1
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Logallo A, Maddock LCH, Mu M, Gravogl L, Jin N, Peñas-Defrutos MN, Meyer K, García-Melchor M, Hevia E. Unlocking the Metalation Applications of TMP-powered Fe and Co(II) bis(amides): Synthesis, Structure and Mechanistic Insights. Angew Chem Int Ed Engl 2024; 63:e202402907. [PMID: 38563772 DOI: 10.1002/anie.202402907] [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: 02/08/2024] [Revised: 03/19/2024] [Accepted: 04/02/2024] [Indexed: 04/04/2024]
Abstract
Typified by LiTMP and TMPMgCl.LiCl, (TMP=2,2,6,6-tetramethylpiperidide), s-block metal amides have found widespread applications in arene deprotonative metalation. On the contrary, transition metal amides lack sufficient basicity to activate these substrates. Breaking new ground in this field, here we present the synthesis and full characterisation of earth-abundant transition metals M(TMP)2 (M=Fe, Co). Uncovering a new reactivity profile towards fluoroarenes, these amide complexes can promote direct M-H exchange processes regioselectively using one or two of their basic amide arms. Remarkably, even when using a perfluorinated substrate, selective C-H metalation occurs leaving C-F bonds intact. Their kinetic basicity can be boosted by LiCl or NBu4Cl additives which enables formation of kinetically activated ate species. Combining spectroscopic and structural studies with DFT calculations, mechanistic insights have been gained on how these low polarity metalation processes take place. M(TMP)2 can also be used to access ferrocene and cobaltocene by direct deprotonation of cyclopentadiene and undergo efficient CO2 insertion of both amide groups under mild reaction conditions.
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Affiliation(s)
- Alessandra Logallo
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Lewis C H Maddock
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Manting Mu
- School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin College Green, Dublin, Ireland
| | - Lisa Gravogl
- Department of Chemistry and Pharmacy, Inorganic Chemistry Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058, Erlangen, Germany
| | - Na Jin
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Marconi N Peñas-Defrutos
- School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin College Green, Dublin, Ireland
- IU CINQUIMA, Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, 47071, Valladolid, Spain
| | - Karsten Meyer
- Department of Chemistry and Pharmacy, Inorganic Chemistry Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058, Erlangen, Germany
| | - Max García-Melchor
- School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin College Green, Dublin, Ireland
| | - Eva Hevia
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
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2
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Jia QQ, Zhang XJ, Zhu L, Huang LZ. Fe(II) coordination transition regulates reductive dechlorination: The overlooked abiotic role of lactate. WATER RESEARCH 2024; 254:121342. [PMID: 38428238 DOI: 10.1016/j.watres.2024.121342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 01/29/2024] [Accepted: 02/18/2024] [Indexed: 03/03/2024]
Abstract
The coordination environment of Fe(II) significantly affect the reductive reactivity of Fe(II). Lactate is a common substrate for enhancing microbial dechlorination, but its effect on abiotic Fe(II)-driven reductive dechlorination is largely ignored. In this study, the structure-reactivity relationship of Fe(II) is investigated by regulating the ratio of lactate:Fe(II). This work shows that lactate-Fe(II) complexing enhances the abiotic Fe(II)-driven reductive dechlorination with the optimum lactate:Fe(II) ratio of 10:20. The formed hydrogen bond (Fe-OH∙∙∙∙∙∙O = C-) and Fe-O-C metal-ligand bond result in a reduced Fe(II) coordination number from six to four, which lead to the transition of Fe(II) coordination geometry from octahedron to tetrahedron/square planar. Coordinatively unsaturated Fe(II) results in the highest reductive dechlorination reactivity towards carbon tetrachloride (k1 = 0.26254 min-1). Excessive lactate concentration (> 10 mM) leads to an increased Fe(II) coordination number from four to six with a decreased reductive reactivity. Electrochemical characterization and XPS results show that lactate-Fe(II)-I (C3H5O3-:Fe(II) = 10:20) has the highest electron-donating capacity. This study reveals the abiotic effect of lactate on reductive dechlorination in a subsurface-reducing environment where Fe(II) is usually abundant.
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Affiliation(s)
- Qian-Qian Jia
- School of Civil Engineering, Wuhan University, No. 8, East Lake South Road, Wuhan, China; State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, 430072 China; School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212100, China
| | - Xue-Jie Zhang
- School of Civil Engineering, Wuhan University, No. 8, East Lake South Road, Wuhan, China; State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, 430072 China
| | - Liandong Zhu
- School of Resources & Environmental Science, Hubei International Scientific and Technological Cooperation Base of Sustainable Resource and Energy, Hubei Key Laboratory of Biomass-Resources Chemistry and Environmental Biotechnology, Wuhan University, Wuhan 430079, China
| | - Li-Zhi Huang
- School of Civil Engineering, Wuhan University, No. 8, East Lake South Road, Wuhan, China; State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, 430072 China.
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3
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Scott JS, Schneider JE, Tewelde EG, Gardner JG, Anferov SW, Filatov AS, Anderson JS. Combining Donor Strength and Oxidative Stability in Scorpionates: A Strongly Donating Fluorinated Mesoionic Tris(imidazol-5-ylidene)borate Ligand. Inorg Chem 2023; 62:21224-21232. [PMID: 38051936 DOI: 10.1021/acs.inorgchem.3c03251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Strongly donating scorpionate ligands support the study of high-valent transition metal chemistry; however, their use is frequently limited by oxidative degradation. To address this concern, we report the synthesis of a tris(imidazol-5-ylidene)borate ligand featuring trifluoromethyl groups surrounding its coordination pocket. This ligand represents the first example of a chelating poly(imidazol-5-ylidene) mesoionic carbene ligand, a scaffold that is expected to be extremely donating. The {NiNO}10 complex of this ligand, as well as that of a previously reported strongly donating tris(imidazol-2-ylidene)borate, has been synthesized and characterized. This new ligand's strong donor properties, as measured by the υNO of its {NiNO}10 complex and natural bonding orbital second-order perturbative energy analysis, are at par with those of the well-studied alkyl-substituted tris(imidazol-2-ylidene)borates, which are known to effectively stabilize high-valent intermediates. The good donor properties of this ligand, despite the electron-withdrawing trifluoromethyl substituents, arise from the strongly donating imidazol-5-ylidene mesoionic carbene arms. These donor properties, when combined with the robustness of trifluoromethyl groups toward oxidative decomposition, suggest this ligand scaffold will be a useful platform in the study of oxidizing high-valent transition-metal species.
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Affiliation(s)
- Joseph S Scott
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Joseph E Schneider
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Eyob G Tewelde
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Joel G Gardner
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Sophie W Anferov
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Alexander S Filatov
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - John S Anderson
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
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4
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Gao Y, Smith JM. Enabling Nucleophilic Reactivity in High-Spin Fe(II) Imido Complexes: From Elementary Steps to Cooperative Catalysis. Acc Chem Res 2023; 56:3392-3403. [PMID: 37955993 DOI: 10.1021/acs.accounts.3c00511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
ConspectusTransition metal complexes featuring an M═NR bond have received great attention as critical intermediates in the synthesis of nitrogen-containing compounds. In general, the properties of the imido ligand in these complexes are dependent on the nature of the metal center. Thus, the imido ligand tends to be nucleophilic in early transition metal complexes and electrophilic in late transition metal complexes. Nonetheless, the supporting ligand can have a dramatic effect on its reactivity. For example, there are sporadic examples of nucleophilic late transition metal imido complexes, often based on strongly donating supporting ligands. Building on these earlier works, in this Article, we show that the imido ligand in a low-coordinate high-spin bis(carbene)borate Fe(II) complex is able to access previously unknown reaction pathways, ultimately leading to new catalytic transformations. We first focus on the synthesis, characterization, and stoichiometric reactivity of a highly nucleophilic Fe(II) imido complex. The entry point for this system is the intermediate-spin three-coordinate Fe(III) imido complex, which is generated from the reaction of an Fe(I) synthon with an organic azide. Alkali metal reduction leads to a series of M+ (M = Li, Na, K) coordinated and charge-separated (M = K(18-C-6)) high-spin Fe(II) imido complexes, all of which have been isolated and fully characterized. Combined with the electronic structure calculations, these results reveal that the alkali ions moderately polarize the Fe═N bond according to K+ ≈ Na+ < Li+. As a result, the basicity of the imido ligand increases from the charged separated complex to K+, Na+, and Li+ coordinated complexes, as validated by intermolecular proton transfer equilibria. The impact of the counterion on imido ligand reactivity is demonstrated through protonation, alkylation, and hydrogen atom abstraction reactions. The counterion also directs the outcome of [2 + 2] reactions with benzophenone, where alkali coordination facilitates double bond metathesis. Building from here, we describe how the unusual nucleophilicity of the high-spin Fe(II) imido complex revealed in stoichiometric reactions can be extended to new catalytic transformations. For example, a [2 + 2] cycloaddition reaction serves as the basis for the catalytic guanylation of carbodiimides under mild conditions. More interestingly, this complex also exhibits the first ene-like reactivity of an M═NR bond in reactions with alkynes, nitriles, and alkenes. These transformations form the basis of catalytic alkyne and nitrile α-deuteration and pKa-dictated alkene transposition reactions, respectively. Mechanistic studies reveal the critical role of metal-ligand cooperativity in facilitating these catalytic transformations and suggest the new avenues for transition metal imido complexes in catalysis that extend beyond classical nitrene transfer chemistry.
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Affiliation(s)
- Yafei Gao
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Jeremy M Smith
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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5
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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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6
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McWilliams SF, Mercado BQ, MacLeod KC, Fataftah MS, Tarrago M, Wang X, Bill E, Ye S, Holland PL. Dynamic effects on ligand field from rapid hydride motion in an iron(ii) dimer with an S = 3 ground state. Chem Sci 2023; 14:2303-2312. [PMID: 36873832 PMCID: PMC9977447 DOI: 10.1039/d2sc06412j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 01/17/2023] [Indexed: 02/11/2023] Open
Abstract
Hydride complexes are important in catalysis and in iron-sulfur enzymes like nitrogenase, but the impact of hydride mobility on local iron spin states has been underexplored. We describe studies of a dimeric diiron(ii) hydride complex using X-ray and neutron crystallography, Mössbauer spectroscopy, magnetism, DFT, and ab initio calculations, which give insight into the dynamics and the electronic structure brought about by the hydrides. The two iron sites in the dimer have differing square-planar (intermediate-spin) and tetrahedral (high-spin) iron geometries, which are distinguished only by the hydride positions. These are strongly coupled to give an S total = 3 ground state with substantial magnetic anisotropy, and the merits of both localized and delocalized spin models are discussed. The dynamic nature of the sites is dependent on crystal packing, as shown by changes during a phase transformation that occurs near 160 K. The change in dynamics of the hydride motion leads to insight into its influence on the electronic structure. The accumulated data indicate that the two sites can trade geometries by rotating the hydrides, at a rate that is rapid above the phase transition temperature but slow below it. This small movement of the hydrides causes large changes in the ligand field because they are strong-field ligands. This suggests that hydrides could be useful in catalysis not only due to their reactivity, but also due to their ability to rapidly modulate the local electronic structure and spin states at metal sites.
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Affiliation(s)
| | | | - K Cory MacLeod
- Department of Chemistry, Yale University New Haven Connecticut USA
| | - Majed S Fataftah
- Department of Chemistry, Yale University New Haven Connecticut USA
| | - Maxime Tarrago
- Max Planck Institute for Chemical Energy Conversion Mülheim an der Ruhr Germany
| | - Xiaoping Wang
- Neutron Sciences Directorate, Oak Ridge National Laboratory Oak Ridge Tennessee USA
| | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion Mülheim an der Ruhr Germany
| | - Shengfa Ye
- Max Planck Institute for Chemical Energy Conversion Mülheim an der Ruhr Germany
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian China
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7
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Noor A. Recent developments in two coordinate transition metal chemistry. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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8
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Keilwerth M, Mao W, Jannuzzi SAV, Grunwald L, Heinemann FW, Scheurer A, Sutter J, DeBeer S, Munz D, Meyer K. From Divalent to Pentavalent Iron Imido Complexes and an Fe(V) Nitride via N-C Bond Cleavage. J Am Chem Soc 2023; 145:873-887. [PMID: 36583993 DOI: 10.1021/jacs.2c09072] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
As key intermediates in metal-catalyzed nitrogen-transfer chemistry, terminal imido complexes of iron have attracted significant attention for a long time. In search of versatile model compounds, the recently developed second-generation N-anchored tris-NHC chelating ligand tris-[2-(3-mesityl-imidazole-2-ylidene)-methyl]amine (TIMMNMes) was utilized to synthesize and compare two series of mid- to high-valent iron alkyl imido complexes, including a reactive Fe(V) adamantyl imido intermediate en route to an isolable Fe(V) nitrido complex. The chemistry toward the iron adamantyl imides was achieved by reacting the Fe(I) precursor [(TIMMNMes)FeI(N2)]+ (1) with 1-adamantyl azide to yield the corresponding trivalent iron imide. Stepwise chemical reduction and oxidation lead to the isostructural series of low-spin [(TIMMNMes)Fe(NAd)]0,1+,2+,3+ (2Ad-5Ad) in oxidation states II to V. The Fe(V) imide [(TIMMNMes)Fe(NAd)]3+ (5Ad) is unstable under ambient conditions and converts to the air-stable nitride [(TIMMNMes)FeV(N)]2+ (6) via N-C bond cleavage. The stability of the pentavalent imide can be increased by derivatizing the nitride [(TIMMNMes)FeIV(N)]+ (7) with an ethyl group using the triethyloxonium salt Et3OPF6. This gives access to the analogous series of ethyl imides [(TIMMNMes)Fe(NEt)]0,1+,2+,3+ (2Et-5Et), including the stable Fe(V) ethyl imide. Iron imido complexes exist in a manifold of different electronic structures, ultimately controlling their diverse reactivities. Accordingly, these complexes were characterized by single-crystal X-ray diffraction analyses, SQUID magnetization, and electrochemical methods, as well as 57Fe Mössbauer, IR vibrational, UV/vis electronic absorption, multinuclear NMR, X-band EPR, and X-ray absorption spectroscopy. Our studies are complemented with quantum chemical calculations, thus providing further insight into the electronic structures of all complexes.
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Affiliation(s)
- Martin Keilwerth
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058 Erlangen, Germany
| | - Weiqing Mao
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058 Erlangen, Germany
| | - Sergio A V Jannuzzi
- Max-Planck-Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Liam Grunwald
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058 Erlangen, Germany.,Department of Chemistry and Applied Biosciences (D-CHAB), ETH Zürich, 8093 Zürich, Switzerland
| | - Frank W Heinemann
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058 Erlangen, Germany
| | - Andreas Scheurer
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058 Erlangen, Germany
| | - Jörg Sutter
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058 Erlangen, Germany
| | - Serena DeBeer
- Max-Planck-Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Dominik Munz
- Inorganic Chemistry: Coordination Chemistry, Saarland University, Campus C4 1, 66123 Saarbrücken, Germany
| | - Karsten Meyer
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstraße 1, 91058 Erlangen, Germany
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9
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Gao Y, Pink M, Carta V, Smith JM. Ene Reactivity of an Fe═NR Bond Enables the Catalytic α-Deuteration of Nitriles and Alkynes. J Am Chem Soc 2022; 144:17165-17172. [PMID: 36070477 DOI: 10.1021/jacs.2c07462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Herein, we report the reactions of an Fe(II) imido complex [Ph2B(tBuIm)2Fe═NDipp]- (1) with internal alkynes and isobutyronitrile, affording the Fe amido allenyl complexes [Ph2B(tBuIm)2Fe(NHDipp)((R1)C═C═C(R2)(H))]- (R1 = Et or nPr; R2 = Me or Et, 2-5) and the Fe amido keteniminate complex [Ph2B(tBuIm)2Fe(NHDipp)(N═C═CMe2)K(THF)]n (8-K), respectively. These transformations represent the previously unknown ene-like reactivity of a metal-ligand multiple bond. Stoichiometric reactions of 2 and 8-K with DippNH2 lead to the regeneration of 3-hexyne and isobutyronitrile, respectively, with concomitant formation of the bis(anilido) complex [Ph2B(tBuIm)2Fe(NHDipp)2]- (9). These results provide the platform for 1 as an efficient catalyst for the selective α-deuteration of nitriles and alkynes by RND2. These results demonstrate a new reaction mode for metal imido complexes and suggest new avenues for using the imido ligand in catalysis.
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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
| | - Veronica Carta
- 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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10
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Richards CA, Rath NP, Neely JM. Isolation and Reactivity of an Iron Azametallacyclobutene Complex. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00151] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Corey A. Richards
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States
| | - Nigam P. Rath
- Department of Chemistry and Biochemistry, University of Missouri-St. Louis, Saint Louis, Missouri 63121, United States
| | - Jamie M. Neely
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States
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11
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Gao Y, Pink M, Smith JM. Alkali Metal Ions Dictate the Structure and Reactivity of an Iron(II) Imido Complex. J Am Chem Soc 2022; 144:1786-1794. [DOI: 10.1021/jacs.1c11429] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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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12
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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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13
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Reckziegel A, Kour M, Battistella B, Mebs S, Beuthert K, Berger R, Werncke CG. High-Spin Imido Cobalt Complexes with Imidyl Radical Character*. Angew Chem Int Ed Engl 2021; 60:15376-15380. [PMID: 33977634 PMCID: PMC8362137 DOI: 10.1002/anie.202103841] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/10/2021] [Indexed: 01/21/2023]
Abstract
We report on the synthesis of a variety of trigonal imido cobalt complexes [Co(NAryl)L2 ]- , (L=N(Dipp)SiMe3 ), Dipp=2,6-diisopropylphenyl) with very long Co-NAryl bonds of around 1.75 Å. Their electronic structure was interrogated using a variety of physical and spectroscopic methods such as EPR or X-Ray absorption spectroscopy which leads to their description as highly unusual imidyl cobalt complexes. Computational analyses corroborate these findings and further reveal that the high-spin state is responsible for the imidyl character. Exchange of the Dipp substituent on the imide by the smaller mesityl function (2,4,6-trimethylphenyl) effectuates the unexpected Me3 Si shift from the ancillary ligand set to the imidyl nitrogen, revealing a highly reactive, nucleophilic character of the imidyl unit.
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Affiliation(s)
- Alexander Reckziegel
- Department of ChemistryPhilipps-University MarburgHans-Meerwein-Strasse 435032MarburgGermany
| | - Manjinder Kour
- Department of ChemistryPhilipps-University MarburgHans-Meerwein-Strasse 435032MarburgGermany
| | - Beatrice Battistella
- Institute of ChemistryHumboldt-Universität zu BerlinBrook-Taylor-Strasse 212489BerlinGermany
| | - Stefan Mebs
- Department of PhysicsFreie Universität zu BerlinArnimallee 1414195BerlinGermany
| | - Katrin Beuthert
- Department of ChemistryPhilipps-University MarburgHans-Meerwein-Strasse 435032MarburgGermany
| | - Robert Berger
- Department of ChemistryPhilipps-University MarburgHans-Meerwein-Strasse 435032MarburgGermany
| | - C. Gunnar Werncke
- Department of ChemistryPhilipps-University MarburgHans-Meerwein-Strasse 435032MarburgGermany
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Reckziegel A, Kour M, Battistella B, Mebs S, Beuthert K, Berger R, Werncke CG. High‐Spin‐Imidocobaltkomplexe mit Imidylradikalcharakter**. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202103841] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Alexander Reckziegel
- Fachbereich Chemie Philipps-Universität Marburg Hans-Meerwein-Straße 4 35032 Marburg Deutschland
| | - Manjinder Kour
- Fachbereich Chemie Philipps-Universität Marburg Hans-Meerwein-Straße 4 35032 Marburg Deutschland
| | - Beatrice Battistella
- Institut für Chemie Humboldt-Universität zu Berlin Brook-Taylor-Straße 2 12489 Berlin Deutschland
| | - Stefan Mebs
- Fachbereich Physik Freie Universität zu Berlin Arnimallee 14 14195 Berlin Deutschland
| | - Katrin Beuthert
- Fachbereich Chemie Philipps-Universität Marburg Hans-Meerwein-Straße 4 35032 Marburg Deutschland
| | - Robert Berger
- Fachbereich Chemie Philipps-Universität Marburg Hans-Meerwein-Straße 4 35032 Marburg Deutschland
| | - C. Gunnar Werncke
- Fachbereich Chemie Philipps-Universität Marburg Hans-Meerwein-Straße 4 35032 Marburg Deutschland
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Gao Y, Carta V, Pink M, Smith JM. Catalytic Carbodiimide Guanylation by a Nucleophilic, High Spin Iron(II) Imido Complex. J Am Chem Soc 2021; 143:5324-5329. [PMID: 33793235 DOI: 10.1021/jacs.1c02068] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reduction of the three-coordinate iron(III) imido [Ph2B(tBuIm)2Fe═NDipp] (1) affords [Ph2B(tBuIm)2Fe═NDipp][K(18-C-6)THF2] (2), a rare example of a high-spin (S = 2) iron(II) imido complex. Unusually for a late metal imido complex, the imido ligand in 2 has nucleophilic character, as demonstrated by the reaction with DippNH2, which establishes an equilibrium with the bis(anilido) complex [Ph2B(tBuIm)2Fe(NHDipp)2][K(18-C-6)THF2] (3). In an unusual transformation, formal insertion of iPrN═C═NiPr into the Fe═N(imido) bond yields the guanidinate [Ph2B(tBuIm)2Fe(iPrN)2CNDipp][K(18-C-6)THF2] (4). Reaction of 4 with excess DippNH2 provides 3, along with the guanidine (iPrNH)2C═NDipp. As suggested by these stoichiometric reactions, 2 is an efficient catalyst for the guanylation of carbodiimides, converting a wide range of aniline substrates under mild conditions.
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Affiliation(s)
- Yafei Gao
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Veronica Carta
- 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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Tarrago M, Römelt C, Nehrkorn J, Schnegg A, Neese F, Bill E, Ye S. Experimental and Theoretical Evidence for an Unusual Almost Triply Degenerate Electronic Ground State of Ferrous Tetraphenylporphyrin. Inorg Chem 2021; 60:4966-4985. [PMID: 33739093 DOI: 10.1021/acs.inorgchem.1c00031] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Iron porphyrins exhibit unrivalled catalytic activity for electrochemical CO2-to-CO conversion. Despite intensive experimental and computational studies in the last 4 decades, the exact nature of the prototypical square-planar [FeII(TPP)] complex (1; TPP2- = tetraphenylporphyrinate dianion) remained highly debated. Specifically, its intermediate-spin (S = 1) ground state was contradictorily assigned to either a nondegenerate 3A2g state with a (dxy)2(dz2)2(dxz,yz)2 configuration or a degenerate 3Egθ state with a (dxy)2(dxz,yz)3(dz2)1/(dz2)2(dxy)1(dxz,yz)3 configuration. To address this question, we present herein a comprehensive, spectroscopy-based theoretical and experimental electronic-structure investigation on complex 1. Highly correlated wave-function-based computations predicted that 3A2g and 3Egθ are well-isolated from other triplet states by ca. 4000 cm-1, whereas their splitting ΔA-E is on par with the effective spin-orbit coupling (SOC) constant of iron(II) (≈400 cm-1). Therfore, we invoked an effective Hamiltonian (EH) operating on the nine magnetic sublevels arising from SOC between the 3A2g and 3Egθ states. This approach enabled us to successfully simulate all spectroscopic data of 1 obtained by variable-temperature and variable-field magnetization, applied-field 57Fe Mössbauer, and terahertz electron paramagnetic resonance measurements. Remarkably, the EH contains only three adjustable parameters, namely, the energy gap without SOC, ΔA-E, an angle θ that describes the mixing of (dxy)2(dxz,yz)3(dz2)1 and (dz2)2(dxy)1(dxz,yz)3 configurations, and the ⟨rd-3⟩ expectation value of the iron d orbitals that is necessary to estimate the 57Fe magnetic hyperfine coupling tensor. The EH simulations revealed that the triplet ground state of 1 is genuinely multiconfigurational with substantial parentages of both 3A2g (<88%) and 3Eg (>12%), owing to their accidental near-triple degeneracy with ΔA-E = +950 cm-1. As a consequence of this peculiar electronic structure, 1 exhibits a huge effective magnetic moment (4.2 μB at 300 K), large temperature-independent paramagnetism, a large and positive axial zero-field splitting, strong easy-plane magnetization (g⊥ ≈ 3 and g∥ ≈ 1.7) and a large and positive internal field at the 57Fe nucleus aligned in the xy plane. Further in-depth analyses suggested that g⊥ ≫ g∥ is a general spectroscopic signature of near-triple orbital degeneracy with more than half-filled pseudodegenerate orbital sets. Implications of the unusual electronic structure of 1 for CO2 reduction are discussed.
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Affiliation(s)
- Maxime Tarrago
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - Christina Römelt
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Joscha Nehrkorn
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Alexander Schnegg
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Shengfa Ye
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany.,State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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17
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Wang L, Cheng J, Ma Y, Chen Q, Leng X, Deng L. Three-coordinate Bis(N-heterocyclic carbene)iron(0) complexes with alkene and alkyne ligation: Synthesis and characterization. Polyhedron 2021. [DOI: 10.1016/j.poly.2021.115054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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18
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Ott JC, Wadepohl H, Gade LH. Metalloradical Reactivity, Charge Transfer, and Atom Abstractions in a T-Shaped Iron(I) Complex. Inorg Chem 2021; 60:3927-3938. [DOI: 10.1021/acs.inorgchem.0c03724] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Jonas C. Ott
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 276, 69120 Heidelberg, Germany
| | - Hubert Wadepohl
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 276, 69120 Heidelberg, Germany
| | - Lutz H. Gade
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 276, 69120 Heidelberg, Germany
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Farasat Z, Nabavizadeh SM, Niroomand Hosseini F, Hoseini SJ, Abu-Omar MM. Ligand-Controlled C sp2-H versus C sp3-H Bond Formation in Cycloplatinated Complexes: A Joint Experimental and Theoretical Mechanistic Investigation. Inorg Chem 2021; 60:1998-2008. [PMID: 33476136 DOI: 10.1021/acs.inorgchem.0c03502] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cyclometalated platinum(II) complexes [PtMe(C∧N)(L)] [1PS: C∧N = 2-phenylpyridinate (ppy), L = SMe2; 1BS: C∧N = benzo[h]quinolate (bhq), L = SMe2; 1PP: C∧N = ppy, L = PPh3; and 1BP: C∧N = bhq, L = PPh3] containing two different cyclometalated ligands and two different ancillary ligands have been investigated in the reaction with CX3CO2H (X = F or H). When L = SMe2, the Pt-Me bond rather than the Pt-C bond of the cycloplatinated complex is cleaved to give the complexes [Pt(C∧N)(CX3CO2)(SMe2)]. When L = PPh3, the selectivity of the reaction is reversed. In the reaction of [PtMe(C∧N)(PPh3)] with CF3CO2H, the Pt-C∧N bond is cleaved rather than the Pt-Me bond. The latter reaction gave [PtMe(κ1N-Hppy)(PPh3)(CF3CO2)] as an equilibrium mixture of two isomers. For L = PPh3, no reaction was observed with CH3CO2H. The reasons for this difference in selectivity for complexes 1 are computationally discussed based on the energy barrier needed for the protonolysis of the Pt-Csp3 bond versus the Pt-Csp2 bond. Two pathways including the direct one-step acid attack at the Pt-C bond (SE2) and stepwise oxidative-addition on the Pt(II) center followed by reductive elimination [SE(ox)] are proposed. A detailed density functional theory (DFT) study of these protonations along with experimental UV-vis kinetics suggests that a one-step electrophilic attack (SE2) at the Pt-C bond is the most likely mechanism for complexes 1, and changing the nature of the ancillary ligand can influence the selectivity in the Pt-C bond cleavage. The effect of the nature of the acid and cyclometalated ligand (C∧N) is also discussed.
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Affiliation(s)
- Zahra Farasat
- Professor Rashidi Laboratory of Organometallic Chemistry, Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71467-13565, Iran
| | - S Masoud Nabavizadeh
- Professor Rashidi Laboratory of Organometallic Chemistry, Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71467-13565, Iran.,Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | | | - S Jafar Hoseini
- Professor Rashidi Laboratory of Organometallic Chemistry, Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71467-13565, Iran
| | - Mahdi M Abu-Omar
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
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20
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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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21
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Chernyshev VM, Denisova EA, Eremin DB, Ananikov VP. The key role of R-NHC coupling (R = C, H, heteroatom) and M-NHC bond cleavage in the evolution of M/NHC complexes and formation of catalytically active species. Chem Sci 2020; 11:6957-6977. [PMID: 33133486 PMCID: PMC7553045 DOI: 10.1039/d0sc02629h] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 06/19/2020] [Indexed: 02/01/2023] Open
Abstract
Complexes of metals with N-heterocyclic carbene ligands (M/NHC) are typically considered the systems of choice in homogeneous catalysis due to their stable metal-ligand framework. However, it becomes obvious that even metal species with a strong M-NHC bond can undergo evolution in catalytic systems, and processes of M-NHC bond cleavage are common for different metals and NHC ligands. This review is focused on the main types of the M-NHC bond cleavage reactions and their impact on activity and stability of M/NHC catalytic systems. For the first time, we consider these processes in terms of NHC-connected and NHC-disconnected active species derived from M/NHC precatalysts and classify them as fundamentally different types of catalysts. Problems of rational catalyst design and sustainability issues are discussed in the context of the two different types of M/NHC catalysis mechanisms.
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Affiliation(s)
- Victor M Chernyshev
- Platov South-Russian State Polytechnic University (NPI) , Prosveschenya 132 , Novocherkassk , 346428 , Russia
| | - Ekaterina A Denisova
- N. D. Zelinsky Institute of Organic Chemistry , Russian Academy of Sciences , Leninsky Prospect 47 , 119991 Moscow , Russian Federation
| | - Dmitry B Eremin
- N. D. Zelinsky Institute of Organic Chemistry , Russian Academy of Sciences , Leninsky Prospect 47 , 119991 Moscow , Russian Federation
- The Bridge@USC , University of Southern California , 1002 Childs Way , Los Angeles , California 90089-3502 , USA
| | - Valentine P Ananikov
- Platov South-Russian State Polytechnic University (NPI) , Prosveschenya 132 , Novocherkassk , 346428 , Russia
- N. D. Zelinsky Institute of Organic Chemistry , Russian Academy of Sciences , Leninsky Prospect 47 , 119991 Moscow , Russian Federation
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22
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Reactions of a Bis(vinyltrimethylsilane)nickel(0) N-Heterocyclic carbene complex with organic azides. J Organomet Chem 2020. [DOI: 10.1016/j.jorganchem.2020.121195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
In this contribution, we provide a comprehensive overview of C-H activation methods promoted by NHC-transition metal complexes, covering the literature since 2002 (the year of the first report on metal-NHC-catalyzed C-H activation) through June 2019, focusing on both NHC ligands and C-H activation methods. This review covers C-H activation reactions catalyzed by group 8 to 11 NHC-metal complexes. Through discussing the role of NHC ligands in promoting challenging C-H activation methods, the reader is provided with an overview of this important area and its crucial role in forging carbon-carbon and carbon-heteroatom bonds by directly engaging ubiquitous C-H bonds.
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Affiliation(s)
- Qun Zhao
- Department of Chemistry , Rutgers University , 73 Warren Street , Newark , New Jersey 07102 , United States
| | - Guangrong Meng
- Department of Chemistry , Rutgers University , 73 Warren Street , Newark , New Jersey 07102 , United States
| | - Steven P Nolan
- Department of Chemistry and Center for Sustainable Chemistry , Ghent University , Krijgslaan 281 , 9000 Ghent , Belgium
| | - Michal Szostak
- Department of Chemistry , Rutgers University , 73 Warren Street , Newark , New Jersey 07102 , United States
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24
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Du J, Chen W, Chen Q, Leng X, Meng YS, Gao S, Deng L. Reactivity of a Two-Coordinate Cobalt(0) Cyclic (Alkyl)(amino)carbene Complex. Organometallics 2020. [DOI: 10.1021/acs.organomet.9b00875] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Jingzhen Du
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, P. R. China
| | - Wenwei Chen
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, P. R. China
| | - Qi Chen
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, P. R. China
| | - Xuebing Leng
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, P. R. China
| | - Yin-Shan Meng
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Song Gao
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Liang Deng
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, P. R. China
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Liu Y, Cheng J, Deng L. Three-Coordinate Formal Cobalt(0), Iron(0), and Manganese(0) Complexes with Persistent Carbene and Alkene Ligation. Acc Chem Res 2020; 53:244-254. [PMID: 31880150 DOI: 10.1021/acs.accounts.9b00492] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Low-coordinate transition-metal species, i.e., metal species with coordination numbers of less than 4, represent a category of ubiquitous reactive intermediates in metal-catalyzed reactions that take place in solution, in metalloenzymes, on supported nanomaterials and single-atom catalysts, and so on. While reactive intermediates are usually transient and hard to isolate, which makes detailed investigation challenging, molecular representatives of low-coordinate transition-metal intermediates can be synthesized by the judicious use of supporting ligands, allowing detailed study of their inherent chemical and physical properties. By the use of bulky nitrogen- and oxygen-based anionic ligands, plenty of three- and two-coordinate group 4-10 metal complexes with the oxidation states of the metal centers being +3, + 2, and +1 have been prepared and subjected to extensive study. Much less known are low-coordinate zero-valent metal complexes, and knowledge about them had been restricted to group 10 metal complexes until very recently. In this Account, we summarize the studies of the synthesis, spectroscopic features, electronic structures, and reactivities of three-coordinate formal cobalt(0), iron(0), and manganese(0) complexes with persistent carbene and alkene ligation. The introduction of the π-accepting alkene ligands 1,3-divinyl-1,1,3,3-tetramethyldisiloxane (dvtms) and vinyltrimethylsilane (vtms) into the reduction reactions of MCl2 (M = Co, Fe, Mn) with persistent carbenes and alkaline metals effectively suppresses ligand C-H bond activation reactions, leading to the successful preparation of three-coordinate formal cobalt(0), iron(0), and manganese(0) complexes LM(η2:η2-dvtms), LM(η2-vtms)2, and L2M(η2-vtms) (M = Co, Fe, Mn; L = N-heterocyclic carbene (NHC), cyclic (alkyl)(amino)carbene (cAAC)). These three-coordinate metal complexes feature pronounced back-donation from the filled metal 3d orbitals to the alkene π* orbital(s), resulting in electronic configurations of (dxy+πalkene*)2(dx2-y2+π'alkene*)2(dz2,dxz,dyz)n (the coordination plane was chosen as the xy plane; n = 5, 4, and 3 for Co, Fe, and Mn, respectively) for the bis(alkene) complexes LM(η2:η2-dvtms) and LM(η2-vtms)2. The alkene ligands in the low-coordinate formal zero-valent metal complexes are amenable to undergo ligand-exchange reactions with better π-accepting ligands. In reactions with organic azides, hydrosilanes, nitrosoarenes, alkynes, etc., the alkene ligands dissociate from the metal coordination sphere, and three-coordinate formal zero-valent metal complexes function as synthons of LnM0 (L = NHC, cAAC; n = 1, 2; M = Co, Fe, Mn) to perform redox reactions with these substrates, affording divalent and tetravalent cobalt, iron, or manganese complexes. These electronic structure and reactivity features hint at the potential of low-coordinate zero-valent group 7-9 metal complexes for the development of new 3d metal catalysts and magnetic materials.
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Affiliation(s)
- Yang Liu
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, P. R. China
| | - Jun Cheng
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, P. R. China
| | - Liang Deng
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, P. R. China
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Kurup SS, Staples RJ, Lord RL, Groysman S. Synthesis of Chromium(II) Complexes with Chelating Bis(alkoxide) Ligand and Their Reactions with Organoazides and Diazoalkanes. MOLECULES (BASEL, SWITZERLAND) 2020; 25:molecules25020273. [PMID: 31936557 PMCID: PMC7024303 DOI: 10.3390/molecules25020273] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/03/2020] [Accepted: 01/07/2020] [Indexed: 12/22/2022]
Abstract
Synthesis of new chromium(II) complexes with chelating bis(alkoxide) ligand [OO]Ph (H2[OO]Ph = [1,1′:4′,1′’-terphenyl]-2,2′’-diylbis(diphenylmethanol)) and their subsequent reactivity in the context of catalytic production of carbodiimides from azides and isocyanides are described. Two different Cr(II) complexes are obtained, as a function of the crystallization solvent: mononuclear Cr[OO]Ph(THF)2 (in toluene/THF, THF = tetrahydrofuran) and dinuclear Cr2([OO]Ph)2 (in CH2Cl2/THF). The electronic structure and bonding in Cr[OO]Ph(THF)2 were probed by density functional theory calculations. Isolated Cr2([OO]Ph)2 undergoes facile reaction with 4-MeC6H4N3, 4-MeOC6H4N3, or 3,5-Me2C6H3N3 to yield diamagnetic Cr(VI) bis(imido) complexes; a structure of Cr[OO]Ph(N(4-MeC6H4))2 was confirmed by X-ray crystallography. The reaction of Cr2([OO]Ph)2 with bulkier azides N3R (MesN3, AdN3) forms paramagnetic products, formulated as Cr[OO]Ph(NR). The attempted formation of a Cr–alkylidene complex (using N2CPh2) instead forms chromium(VI) bis(diphenylmethylenehydrazido) complex Cr[OO]Ph(NNCPh2)2. Catalytic formation of carbodiimides was investigated for the azide/isocyanide mixtures containing various aryl azides and isocyanides. The formation of carbodiimides was found to depend on the nature of organoazide: whereas bulky mesitylazide led to the formation of carbodiimides with all isocyanides, no carbodiimide formation was observed for 3,5-dimethylphenylazide or 4-methylphenylazide. Treatment of Cr2([OO]Ph)2 or H2[OO]Ph with NO+ leads to the formation of [1,2-b]-dihydroindenofluorene, likely obtained via carbocation-mediated cyclization of the ligand.
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Affiliation(s)
- Sudheer S. Kurup
- Department of Chemistry, Wayne State University, 5101 Cass Ave., Detroit, MI 48202, USA;
| | - Richard J. Staples
- Department of Chemistry, Michigan State University, 578 S Shaw Ln, East Lansing, MI 48824, USA;
| | - Richard L. Lord
- Department of Chemistry, Grand Valley State University, 1 Campus Dr, Allendale, MI 49401, USA
- Correspondence: (R.L.L.); (S.G.)
| | - Stanislav Groysman
- Department of Chemistry, Wayne State University, 5101 Cass Ave., Detroit, MI 48202, USA;
- Correspondence: (R.L.L.); (S.G.)
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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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28
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Lu X, Lee YM, Seo MS, Nam W. Proton-promoted disproportionation of iron(v)-imido TAML to iron(v)-imido TAML cation radical and iron(iv) TAML. Chem Commun (Camb) 2020; 56:11207-11210. [DOI: 10.1039/d0cc05145d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
An iron(v)-imido TAML complex is disproportionated to give an iron(v)-imido TAML cation radical and an iron(iv) TAML upon addition of acids.
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Affiliation(s)
- Xiaoyan Lu
- Department of Chemistry and Nano Science
- Ewha Womans University
- Seoul 03760
- Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science
- Ewha Womans University
- Seoul 03760
- Korea
| | - Mi Sook Seo
- Department of Chemistry and Nano Science
- Ewha Womans University
- Seoul 03760
- Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science
- Ewha Womans University
- Seoul 03760
- Korea
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29
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Wei K, Yang T, Chen Q, Liang S, Yu W. Iron-catalysed 1,2-aryl migration of tertiary azides. Chem Commun (Camb) 2020; 56:11685-11688. [DOI: 10.1039/d0cc04579a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
1,2-Carbon to nitrogen aryl migration of α,α-diaryl tertiary azides was realized by using FeCl2 and N-heterocyclic carbene SIPr·HCl as a catalyst.
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Affiliation(s)
- Kaijie Wei
- State Key Laboratory of Applied Organic Chemistry
- College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou 730000
- China
| | - Tonghao Yang
- State Key Laboratory of Applied Organic Chemistry
- College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou 730000
- China
| | - Qing Chen
- State Key Laboratory of Applied Organic Chemistry
- College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou 730000
- China
| | - Siyu Liang
- State Key Laboratory of Applied Organic Chemistry
- College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou 730000
- China
| | - Wei Yu
- State Key Laboratory of Applied Organic Chemistry
- College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou 730000
- China
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30
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Peters M, Baabe D, Maekawa M, Bockfeld D, Zaretzke MK, Tamm M, Walter MD. Pogo-Stick Iron and Cobalt Complexes: Synthesis, Structures, and Magnetic Properties. Inorg Chem 2019; 58:16475-16486. [PMID: 31769666 DOI: 10.1021/acs.inorgchem.9b02411] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis, structures, and magnetic properties of monomeric half-sandwich iron and cobalt imidazolin-2-iminato complexes have been comprehensively investigated. Salt metathesis reactions of [Cp'M(μ-I)]2 (1-M, M = Fe, Co; Cp' = η5-1,2,4-tri-tert-butylcyclopentadienyl) with [ImDippNLi]2 (ImDippN = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-iminato) furnishes the terminal half-sandwich compounds [Cp'M(NImDipp)] (2-M, M = Fe, Co), which can be regarded as models for elusive half-sandwich iron and cobalt imido complexes. X-ray diffraction analysis confirmed the structure motif of a one-legged piano stool. Complex 2-Co can also be prepared by an acid-base reaction between [Cp'Co{N(SiMe3)2}] (3-Co) and ImDippNH. The electronic and magnetic properties of 2-M and 3-Co were probed by 57Fe Mössbauer spectroscopy (M = Fe), X-band EPR spectroscopy (M = Co), and solid-state magnetic susceptibility measurements. In particular, the central metal atom adopts a high-spin (S = 2) state in 2-Fe, while the cobalt complex 2-Co represents a rare example of a Co(II) species with a coordination number different from six displaying a low-spin to high-spin spin-crossover (SCO) behavior. The experimental observations are complemented by DFT calculations.
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Affiliation(s)
- Marius Peters
- Institut für Anorganische und Analytische Chemie , Technische Universität Braunschweig , Hagenring 30 , 38106 Braunschweig , Germany
| | - Dirk Baabe
- Institut für Anorganische und Analytische Chemie , Technische Universität Braunschweig , Hagenring 30 , 38106 Braunschweig , Germany
| | - Miyuki Maekawa
- Institut für Anorganische und Analytische Chemie , Technische Universität Braunschweig , Hagenring 30 , 38106 Braunschweig , Germany
| | - Dirk Bockfeld
- Institut für Anorganische und Analytische Chemie , Technische Universität Braunschweig , Hagenring 30 , 38106 Braunschweig , Germany
| | - Marc-Kevin Zaretzke
- Institut für Anorganische und Analytische Chemie , Technische Universität Braunschweig , Hagenring 30 , 38106 Braunschweig , Germany
| | - Matthias Tamm
- Institut für Anorganische und Analytische Chemie , Technische Universität Braunschweig , Hagenring 30 , 38106 Braunschweig , Germany
| | - Marc D Walter
- Institut für Anorganische und Analytische Chemie , Technische Universität Braunschweig , Hagenring 30 , 38106 Braunschweig , Germany
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31
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Dong Y, Lukens JT, Clarke RM, Zheng SL, Lancaster KM, Betley TA. Synthesis, characterization and C-H amination reactivity of nickel iminyl complexes. Chem Sci 2019; 11:1260-1268. [PMID: 34123250 PMCID: PMC8147896 DOI: 10.1039/c9sc04879k] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Metalation of the deprotonated dipyrrin (AdFL)Li with NiCl2(py)2 afforded the divalent Ni product (AdFL)NiCl(py)2 (1) (AdFL: 1,9-di(1-adamantyl)-5-perfluorophenyldipyrrin; py: pyridine). To generate a reactive synthon on which to explore oxidative group transfer, we used potassium graphite to reduce 1, affording the monovalent Ni synthon (AdFL)Ni(py) (2) and concomitant production of a stoichiometric equivalent of KCl and pyridine. Slow addition of mesityl- or 1-adamantylazide in benzene to 2 afforded the oxidized Ni complexes (AdFL)Ni(NMes) (3) and (AdFL)Ni(NAd) (4), respectively. Both 3 and 4 were characterized by multinuclear NMR, EPR, magnetometry, single-crystal X-ray crystallography, theoretical calculations, and X-ray absorption spectroscopies to provide a detailed electronic structure picture of the nitrenoid adducts. X-ray absorption near edge spectroscopy (XANES) on the Ni reveals higher energy Ni 1s → 3d transitions (3: 8333.2 eV; 4: 8333.4 eV) than NiI or unambiguous NiII analogues. N K-edge X-ray absorption spectroscopy performed on 3 and 4 reveals a common low-energy absorption present only for 3 and 4 (395.4 eV) that was assigned via TDDFT as an N 1s promotion into a predominantly N-localized, singly occupied orbital, akin to metal-supported iminyl complexes reported for iron. On the continuum of imido (i.e., NR2−) to iminyl (i.e., 2NR−) formulations, the complexes are best described as NiII-bound iminyl species given the N K-edge and TDDFT results. Given the open-shell configuration (S = 1/2) of the iminyl adducts, we then examined their propensity to undergo nitrenoid-group transfer to organic substrates. The adamantyl complex 4 readily consumes 1,4-cyclohexadiene (CHD) via H-atom abstraction to afford the amide (AdFL)Ni(NHAd) (5), whereas no reaction was observed upon treatment of the mesityl variant 3 with excess amount of CHD over 3 hours. Toluene can be functionalized by 4 at room temperature, exclusively affording the N-1-adamantyl-benzylidene (6). Slow addition of the organoazide substrate (4-azidobutyl)benzene (7) with 2 exclusively forms 4-phenylbutanenitrile (8) as opposed to an intramolecular cyclized pyrrolidine, resulting from facile β-H elimination outcompeting H-atom abstraction from the benzylic position, followed by rapid H2-elimination from the intermediate Ni hydride ketimide intermediate. Nickel-supported nitrenoids exhibit iminyl character, as determined by multi-edge XAS and TDDFT analysis, demonstrate efficacy for C–H activation and nitrene transfer chemistry.![]()
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Affiliation(s)
- Yuyang Dong
- Department of Chemistry and Chemical Biology, Harvard University 12 Oxford Street Cambridge Massachusetts 02138 USA
| | - James T Lukens
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University Ithaca New York 14853 USA
| | - Ryan M Clarke
- Department of Chemistry and Chemical Biology, Harvard University 12 Oxford Street Cambridge Massachusetts 02138 USA
| | - Shao-Liang Zheng
- Department of Chemistry and Chemical Biology, Harvard University 12 Oxford Street Cambridge Massachusetts 02138 USA
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University Ithaca New York 14853 USA
| | - Theodore A Betley
- Department of Chemistry and Chemical Biology, Harvard University 12 Oxford Street Cambridge Massachusetts 02138 USA
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32
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Cheng J, Chen Q, Leng X, Ye S, Deng L. Three-Coordinate Iron(0) Complexes with N-Heterocyclic Carbene and Vinyltrimethylsilane Ligation: Synthesis, Characterization, and Ligand Substitution Reactions. Inorg Chem 2019; 58:13129-13141. [PMID: 31536336 DOI: 10.1021/acs.inorgchem.9b02009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Low-coordinate iron(0) species are implicated as intermediates in a range of iron-catalyzed organic transformations. Isolable iron(0) complexes with coordination numbers of less than four, however, are rarely known. In continuing with our interests in three-coordinate iron(0) complexes with N-heterocyclic carbene (NHC) and alkene ligation, we report herein the synthesis and ligand substitution reactivity of three-coordinate iron(0) complexes featuring monodentate alkene ligands, [(NHC)Fe(η2-vtms)2] (vtms = vinyltrimethylsilane, NHC = 1,3-bis(2',6'-diisopropylphenyl)-imidazol-2-ylidene (IPr), 1; 1,3-bis(2',6'-diisopropylphenyl)-4,5-tetramethylene-imidazol-2-ylidene (cyIPr), 2; 1,3-bis(2',6'-diisopropylphenyl)-4,5,6,7-tetrahydro-1,3-diazepin-2-ylidene (7-IPr), 3). Complexes 1-3 were synthesized from the one-pot reactions of ferrous dihalides with the N-(2,6-diisopropylphenyl)-substituted NHC ligands, vtms, and KC8. Reactivity study of 1 revealed its facile ligand substitution reactions with terminal aryl alkynes, ketones, isocyanides, and CO, by which iron(0) complexes [(IPr)Fe(η2-HCCAr)] (Ar = Ph, 5; p-CH3C6H4, 6; 3,5-(CF3)2C6H3, 7), [(IPr)Fe(η2-OCPh2)2] (8), [(IPr)Fe(CNR)4] (R = 2,6-Me2C6H3, 9; But, 10), and (IPr)Fe(CO)4 (11) were prepared in good yields. These iron(0) complexes have been characterized by 1H NMR, solution magnetic susceptibility measurement, single-crystal X-ray diffraction study, 57Fe Mössbauer spectroscopy, and elemental analysis. Characterization data and computational studies suggest S = 1 ground-spin states for three-coordinate iron(0) complexes 1-3 and 5-8 and S = 0 ground states for 9-11. Theoretical studies on the three-coordinate complexes 1, 6, and 8 indicated pronounced metal-to-ligand backdonation from occupied Fe 3d orbitals to the π* orbitals of the C═C, C≡C, and C═O moieties of the π ligands. In addition, 1 proved an effective precatalyst for the cyclotrimerization reaction of alkynes.
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Affiliation(s)
- Jun Cheng
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road , Shanghai , 200032 , PR China
| | - Qi Chen
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road , Shanghai , 200032 , PR China
| | - Xuebing Leng
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road , Shanghai , 200032 , PR China
| | - Shengfa Ye
- Max-Planck Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1 , Mülheim an der Ruhr D-45470 , Germany
| | - Liang Deng
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road , Shanghai , 200032 , PR China
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