1
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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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2
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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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3
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Mishra D, Rajkhowa S, Phukan P. Unanticipated switch of reactivity of isonitrile via N≡C bond scission: Cascade formation of symmetrical sulfonyl guanidine. iScience 2023; 26:107258. [PMID: 37520733 PMCID: PMC10384224 DOI: 10.1016/j.isci.2023.107258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/02/2023] [Accepted: 06/27/2023] [Indexed: 08/01/2023] Open
Abstract
Unanticipated formation of symmetrical sulfonyl guanidine was observed while treating isonitriles with N,N-dibromoarylsulfonamides in absence of an external amine source. Interesting feature of this work is that one molecule of isonitrile initially reacts with dibromoarylsulfonamide via the C-end to produce the intermediate carbodiimide while the other molecule undergoes C≡N triple bond cleavage to react as amine source with the intermediate. This switch of reactivity from C-center to N-center of the isonitrile generated symmetrical guanidine.
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Affiliation(s)
- Debashish Mishra
- Department of Chemistry, Gauhati University, Guwahati, Assam 781014, India
| | - Sagarika Rajkhowa
- Department of Chemistry, Gauhati University, Guwahati, Assam 781014, India
| | - Prodeep Phukan
- Department of Chemistry, Gauhati University, Guwahati, Assam 781014, India
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4
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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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5
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Mitchell BS, Chirila A, Kephart JA, Boggiano AC, Krajewski SM, Rogers D, Kaminsky W, Velian A. Metal-Support Interactions in Molecular Single-Site Cluster Catalysts. J Am Chem Soc 2022; 144:18459-18469. [PMID: 36170652 DOI: 10.1021/jacs.2c07033] [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
This study provides atomistic insights into the interface between a single-site catalyst and a transition metal chalcogenide support and reveals that peak catalytic activity occurs when edge/support redox cooperativity is maximized. A molecular platform MCo6Se8(PEt3)4(L)2 (1-M, M = Cr, Mn, Fe, Co, Cu, and Zn) was designed in which the active site (M)/support (Co6Se8) interactions are interrogated by systematically probing the electronic and structural changes that occur as the identity of the metal varies. All 3d transition metal 1-M clusters display remarkable catalytic activity for coupling tosyl azide and tert-butyl isocyanide, with Mn and Co derivatives showing the fastest turnover in the series. Structural, electronic, and magnetic characterization of the clusters was performed using single crystal X-ray diffraction, 1H and 31P nuclear magnetic resonance spectroscopy, electronic absorption spectroscopy, cyclic voltammetry, and computational methods. Distinct metal/support redox regimes can be accessed in 1-M based on the energy of the edge metal's frontier orbitals with respect to those of the cluster support. As the degree of electronic interaction between the edge and the support increases, a cooperative regime is reached wherein the support can deliver electrons to the catalytic site, increasing the reactivity of key metal-nitrenoid intermediates.
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Affiliation(s)
- Benjamin S Mitchell
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Andrei Chirila
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Jonathan A Kephart
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Andrew C Boggiano
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Sebastian M Krajewski
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Dylan Rogers
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Werner Kaminsky
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Alexandra Velian
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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6
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McSkimming A, Thompson NB. Four-Coordinate Fe N 2 and Imido Complexes Supported by a Hemilabile NNC Heteroscorpionate Ligand. Inorg Chem 2022; 61:12318-12326. [PMID: 35895990 PMCID: PMC9367695 DOI: 10.1021/acs.inorgchem.2c01656] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Inspired by mechanistic proposals for N2 reduction
at
the nitrogenase FeMo cofactor, we report herein a new, strongly σ-donating
heteroscorpionate ligand featuring two weak-field pyrazoles and an
alkyl donor. This ligand supports four-coordinate Fe(I)-N2, Fe(II)-Cl, and Fe(III)-imido complexes, which we have characterized
using a variety of spectroscopic and computational methods. Structural
and quantum mechanical analysis reveal the nature of the Fe–C
bonds to be essentially invariant between the complexes, with conversion
between the (formally) low-valent Fe-N2 and high-valent
Fe-imido complexes mediated by pyrazole hemilability. This presents
a useful strategy for substrate reduction at such low-coordinate centers
and suggests a mechanism by which FeMoco might accommodate the binding
of both π-acidic and π-basic nitrogenous substrates. We report a new, strongly σ-donating
NNC heteroscorpionate
ligand and its Fe(I)-N2, Fe(II)-Cl and Fe(III)-imido complexes.
Conversion between the low-valent Fe-N2 and high-valent
Fe-imido complexes is mediated by pyrazole hemilability, presenting
a useful strategy for substrate reduction at such low-coordinate centers.
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Affiliation(s)
- Alex McSkimming
- Department of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - Niklas B Thompson
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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7
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Schüler P, Krieck S, Görls H, Liebing P, Westerhausen M. Sterically shielded primary anilides of the alkaline-earth metals of the type (thf) nAe(NH-Ar*) 2 (Ae = Mg, Ca, Sr, and Ba; Ar* = bulky aryl). Dalton Trans 2022; 51:8461-8471. [PMID: 35603695 DOI: 10.1039/d2dt01121b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Metalation of 2,4,6-triphenylphenylamine (H2N-C6H2-2,4,6-Ph3, 1a) and 4-methyl-2,6-bis(diphenylmethyl)aniline (2,6-bis(diphenylmethyl)-p-toluidine, H2N-C6H2-4-Me-2,6-(CHPh2)2, 2a) with dibutylmagnesium and Ae[N(SiMe3)2]2 with a stoichiometric 1 : 2 ratio in THF at room temperature yields the corresponding primary anilides [(thf)nAe{N(H)-C6H2-2,4,6-Ph3}2] (Ae/n = Mg/2 (1b), Ca/2 (1c), Sr/3 (1d), and Ba/3 (1e)) and [(thf)nAe{N(H)-C6H2-4-Me-2,6-(CHPh2)2}2] (Ae/n = Mg/2 (2b), Ca/3 (2c) and Sr/2 (2d)), respectively. The 1 : 1 reaction of Mg(n/sBu)2 and MgPh2 with 2a leads to the formation of heteroleptic [(thf)2Mg(R){N(H)-C6H2-4-Me-2,6-(CHPh2)2}] (R = n/sBu (2bBu), Ph (2bPh)). At 50 °C, the strontium complex 2d liberates one equivalent of 2avia intramolecular deprotonation of the triarylmethyl functionality yielding dinuclear [(thf)2Sr{N(H)-C6H2-4-Me-2-(CPh2)-6-(CHPh2)2}]2 (2d'). The barium compound is significantly more reactive and regardless of applied stoichiometry the isotypic barium congener [(thf)2Ba{N(H)-C6H2-4-Me-2-(CPh2)-6-(CHPh2)2}]2 (2e') forms. The molecular structures of 1c, 2d, 2d', and 2e' are stabilized by metal-phenyl π-interactions.
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Affiliation(s)
- Philipp Schüler
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, D-07743 Jena, Germany.
| | - Sven Krieck
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, D-07743 Jena, Germany.
| | - Helmar Görls
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, D-07743 Jena, Germany.
| | - Phil Liebing
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, D-07743 Jena, Germany.
| | - Matthias Westerhausen
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, D-07743 Jena, Germany.
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8
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Feng H, Yang D, Mei T, Zhang Y, Wang B, Qu J. Synthesis and Structure of Thiolate‐Bridged Diiron and Dicobalt Complexes Supported by Modified β‐Diketiminate Ligand. Eur J Inorg Chem 2022. [DOI: 10.1002/ejic.202200290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Huajin Feng
- Dalian University of Technology State Key Laboratory of Fine Chemicals CHINA
| | - Dawei Yang
- Dalian University of Technology State Key Laboratory of Fine Chemicals 2# Linggong Road 116024 Dalian CHINA
| | - Tao Mei
- Dalian University of Technology State Key Laboratory of Fine Chemicals CHINA
| | - Yahui Zhang
- Dalian University of Technology State Key Laboratory of Fine Chemicals CHINA
| | - Baomin Wang
- Dalian University of Technology State Key Laboratory of Fine Chemicals CHINA
| | - Jingping Qu
- Dalian University of Technology State Key Laboratory of Fine Chemicals CHINA
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9
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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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10
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Chatterjee S, Harden I, Bistoni G, Castillo RG, Chabbra S, van Gastel M, Schnegg A, Bill E, Birrell JA, Morandi B, Neese F, DeBeer S. A Combined Spectroscopic and Computational Study on the Mechanism of Iron-Catalyzed Aminofunctionalization of Olefins Using Hydroxylamine Derived N-O Reagent as the "Amino" Source and "Oxidant". J Am Chem Soc 2022; 144:2637-2656. [PMID: 35119853 PMCID: PMC8855425 DOI: 10.1021/jacs.1c11083] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
![]()
Herein, we study
the mechanism of iron-catalyzed direct synthesis
of unprotected aminoethers from olefins by a hydroxyl amine derived
reagent using a wide range of analytical and spectroscopic techniques
(Mössbauer, Electron Paramagnetic Resonance, Ultra-Violet Visible
Spectroscopy, X-ray Absorption, Nuclear Resonance Vibrational Spectroscopy,
and resonance Raman) along with high-level quantum chemical calculations.
The hydroxyl amine derived triflic acid salt acts as the “oxidant”
as well as “amino” group donor. It activates the high-spin
Fe(II) (St = 2) catalyst [Fe(acac)2(H2O)2] (1) to generate
a high-spin (St = 5/2) intermediate (Int I), which decays to a second intermediate (Int II) with St = 2. The analysis of spectroscopic
and computational data leads to the formulation of Int I as [Fe(III)(acac)2-N-acyloxy] (an alkyl-peroxo-Fe(III)
analogue). Furthermore, Int II is formed by N–O
bond homolysis. However, it does not generate a high-valent
Fe(IV)(NH) species (a Fe(IV)(O) analogue), but instead a high-spin
Fe(III) center which is strongly antiferromagnetically coupled (J = −524 cm–1) to an iminyl radical,
[Fe(III)(acac)2-NH·], giving St = 2. Though Fe(NH) complexes as isoelectronic surrogates
to Fe(O) functionalities are known, detection of a high-spin Fe(III)-N-acyloxy intermediate (Int I), which undergoes
N–O bond cleavage to generate the active iron–nitrogen
intermediate (Int II), is unprecedented. Relative to
Fe(IV)(O) centers, Int II features a weak elongated Fe–N
bond which, together with the unpaired electron density along the
Fe–N bond vector, helps to rationalize its propensity for N-transfer reactions onto styrenyl olefins, resulting in
the overall formation of aminoethers. This study thus demonstrates
the potential of utilizing the iron-coordinated nitrogen-centered
radicals as powerful reactive intermediates in catalysis.
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Affiliation(s)
- Sayanti Chatterjee
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany.,Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Ingolf Harden
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Giovanni Bistoni
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Rebeca G Castillo
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Sonia Chabbra
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Alexander Schnegg
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - James A Birrell
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Bill Morandi
- ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland.,Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
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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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Wong AS, Zhang B, Li B, Neidig ML, Byers JA. Air-Stable Iron-Based Precatalysts for Suzuki–Miyaura Cross-Coupling Reactions between Alkyl Halides and Aryl Boronic Esters. Org Process Res Dev 2021; 25:2461-2472. [DOI: 10.1021/acs.oprd.1c00235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Alexander S. Wong
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Bufan Zhang
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Bo Li
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Michael L. Neidig
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Jeffery A. Byers
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
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14
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Abstract
Sterically bulky β-diketiminate (or Nacnac) ligand systems have recently shown the ability to kinetically stabilize highly reactive low-oxidation state main group complexes. Metal halide precursors to such systems can be formed via salt metathesis reactions involving alkali metal complexes of these large ligand frameworks. Herein, we report the synthesis and characterization of lithium and potassium complexes of the super bulky anionic β-diketiminate ligands, known [TCHPNacnac]− and new [TCHP/DipNacnac]− (ArNacnac = [(ArNCMe)2CH]−) (Ar = 2,4,6-tricyclohexylphenyl (TCHP) or 2,6-diisopropylphenyl (Dip)). The reaction of the proteo-ligands, ArNacnacH, with nBuLi give the lithium etherate compounds, [(TCHPNacnac)Li(OEt2)] and [(TCHP/DipNacnac)Li(OEt2)], which were isolated and characterized by multinuclear NMR spectroscopy and X-ray crystallography. The unsolvated potassium salts, [{K(TCHPNacnac)}2] and [{K(TCHP/DipNacnac)}∞], were also synthesized and characterized in solution by NMR spectroscopy. In the solid state, these highly reactive potassium complexes exhibit differing alkali metal coordination modes, depending on the ligand involved. These group 1 complexes have potential as reagents for the transfer of the bulky ligand fragments to metal halides, and for the subsequent stabilization of low-oxidation state metal complexes.
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15
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Bailey GA, Buss JA, Oyala PH, Agapie T. Terminal, Open-Shell Mo Carbide and Carbyne Complexes: Spin Delocalization and Ligand Noninnocence. J Am Chem Soc 2021; 143:13091-13102. [PMID: 34379389 DOI: 10.1021/jacs.1c03806] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Open-shell compounds bearing metal-carbon triple bonds, such as carbides and carbynes, are of significant interest as plausible intermediates in the reductive catenation of C1 oxygenates. Despite the abundance of closed-shell carbynes reported, open-shell variants are very limited, and an open-shell carbide has yet to be reported. Herein, we report the synthesis of the first terminal, open-shell carbide complexes, [K][1] and [1][BArF4] (1 = P2Mo(≡C:)(CO), P2 = a terphenyl diphosphine ligand), which differ by two redox states, as well as a series of related open-shell carbyne complexes. The complexes are characterized by single-crystal X-ray diffraction and NMR, EPR, and IR spectroscopies, while the electronic structures are probed by EPR studies and DFT calculations to assess spin delocalization. In the d1 complexes, the spin is primarily localized on the metal (∼55-77% Mo dxy) with delocalization on the triply bonded carbon of ∼0.05-0.09 e-. In the reduced carbide [K][1], a direct metal-arene interaction enables ancillary ligand reduction, resulting in reduced radical character on the terminal carbide (⩽0.02 e-). Reactivity studies with [K][1] reveal the formation of mixed-valent C-C coupled products at -40 °C, illustrating how productive reactivity manifolds can be engendered through the manipulation of redox states. Combined, the results inform on the electronic structure and reactivity of a new and underrepresented class of compounds with potential significance to a wide array of reactions involving open-shell species.
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Affiliation(s)
- Gwendolyn A Bailey
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Joshua A Buss
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Paul H Oyala
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Theodor Agapie
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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16
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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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17
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Twycross D, Davey CJ, Cole ML, McKay AI. Stereoelectronic Characterization and Catalytic Potential of a 1,3‐Bis(2,6‐terphenyl)‐Substituted N‐Heterocyclic Carbene. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Daniel Twycross
- School of Chemistry University of New South Wales Kensington NSW, 2052 Australia
| | - Christopher J. Davey
- School of Chemistry University of New South Wales Kensington NSW, 2052 Australia
| | - Marcus L. Cole
- School of Chemistry University of New South Wales Kensington NSW, 2052 Australia
| | - Alasdair I. McKay
- School of Chemistry University of New South Wales Kensington NSW, 2052 Australia
- School of Chemistry Monash University Clayton VIC 3080 Australia
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18
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Grant LN, Bhunia M, Pinter B, Rebreyend C, Carroll ME, Carroll PJ, de Bruin B, Mindiola DJ. Pursuit of an Electron Deficient Titanium Nitride. Inorg Chem 2021; 60:5635-5646. [PMID: 33825450 DOI: 10.1021/acs.inorgchem.0c03644] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The nitride salt [(PN)2Ti≡N{μ2-K(OEt2)}]2 (1) (PN- = (N-(2-PiPr2-4-methylphenyl)-2,4,6-Me3C6H2) can be oxidized with two equiv of I2 or four equiv of ClCPh3 to produce the phosphinimide-halide complexes (NPN')(PN)Ti(X) (X- = I (2), Cl (3); NPN' = N-(2-NPiPr2-4-methylphenyl)-2,4,6-Me3C6H22-), respectively. In the case of 2, H2 was found to be one of the other products; whereas, HCPh3 and Gomberg's dimer were observed upon the formation of 3. Independent studies suggest that the oxidation of 1 could imply the formation of the transient nitridyl species [(PN)2Ti(≡N•)] (A), which can either oxidize the proximal phosphine atom to produce the Ti(III) intermediate [(NPN')(PN)Ti] (B) or, alternatively, engage in H atom abstraction to form the parent imido (PN)2Ti≡NH (4). The latter was independently prepared and was found to photochemically convert to the titanium-hydride, (NPN')(PN)Ti(H) (5). Isotopic labeling studies using (PN)2Ti≡ND (4-d1) as well as reactivity studies of 5 with a hydride abstractor demonstrate the presence of the hydride ligand in 5. An alternative route to putative A was observed via a photochemically promoted incomplete reduction of the azide ligand in (PN)2Ti(N3) (6) to 4. This process was accompanied by some formation of 5. Frozen matrix X-band EPR studies of 6, performed under photolytic conditions, were consistent with species B being formed under these reaction conditions, originating from a low barrier N-insertion into the phosphine group in the putative nitridyl species A. Computational studies were also undertaken to discover the mechanism and plausibility of the divergent pathways (via intermediates A and B) in the formation of 2 and 3, and to characterize the bonding and electronic structure of the elusive nitrogen-centered radical in A.
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Affiliation(s)
- Lauren N Grant
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Mrinal Bhunia
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Balazs Pinter
- Department of Chemistry, Universidad Técnica Federico Santa María, Valparaíso 2390123, Chile
| | - Christophe Rebreyend
- Department of Homogeneous Catalysis, Universiteit van Amsterdam, Faculty of Science, van 't Hoff Institute for Molecular Sciences, Postbus 94720, Amsterdam
| | - Maria E Carroll
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Patrick J Carroll
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Bas de Bruin
- Department of Homogeneous Catalysis, Universiteit van Amsterdam, Faculty of Science, van 't Hoff Institute for Molecular Sciences, Postbus 94720, Amsterdam
| | - Daniel J Mindiola
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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19
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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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20
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Margulieux GW, Kim S, Chirik PJ. Determination of the N-H Bond Dissociation Free Energy in a Pyridine(diimine)molybdenum Complex Prepared by Proton-Coupled Electron Transfer. Inorg Chem 2020; 59:15394-15401. [PMID: 33016073 DOI: 10.1021/acs.inorgchem.0c02382] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The pyridine(diimine)molybdenum bis(imido) complex (iPrPDI)Mo(═NTol)2 (Tol = 4-methylphenyl) was synthesized by the addition of 2 equiv of 4-methylphenylazide to the corresponding molybdenum benzene derivative, (iPrPDI)Mo(η6-C6H6) [iPrPDI = 2,6-(2,6-iPr2C6H3N═CMe)2C5H3N]. Protonation of (iPrPDI)Mo(═NTol)2 with 2,6-lutinidum triflate yielded a cationic molybdenum amido complex, [(iPrPDI)Mo(NHTol)(═NTol)][OTf], which was further transformed into the neutral molybdenum amido (iPrPDI)Mo(NHTol)(═NTol) by reduction with zinc powder. A series of spectroscopic, synthetic, and pKa determination studies along with electrochemical measurements by the protonation-reduction pathway were used to establish an N-H bond dissociation free energy (BDFE) between 65 and 69 kcal/mol for the molybdenum imido-amido compound, (iPrPDI)Mo(NHTol)(═NTol). Full-molecule density functional theory studies provided a computed value of 61 kcal/mol. By contrast, reduction of (iPrPDI)Mo(═NTol)2 with KC8 afforded the corresponding anionic molybdenum complex K[(iPrPDI)Mo(═NTol)2], which has a potassium cation intercalated with the pyridine and tolyl groups. Protonation of K[(iPrPDI)Mo(═NTol)2] with the weak amidinium acid [TBD(H)][BArF24] (TBD = triazabicyclodecene; BArF24 = B[3,5-(CF3)2C6H3]4) also produced the neutral molybdenum amido complex (iPrPDI)Mo(NHTol)(═NTol). Measurement of the pKa and oxidation potential of K[(iPrPDI)Mo(═NTol)2] provided a range of 69-73 kcal/mol for the N-H BDFE of (iPrPDI)Mo(NHTol)(═NTol), in good agreement with the protonation-reduction route and completing the square scheme. The similar pKa and redox potentials obtained from each pathway demonstrate that both sequences are energetically feasible for proton-coupled electron-transfer (PCET) events. This study on the determination of N-H BDFE of the molybdenum amido complex renders fundamental insight into the N2 reduction cycle by PCET.
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Affiliation(s)
- Grant W Margulieux
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Sangmin Kim
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Paul J Chirik
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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21
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Zovko C, Bestgen S, Schoo C, Görner A, Goicoechea JM, Roesky PW. A Phosphine Functionalized β-Diketimine Ligand for the Synthesis of Manifold Metal Complexes. Chemistry 2020; 26:13191-13202. [PMID: 32285968 PMCID: PMC7693294 DOI: 10.1002/chem.202001357] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Indexed: 01/23/2023]
Abstract
A bis(diphenyl)-phosphine functionalized β-diketimine (PNac-H) was synthesized as a flexible ligand for transition metal complexes. The newly designed ligand features symmetrically placed phosphine moieties around a β-diketimine unit, forming a PNNP-type pocket. Due to the hard and soft donor atoms (N vs. P) the ligand can stabilize various coordination polyhedra. A complete series ranging from coordination numbers 2 to 6 was realized. Linear, trigonal planar, square planar, tetrahedral, square pyramidal, and octahedral coordination arrangements containing the PNac-ligand around the metal center were observed by using suitable metal sources. Hereby, PNac-H or its anion PNac- acts as mono-, bi- and tetradendate ligand. Such a broad flexibility is unusual for a rigid tetradentate system. The structural motifs were realized by treatment of PNac-H with a series of late transition metal precursors, for example, silver, gold, nickel, copper, platinum, and rhodium. The new complexes have been fully characterized by single crystal X-ray diffraction, NMR, IR, UV/Vis spectroscopy, mass spectrometry as well as elemental analysis. Additionally, selected complexes were investigated regarding their photophysical properties. Thus, PNac-H proved to be an ideal ligand platform for the selective coordination and stabilization of various metal ions in diverse polyhedra and oxidation states.
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Affiliation(s)
- Christina Zovko
- Institute of Inorganic ChemistryKarlsruhe Institute of Technology (KIT)Engesserstraβe 1576131KarlsruheGermany
| | - Sebastian Bestgen
- Institute of Inorganic ChemistryKarlsruhe Institute of Technology (KIT)Engesserstraβe 1576131KarlsruheGermany
- Department of Chemistry, Chemistry Research LaboratoryUniversity of Oxford12 Mansfield RoadOxfordOX1 3TAUK
| | - Christoph Schoo
- Institute of Inorganic ChemistryKarlsruhe Institute of Technology (KIT)Engesserstraβe 1576131KarlsruheGermany
| | - Anne Görner
- Institute of Inorganic ChemistryKarlsruhe Institute of Technology (KIT)Engesserstraβe 1576131KarlsruheGermany
| | - Jose M. Goicoechea
- Department of Chemistry, Chemistry Research LaboratoryUniversity of Oxford12 Mansfield RoadOxfordOX1 3TAUK
| | - Peter W. Roesky
- Institute of Inorganic ChemistryKarlsruhe Institute of Technology (KIT)Engesserstraβe 1576131KarlsruheGermany
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22
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Grass A, Wannipurage D, Lord RL, Groysman S. Group-transfer chemistry at transition metal centers in bulky alkoxide ligand environments. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2019.213044] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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23
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Sabenya G, Gamba I, Gómez L, Clémancey M, Frisch JR, Klinker EJ, Blondin G, Torelli S, Que L, Martin-Diaconescu V, Latour JM, Lloret-Fillol J, Costas M. Octahedral iron(iv)-tosylimido complexes exhibiting single electron-oxidation reactivity. Chem Sci 2019; 10:9513-9529. [PMID: 32055323 PMCID: PMC6979323 DOI: 10.1039/c9sc02526j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 08/17/2019] [Indexed: 11/28/2022] Open
Abstract
High valent iron species are very reactive molecules involved in oxidation reactions of relevance to biology and chemical synthesis. Herein we describe iron(iv)-tosylimido complexes [FeIV(NTs)(MePy2tacn)](OTf)2 (1(IV)[double bond, length as m-dash]NTs) and [FeIV(NTs)(Me2(CHPy2)tacn)](OTf)2 (2(IV)[double bond, length as m-dash]NTs), (MePy2tacn = N-methyl-N,N-bis(2-picolyl)-1,4,7-triazacyclononane, and Me2(CHPy2)tacn = 1-(di(2-pyridyl)methyl)-4,7-dimethyl-1,4,7-triazacyclononane, Ts = Tosyl). 1(IV)[double bond, length as m-dash]NTs and 2(IV)[double bond, length as m-dash]NTs are rare examples of octahedral iron(iv)-imido complexes and are isoelectronic analogues of the recently described iron(iv)-oxo complexes [FeIV(O)(L)]2+ (L = MePy2tacn and Me2(CHPy2)tacn, respectively). 1(IV)[double bond, length as m-dash]NTs and 2(IV)[double bond, length as m-dash]NTs are metastable and have been spectroscopically characterized by HR-MS, UV-vis, 1H-NMR, resonance Raman, Mössbauer, and X-ray absorption (XAS) spectroscopy as well as by DFT computational methods. Ferric complexes [FeIII(HNTs)(L)]2+, 1(III)-NHTs (L = MePy2tacn) and 2(III)-NHTs (L = Me2(CHPy2)tacn) have been isolated after the decay of 1(IV)[double bond, length as m-dash]NTs and 2(IV)[double bond, length as m-dash]NTs in solution, spectroscopically characterized, and the molecular structure of [FeIII(HNTs)(MePy2tacn)](SbF6)2 determined by single crystal X-ray diffraction. Reaction of 1(IV)[double bond, length as m-dash]NTs and 2(IV)[double bond, length as m-dash]NTs with different p-substituted thioanisoles results in the transfer of the tosylimido moiety to the sulphur atom producing sulfilimine products. In these reactions, 1(IV)[double bond, length as m-dash]NTs and 2(IV)[double bond, length as m-dash]NTs behave as single electron oxidants and Hammett analyses of reaction rates evidence that tosylimido transfer is more sensitive than oxo transfer to charge effects. In addition, reaction of 1(IV)[double bond, length as m-dash]NTs and 2(IV)[double bond, length as m-dash]NTs with hydrocarbons containing weak C-H bonds results in the formation of 1(III)-NHTs and 2(III)-NHTs respectively, along with the oxidized substrate. Kinetic analyses indicate that reactions proceed via a mechanistically unusual HAT reaction, where an association complex precedes hydrogen abstraction.
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Affiliation(s)
- Gerard Sabenya
- Institut de Química Computacional i Catàlisi (IQCC) , Departament de Química , Universitat de Girona , Campus Montilivi , E17071 Girona , Spain .
| | - Ilaria Gamba
- Institut de Química Computacional i Catàlisi (IQCC) , Departament de Química , Universitat de Girona , Campus Montilivi , E17071 Girona , Spain .
| | - Laura Gómez
- Institut de Química Computacional i Catàlisi (IQCC) , Departament de Química , Universitat de Girona , Campus Montilivi , E17071 Girona , Spain .
| | - Martin Clémancey
- Univ. Grenoble-Alpes , CNRS , CEA , IRIG , DIESE , CBM , Grenoble 38000 , France
| | - Jonathan R Frisch
- Department of Chemistry , University of Minnesota , Pleasant Str 207 , Minneapolis , Minnesota , USA
| | - Eric J Klinker
- Department of Chemistry , University of Minnesota , Pleasant Str 207 , Minneapolis , Minnesota , USA
| | - Geneviève Blondin
- Univ. Grenoble-Alpes , CNRS , CEA , IRIG , DIESE , CBM , Grenoble 38000 , France
| | - Stéphane Torelli
- Univ. Grenoble-Alpes , CNRS , CEA , IRIG , DIESE , CBM , Grenoble 38000 , France
| | - Lawrence Que
- Department of Chemistry , University of Minnesota , Pleasant Str 207 , Minneapolis , Minnesota , USA
| | - Vlad Martin-Diaconescu
- Institut de Química Computacional i Catàlisi (IQCC) , Departament de Química , Universitat de Girona , Campus Montilivi , E17071 Girona , Spain .
- Institute of Chemical Research of Catalonia (ICIQ) , The Barcelona Institute of Science and Technology , Avinguda Països Catalans 16 , 43007 Tarragona , Spain .
| | - Jean-Marc Latour
- Univ. Grenoble-Alpes , CNRS , CEA , IRIG , DIESE , CBM , Grenoble 38000 , France
| | - Julio Lloret-Fillol
- Institut de Química Computacional i Catàlisi (IQCC) , Departament de Química , Universitat de Girona , Campus Montilivi , E17071 Girona , Spain .
- Institute of Chemical Research of Catalonia (ICIQ) , The Barcelona Institute of Science and Technology , Avinguda Països Catalans 16 , 43007 Tarragona , Spain .
- Catalan Institution for Research and Advanced Studies (ICREA) , Passeig Lluïs Companys, 23 , 08010 , Barcelona , Spain
| | - Miquel Costas
- Institut de Química Computacional i Catàlisi (IQCC) , Departament de Química , Universitat de Girona , Campus Montilivi , E17071 Girona , Spain .
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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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25
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Hakey BM, Darmon JM, Akhmedov NG, Petersen JL, Milsmann C. Reactivity of Pyridine Dipyrrolide Iron(II) Complexes with Organic Azides: C–H Amination and Iron Tetrazene Formation. Inorg Chem 2019; 58:11028-11042. [PMID: 31364852 DOI: 10.1021/acs.inorgchem.9b01560] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Brett M. Hakey
- C. Eugene Bennett Department of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Jonathan M. Darmon
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Novruz G. Akhmedov
- C. Eugene Bennett Department of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Jeffrey L. Petersen
- C. Eugene Bennett Department of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Carsten Milsmann
- C. Eugene Bennett Department of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
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26
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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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27
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Anneser MR, Elpitiya GR, Townsend J, Johnson EJ, Powers XB, DeJesus JF, Vogiatzis KD, Jenkins DM. Unprecedented Five‐Coordinate Iron(IV) Imides Generate Divergent Spin States Based on the Imide R‐Groups. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201903132] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Markus R. Anneser
- Department of Chemistry University of Tennessee Knoxville TN 37996 USA
| | - Gaya R. Elpitiya
- Department of Chemistry University of Tennessee Knoxville TN 37996 USA
| | - Jacob Townsend
- Department of Chemistry University of Tennessee Knoxville TN 37996 USA
| | - Elizabeth J. Johnson
- Department of Chemistry and Chemical Biology Harvard University Cambridge MA 02138 USA
| | - Xian B. Powers
- Department of Chemistry University of Tennessee Knoxville TN 37996 USA
| | - Joseph F. DeJesus
- Department of Chemistry University of Tennessee Knoxville TN 37996 USA
| | | | - David M. Jenkins
- Department of Chemistry University of Tennessee Knoxville TN 37996 USA
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28
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Anneser MR, Elpitiya GR, Townsend J, Johnson EJ, Powers XB, DeJesus JF, Vogiatzis KD, Jenkins DM. Unprecedented Five-Coordinate Iron(IV) Imides Generate Divergent Spin States Based on the Imide R-Groups. Angew Chem Int Ed Engl 2019; 58:8115-8118. [PMID: 30974012 PMCID: PMC6546507 DOI: 10.1002/anie.201903132] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Indexed: 01/05/2023]
Abstract
Three five-coordinate iron(IV) imide complexes have been synthesized and characterized. These novel structures have disparate spin states on the iron as a function of the R-group attached to the imide, with alkyl groups leading to low-spin diamagnetic (S=0) complexes and an aryl group leading to an intermediate-spin (S=1) complex. The different spin states lead to significant differences in the bonding about the iron center as well as the spectroscopic properties of these complexes. Mössbauer spectroscopy confirmed that all three imide complexes are in the iron(IV) oxidation state. The combination of diamagnetism and 15 N labeling allowed for the first 15 N NMR resonance recorded on an iron imide. Multi-reference calculations corroborate the experimental structural findings and suggest how the bonding is distinctly different on the imide ligand between the two spin states.
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Affiliation(s)
- Markus R Anneser
- Department of Chemistry, University of Tennessee, Knoxville, TN, 37996, USA
| | - Gaya R Elpitiya
- Department of Chemistry, University of Tennessee, Knoxville, TN, 37996, USA
| | - Jacob Townsend
- Department of Chemistry, University of Tennessee, Knoxville, TN, 37996, USA
| | - Elizabeth J Johnson
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Xian B Powers
- Department of Chemistry, University of Tennessee, Knoxville, TN, 37996, USA
| | - Joseph F DeJesus
- Department of Chemistry, University of Tennessee, Knoxville, TN, 37996, USA
| | | | - David M Jenkins
- Department of Chemistry, University of Tennessee, Knoxville, TN, 37996, USA
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29
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Cheng J, Liu J, Leng X, Lohmiller T, Schnegg A, Bill E, Ye S, Deng L. A Two-Coordinate Iron(II) Imido Complex with NHC Ligation: Synthesis, Characterization, and Its Diversified Reactivity of Nitrene Transfer and C-H Bond Activation. Inorg Chem 2019; 58:7634-7644. [PMID: 31083985 PMCID: PMC6750749 DOI: 10.1021/acs.inorgchem.9b01147] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Iron
terminal imido species are typically implicated as reaction intermediates
in iron-catalyzed transformations. While a large body of work has
been devoted to mid- and high-valent iron imidos, to date the chemistry
of iron(II) imidos has remained largely unexplored due to the difficulty
in accessing them. Herein, we present a study on the two-coordinate
iron(II) imido complex [(IPr)Fe(NArTrip)] (3; IPr = 1,3-bis(2′,6′-diisopropylphenyl)imidazol-2-ylidene;
ArTrip = 2,6-bis(2′,4′,6′-triisopropylphenyl)phenyl)
prepared from the reaction of an iron(0) complex with the bulky azide
ArTripN3. Spectroscopic investigations in combination
with DFT calculations established a high-spin S =
2 ground spin state for 3, consistent with its long Fe–N
multiple bond of 1.715(2) Å revealed by X-ray diffraction analysis.
Complex 3 exhibits unusual activity of nitrene transfer
and C–H bond activation in comparison to the reported iron
imido complexes. Specifically, the reactions of 3 with
CH2=CHArCF3, an electron-deficient alkene,
and CO, a strong π acid, readily afford nitrene transfer products,
ArCF3CH=CHNHArTrip and ArTripNCO, respectively, yet no similar reaction occurs when 3 is treated with electron-rich alkenes and PMe3. Moreover, 3 is inert toward the weak C(sp3)–H bonds
in 1,4-cyclohexadiene, THF, and toluene, whereas it can cleave the
stronger C(sp)–H bond in p-trifluoromethylphenylacetylene
to form an iron(II) amido alkynyl complex. Interestingly, intramolecular
C(sp3)–H bond functionalization was observed by
adding (p-Tol)2CN2 to 3. The unique reactivity of 3 is attributed to
its low-coordinate nature and the high negative charge population
on the imido N atom, which render its iron–imido unit nucleophilic
in nature. The two-coordinate iron(II)
imido complex (IPr)Fe(NArTrip) (3) exhibits
a high-spin ground state (S = 2) and was found to
be reactive toward electron-deficient alkene, diazo compounds, terminal
alkyne, et al., in which diversified reactivities of nitrene transfer,
C−H bond activation, and C−N bond formation have been
observed. The reactivity pattern reflects the nucleophilic nature
of the imido moiety of the high-spin iron(II) complex.
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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, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 345 Lingling Road , Shanghai 200032 , People's Republic of China
| | - Jian Liu
- 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 , People's Republic of 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 , People's Republic of China
| | - Thomas Lohmiller
- Berlin Joint EPR Lab , Helmholtz-Zentrum Berlin für Materialien und Energie , Berlin , Germany
| | - Alexander Schnegg
- Max-Planck-Institut für Chemische Energiekonversion , Mülheim an der Ruhr D-45470 , Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion , Mülheim an der Ruhr D-45470 , Germany
| | - 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, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 345 Lingling Road , Shanghai 200032 , People's Republic of China
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30
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Abstract
Reduction of (ArL)CoIIBr (ArL = 5-mesityl-1,9-(2,4,6-Ph3C6H2)dipyrrin) with potassium graphite afforded the novel CoI synthon (ArL)CoI. Treatment of (ArL)CoI with a stoichiometric amount of various alkyl azides (N3R) furnished three-coordinate CoIII alkyl imidos (ArL)Co(NR), as confirmed by single-crystal X-ray diffraction (R: CMe2Bu, CMe2(CH2)2CHMe2). The exclusive formation of four-coordinate cobalt tetrazido complexes (ArL)Co(κ2-N4R2) was observed upon addition of excess azide, inhibiting any subsequent C-H amination. However, when a weak C-H bond is appended to the imido moiety, as in the case of (4-azido-4-methylpentyl)benzene, intramolecular C-H amination kinetically outcompetes formation of the corresponding tetrazene species to generate 2,2-dimethyl-5-phenylpyrrolidine in a catalytic fashion without requiring product sequestration. The imido (ArL)Co(NAd) exists in equilibrium in the presence of pyridine with a four-coordinate cobalt imido (ArL)Co(NAd)(py) ( Ka = 8.04 M-1), as determined by 1H NMR titration experiments. Kinetic studies revealed that pyridine binding slows down the formation of the tetrazido complex by blocking azide coordination to the CoIII imido. Further, (ArL)Co(NR)(py) displays enhanced C-H amination reactivity compared to that of the pyridine-free complex, enabling higher catalytic turnover numbers under milder conditions. The mechanism of C-H amination was probed via kinetic isotope effect experiments [ kH/ kD = 10.2(9)] and initial rate analysis with para-substituted azides, suggesting a two-step radical pathway. Lastly, the enhanced reactivity of (ArL)Co(NR)(py) can be correlated to a higher spin-state population, resulting in a decreased crystal field due to a geometry change upon pyridine coordination.
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Affiliation(s)
- Yunjung Baek
- 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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31
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Zhao X, Liang S, Fan X, Yang T, Yu W. Iron-Catalyzed Intramolecular C–H Amination of α-Azidyl Amides. Org Lett 2019; 21:1559-1563. [DOI: 10.1021/acs.orglett.8b03927] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xiaopeng Zhao
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, P. R. China
| | - Siyu Liang
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, P. R. China
| | - Xing Fan
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, P. R. China
| | - Tonghao Yang
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, P. R. China
| | - Wei Yu
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, P. R. China
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32
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Leverett AR, Diachenko V, Cole ML, McKay AI. Kinetic stabilization of low-oxidation state and terminal hydrido main group metal complexes by a sterically demanding N,N′-bis(2,6-terphenyl)triazenide. Dalton Trans 2019; 48:13197-13204. [DOI: 10.1039/c9dt02562f] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Thermally robust main group metal complexes featuring terminal hydride ligands are achieved by deploying a sterically demanding N,N′-bis(2,6-terphenyl)triazenide ligand.
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Affiliation(s)
| | - Vera Diachenko
- School of Chemistry
- University of New South Wales
- Australia
| | - Marcus L. Cole
- School of Chemistry
- University of New South Wales
- Australia
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33
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McKay AI, Cole ML. Structural diversity in a homologous series of donor free alkali metal complexes bearing a sterically demanding triazenide. Dalton Trans 2019; 48:2948-2952. [DOI: 10.1039/c8dt04983a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The isolation and structural characterization of donor free alkali metal complexes of a bis(terphenyl) substituted triazenide are presented.
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Affiliation(s)
| | - Marcus L. Cole
- School of Chemistry
- University of New South Wales
- Australia
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34
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Cruz TFC, Pereira LCJ, Waerenborgh JC, Veiros LF, Gomes PT. Hydroboration of terminal olefins with pinacolborane catalyzed by new 2-iminopyrrolyl iron(ii) complexes. Catal Sci Technol 2019. [DOI: 10.1039/c8cy02319k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
New Fe(ii) mono(2-iminopyrrolyl) complexes catalyze the hydroboration of terminal olefins with pinacolborane via a borane oxidative addition pathway.
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Affiliation(s)
- Tiago F. C. Cruz
- Centro de Química Estrutural
- Departamento de Engenharia Química
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
| | - Laura C. J. Pereira
- C2TN-Centro de Ciências e Tecnologias Nucleares
- Instituto Superior Técnico
- Universidade de Lisboa
- 2695-066 Bobadela LRS
- Portugal
| | - João C. Waerenborgh
- C2TN-Centro de Ciências e Tecnologias Nucleares
- Instituto Superior Técnico
- Universidade de Lisboa
- 2695-066 Bobadela LRS
- Portugal
| | - Luís F. Veiros
- Centro de Química Estrutural
- Departamento de Engenharia Química
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
| | - Pedro T. Gomes
- Centro de Química Estrutural
- Departamento de Engenharia Química
- Instituto Superior Técnico
- Universidade de Lisboa
- 1049-001 Lisboa
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35
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Goetz MK, Hill EA, Filatov AS, Anderson JS. Isolation of a Terminal Co(III)-Oxo Complex. J Am Chem Soc 2018; 140:13176-13180. [PMID: 30078327 DOI: 10.1021/jacs.8b07399] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Late transition metal oxo complexes with high d-electron counts have been implicated as intermediates in a wide variety of important catalytic reactions; however, their reactive nature has often significantly limited their study. While some examples of these species have been isolated and characterized, complexes with d-electron counts >4 are exceedingly rare. Here we report that use of a strongly donating tris(imidazol-2-ylidene)borate scaffold enables the isolation of two highly unusual CoIII-oxo complexes which have been thoroughly characterized by a suite of physical techniques including single crystal X-ray diffraction. These complexes display O atom and H atom transfer reactivity and demonstrate that terminal metal oxo complexes with six d-electrons can display strong metal-oxygen bonding and sufficient stability to enable their characterization. The unambiguous assignment of these complexes supports the viability of related species that are frequently invoked, but rarely observed, in the types of catalytic reactions mentioned above. The studies described here change our understanding of the reactivity and bonding in late transition metal oxo complexes and open the door to further study of the properties of this class of elusive and important intermediates.
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Affiliation(s)
- McKenna K Goetz
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
| | - Ethan A Hill
- 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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36
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Bonyhady SJ, DeRosha DE, Vela J, Vinyard DJ, Cowley RE, Mercado BQ, Brennessel WW, Holland PL. Iron and Cobalt Diazoalkane Complexes Supported by β-Diketiminate Ligands: A Synthetic, Spectroscopic, and Computational Investigation. Inorg Chem 2018; 57:5959-5972. [DOI: 10.1021/acs.inorgchem.8b00468] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Simon J. Bonyhady
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Daniel E. DeRosha
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Javier Vela
- Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, New York 14627, United States
| | - David J. Vinyard
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Ryan E. Cowley
- Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, New York 14627, United States
| | - Brandon Q. Mercado
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - William W. Brennessel
- Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, New York 14627, United States
| | - Patrick L. Holland
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
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37
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van Leest NP, Epping RF, van Vliet KM, Lankelma M, van den Heuvel EJ, Heijtbrink N, Broersen R, de Bruin B. Single-Electron Elementary Steps in Homogeneous Organometallic Catalysis. ADVANCES IN ORGANOMETALLIC CHEMISTRY 2018. [DOI: 10.1016/bs.adomc.2018.07.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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38
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Lin Z, Thacker NC, Sawano T, Drake T, Ji P, Lan G, Cao L, Liu S, Wang C, Lin W. Metal-organic layers stabilize earth-abundant metal-terpyridine diradical complexes for catalytic C-H activation. Chem Sci 2017; 9:143-151. [PMID: 29629082 PMCID: PMC5869321 DOI: 10.1039/c7sc03537c] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Accepted: 10/30/2017] [Indexed: 12/03/2022] Open
Abstract
Metal–organic layers stabilize FeII or CoII-terpyridine diradical complexes to catalyze alkylazide Csp3–H amination and benzylic C–H borylation, respectively.
We report the synthesis of a terpyridine-based metal–organic layer (TPY-MOL) and its metalation with CoCl2 and FeBr2 to afford CoCl2·TPY-MOL and FeBr2·TPY-MOL, respectively. Upon activation with NaEt3BH, CoCl2·TPY-MOL catalyzed benzylic C–H borylation of methylarenes whereas FeBr2·TPY-MOL catalyzed intramolecular Csp3–H amination of alkyl azides to afford pyrrolidines and piperidines. X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), X-ray photoelectron spectroscopy, UV-Vis-NIR spectroscopy, and electron paramagnetic spectroscopy (EPR) measurements as well as density functional theory (DFT) calculations identified M(THF)2·TPY-MOL (M = Co or Fe) as the active catalyst with a MII-(TPY˙˙)2– electronic structure featuring divalent metals and TPY diradical dianions. We believe that site isolation stabilizes novel MII-(TPY˙˙)2– (M = Co or Fe) species in the MOLs to endow them with unique and enhanced catalytic activities for Csp3–H borylation and intramolecular amination over their homogeneous counterparts. The MOL catalysts are also superior to their metal–organic framework analogs owing to the removal of diffusion barriers. Our work highlights the potential of MOLs as a novel 2D molecular material platform for designing single-site solid catalysts without diffusional constraints.
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Affiliation(s)
- Zekai Lin
- Department of Chemistry , University of Chicago , 929 E. 57th St. , Chicago , Illinois 60637 , USA .
| | - Nathan C Thacker
- Department of Chemistry , University of Chicago , 929 E. 57th St. , Chicago , Illinois 60637 , USA .
| | - Takahiro Sawano
- Department of Chemistry , University of Chicago , 929 E. 57th St. , Chicago , Illinois 60637 , USA .
| | - Tasha Drake
- Department of Chemistry , University of Chicago , 929 E. 57th St. , Chicago , Illinois 60637 , USA .
| | - Pengfei Ji
- Department of Chemistry , University of Chicago , 929 E. 57th St. , Chicago , Illinois 60637 , USA .
| | - Guangxu Lan
- Department of Chemistry , University of Chicago , 929 E. 57th St. , Chicago , Illinois 60637 , USA .
| | - Lingyun Cao
- Collaborative Innovation Center of Chemistry for Energy Materials , State Key Laboratory of Physical Chemistry of Solid Surfaces , Department of Chemistry , College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , PR China
| | - Shubin Liu
- Research Computing Center , University of North Carolina , Chapel Hill , North Carolina 27599-3420 , USA
| | - Cheng Wang
- Collaborative Innovation Center of Chemistry for Energy Materials , State Key Laboratory of Physical Chemistry of Solid Surfaces , Department of Chemistry , College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , PR China
| | - Wenbin Lin
- Department of Chemistry , University of Chicago , 929 E. 57th St. , Chicago , Illinois 60637 , USA . .,Collaborative Innovation Center of Chemistry for Energy Materials , State Key Laboratory of Physical Chemistry of Solid Surfaces , Department of Chemistry , College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 361005 , PR China
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39
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Maity AK, Murillo J, Metta-Magaña AJ, Pinter B, Fortier S. A Terminal Iron(IV) Nitride Supported by a Super Bulky Guanidinate Ligand and Examination of Its Electronic Structure and Reactivity. J Am Chem Soc 2017; 139:15691-15700. [PMID: 28953380 DOI: 10.1021/jacs.7b06919] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Utilizing the bulky guanidinate ligand [LAr*]- (LAr* = (Ar*N)2C(R), Ar* = 2,6-bis(diphenylmethyl)-4-tert-butylphenyl, R = NCtBu2) for kinetic stabilization, the synthesis of a rare terminal Fe(IV) nitride complex is reported. UV irradiation of a pyridine solution of the Fe(II) azide [LAr*]FeN3(py) (3-py) at 0 °C cleanly generates the Fe(IV) nitride [LAr*]FeN(py) (1). The 15N NMR spectrum of the 115N (50% Fe≡15N) isotopomer shows a resonance at 1016 ppm (vs externally referenced CH3NO2 at 380 ppm), comparable to that known for other terminal iron nitrides. Notably, the computed structure of 1 reveals an iron center with distorted tetrahedral geometry, τ4 = 0.72, featuring a short Fe≡N bond (1.52 Å). Inspection of the frontier orbital ordering of 1 shows a relatively small HOMO/LUMO gap with the LUMO comprised by Fe(dxz,yz)N(px,y) π*-orbitals, a splitting that is manifested in the electronic absorption spectrum of 1 (λ = 610 nm, ε = 1375 L·mol-1·cm-1; λ = 613 nm (calcd)). Complex 1 persists in low-temperature solutions of pyridine but becomes unstable at room temperature, gradually converting to the Fe(II) hydrazide product [κ2-(tBu2CN)C(η6-NAr*)(N-NAr*)]Fe (4) upon standing via intramolecular N-atom insertion. This reactivity of the Fe≡N moiety was assessed through molecular orbital analysis, which suggests electrophilic character at the nitride functionality. Accordingly, treatment of 1 with the nucleophiles PMe2Ph and Ar-N≡C (Ar = 2,6-dimethylphenyl) leads to partial N-atom transfer and formation of the Fe(II) addition products [LAr*]Fe(N═PMe2Ph)(py) (5) and [LAr*]Fe(N═C═NAr)(py) (6). Similarly, 1 reacts with PhSiH3 to give [LAr*]Fe[N(H)(SiH2Ph)](py) (7) which Fukui analysis shows to proceed via electrophilic insertion of the nitride into the Si-H bond.
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Affiliation(s)
- Arnab K Maity
- Department of Chemistry, University of Texas at El Paso , El Paso, Texas 79968, United States
| | - Jesse Murillo
- Department of Chemistry, University of Texas at El Paso , El Paso, Texas 79968, United States
| | | | - Balazs Pinter
- Computational OrganoMetallic and Inorganic Chemistry Group, Eenheid Algemene Chemie, Vrije Universiteit Brussel , Pleinlaan 2, Brussels 1050, Belgium
| | - Skye Fortier
- Department of Chemistry, University of Texas at El Paso , El Paso, Texas 79968, United States
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40
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Wilding MJT, Iovan DA, Wrobel AT, Lukens JT, MacMillan SN, Lancaster KM, Betley TA. Direct Comparison of C-H Bond Amination Efficacy through Manipulation of Nitrogen-Valence Centered Redox: Imido versus Iminyl. J Am Chem Soc 2017; 139:14757-14766. [PMID: 28937756 PMCID: PMC5821126 DOI: 10.1021/jacs.7b08714] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reduction of previously reported iminyl radical (ArL)FeCl(•N(C6H4-p-tBu)) (2) with potassium graphite furnished the corresponding high-spin (S = 5/2) imido (ArL)Fe(N(C6H4-p-tBu)) (3) (ArL = 5-mesityl-1,9-(2,4,6-Ph3C6H2)dipyrrin). Oxidation of the three-coordinate imido (ArL)Fe(NAd) (5) with chlorotriphenylmethane afforded (ArL)FeCl(•NAd) (6) with concomitant expulsion of Ph3C(C6H5)CPh2. The respective aryl/alkyl imido/iminyl pairs (3, 2; 5, 6) have been characterized by EPR, zero-field 57Fe Mössbauer, magnetometry, single crystal X-ray diffraction, XAS, and EXAFS for 6. The high-spin (S = 5/2) imidos exhibit characteristically short Fe-N bonds (3: 1.708(4) Å; 5: 1.674(11) Å), whereas the corresponding iminyls exhibit elongated Fe-N bonds (2: 1.768(2) Å; 6: 1.761(6) Å). Comparison of the pre-edge absorption feature (1s → 3d) in the X-ray absorption spectra reveals that the four imido/iminyl complexes share a common iron oxidation level consistent with a ferric formulation (3: 7111.5 eV, 2: 7111.5 eV; 5: 7112.2 eV, 6: 7112.4 eV) as compared with a ferrous amine adduct (ArL)FeCl(NH2Ad) (7: 7110.3 eV). N K-edge X-ray absorption spectra reveal a common low-energy absorption present only for the iminyl species 2 (394.5 eV) and 6 (394.8 eV) that was assigned as a N 1s promotion into a N-localized, singly occupied iminyl orbital. Kinetic analysis of the reaction between the respective iron imido and iminyl complexes with toluene yielded the following activation parameters: Ea (kcal/mol) 3: 12.1, 2: 9.2; 5: 11.5, 6: 7.1. The attenuation of the Fe-N bond interaction on oxidation from an imido to an iminyl complex leads to a reduced enthalpic barrier [Δ(ΔH‡) ≈ 5 kcal/mol]; the alkyl iminyl 6 has a reduced enthalpic barrier (1.84 kcal/mol) as compared with the aryl iminyl 2 (3.84 kcal/mol), consistent with iminyl radical delocalization into the aryl substituent in 2 as compared with 6.
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Affiliation(s)
- Matthew J. T. Wilding
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Diana A. Iovan
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Alexandra T. Wrobel
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - James T. Lukens
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Samantha N. MacMillan
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Kyle M. Lancaster
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, 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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41
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Wilding MJT, Iovan DA, Betley TA. High-Spin Iron Imido Complexes Competent for C-H Bond Amination. J Am Chem Soc 2017; 139:12043-12049. [PMID: 28777558 PMCID: PMC5821117 DOI: 10.1021/jacs.7b06682] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Reduction of previously reported (ArL)FeCl with potassium graphite furnished a low-spin (S = 1/2) iron complex (ArL)Fe which features an intramolecular η6-arene interaction and can be utilized as an FeI synthon (ArL = 5-mesityl-1,9-(2,4,6-Ph3C6H2)dipyrrin). Treatment of (ArL)Fe with adamantyl azide or mesityl azide led to the formation of the high-spin (S = 5/2), three-coordinate imidos (ArL)Fe(NAd) and (ArL)Fe(NMes), respectively, as determined by EPR, zero-field 57Fe Mössbauer, magnetometry, and single crystal X-ray diffraction. The high-spin iron imidos are reactive with a variety of substrates: (ArL)Fe(NAd) reacts with azide yielding a ferrous tetrazido (ArL)Fe(κ2-N4Ad2), undergoes intermolecular nitrene transfer to phosphine, abstracts H atoms from weak C-H bonds (1,4-cyclohexadiene, 2,4,6-tBu3C6H2OH) to afford ferrous amido product (ArL)Fe(NHAd), and can mediate intermolecular C-H amination of toluene [PhCH3/PhCD3 kH/kD: 15.5(3); PhCH2D kH/kD: 11(1)]. The C-H bond functionalization reactivity is rationalized from a two-step mechanism wherein each step occurs via maximal energy and orbital overlap between the imido fragment and the C-H bond containing substrate.
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Affiliation(s)
- Matthew J. T. Wilding
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Diana A. Iovan
- 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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42
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Jacobs BP, Wolczanski PT, Jiang Q, Cundari TR, MacMillan SN. Rare Examples of Fe(IV) Alkyl-Imide Migratory Insertions: Impact of Fe-C Covalency in (Me 2IPr)Fe(═NAd)R 2 (R = neoPe, 1-nor). J Am Chem Soc 2017; 139:12145-12148. [PMID: 28796945 DOI: 10.1021/jacs.7b06960] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The iron(IV) imide complexes, (Me2IPr)-R2Fe=NAd (R = neoPe (3a), 1-nor (3b)) undergo migratory insertion to iron(II) amides (Me2IPr)RFe{NR(Ad)} (R = neoPe (4a), 1-nor (4b)) without evidence of imidyl or free nitrene character. By increasing the field strength about iron, odd-electron reactivity was circumvented via increased covalency.
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Affiliation(s)
- Brian P Jacobs
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University , Ithaca, New York 14853, United States
| | - Peter T Wolczanski
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University , Ithaca, New York 14853, United States
| | - Quan Jiang
- Department of Chemistry, CASCaM, University of North Texas , Denton, Texas 76201, United States
| | - Thomas R Cundari
- Department of Chemistry, CASCaM, University of North Texas , Denton, Texas 76201, United States
| | - Samantha N MacMillan
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University , Ithaca, New York 14853, United States
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43
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Reiners M, Maekawa M, Daniliuc CG, Freytag M, Jones PG, White PS, Hohenberger J, Sutter J, Meyer K, Maron L, Walter MD. Reactivity studies on [Cp'Fe(μ-I)] 2: nitrido-, sulfido- and diselenide iron complexes derived from pseudohalide activation. Chem Sci 2017; 8:4108-4122. [PMID: 30155215 PMCID: PMC6099922 DOI: 10.1039/c7sc00570a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/29/2017] [Indexed: 11/21/2022] Open
Abstract
Facile pseudohalide activation occurs in the reaction of SCN–, SeCN– and N3– with the iron half-sandwich [Cp′Fe(μ-I)]2.
The iron half-sandwich [Cp′Fe(μ-I)]2 (Cp′ = 1,2,4-(Me3C)3C5H2, 1) reacts with the pseudohalides NCO–, SCN–, SeCN– and N3– to give [Cp′Fe(μ-NCO)]2 (2), [Cp′Fe(μ-S)]2 (3), [Cp′Fe(μ-Se2)]2 (4) and [Cp′Fe(μ-N)]2 (5), respectively. Various spectroscopic techniques including X-ray diffraction, solid-state magnetic susceptibility studies and 57Fe Mössbauer spectroscopy were employed in the characterization of these species. Mössbauer spectroscopy shows a decreasing isomer shift with increasing formal oxidation state, ranging from Fe(ii) to Fe(iv), in complexes 1 to 5. The sulfido-bridged dimer 3 exhibits strong antiferromagnetic coupling between the Fe(iii) centers. This leads to temperature-independent paramagnetism (TIP) at low temperature, from which the energy gap between the ground and the excited state can be estimated to be 2J = ca. 700 cm–1. The iron(iv) nitrido complex [Cp′Fe(μ-N)]2 (5) shows no reactivity towards H2 (10 atm), but undergoes clean reactions with CO (5 bar) and XylNC (Xyl = 2,6-Me2C6H3) to form the diamagnetic isocyanate and carbodiimide complexes [Cp′Fe(CO)2(NCO)] (7) and [Cp′Fe(CNXyl)2(NCNXyl)] (8), respectively. All compounds were fully characterized, and density functional theory (DFT) computations provide useful insights into their formation and the electronic structures of complexes 3 and 5.
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Affiliation(s)
- Matthias Reiners
- Technische Universität Braunschweig , Institut für Anorganische und Analytische Chemie , Hagenring 30 , 38106 Braunschweig , Germany .
| | - Miyuki Maekawa
- Technische Universität Braunschweig , Institut für Anorganische und Analytische Chemie , Hagenring 30 , 38106 Braunschweig , Germany .
| | - Constantin G Daniliuc
- Technische Universität Braunschweig , Institut für Anorganische und Analytische Chemie , Hagenring 30 , 38106 Braunschweig , Germany .
| | - Matthias Freytag
- Technische Universität Braunschweig , Institut für Anorganische und Analytische Chemie , Hagenring 30 , 38106 Braunschweig , Germany .
| | - Peter G Jones
- Technische Universität Braunschweig , Institut für Anorganische und Analytische Chemie , Hagenring 30 , 38106 Braunschweig , Germany .
| | - Peter S White
- University of North Carolina at Chapel Hill , Department of Chemistry , Chapel Hill , North Carolina 27599-3290 , USA
| | - Johannes Hohenberger
- University of Erlangen-Nürnberg , Department of Chemistry & Pharmacy , Inorganic Chemistry , Egerlandstr. 1 , 91058 Erlangen , Germany
| | - Jörg Sutter
- University of Erlangen-Nürnberg , Department of Chemistry & Pharmacy , Inorganic Chemistry , Egerlandstr. 1 , 91058 Erlangen , Germany
| | - Karsten Meyer
- University of Erlangen-Nürnberg , Department of Chemistry & Pharmacy , Inorganic Chemistry , Egerlandstr. 1 , 91058 Erlangen , Germany
| | - Laurent Maron
- Université de Toulouse , INSA-UPS-LPCNO , CNRS-LPCNO , 135 Avenue de Rangueil , F-31077 Toulouse , France .
| | - Marc D Walter
- Technische Universität Braunschweig , Institut für Anorganische und Analytische Chemie , Hagenring 30 , 38106 Braunschweig , Germany .
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44
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Bucinsky L, Breza M, Lee WT, Hickey AK, Dickie DA, Nieto I, DeGayner JA, Harris TD, Meyer K, Krzystek J, Ozarowski A, Nehrkorn J, Schnegg A, Holldack K, Herber RH, Telser J, Smith JM. Spectroscopic and Computational Studies of Spin States of Iron(IV) Nitrido and Imido Complexes. Inorg Chem 2017; 56:4752-4769. [PMID: 28379707 DOI: 10.1021/acs.inorgchem.7b00512] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
High-oxidation-state metal complexes with multiply bonded ligands are of great interest for both their reactivity as well as their fundamental bonding properties. This paper reports a combined spectroscopic and theoretical investigation into the effect of the apical multiply bonded ligand on the spin-state preferences of threefold symmetric iron(IV) complexes with tris(carbene) donor ligands. Specifically, singlet (S = 0) nitrido [{PhB(ImR)3}FeN], R = tBu (1), Mes (mesityl, 2) and the related triplet (S = 1) imido complexes, [{PhB(ImR)3}Fe(NR')]+, R = Mes, R' = 1-adamantyl (3), tBu (4), were investigated by electronic absorption and Mössbauer effect spectroscopies. For comparison, two other Fe(IV) nitrido complexes, [(TIMENAr)FeN]+ (TIMENAr = tris[2-(3-aryl-imidazol-2-ylidene)ethyl]amine; Ar = Xyl (xylyl), Mes), were investigated by 57Fe Mössbauer spectroscopy, including applied-field measurements. The paramagnetic imido complexes 3 and 4 were also studied by magnetic susceptibility measurements (for 3) and paramagnetic resonance spectroscopy: high-frequency and -field electron paramagnetic resonance (for 3 and 4) and frequency-domain Fourier-transform (FD-FT) terahertz electron paramagnetic resonance (for 3), which reveal their zero-field splitting parameters. Experimentally correlated theoretical studies comprising ligand-field theory and quantum chemical theory, the latter including both density functional theory and ab initio methods, reveal the key role played by the Fe 3dz2 (a1) orbital in these systems: the nature of its interaction with the nitrido or imido ligand dictates the spin-state preference of the complex. The ability to tune the spin state through the energy and nature of a single orbital has general relevance to the factors controlling spin states in complexes with applicability as single molecule devices.
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Affiliation(s)
- Lukas Bucinsky
- Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology , Radlinského 9, SK-81237 Bratislava, Slovakia
| | - Martin Breza
- Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology , Radlinského 9, SK-81237 Bratislava, Slovakia
| | - Wei-Tsung Lee
- Department of Chemistry, Indiana University , 800 E. Kirkwood Avenue, Bloomington, Indiana 47401, United States.,Department of Chemistry and Biochemistry, New Mexico State University , Las Cruces, New Mexico 88003, United States
| | - Anne K Hickey
- Department of Chemistry, Indiana University , 800 E. Kirkwood Avenue, Bloomington, Indiana 47401, United States
| | - Diane A Dickie
- Department of Chemistry and Chemical Biology, The University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Ismael Nieto
- Department of Chemistry and Biochemistry, New Mexico State University , Las Cruces, New Mexico 88003, United States
| | - Jordan A DeGayner
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - T David Harris
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Karsten Meyer
- Department of Chemistry and Pharmacy, Friedrich-Alexander-University Erlangen-Nürnberg , Egerlandstraße 1, D-91058 Erlangen, Germany
| | - J Krzystek
- National High Magnetic Field Laboratory, Florida State University , Tallahassee, Florida 32310, United States
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory, Florida State University , Tallahassee, Florida 32310, United States
| | - Joscha Nehrkorn
- Department of Chemistry, University of Washington , Seattle, Washington 98195, United States
| | | | | | - Rolfe H Herber
- Racah Institute of Physics, The Hebrew University of Jerusalem , 91904 Jerusalem, Israel
| | - Joshua Telser
- Department of Biological, Chemical and Physical Sciences, Roosevelt University , Chicago, Illinois 60605, United States
| | - Jeremy M Smith
- Department of Chemistry, Indiana University , 800 E. Kirkwood Avenue, Bloomington, Indiana 47401, United States.,Department of Chemistry and Biochemistry, New Mexico State University , Las Cruces, New Mexico 88003, United States
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45
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Reesbeck ME, Grubel K, Kim D, Brennessel WW, Mercado BQ, Holland PL. Diazoalkanes in Low-Coordinate Iron Chemistry: Bimetallic Diazoalkyl and Alkylidene Complexes of Iron(II). Inorg Chem 2017; 56:1019-1022. [PMID: 28067506 DOI: 10.1021/acs.inorgchem.6b01952] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The addition of (trimethylsilyl)diazomethane and its conjugate base to iron β-diketiminate precursors gives novel dinuclear complexes in which the bridges are either diazomethane derivatives or an alkylidene. One product is an unusual bridging alkylidene complex containing two three-coordinate iron(II) centers. On the other hand, syntheses using the deprotonated diazomethane give two bridging diazomethyl species with binding modes that have not been observed in iron complexes previously. In the presence of a coordinating tetrahydrofuran solvent, a diiron(II) compound with μ-N bridges rearranges to a more stable isomer with μ-N,C bridges, a process that is accompanied by a 1,3-shift of a silyl group.
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Affiliation(s)
- Megan E Reesbeck
- Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Katarzyna Grubel
- Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Daniel Kim
- Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - William W Brennessel
- Department of Chemistry, University of Rochester , 120 Trustee Road, Rochester, New York 14627, United States
| | - Brandon Q Mercado
- Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Patrick L Holland
- Department of Chemistry, Yale University , 225 Prospect Street, New Haven, Connecticut 06520, United States
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46
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Determining and Understanding N-H Bond Strengths in Synthetic Nitrogen Fixation Cycles. TOP ORGANOMETAL CHEM 2017. [DOI: 10.1007/3418_2016_8] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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47
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Pearce AJ, Cassabaum AA, Gast GE, Frontiera RR, Tonks IA. Redox Non-Innocent Behavior of a Terminal Iridium Hydrazido(2−) Triple Bond. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201607648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Adam J. Pearce
- Department of Chemistry; University of Minnesota-Twin Cities; 207 Pleasant St SE Minneapolis MN 55455 USA
| | - Alyssa A. Cassabaum
- Department of Chemistry; University of Minnesota-Twin Cities; 207 Pleasant St SE Minneapolis MN 55455 USA
| | - Grace E. Gast
- Department of Chemistry; University of Minnesota-Twin Cities; 207 Pleasant St SE Minneapolis MN 55455 USA
| | - Renee R. Frontiera
- Department of Chemistry; University of Minnesota-Twin Cities; 207 Pleasant St SE Minneapolis MN 55455 USA
| | - Ian A. Tonks
- Department of Chemistry; University of Minnesota-Twin Cities; 207 Pleasant St SE Minneapolis MN 55455 USA
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48
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Pearce AJ, Cassabaum AA, Gast GE, Frontiera RR, Tonks IA. Redox Non-Innocent Behavior of a Terminal Iridium Hydrazido(2-) Triple Bond. Angew Chem Int Ed Engl 2016; 55:13169-13173. [PMID: 27654844 PMCID: PMC5392362 DOI: 10.1002/anie.201607648] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Indexed: 11/08/2022]
Abstract
The synthesis of the first terminal Group 9 hydrazido(2-) complex, Cp*IrN(TMP) (6) (TMP=2,2,6,6-tetramethylpiperidine) is reported. Electronic structure and X-ray diffraction analysis indicate that this complex contains an Ir-N triple bond, similar to Bergman's seminal Cp*Ir(Nt Bu) imido complex. However, in sharp contrast to Bergman's imido, 6 displays remarkable redox non-innocent reactivity owing to the presence of the Nβ lone pair. Treatment of 6 with MeI results in electron transfer from Nβ to Ir prior to oxidative addition of MeI to the iridium center. This behavior opens the possibility of carrying out facile oxidative reactions at a formally IrIII metal center through a hydrazido(2-)/isodiazene valence tautomerization.
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Affiliation(s)
- Adam J Pearce
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant St SE, Minneapolis, MN, 55455, USA
| | - Alyssa A Cassabaum
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant St SE, Minneapolis, MN, 55455, USA
| | - Grace E Gast
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant St SE, Minneapolis, MN, 55455, USA
| | - Renee R Frontiera
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant St SE, Minneapolis, MN, 55455, USA
| | - Ian A Tonks
- Department of Chemistry, University of Minnesota-Twin Cities, 207 Pleasant St SE, Minneapolis, MN, 55455, USA.
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49
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Pappas I, Chirik PJ. Catalytic Proton Coupled Electron Transfer from Metal Hydrides to Titanocene Amides, Hydrazides and Imides: Determination of Thermodynamic Parameters Relevant to Nitrogen Fixation. J Am Chem Soc 2016; 138:13379-13389. [DOI: 10.1021/jacs.6b08009] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Iraklis Pappas
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Paul J. Chirik
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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50
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Cundari TR. Methane Manifesto: A Theorist’s Perspective on Catalytic Light Alkane Functionalization. COMMENT INORG CHEM 2016. [DOI: 10.1080/02603594.2016.1242487] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Thomas R. Cundari
- Department of Chemistry, University of North Texas, Denton, Texas, USA
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