | - Robert J Gilliard
- Department of Chemistry, University of Virginia, 409 McCormick Rd./PO Box 400319, 22904, Charlottesville, VA, USA
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6
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Zámbó GG, Mayr J, Sauer MJ, Schlachta TP, Reich RM, Kühn FE. The first macrocyclic abnormally coordinating tetra-1,2,3-triazole-5-ylidene iron complex: a promising candidate for olefin epoxidation. Dalton Trans 2022; 51:13591-13595. [PMID: 36039702 DOI: 10.1039/d2dt02561b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The first macrocyclic and abnormally coordinating, mesoionic N-heterocyclic carbene iron complex has been synthesised and characterised via ESI-MS, EA, SC-XRD, CV, NMR and UV/Vis spectroscopy. 13C-NMR spectroscopy and CV measurements indicate a strong σ-donor ability of the carbene moieties, suggesting an efficient catalytic activity of the iron complex in oxidation reactions. Initial tests in the epoxidation of cis-cyclooctene as a model substrate confirm this assumption.
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Affiliation(s)
- Greta G Zámbó
- Molecular Catalysis, Department of Chemistry and Catalysis Research Centre, Technische Universität München, Lichtenbergstr. 4, 85784 Garching bei München, Germany.
| | - Johannes Mayr
- Molecular Catalysis, Department of Chemistry and Catalysis Research Centre, Technische Universität München, Lichtenbergstr. 4, 85784 Garching bei München, Germany.
| | - Michael J Sauer
- Molecular Catalysis, Department of Chemistry and Catalysis Research Centre, Technische Universität München, Lichtenbergstr. 4, 85784 Garching bei München, Germany.
| | - Tim P Schlachta
- Molecular Catalysis, Department of Chemistry and Catalysis Research Centre, Technische Universität München, Lichtenbergstr. 4, 85784 Garching bei München, Germany.
| | - Robert M Reich
- Molecular Catalysis, Department of Chemistry and Catalysis Research Centre, Technische Universität München, Lichtenbergstr. 4, 85784 Garching bei München, Germany.
| | - Fritz E Kühn
- Molecular Catalysis, Department of Chemistry and Catalysis Research Centre, Technische Universität München, Lichtenbergstr. 4, 85784 Garching bei München, Germany.
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7
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Blatchford KM, Mize CJ, Roy S, Jenkins DM. Toward asymmetric aziridination with an iron complex supported by a D2-symmetric tetra-NHC. Dalton Trans 2022; 51:6153-6156. [PMID: 35380151 PMCID: PMC9019631 DOI: 10.1039/d2dt00772j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A neutral D2-symmetric macrocyclic tetra-N-heterocyclic carbene ligand was synthesized. The macrocycle was ligated to iron(ii) via transmetalation from an isolated silver complex that has two conformers. The iron complex catalyzed the first stereospecific aziridination between aryl azides and aliphatic alkenes, albeit with low ee's. A macrocyclic C2-symmetric tetra-NHC iron(ii) complex was synthesized and tested for asymmetric aziridination between aryl azides and alkenes.![]()
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Affiliation(s)
- Kevin M Blatchford
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
| | - Carson J Mize
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
| | - Sharani Roy
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
| | - David M Jenkins
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
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8
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Carroll XB, Errulat D, Murugesu M, Jenkins DM. Late Lanthanide Macrocyclic Tetra-NHC Complexes. Inorg Chem 2022; 61:1611-1619. [PMID: 34990145 DOI: 10.1021/acs.inorgchem.1c03416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An isostructural set of macrocyclic tetra-N-heterocyclic carbene (NHC) complexes were synthesized on late lanthanides including Lu, Yb, Ho, Dy, and Gd. They were characterized by single-crystal X-ray diffraction, multinuclear NMR, electrochemistry, and SQUID magnetometry. Solid-state structures show that all complexes are in a highly distorted square-pyramidal geometry with an axial HMDS ligand. 1H NMR for Lu, Yb, and Dy demonstrates that these geometries are maintained in solution. Electrochemical measurements on the Yb complex show that the NHCs are very strong σ-donors compared to other organometallic Yb complexes. Magnetic measurements of the Yb and Dy complexes reveal slow relaxation of the magnetization in both complexes. The highly anisotropic Dy complex possesses an energy barrier to spin reversal of 52.42 K/36.43 cm-1 and waist-restricted hysteresis up to 2.8 K. Finally, an 18-atom macrocycle variant of the Lu complex was synthesized for comparison in reactivity and stability. These complexes are the first lanthanides prepared with macrocyclic NHCs and suggest that NHCs may be a promising ligand for developing single-molecule magnets.
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Affiliation(s)
- Xian B Carroll
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Dylan Errulat
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Muralee Murugesu
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - David M Jenkins
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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9
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Hakey BM, Leary DC, Xiong J, Harris CF, Darmon JM, Petersen JL, Berry JF, Guo Y, Milsmann C. High Magnetic Anisotropy of a Square-Planar Iron-Carbene Complex. Inorg Chem 2021; 60:18575-18588. [PMID: 34431660 DOI: 10.1021/acs.inorgchem.1c01860] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Among Earth-abundant catalyst systems, iron-carbene intermediates that perform C-C bond forming reactions such as cyclopropanation of olefins and C-H functionalization via carbene insertion are rare. Detailed descriptions of the possible electronic structures for iron-carbene bonds are imperative to obtain better mechanistic insights and enable rational catalyst design. Here, we report the first square-planar iron-carbene complex (MesPDPPh)Fe(CPh2), where [MesPDPPh]2- is the doubly deprotonated form of [2,6-bis(5-(2,4,6-trimethylphenyl)-3-phenyl-1H-pyrrol-2-yl)pyridine]. The compound was prepared via reaction of the disubstituted diazoalkane N2CPh2 with (MesPDPPh)Fe(thf) and represents a rare example of a structurally characterized, paramagnetic iron-carbene complex. Temperature-dependent magnetic susceptibility measurements and applied-field Mössbauer spectroscopic studies revealed an orbitally near-degenerate S = 1 ground state with large unquenched orbital angular momentum resulting in high magnetic anisotropy. Spin-Hamiltonian analysis indicated that this S = 1 spin system has uniaxial magnetic properties arising from a ground MS = ±1 non-Kramers doublet that is well-separated from the MS = 0 sublevel due to very large axial zero-field splitting (D = -195 cm-1, E/D = 0.02 estimated from magnetic susceptibility data). This remarkable electronic structure gives rise to a very large, positive magnetic hyperfine field of more than +60 T for the 57Fe nucleus along the easy magnetization axis observed by Mössbauer spectroscopy. Computational analysis with complete active space self-consistent field (CASSCF) calculations provides a detailed electronic structure analysis and confirms that (MesPDPPh)Fe(CPh2) exhibits a multiconfigurational ground state. The majority contribution originates from a configuration best described as a singlet carbene coordinated to an intermediate-spin FeII center with a (dxy)2{(dxz),(dz2)}3(dyz)1(dx2-y2)0 configuration featuring near-degenerate dxz and dz2 orbitals.
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Affiliation(s)
- Brett M Hakey
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Dylan C Leary
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Jin Xiong
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Caleb F Harris
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Jonathan M Darmon
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Jeffrey L Petersen
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - John F Berry
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Carsten Milsmann
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
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10
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Pickl T, Pöthig A. Bimetallic Platinum Group Complexes of a Macrocyclic Pyrazolate/NHC Hybrid Ligand. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Thomas Pickl
- Catalysis Research Center & Department of Chemistry, Chair of Inorganic and Metal−Organic Chemistry, Technische Universität München, Ernst-Otto-Fischer Str. 1, D-85748 Garching b. München, Germany
| | - Alexander Pöthig
- Catalysis Research Center & Department of Chemistry, Chair of Inorganic and Metal−Organic Chemistry, Technische Universität München, Ernst-Otto-Fischer Str. 1, D-85748 Garching b. München, Germany
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11
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DeJesus JF, Kerr RWF, Penchoff DA, Carroll XB, Peterson CC, Arnold PL, Jenkins DM. Actinide tetra-N-heterocyclic carbene 'sandwiches'. Chem Sci 2021; 12:7882-7887. [PMID: 34168841 PMCID: PMC8188502 DOI: 10.1039/d1sc01007g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 04/15/2021] [Indexed: 11/21/2022] Open
Abstract
Highly-symmetrical, thorium and uranium octakis-carbene 'sandwich' complexes have been prepared by 'sandwiching' the An(iv) cations between two anionic macrocyclic tetra-NHC ligands, one with sixteen atoms and the other with eighteen atoms. The complexes were characterized by a range of experimental methods and DFT calculations. X-ray crystallography confirms the geometry at the metal centre can be set by the size of the macrocyclic ring, leading to either square prismatic or square anti-prismatic shapes; the geometry of the latter is retained in solution, which also undergoes reversible, electrochemical one-electron oxidation or reduction for the uranium variant. DFT calculations reveal a frontier orbital picture that is similar to thorocene and uranocene, in which the NHC ligands show almost exclusively σ-donation to the metal without π-backbonding.
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Affiliation(s)
- Joseph F DeJesus
- Department of Chemistry, The University of Tennessee Knoxville Tennessee 37996 USA
| | - Ryan W F Kerr
- School of Chemistry, University of Edinburgh West Mains Road Edinburgh EH9 3JJ UK
| | - Deborah A Penchoff
- Howard H. Baker Jr. Center for Public Policy, The University of Tennessee Knoxville Tennessee 37996 USA
| | - Xian B Carroll
- Department of Chemistry, The University of Tennessee Knoxville Tennessee 37996 USA
| | - Charles C Peterson
- Howard H. Baker Jr. Center for Public Policy, The University of Tennessee Knoxville Tennessee 37996 USA
- Research IT Services, University of North Texas Denton Texas 76201 USA
| | - Polly L Arnold
- School of Chemistry, University of Edinburgh West Mains Road Edinburgh EH9 3JJ UK
| | - David M Jenkins
- Department of Chemistry, The University of Tennessee Knoxville Tennessee 37996 USA
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12
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Massie AA, Schremmer C, Rüter I, Dechert S, Siewert I, Meyer F. Selective Electrocatalytic CO 2 Reduction to CO by an NHC-Based Organometallic Heme Analogue. ACS Catal 2021. [DOI: 10.1021/acscatal.0c04518] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Allyssa A. Massie
- Institute of Inorganic Chemistry, University of Göttingen, D-37077 Göttingen, Germany
| | - Claudia Schremmer
- Institute of Inorganic Chemistry, University of Göttingen, D-37077 Göttingen, Germany
| | - Isabelle Rüter
- Institute of Inorganic Chemistry, University of Göttingen, D-37077 Göttingen, Germany
| | - Sebastian Dechert
- Institute of Inorganic Chemistry, University of Göttingen, D-37077 Göttingen, Germany
| | - Inke Siewert
- Institute of Inorganic Chemistry, University of Göttingen, D-37077 Göttingen, Germany
| | - Franc Meyer
- Institute of Inorganic Chemistry, University of Göttingen, D-37077 Göttingen, Germany
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13
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Wang HX, Wan Q, Low KH, Zhou CY, Huang JS, Zhang JL, Che CM. Stable group 8 metal porphyrin mono- and bis(dialkylcarbene) complexes: synthesis, characterization, and catalytic activity. Chem Sci 2020; 11:2243-2259. [PMID: 32180931 PMCID: PMC7047983 DOI: 10.1039/c9sc05432d] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 12/30/2019] [Indexed: 12/17/2022] Open
Abstract
Alkyl-substituted carbene (CHR or CR2, R = alkyl) complexes have been extensively studied for alkylcarbene (CHR) ligands coordinated with high-valent early transition metal ions (a.k.a. Schrock carbenes or alkylidenes), yet dialkylcarbene (CR2) complexes remain less developed with bis(dialkylcarbene) species being little (if at all) explored. Herein, several group 8 metal porphyrin dialkylcarbene complexes, including Fe- and Ru-mono(dialkylcarbene) complexes [M(Por)(Ad)] (1a,b, M = Fe, Por = porphyrinato dianion, Ad = 2-adamantylidene; 2a,b, M = Ru) and Os-bis(dialkylcarbene) complexes [Os(Por)(Ad)2] (3a-c), are synthesized and crystallographically characterized. Detailed investigations into their electronic structures reveal that these complexes are formally low-valent M(ii)-carbene in nature. These complexes display remarkable thermal stability and chemical inertness, which are rationalized by a synergistic effect of strong metal-carbene covalency, hyperconjugation, and a rigid diamondoid carbene skeleton. Various spectroscopic techniques and DFT calculations suggest that the dialkylcarbene Ad ligand is unique compared to other common carbene ligands as it acts as both a potent σ-donor and π-acceptor; its unique electronic and structural features, together with the steric effect of the porphyrin macrocycle, make its Fe porphyrin complex 1a an active and robust catalyst for intermolecular diarylcarbene transfer reactions including cyclopropanation (up to 90% yield) and X-H (X = S, N, O, C) insertion (up to 99% yield) reactions.
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Affiliation(s)
- Hai-Xu Wang
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong SAR , China .
| | - Qingyun Wan
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong SAR , China .
| | - Kam-Hung Low
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong SAR , China .
| | - Cong-Ying Zhou
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong SAR , China .
- College of Chemistry and Materials Science , Jinan University , Guangzhou , China
| | - Jie-Sheng Huang
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong SAR , China .
| | - Jun-Long Zhang
- Beijing National Laboratory for Molecular Sciences , College of Chemistry and Molecular Engineering , Peking University , Beijing , China
| | - Chi-Ming Che
- State Key Laboratory of Synthetic Chemistry , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong SAR , China .
- HKU Shenzhen Institute of Research & Innovation , Shenzhen , China
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14
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Liang Q, Song D. Iron N-heterocyclic carbene complexes in homogeneous catalysis. Chem Soc Rev 2020; 49:1209-1232. [DOI: 10.1039/c9cs00508k] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
This review article summarizes recent development of homogeneous iron N-heterocyclic carbene catalysts.
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Affiliation(s)
- Qiuming Liang
- Davenport Chemical Research Laboratories
- Department of Chemistry
- University of Toronto
- Toronto
- Canada
| | - Datong Song
- Davenport Chemical Research Laboratories
- Department of Chemistry
- University of Toronto
- Toronto
- Canada
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