1
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Smith BA, Hakimov S, Jenkins DM, Vogiatzis KD. Ligand engineering of tetra N-heterocyclic carbenes for boosting catalytic aziridination. Dalton Trans 2024. [PMID: 39157935 DOI: 10.1039/d4dt01084a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2024]
Abstract
A comprehensive computational study on the underlying reactivity of iron tetra-NHC complexes for C2 + N1 aziridination catalysis is presented. A library of 18 unique iron tetra-NHC complexes was constructed, and a computational screening was performed on the reaction barriers associated with the rate-determining step (formation of an open chain radical intermediate). Thermodynamic barriers were computed along with a variety of steric and electronic properties, including the percentage of buried volume, orbital energies and ETS-NOCV analysis, which were used to identify key characteristics related to reactivity. The analysis performed in this study successfully identified key differences in tetracarbenes, such as linking groups (BMe2 or CH2) and the identity of the NHC groups (imidazole, imidazoline or benzimidazole) in terms of sterics, electronics and thermodynamics. Additionally, we have proposed two reaction pathways based on electronic structure arguments for the formation of the key open-chain radical intermediate. The first reaction pathway proceeds through a σ-hole channel where the Fe(IV)-imide intermediate evolves into Fe(III)-imidyl radical through electron donation into the antibonding σ* orbital, while the second involves a Fe(III)-imidyl radical formed through a π-hole channel (donation into π*). These pathways are consistent with the isoelectronic iron(IV)-oxo species for hydrogen atom abstraction mechanisms and they can be used as descriptors of the rate-determining step of the aziridination reaction.
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Affiliation(s)
- Brett A Smith
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996-1600, USA.
| | - Somon Hakimov
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996-1600, USA.
| | - David M Jenkins
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996-1600, USA.
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2
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Lakk-Bogáth D, Török P, Pintarics D, Kaizer J. A Mechanistic Study on Iron-Based Styrene Aziridination: Understanding Epoxidation via Nitrene Hydrolysis. Molecules 2024; 29:3470. [PMID: 39124875 PMCID: PMC11314292 DOI: 10.3390/molecules29153470] [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: 06/14/2024] [Revised: 07/19/2024] [Accepted: 07/22/2024] [Indexed: 08/12/2024] Open
Abstract
Transition-metal-catalyzed nitrene transfer reactions are typically performed in organic solvents under inert and anhydrous conditions due to the involved air and water-sensitive nature of reactive intermediates. Overall, this study provides insights into the iron-based ([FeII(PBI)3](CF3SO3)2 (1), where PBI = 2-(2-pyridyl)benzimidazole), catalytic and stoichiometric aziridination of styrenes using PhINTs ([(N-tosylimino)iodo]benzene), highlighting the importance of reaction conditions including the effects of the solvent, co-ligands (para-substituted pyridines), and substrate substituents on the product yields, selectivity, and reaction kinetics. The aziridination reactions with 1/PhINTs showed higher conversion than epoxidation with 1/PhIO (iodosobenzene). However, the reaction with PhINTs was less selective and yielded more products, including styrene oxide, benzaldehyde, and 2-phenyl-1-tosylaziridine. Therefore, the main aim of this study was to investigate the potential role of water in the formation of oxygen-containing by-products during radical-type nitrene transfer catalysis. During the catalytic tests, a lower yield was obtained in a protic solvent (trifluoroethanol) than in acetonitrile. In the case of the catalytic oxidation of para-substituted styrenes containing electron-donating groups, higher yield, TON, and TOF were achieved than those with electron-withdrawing groups. Pseudo-first-order kinetics were observed for the stoichiometric oxidation, and the second-order rate constants (k2 = 7.16 × 10-3 M-1 s-1 in MeCN, 2.58 × 10-3 M-1 s-1 in CF3CH2OH) of the reaction were determined. The linear free energy relationships between the relative reaction rates (logkrel) and the total substituent effect (TE, 4R-PhCHCH2) parameters with slopes of 1.48 (MeCN) and 1.89 (CF3CH2OH) suggest that the stoichiometric aziridination of styrenes can be described through the formation of a radical intermediate in the rate-determining step. Styrene oxide formation during aqueous styrene aziridination most likely results from oxygen atom transfer via in situ iron oxo/oxyl radical complexes, which are formed through the hydrolysis of [FeIII(N•Ts)] under experimental conditions.
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Affiliation(s)
| | | | | | - József Kaizer
- Research Group of Bioorganic and Bio-Coordination Chemistry, University of Pannonia, H-8201 Veszprém, Hungary; (D.L.-B.); (P.T.); (D.P.)
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3
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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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4
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Liang S, Jensen MP. [Fe(NCMe) 6](BF 4) 2 is a bifunctional catalyst for styrene aziridination by nitrene transfer and heterocycle expansion by subsequent dipolar insertion. J Inorg Biochem 2024; 256:112551. [PMID: 38678911 DOI: 10.1016/j.jinorgbio.2024.112551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 03/24/2024] [Accepted: 04/04/2024] [Indexed: 05/01/2024]
Abstract
The solvated iron(II) salt [Fe(NCMe)6](BF4)2 (Me = methyl) is shown to be a bifunctional catalyst with respect to aziridination of styrene. The salt serves as an active catalyst for nitrene transfer from PhINTs to styrene to form 2-phenyl-N-tosylaziridine (Ph = phenyl; Ts = tosyl, -S{O}2-p-C6H4Me). The iron(II) salt also acts as a Lewis acid in non-coordinating CH2Cl2 solution, to catalyze heterolytic CN bond cleavage of the aziridine and insertion of dipolarophiles. The 1,3-zwitterionic intermediate is presumably supported by interaction of the metal dication with the anion, and by resonance stabilization of the carbocation. Nucleophilic dipolarophiles then insert to give a five-membered heterocyclic ring. The result is a two-step cycloaddition, formally [2 + 1 + 2], that is typically regiospecific, but not stereospecific. This reaction mechanism was confirmed by conducting a series of one-step, [3 + 2] additions of unsaturated molecules into pre-formed 2-phenyl-N-tosylaziridine, also catalyzed by [Fe(NCMe)6](BF4)2. Relevant substrates include styrenes, carbonyl compounds and alkynes. These yield five-membered heterocylic rings, including pyrrolidines, oxazolidines and dihydropyrroles, respectively. The reaction scope appears limited only by the barrier to formation of the dipolar intermediate, and by the nucleophilicity of the captured dipolarophile. The bifunctionality of an inexpensive, earth-abundant and non-toxic catalyst suggests a general strategy for one-pot construction of heterocyclic rings, as demonstrated specifically for pyrrolidine ring formation.
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Affiliation(s)
- Shengwen Liang
- Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA
| | - Michael P Jensen
- Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA.
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5
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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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6
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Zars E, Pick L, Swain A, Bhunia M, Carroll PJ, Munz D, Meyer K, Mindiola DJ. Iron-Catalyzed Intermolecular C-H Amination Assisted by an Isolated Iron-Imido Radical Intermediate. Angew Chem Int Ed Engl 2023:e202311749. [PMID: 37815099 DOI: 10.1002/anie.202311749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 10/02/2023] [Accepted: 10/03/2023] [Indexed: 10/11/2023]
Abstract
Here we report the use of a base metal complex [(tBu pyrpyrr2 )Fe(OEt2 )] (1-OEt2 ) (tBu pyrpyrr2 2- =3,5-tBu2 -bis(pyrrolyl)pyridine) as a catalyst for intermolecular amination of Csp3 -H bonds of 9,10-dihydroanthracene (2 a) using 2,4,6-trimethyl phenyl azide (3 a) as the nitrene source. The reaction is complete within one hour at 80 °C using as low as 2 mol % 1-OEt2 with control in selectivity for single C-H amination versus double C-H amination. Catalytic C-H amination reactions can be extended to other substrates such as cyclohexadiene and xanthene derivatives and can tolerate a variety of aryl azides having methyl groups in both ortho positions. Under stoichiometric conditions the imido radical species [(tBu pyrpyrr2 )Fe{=N(2,6-Me2 -4-tBu-C6 H2 )] (1-imido) can be isolated in 56 % yield, and spectroscopic, magnetometric, and computational studies confirmed it to be an S = 1 FeIV complex. Complex 1-imido reacts with 2 a to produce the ferrous aniline adduct [(tBu pyrpyrr2 )Fe{NH(2,6-Me2 -4-tBu-C6 H2 )(C14 H11 )}] (1-aniline) in 45 % yield. Lastly, it was found that complexes 1-imido and 1-aniline are both competent intermediates in catalytic intermolecular C-H amination.
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Affiliation(s)
- Ethan Zars
- Department of Chemistry, University of Pennsylvania, 231 S 34th St, Philadelphia, PA-19104, USA
| | - Lisa Pick
- Department of Chemistry & Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen - Nürnberg (FAU), 91058, Erlangen, Germany
| | - Abinash Swain
- Inorganic Chemistry: Coordination Chemistry, Saarland University, Campus C4 1, 66123, Saarbrücken, Germany
| | - Mrinal Bhunia
- Department of Chemistry, University of Pennsylvania, 231 S 34th St, Philadelphia, PA-19104, USA
| | - Patrick J Carroll
- Department of Chemistry, University of Pennsylvania, 231 S 34th St, Philadelphia, PA-19104, USA
| | - Dominik Munz
- Inorganic Chemistry: Coordination Chemistry, Saarland University, Campus C4 1, 66123, Saarbrücken, Germany
| | - Karsten Meyer
- Department of Chemistry & Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen - Nürnberg (FAU), 91058, Erlangen, Germany
| | - Daniel J Mindiola
- Department of Chemistry, University of Pennsylvania, 231 S 34th St, Philadelphia, PA-19104, USA
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7
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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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8
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Xiong J, Liu Q, Lavina B, Hu MY, Zhao J, Alp EE, Deng L, Ye S, Guo Y. Spin polarization assisted facile C-H activation by an S = 1 iron(iv)-bisimido complex: a comprehensive spectroscopic and theoretical investigation. Chem Sci 2023; 14:2808-2820. [PMID: 36937578 PMCID: PMC10016330 DOI: 10.1039/d2sc06273a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 02/14/2023] [Indexed: 02/17/2023] Open
Abstract
High valent iron terminal imido species (Fe[double bond, length as m-dash]NR) have been shown to be key reactive intermediates in C-H functionalization. However, the detailed structure-reactivity relationship in Fe[double bond, length as m-dash]NR species derived from studies of structurally well-characterized high-valent Fe[double bond, length as m-dash]NR complexes are still scarce, and the impact of imido N-substituents (electron-donating vs. electron-withdrawing) on their electronic structures and reactivities has not been thoroughly explored. In this study, we report spectroscopic and computational studies on a rare S = 1 iron(iv)-bisimido complex featuring trifluoromethyl groups on the imido N-substituents, [(IPr)Fe(NC(CF3)2Ph)2] (2), and two closely related S = 0 congeners bearing alkyl and aryl substituents, [(IPr)Fe(NC(CMe3)2Ph)2] (3) and [(IPr)Fe(NDipp)2] (1), respectively. Compared with 1 and 3, 2 exhibits a decreased Fe[double bond, length as m-dash]NR bond covalency due to the electron-withdrawing and the steric effect of the N-substituents, which further leads to a pseudo doubly degenerate ground electronic structure and spin polarization induced β spin density on the imido nitrogens. This unique electronic structure, which differs from those of the well-studied Fe(iv)-oxido complexes and many previously reported Fe(iv)-imido complexes, provides both kinetic and thermodynamic advantages for facile C-H activation, compared to the S = 0 counterparts.
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Affiliation(s)
- Jin Xiong
- Department of Chemistry, Carnegie Mellon University Pittsburgh Pennsylvania 15213 USA
| | - Qing Liu
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences Shanghai 200032 P. R. China
| | - Barbara Lavina
- Advanced Photon Source, Argonne National Laboratory Argonne Illinois 60439 USA
- Center for Advanced Radiation Sources, University of Chicago Chicago Illinois 60439 USA
| | - Michael Y Hu
- Advanced Photon Source, Argonne National Laboratory Argonne Illinois 60439 USA
| | - Jiyong Zhao
- Advanced Photon Source, Argonne National Laboratory Argonne Illinois 60439 USA
| | - Esen E Alp
- Advanced Photon Source, Argonne National Laboratory Argonne Illinois 60439 USA
| | - Liang Deng
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences Shanghai 200032 P. R. China
| | - Shengfa Ye
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 P. R. China
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University Pittsburgh Pennsylvania 15213 USA
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9
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Bhutto SM, Hooper RX, Mercado BQ, Holland PL. Mechanism of Nitrogen-Carbon Bond Formation from Iron(IV) Disilylhydrazido Intermediates during N 2 Reduction. J Am Chem Soc 2023; 145:4626-4637. [PMID: 36794981 DOI: 10.1021/jacs.2c12382] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
We recently reported a reaction sequence that activates C-H bonds in simple arenes as well as the N-N triple bond in N2, delivering the aryl group to N2 to form a new N-C bond (Nature 2020, 584, 221). This enables the transformation of abundant feedstocks (arenes and N2) into N-containing organic compounds. The key N-C bond forming step occurs upon partial silylation of N2. However, the pathway through which reduction, silylation, and migration occurred was unknown. Here, we describe synthetic, structural, magnetic, spectroscopic, kinetic, and computational studies that elucidate the steps of this transformation. N2 must be silylated twice at the distal N atom before aryl migration can occur, and sequential silyl radical and silyl cation addition is a kinetically competent pathway to a formally iron(IV)-NN(SiMe3)2 intermediate that can be isolated at low temperature. Kinetic studies show its first-order conversion to the migrated product, and DFT calculations indicate a concerted transition state for migration. The electronic structure of the formally iron(IV) intermediate is examined using DFT and CASSCF calculations, which reveal contributions from iron(II) and iron(III) resonance forms with oxidized NNSi2 ligands. The depletion of electron density from the Fe-coordinated N atom makes it electrophilic enough to accept the incoming aryl group. This new pathway for the N-C bond formation offers a method for functionalizing N2 using organometallic chemistry.
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Affiliation(s)
- Samuel M Bhutto
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520, United States
| | - Reagan X Hooper
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520, United States
| | - Brandon Q Mercado
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520, United States
| | - Patrick L Holland
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520, United States
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10
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Chen X, Tian Z, Yang Q, Zhang L, Yang Q, Chen L, Lu Z. Cost-Effective H 2 O 2 -Regeneration of Powdered Activated Carbon by Isolated Fe Sites. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2204079. [PMID: 36399640 PMCID: PMC9839841 DOI: 10.1002/advs.202204079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/14/2022] [Indexed: 06/16/2023]
Abstract
The reuse of powdered activated carbon (PAC) vitally determines the economics and security of the PAC-based adsorption process, while state-of-the-art PAC regeneration technologies are usually unsatisfactory. Here, it is demonstrated that isolated Fe sites anchored on commercial PAC enable fast H2 O2 activation to produce Fe-based reactive oxygen species for highly efficient PAC regeneration at room temperature. Taking rhodamine B as a representative pollutant, PAC decorated with isolated Fe sites realize H2 O2 based regeneration with negligible adsorption capacity degradation for 10 cycles. Moreover, in terms of the PAC loss rate, this technology is greatly superior to traditional Fenton-based regeneration technology. Further operando experiments and theoretical calculations reveal that the high regeneration performance can be attributed to the isolated HOFeO motifs, which activate H2 O2 via a nonradical reaction pathway. These findings provide a very promising strategy toward reducing the cost of H2 O2 -based PAC regeneration technology.
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Affiliation(s)
- Xu Chen
- Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang ProvinceQianwan Institute of CNITECHNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingboZhejiang315201P. R. China
- University of Chinese Academy of SciencesBeijing100049P. R. China
| | - Ziqi Tian
- Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang ProvinceQianwan Institute of CNITECHNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingboZhejiang315201P. R. China
- University of Chinese Academy of SciencesBeijing100049P. R. China
| | - Qihao Yang
- Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang ProvinceQianwan Institute of CNITECHNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingboZhejiang315201P. R. China
- University of Chinese Academy of SciencesBeijing100049P. R. China
| | - Linjuan Zhang
- Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang ProvinceQianwan Institute of CNITECHNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingboZhejiang315201P. R. China
- Key Laboratory of Interfacial Physics and TechnologyShanghai Institute of Applied PhysicsChinese Academy of SciencesShanghai201800P. R. China
| | - Qiu Yang
- Ningbo New Material Testing and Evaluation Center Co., LtdNingbo New Materials Innovation CenterNingboZhejiang315201P. R. China
| | - Liang Chen
- University of Chinese Academy of SciencesBeijing100049P. R. China
| | - Zhiyi Lu
- Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang ProvinceQianwan Institute of CNITECHNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingboZhejiang315201P. R. China
- University of Chinese Academy of SciencesBeijing100049P. R. China
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11
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Mao W, Fehn D, Heinemann FW, Scheurer A, van Gastel M, Jannuzzi SAV, DeBeer S, Munz D, Meyer K. Umpolung in a Pair of Cobalt(III) Terminal Imido/Imidyl Complexes. Angew Chem Int Ed Engl 2022; 61:e202206848. [PMID: 35674679 PMCID: PMC9541304 DOI: 10.1002/anie.202206848] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Indexed: 11/12/2022]
Abstract
Reaction of the CoI complex [(TIMMNmes )CoI ](PF6 ) (1) (TIMMNmes =tris-[2-(3-mesityl-imidazolin-2-ylidene)-methyl]amine) with mesityl azide yields the CoIII imide [(TIMMNmes )CoIII (NMes)](PF6 ) (2). Oxidation of 2 with [FeCp2 ](PF6 ) provides access to a rare CoIII imidyl [(TIMMNmes )Co(NMes)](PF6 )2 (3). Single-crystal X-ray diffractometry and EPR spectroscopy confirm the molecular structure of 3 and its S= 1 / 2 ground state. ENDOR, X-ray absorption spectroscopy and computational analyses indicate a ligand-based oxidation; thus, an imidyl-radical electronic structure for 3. Migratory insertion of one ancillary NHC to the imido ligand in 2 gives the CoI N-heterocyclic imine (4) within 12 h. Conversely, it takes merely 0.5 h for 3 to transform to the CoII congener (5). The migratory insertion in 2 occurs via a nucleophilic attack of the imido ligand at the NHC to give 4, whereas in 3, a nucleophilic attack of the NHC at the electrophilic imidyl ligand yields 5. The reactivity shunt upon oxidation of 2 to 3 confirms an umpolung of the imido ligand.
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Affiliation(s)
- Weiqing Mao
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
| | - Dominik Fehn
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
| | - Frank W. Heinemann
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
| | - Andreas Scheurer
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
| | - Maurice van Gastel
- Max-Planck-Institut für KohlenforschungKaiser-Wilhelm-Platz 145470Mülheim an der RuhrGermany
| | - Sergio A. V. Jannuzzi
- Max Planck Institute for Chemical Energy ConversionStiftstr. 34–3645470Mülheim an der RuhrGermany
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy ConversionStiftstr. 34–3645470Mülheim an der RuhrGermany
| | - Dominik Munz
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
- Current address: Saarland UniversityInorganic Chemistry: Coordination ChemistryCampus C4.166123SaarbrückenGermany
| | - Karsten Meyer
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
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12
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Mao W, Fehn D, Heinemann FW, Scheurer A, van Gastel M, Jannuzzi SAV, DeBeer S, Munz D, Meyer K. Umpolung in a Pair of Cobalt(III) Terminal Imido/Imidyl Complexes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202206848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Weiqing Mao
- Friedrich-Alexander-Universität Erlangen-Nürnberg: Friedrich-Alexander-Universitat Erlangen-Nurnberg Department of Chemistry and Pharmacy GERMANY
| | - Dominik Fehn
- Friedrich-Alexander-Universität Erlangen-Nürnberg: Friedrich-Alexander-Universitat Erlangen-Nurnberg Department of Chemistry and Pharmacy GERMANY
| | - Frank W. Heinemann
- Friedrich-Alexander-Universität Erlangen-Nürnberg: Friedrich-Alexander-Universitat Erlangen-Nurnberg Department of Chemistry and Pharmacy GERMANY
| | - Andreas Scheurer
- Friedrich-Alexander-Universität Erlangen-Nürnberg: Friedrich-Alexander-Universitat Erlangen-Nurnberg Department of Chemistry and Pharmacy GERMANY
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung: Max-Planck-Institut fur Kohlenforschung Spectroscopy GERMANY
| | | | - Serena DeBeer
- Max-Planck-Institut für chemische Energiekonversion: Max-Planck-Institut fur chemische Energiekonversion Spectroscopy GERMANY
| | - Dominik Munz
- Saarland University: Universitat des Saarlandes Inorganic Chemistry: Coordination Chemistry GERMANY
| | - Karsten Meyer
- Friedrich-Alexander-Universität Erlangen-Nürnberg: Friedrich-Alexander-Universitat Erlangen-Nurnberg Department Chemie und Pharmazie Anorganische ChemieEgerlandstr. 1 91058 Erlangen GERMANY
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13
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Cordes Née Kupper C, Klawitter I, Rüter I, Dechert S, Demeshko S, Ye S, Meyer F. Organometallic μ-Nitridodiiron Complexes in Oxidation States Ranging from (III/III) to (IV/IV). Inorg Chem 2022; 61:7153-7164. [PMID: 35475617 DOI: 10.1021/acs.inorgchem.2c00685] [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
Iron complexes with nitrido ligands are of interest as molecular analogues of key intermediates during N2-to-NH3 conversion in industrial or enzymatic processes. Dinuclear iron complexes with a bridging nitrido unit are mostly known in relatively high oxidation states (III/IV or IV/IV), originating from the decomposition of azidoiron precursors via high-valent Fe≡N intermediates. The use of a tetra-NHC macrocyclic scaffold ligand (NHC = N-heterocyclic carbene) has now allowed for the isolation of a series of organometallic μ-nitridodiiron complexes ranging from the mid-valent FeIII-N-FeIII (1) via mixed-valent FeIII-N-FeIV (type 4) to the high-valent FeIV-N-FeIV (type 5) species that are interconverted at moderate potentials, accompanied by axial ligand binding at the FeIV sites. Magnetic measurements and electron paramagnetic resonance spectroscopy showed the homovalent complexes to be diamagnetic and the mixed-valent system to feature an S = 1/2 ground state due to very strong antiferromagnetic coupling. The bonding in the Fe-N-Fe moiety has been further probed by crystallographic structure determination, 57Fe Mössbauer and UV-vis spectroscopies, as well as density functional theory computations, which revealed high covalency and nearly identical Fe-N distances across this redox series. The latter has been rationalized in terms of the nonbonding nature of the combination of Fe dz2 atomic orbitals from which electrons are successively removed upon oxidation, and these redox processes are best described as being metal-centered. The tetra-NHC-ligated μ-nitridodiiron series complements a set of related complexes with single-atom μ-oxido and μ-phosphido bridges, but the Fe-N-Fe core exhibits a comparatively high stability over several oxidation states. This promises interesting applications in view of the manifold catalytic uses of μ-nitridodiiron complexes based on macrocyclic N-donor porphinato(2-) or phthalocyaninato(2-) ligands.
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Affiliation(s)
- Claudia Cordes Née Kupper
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Iris Klawitter
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Isabelle Rüter
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Sebastian Dechert
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Serhiy Demeshko
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Shengfa Ye
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
| | - Franc Meyer
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
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14
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Baek Y, Betley TA. Reversible C-C Bond Cleavage of a Cobalt Diketimide into an Elusive Cobalt Aryl Nitrenoid Complex. Angew Chem Int Ed Engl 2022; 61:e202115437. [PMID: 35172039 PMCID: PMC9007855 DOI: 10.1002/anie.202115437] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Indexed: 11/09/2022]
Abstract
The reactivity of (Tr L)Co (Tr L=5-mesityl-1,9-(trityl)dipyrrin) toward various aryl azides was examined to elucidate the electronic structure and reactivity of dipyrrinato cobalt aryl nitrenoid complexes. Herein, we demonstrate the synthesis of a CoII diketimide complex [(Tr L)Co(NC6 F5 )]2 and its reversible C-C bond cleavage to yield a monomeric Co nitrenoid complex (Tr L)Co(NC6 F5 ). Exposure of [(Tr L)Co(NC6 F5 )]2 to an excess amount of an H-atom donor cleanly affords the CoII anilide complex (Tr L)Co(NHC6 F5 ). The half-order decay of [(Tr L)Co(NC6 F5 )]2 via H-atom abstraction (HAA) reveals saturation kinetic behavior indicating a pre-equilibrium between [(Tr L)Co(NC6 F5 )]2 and (Tr L)Co(NC6 F5 ) prior to HAA. Furthermore, (Tr L)Co(NC6 F5 ) undergoes reductive coupling with another equivalent of azide to furnish the four-coordinate tetrazido complex (Tr L)Co(κ2 -N4 (C6 F5 )2 ), expulsion of a fluorine atom to afford (Tr L)CoF, and N-group transfer reactivity to PPh3 .
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Affiliation(s)
- Yunjung Baek
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA
| | - Theodore A Betley
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA
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15
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Basappa S, Bhawar R, Nagaraju DH, Bose SK. Recent advances in the chemistry of the phosphaethynolate and arsaethynolate anions. Dalton Trans 2022; 51:3778-3806. [PMID: 35108724 DOI: 10.1039/d1dt03994f] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Over the past decade, the reactivity of 2-phosphaethynolate (OCP-), a heavier analogue of the cyanate anion, has been the subject of momentous interest in the field of modern organometallic chemistry. It is used as a precursor to novel phosphorus-containing heterocycles and as a ligand in decarbonylative processes, serving as a synthetic equivalent of a phosphinidene derivative. This perspective aims to describe advances in the reactivities of phosphaethynolate and arsaethynolate anions (OCE-; E = P, As) with main-group element, transition metal, and f-block metal scaffolds. Further, the unique structures and bonding properties are discussed based on spectroscopic and theoretical studies.
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Affiliation(s)
- Suma Basappa
- Centre for Nano and Material Sciences (CNMS), Jain University, Jain Global Campus, Bangalore-562112, India.
| | - Ramesh Bhawar
- Centre for Nano and Material Sciences (CNMS), Jain University, Jain Global Campus, Bangalore-562112, India.
| | - D H Nagaraju
- Department of Chemistry, School of Applied Sciences, Reva University, Bangalore 560064, India.
| | - Shubhankar Kumar Bose
- Centre for Nano and Material Sciences (CNMS), Jain University, Jain Global Campus, Bangalore-562112, India.
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16
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Baek Y, Betley TA. Reversible C−C Bond Cleavage of a Cobalt Diketimide into an Elusive Cobalt Aryl Nitrenoid Complex. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Yunjung Baek
- Department of Chemistry and Chemical Biology Harvard University 12 Oxford Street Cambridge MA 02138 USA
| | - Theodore A. Betley
- Department of Chemistry and Chemical Biology Harvard University 12 Oxford Street Cambridge MA 02138 USA
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17
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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: 4] [Impact Index Per Article: 2.0] [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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18
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Yang PC, Yu KP, Hsieh CT, Zou J, Fang CT, Liu HK, Pao CW, Deng L, Cheng MJ, Lin CY. Stabilization of a high-spin three-coordinate Fe(III) imidyl complex by radical delocalization. Chem Sci 2022; 13:9637-9643. [PMID: 36091897 PMCID: PMC9400638 DOI: 10.1039/d2sc02699f] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 07/04/2022] [Indexed: 11/21/2022] Open
Abstract
High-spin, late transition metal imido complexes have attracted significant interest due to their group transfer reactivity and catalytic C−H activation of organic substrates. Reaction of a new two-coordinate iron complex,...
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Affiliation(s)
- Po-Chun Yang
- Department of Chemistry, National Cheng Kung University No. 1 University Road Tainan 701014 Taiwan
| | - Kuan-Po Yu
- Department of Chemistry, National Cheng Kung University No. 1 University Road Tainan 701014 Taiwan
| | - Chi-Tien Hsieh
- Department of Chemistry, National Cheng Kung University No. 1 University Road Tainan 701014 Taiwan
| | - Junjie Zou
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 P. R. China
| | - Chia-Te Fang
- Department of Chemistry, National Cheng Kung University No. 1 University Road Tainan 701014 Taiwan
| | - Hsin-Kuan Liu
- Core Facility Center, National Cheng Kung University No. 1 University Road Tainan 701014 Taiwan
| | - Chih-Wen Pao
- National Synchrotron Radiation Research Center 101 Hsin-Ann Road Hsinchu 300092 Taiwan
| | - Liang Deng
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 P. R. China
| | - Mu-Jeng Cheng
- Department of Chemistry, National Cheng Kung University No. 1 University Road Tainan 701014 Taiwan
| | - Chun-Yi Lin
- Department of Chemistry, National Cheng Kung University No. 1 University Road Tainan 701014 Taiwan
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19
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Reith S, Demeshko S, Battistella B, Reckziegel A, Schneider C, Stoy A, Lichtenberg C, Meyer F, Munz D, Werncke CG. Between imide, imidyl and nitrene – an imido iron complex in two oxidation states. Chem Sci 2022; 13:7907-7913. [PMID: 35865905 PMCID: PMC9258327 DOI: 10.1039/d2sc01088g] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 05/28/2022] [Indexed: 01/11/2023] Open
Abstract
Imidyl and nitrene metal species play an important role in the N-functionalisation of unreactive C–H bonds as well as the aziridination of olefines. We report on the synthesis of the trigonal imido iron complexes [Fe(NMes)L2]0,− (L = –N{Dipp}SiMe3); Dipp = 2,6-diisopropyl-phenyl; Mes = (2,4,6-trimethylphenyl) via reaction of mesityl azide (MesN3) with the linear iron precursors [FeL2]0,−. UV-vis-, EPR-, 57Fe Mössbauer spectroscopy, magnetometry, and computational methods suggest for the reduced form an electronic structure as a ferromagnetically coupled iron(ii) imidyl radical, whereas oxidation leads to mixed iron(iii) imidyl and electrophilic iron(ii) nitrene character. Reactivity studies show that both complexes are capable of H atom abstraction from C–H bonds. Further, the reduced form [Fe(NMes)L2]− reacts nucleophilically with CS2 by inserting into the imido iron bond, as well as electrophilically with CO under nitrene transfer. The neutral [Fe(NMes)L2] complex shows enhanced electrophilic behavior as evidenced by nitrene transfer to a phosphine, yet in combination with an overall reduced reactivity. A pair of trigonal imido iron complexes ([Fe(NMes)L2]0,−) in two oxidation states is reported. The anionic complex K{crypt.222}[Fe(NMes)L2] is best described as an iron(ii) imide.![]()
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Affiliation(s)
- Sascha Reith
- Philipps-University Marburg, Department of Chemistry, Hans-Meerwein-Str. 4, D-35037 Marburg, Germany
| | - Serhiy Demeshko
- University of Göttingen, Institute of Inorganic Chemistry, Tammannstr. 4, D-37077 Göttingen, Germany
| | - Beatrice Battistella
- Humboldt-University, Berlin Institute for Chemistry, Brook-Taylor-Str. 2, D-12489 Berlin, Germany
| | - Alexander Reckziegel
- Philipps-University Marburg, Department of Chemistry, Hans-Meerwein-Str. 4, D-35037 Marburg, Germany
| | - Christian Schneider
- Philipps-University Marburg, Department of Chemistry, Hans-Meerwein-Str. 4, D-35037 Marburg, Germany
| | - Andreas Stoy
- Philipps-University Marburg, Department of Chemistry, Hans-Meerwein-Str. 4, D-35037 Marburg, Germany
| | - Crispin Lichtenberg
- Philipps-University Marburg, Department of Chemistry, Hans-Meerwein-Str. 4, D-35037 Marburg, Germany
| | - Franc Meyer
- University of Göttingen, Institute of Inorganic Chemistry, Tammannstr. 4, D-37077 Göttingen, Germany
| | - Dominik Munz
- Saarland University, Inorganic Chemistry: Coordination Chemistry, Campus C4.1, D-66123 Saarbrücken, Germany
- Friedrich-Alexander University Erlangen-Nürnberg, Inorganic Chemistry, Egerlandstr. 1, D-91058 Erlangen, Germany
| | - C. Gunnar Werncke
- Philipps-University Marburg, Department of Chemistry, Hans-Meerwein-Str. 4, D-35037 Marburg, Germany
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20
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Richards CA, Rath NP, Neely JM. Iron-Catalyzed Alkyne Carboamination via an Isolable Iron Imide Complex. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00454] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Corey A. Richards
- Department of Chemistry, Saint Louis University, St. Louis, Missouri 63103, United States
| | - Nigam P. Rath
- Department of Chemistry and Biochemistry, University of Missouri—St. Louis, St. Louis, Missouri 63121, United States
| | - Jamie M. Neely
- Department of Chemistry, Saint Louis University, St. Louis, Missouri 63103, United States
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21
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Mao W, Fehn D, Heinemann FW, Scheurer A, Munz D, Meyer K. A Pair of Cobalt(III/IV) Terminal Imido Complexes. Angew Chem Int Ed Engl 2021; 60:16480-16486. [PMID: 33847448 PMCID: PMC8362208 DOI: 10.1002/anie.202103170] [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: 03/03/2021] [Revised: 03/29/2021] [Indexed: 12/16/2022]
Abstract
The reaction of the cobalt(I) complex [(TIMMNmes )CoI ](BPh4 ) (2) (TIMMNmes =tris-[2-(3-mesitylimidazolin-2-ylidene)methyl]amine) with 1-adamantylazide yields the cobalt(III) imido complex [(TIMMNmes )CoIII (NAd)](BPh4 ) (3) with concomitant release of dinitrogen. The N-anchor in diamagnetic 3 features an unusual, planar tertiary amine, which results from repulsive electrostatic interaction with the filled d(z2 )-orbital of the cobalt ion and negative hyperconjugation with the neighboring methylene groups. One-electron oxidation of 3 with [FeCp2 ](OTf) provides access to the rare, high-valent cobalt(IV) imido complex [(TIMMNmes )CoIV (NAd)](OTf)2 (4). Despite a half-life of less than 1 h at room temperature, 4 could be isolated at low temperatures in analytically pure form. Single-crystal X-ray diffractometry and EPR spectroscopy corroborate the molecular structure and the d5 low-spin, S= 1 / 2 , electron configuration. A computational analysis of 4 suggests high covalency within the CoIV =NAd bond with non-negligible spin density located at the imido moiety, which translates into substantial triplet nitrene character.
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Affiliation(s)
- Weiqing Mao
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
| | - Dominik Fehn
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
| | - Frank W. Heinemann
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
| | - Andreas Scheurer
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
| | - Dominik Munz
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
- Current address: Saarland UniversityInorganic Chemistry: Coordination ChemistryCampus C4.166123SaarbrückenGermany
| | - Karsten Meyer
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)Inorganic ChemistryEgerlandstrasse 191058ErlangenGermany
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22
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Sahoo D, Iovan DA. Toward understanding highly electron-withdrawing terminal Fe(IV) imides. Chem 2021. [DOI: 10.1016/j.chempr.2021.06.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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23
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Mao W, Fehn D, Heinemann FW, Scheurer A, Munz D, Meyer K. A Pair of Cobalt(III/IV) Terminal Imido Complexes. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202103170] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Weiqing Mao
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Inorganic Chemistry Egerlandstrasse 1 91058 Erlangen Germany
| | - Dominik Fehn
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Inorganic Chemistry Egerlandstrasse 1 91058 Erlangen Germany
| | - Frank W. Heinemann
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Inorganic Chemistry Egerlandstrasse 1 91058 Erlangen Germany
| | - Andreas Scheurer
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Inorganic Chemistry Egerlandstrasse 1 91058 Erlangen Germany
| | - Dominik Munz
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Inorganic Chemistry Egerlandstrasse 1 91058 Erlangen Germany
- Current address: Saarland University Inorganic Chemistry: Coordination Chemistry Campus C4.1 66123 Saarbrücken Germany
| | - Karsten Meyer
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Inorganic Chemistry Egerlandstrasse 1 91058 Erlangen Germany
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24
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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: 9] [Impact Index Per Article: 3.0] [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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25
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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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26
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Schlagintweit JF, Altmann PJ, Böth AD, Hofmann BJ, Jandl C, Kaußler C, Nguyen L, Reich RM, Pöthig A, Kühn FE. Activation of Molecular Oxygen by a Cobalt(II) Tetra-NHC Complex*. Chemistry 2021; 27:1311-1315. [PMID: 33125815 PMCID: PMC7898330 DOI: 10.1002/chem.202004758] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Indexed: 11/24/2022]
Abstract
The first dicobalt(III) μ2 -peroxo N-heterocyclic carbene (NHC) complex is reported. It can be quantitatively generated from a cobalt(II) compound bearing a 16-membered macrocyclic tetra-NHC ligand via facile activation of dioxygen from air at ambient conditions. The reaction proceeds via an end-on superoxo intermediate as demonstrated by EPR studies and DFT. The peroxo moiety can be cleaved upon addition of acetic acid, yielding the corresponding CoIII acetate complex going along with H2 O2 formation. In contrast, both CoII and CoIII complexes are also studied as catalysts to utilize air for olefin and alkane oxidation reactions; however, not resulting in product formation. The observations are rationalized by DFT-calculations, suggesting a nucleophilic nature of the dicobalt(III) μ2 -peroxo complex. All isolated compounds are characterized by NMR, ESI-MS, elemental analysis, EPR and SC-XRD.
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Affiliation(s)
- Jonas F. Schlagintweit
- Molecular CatalysisCatalysis Research Center and Department of ChemistryTechnische Universität MünchenLichtenbergstraße 485747Garching bei MünchenGermany
| | - Philipp J. Altmann
- Molecular CatalysisCatalysis Research Center and Department of ChemistryTechnische Universität MünchenLichtenbergstraße 485747Garching bei MünchenGermany
- Single Crystal XRD Laboratory of the Catalysis Research CenterTechnische Universität MünchenErnst-Otto-Fischer-Str. 185747Garching bei MünchenGermany
| | - Alexander D. Böth
- Molecular CatalysisCatalysis Research Center and Department of ChemistryTechnische Universität MünchenLichtenbergstraße 485747Garching bei MünchenGermany
| | - Benjamin J. Hofmann
- Molecular CatalysisCatalysis Research Center and Department of ChemistryTechnische Universität MünchenLichtenbergstraße 485747Garching bei MünchenGermany
| | - Christian Jandl
- Single Crystal XRD Laboratory of the Catalysis Research CenterTechnische Universität MünchenErnst-Otto-Fischer-Str. 185747Garching bei MünchenGermany
| | - Clemens Kaußler
- Molecular CatalysisCatalysis Research Center and Department of ChemistryTechnische Universität MünchenLichtenbergstraße 485747Garching bei MünchenGermany
| | - Linda Nguyen
- Molecular CatalysisCatalysis Research Center and Department of ChemistryTechnische Universität MünchenLichtenbergstraße 485747Garching bei MünchenGermany
- Ausbildungszentrum der Technischen Universität MünchenTechnische Universität MünchenLichtenbergstraße 485747Garching bei MünchenGermany
| | - Robert M. Reich
- Molecular CatalysisCatalysis Research Center and Department of ChemistryTechnische Universität MünchenLichtenbergstraße 485747Garching bei MünchenGermany
| | - Alexander Pöthig
- Single Crystal XRD Laboratory of the Catalysis Research CenterTechnische Universität MünchenErnst-Otto-Fischer-Str. 185747Garching bei MünchenGermany
| | - Fritz E. Kühn
- Molecular CatalysisCatalysis Research Center and Department of ChemistryTechnische Universität MünchenLichtenbergstraße 485747Garching bei MünchenGermany
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27
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Gao Y, Pink M, Smith JM. Iron(II) Complexes of an Anionic Bis(ylide)diphenylborate Ligand. Inorg Chem 2020; 59:17303-17309. [DOI: 10.1021/acs.inorgchem.0c02575] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yafei Gao
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Maren Pink
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Jeremy M. Smith
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
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28
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Prakash O, Chábera P, Rosemann NW, Huang P, Häggström L, Ericsson T, Strand D, Persson P, Bendix J, Lomoth R, Wärnmark K. A Stable Homoleptic Organometallic Iron(IV) Complex. Chemistry 2020; 26:12728-12732. [PMID: 32369645 PMCID: PMC7590184 DOI: 10.1002/chem.202002158] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Indexed: 11/08/2022]
Abstract
A homoleptic organometallic FeIV complex that is stable in both solution and in the solid state at ambient conditions has been synthesized and isolated as [Fe(phtmeimb)2 ](PF6 )2 (phtmeimb=[phenyl(tris(3-methylimidazolin-2-ylidene))borate]- ). This FeIV N-heterocyclic carbene (NHC) complex was characterized by 1 H NMR, HR-MS, elemental analysis, scXRD analysis, electrochemistry, Mößbauer spectroscopy, and magnetic susceptibility. The two latter techniques unequivocally demonstrate that [Fe(phtmeimb)2 ](PF6 )2 is a triplet FeIV low-spin S=1 complex in the ground state, in agreement with quantum chemical calculations. The electronic absorption spectrum of [Fe(phtmeimb)2 ](PF6 )2 in acetonitrile shows an intense absorption band in the red and near IR, due to LMCT (ligand-to-metal charge transfer) excitation. For the first time the excited state dynamics of a FeIV complex was studied and revealed a ≈0.8 ps lifetime of the 3 LMCT excited state of [Fe(phtmeimb)2 ](PF6 )2 in acetonitrile.
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Affiliation(s)
- Om Prakash
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, Lund, 22100, Sweden
| | - Pavel Chábera
- Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, Lund, 22100, Sweden
| | - Nils W Rosemann
- Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, Lund, 22100, Sweden
| | - Ping Huang
- Department of Chemistry, Ångström Laboratory, Uppsala University, Box 523, Uppsala, 75120, Sweden
| | - Lennart Häggström
- Department of Physics, Ångström Laboratory, Uppsala University, Box 528, Uppsala, 751 21, Sweden
| | - Tore Ericsson
- Department of Physics, Ångström Laboratory, Uppsala University, Box 528, Uppsala, 751 21, Sweden
| | - Daniel Strand
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, Lund, 22100, Sweden
| | - Petter Persson
- Theoretical Chemistry Division, Department of Chemistry, Lund University, Box 124, Lund, 22100, Sweden
| | - Jesper Bendix
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Reiner Lomoth
- Department of Chemistry, Ångström Laboratory, Uppsala University, Box 523, Uppsala, 75120, Sweden
| | - Kenneth Wärnmark
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, Lund, 22100, Sweden
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29
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Coin G, Patra R, Rana S, Biswas JP, Dubourdeaux P, Clémancey M, de Visser SP, Maiti D, Maldivi P, Latour JM. Fe-Catalyzed Aziridination Is Governed by the Electron Affinity of the Active Imido-Iron Species. ACS Catal 2020. [DOI: 10.1021/acscatal.0c01427] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Guillaume Coin
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, LCBM, 38000 Grenoble, France
- Univ. Grenoble Alpes, CEA, CNRS, DCM, 38000 Grenoble, France
| | - Ranjan Patra
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, LCBM, 38000 Grenoble, France
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, DIESE, SYMMES, 38000 Grenoble, France
- Amity Institute of Click Chemistry Research & Studies (AICCRS), Amity University, Sector-125, Noida, India
| | - Sujoy Rana
- Department of Chemistry, University of North Bengal, Raja Rammohunpur, Darjeeling, West Bengal 734013, India
| | | | | | - Martin Clémancey
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, LCBM, 38000 Grenoble, France
| | - Sam P. de Visser
- Manchester Institute of Biotechnology and Department of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Debabrata Maiti
- Department of Chemistry, IIT Bombay, Powai, Mumbai 400076, India
| | - Pascale Maldivi
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, DIESE, SYMMES, 38000 Grenoble, France
| | - Jean-Marc Latour
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, LCBM, 38000 Grenoble, France
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30
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DeJesus JF, Jenkins DM. A Chiral Macrocyclic Tetra-N-Heterocyclic Carbene Yields an "All Carbene" Iron Alkylidene Complex. Chemistry 2020; 26:1429-1435. [PMID: 31788868 PMCID: PMC7024548 DOI: 10.1002/chem.201905360] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Indexed: 01/12/2023]
Abstract
The first chiral macrocyclic tetra-N-heterocyclic carbene (NHC) ligand has been synthesized. The macrocycle, prepared in high yield and large scale, was ligated onto palladium and iron to give divalent C2 -symmetric square planar complexes. Multinuclear NMR and single crystal X-ray diffraction demonstrated that there are two distinct NHCs on each ligand, due to the bridging chiral cyclohexane. Oxidation of the iron(II) complex with trimethylamine N-oxide yielded a bridging oxo complex. Diazodiphenylmethane reacted with the iron(II) complex at room temperature to give a paramagnetic diazoalkane complex; the same reaction yielded the "all carbene" complex at elevated temperature. Electrochemical measurements support the assignment of the "all carbene" complex being an alkylidene. Notably, the diazoalkane complex can be directly transformed into the alkylidene complex, which had not been previously demonstrated on iron. Finally, a test catalytic reaction with a diazoalkane on the iron(II) complex does not yield the expected cyclopropane, but actually the azine compound.
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Affiliation(s)
- Joseph F DeJesus
- 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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31
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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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32
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Halcrow MA. Manipulating metal spin states for biomimetic, catalytic and molecular materials chemistry. Dalton Trans 2020; 49:15560-15567. [DOI: 10.1039/d0dt01919d] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The relationship between ligand design and spin state in base metal compounds is surveyed. Implications and applications of these principles for light-harvesting dyes, catalysis and materials chemistry are summarised.
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33
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Mageed AH. Chemistry of macrocyclic tetracarbene complexes: Synthesis, structure, reactivity and catalytic application. J Organomet Chem 2019. [DOI: 10.1016/j.jorganchem.2019.120965] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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34
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Baek Y, Hennessy ET, Betley TA. Direct Manipulation of Metal Imido Geometry: Key Principles to Enhance C-H Amination Efficacy. J Am Chem Soc 2019; 141:16944-16953. [PMID: 31550162 DOI: 10.1021/jacs.9b09015] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We report the catalytic C-H amination mediated by an isolable CoIII imido complex (TrL)Co(NR) supported by a sterically demanding dipyrromethene ligand (TrL = 5-mesityl-1,9-(trityl)dipyrrin). Metalation of (TrL)Li with CoCl2 in THF afforded a high-spin (S = 3/2) three-coordinate complex (TrL)CoCl. Chemical reduction of (TrL)CoCl with potassium graphite yielded the high-spin (S = 1) CoI synthon (TrL)Co which is stabilized through an intramolecular η6-arene interaction. Treatment of (TrL)Co with a stoichiometric amount of 1-azidoadamantane (AdN3) furnished a three-coordinate, diamagnetic CoIII imide (TrL)Co(NAd) as confirmed by single-crystal X-ray diffraction, revealing a rare trigonal pyramidal geometry with an acute Co-Nimido-C angle 145.0(3)°. Exposure of 1-10 mol % of (TrL)Co to linear alkyl azides (RN3) resulted in catalytic formation of substituted N-heterocycles via intramolecular C-H amination of a range of C-H bonds, including primary C-H bonds. The mechanism of the C-N bond formation was probed via initial rate kinetic analysis and kinetic isotope effect experiments [kH/kD = 38.4(1)], suggesting a stepwise H-atom abstraction followed by radical recombination. In contrast to the previously reported C-H amination mediated by (ArL)Co(NR) (ArL = 5-mesityl-1,9-(2,4,6-Ph3C6H2)dipyrrin), (TrL)Co(NR) displays enhanced yields and rates of C-H amination without the aid of a cocatalyst, and no catalyst degradation to a tetrazene species was observed, as further supported by the pyridine inhibition effect on the rate of C-H amination. Furthermore, (TrL)Co(NAd) exhibits an extremely low one-electron reduction potential (E°red = -1.98 V vs [Cp2Fe]+/0) indicating that the highly basic terminal imido unit contributes to the driving force for H-atom abstraction.
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Affiliation(s)
- Yunjung Baek
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
| | - Elisabeth T Hennessy
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
| | - Theodore A Betley
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
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35
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Ghosh M, Cramer HH, Dechert S, Demeshko S, John M, Hansmann MM, Ye S, Meyer F. A μ-Phosphido Diiron Dumbbell in Multiple Oxidation States. Angew Chem Int Ed Engl 2019; 58:14349-14356. [PMID: 31350785 PMCID: PMC6790664 DOI: 10.1002/anie.201908213] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Indexed: 11/06/2022]
Abstract
The reaction of the ferrous complex [LFe(NCMe)2 ](OTf)2 (1), which contains a macrocyclic tetracarbene as ligand (L), with Na(OCP) generates the OCP- -ligated complex [LFe(PCO)(CO)]OTf (2) together with the dinuclear μ-phosphido complex [(LFe)2 P](OTf)3 (3), which features an unprecedented linear Fe-(μ-P)-Fe motif and a "naked" P-atom bridge that appears at δ=+1480 ppm in the 31 P NMR spectrum. 3 exhibits rich redox chemistry, and both the singly and doubly oxidized species 4 and 5 could be isolated and fully characterized. X-ray crystallography, spectroscopic studies, in combination with DFT computations provide a comprehensive electronic structure description and show that the Fe-(μ-P)-Fe core is highly covalent and structurally invariant over the series of oxidation states that are formally described as ranging from FeIII FeIII to FeIV FeIV . 3-5 now add a higher homologue set of complexes to the many systems with Fe-(μ-O)-Fe and Fe-(μ-N)-Fe core structures that are prominent in bioinorganic chemistry and catalysis.
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Affiliation(s)
- Munmun Ghosh
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstrasse 437077GöttingenGermany
| | - Hanna H. Cramer
- Max-Planck Institut für Chemische EnergiekonversionStiftstrasse 34–3645470Mülheim an der RuhrGermany
| | - Sebastian Dechert
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstrasse 437077GöttingenGermany
| | - Serhiy Demeshko
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstrasse 437077GöttingenGermany
| | - Michael John
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstrasse 437077GöttingenGermany
| | - Max M. Hansmann
- Institut für Organische und Biomolekulare ChemieGeorg-August-Universität GöttingenTammannstrasse 237077GöttingenGermany
| | - Shengfa Ye
- Max-Planck Institut für KohlenforschungStiftstrasse 34–3645470Mülheim an der RuhrGermany
| | - Franc Meyer
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstrasse 437077GöttingenGermany
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36
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Ghosh M, Cramer HH, Dechert S, Demeshko S, John M, Hansmann MM, Ye S, Meyer F. A μ‐Phosphido Diiron Dumbbell in Multiple Oxidation States. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201908213] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Munmun Ghosh
- Institut für Anorganische Chemie Georg-August-Universität Göttingen Tammannstrasse 4 37077 Göttingen Germany
| | - Hanna H. Cramer
- Max-Planck Institut für Chemische Energiekonversion Stiftstrasse 34–36 45470 Mülheim an der Ruhr Germany
| | - Sebastian Dechert
- Institut für Anorganische Chemie Georg-August-Universität Göttingen Tammannstrasse 4 37077 Göttingen Germany
| | - Serhiy Demeshko
- Institut für Anorganische Chemie Georg-August-Universität Göttingen Tammannstrasse 4 37077 Göttingen Germany
| | - Michael John
- Institut für Anorganische Chemie Georg-August-Universität Göttingen Tammannstrasse 4 37077 Göttingen Germany
| | - Max M. Hansmann
- Institut für Organische und Biomolekulare Chemie Georg-August-Universität Göttingen Tammannstrasse 2 37077 Göttingen Germany
| | - Shengfa Ye
- Max-Planck Institut für Kohlenforschung Stiftstrasse 34–36 45470 Mülheim an der Ruhr Germany
| | - Franc Meyer
- Institut für Anorganische Chemie Georg-August-Universität Göttingen Tammannstrasse 4 37077 Göttingen Germany
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37
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Anneser MR, Powers XB, Peck KM, Jensen IM, Jenkins DM. One macrocyclic ligand, four oxidation states: A 16-atom ringed dianionic tetra-NHC macrocycle and its Cr(II) through Cr(V) complexes. Organometallics 2019; 38:3369-3376. [PMID: 31527992 PMCID: PMC6746431 DOI: 10.1021/acs.organomet.9b00476] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Despite chromium being among the first transition metals ever reported to bind to an NHC, chromium NHC complexes, especially in mid and high oxidation states, have received scant attention. Herein, the synthesis, characterization, and reactivity of a series of Cr(II) to Cr(V) complexes bearing a 16-atom ringed dianionic tetra-NHC macrocycle are reported. The Cr(II) dimer is diamagnetic and displays a very short Cr-Cr quadruple bond, unprecedented for Cr-NHC complexes to date. Oxidative cleavage of the Cr-Cr bond leads to the formation of a highly stable diamagnetic Cr(IV) oxo complex. Similar reactions with organic azides lead to paramagnetic Cr(IV) imide complexes. Notably, the Cr(IV) oxo can be oxidized in a reversible reaction to yield a Cr(V) cationic oxo complex, which is a very rare high oxidation state Cr-NHC-compound. This Cr(V) oxo undergoes stoichiometric oxygen atom transfer. Similar reactions were attempted with molybdenum and tungsten to form macrocyclic NHC complexes, but only a molybdenum dimer could be isolated.
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Affiliation(s)
- Markus R. Anneser
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Xian B. Powers
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - KatieAnn M. Peck
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Isabel M. Jensen
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - David M. Jenkins
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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38
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Isbill SB, Chandrachud PP, Kern JL, Jenkins DM, Roy S. Elucidation of the Reaction Mechanism of C 2 + N 1 Aziridination from Tetracarbene Iron Catalysts. ACS Catal 2019; 9:6223-6233. [PMID: 31534826 DOI: 10.1021/acscatal.9b01306] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A combined computational and experimental study was undertaken to elucidate the mechanism of catalytic C2 + N1 aziridination supported by tetracarbene iron complexes. Three specific aspects of the catalytic cycle were addressed. First, how do organic azides react with different iron catalysts and why are alkyl azides ineffective for some catalysts? Computation of the catalytic pathway using density functional theory (DFT) revealed that an alkyl azide needs to overcome a higher activation barrier than an aryl azide to form an iron imide, and the activation barrier with the first-generation catalyst is higher than the activation barrier with the second-generation variant. Second, does the aziridination from the imide complex proceed through an open-chain radical intermediate that can change stereochemistry or, instead, via an azametallacyclobutane intermediate that retains stereochemistry? DFT calculations show that the formation of aziridine proceeds via the open-chain radical intermediate, which qualitatively explains the formation of both aziridine diastereomers as seen in experiments. Third, how can the formation of the side product, a metallotetrazene, be prevented, which would improve the yield of aziridine at lower alkene loading? DFT and experimental results demonstrate that sterically bulky organic azides prohibit formation of the metallotetrazene and, thus, allow lower alkene loading for effective catalysis. These multiple insights of different aspects of the catalytic cycle are critical for developing improved catalysts for C2 + N1 aziridination.
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Affiliation(s)
- Sara B. Isbill
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Preeti P. Chandrachud
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Jesse L. Kern
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - David M. Jenkins
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Sharani Roy
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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