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Werncke CG, Müller I, Weißer K, Limberg C. Divergent Interaction of (Iso)nitriles with a Linear Iron(I) Silylamide─A Combined Structural, Spectroscopic, and Computational Study. Inorg Chem 2024. [PMID: 39066707 DOI: 10.1021/acs.inorgchem.4c02882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Nitriles and isonitriles are important σ-donor ligands in coordination chemistry. Isonitriles also function in low-valent complexes as π-acceptor ligands similar to CO. Herein we present the unusual behavior of the highly reducing, high-spin iron(I) complex [Fe(hmds)2]- toward these compound classes. Rare examples of side-on coordination of nitriles to the metal center are observed. Insights gained by 57Fe Mössbauer spectroscopy as well as DFT and CASSCF calculations give an interplay between the resonance structures of not only an iron(I) π-complex and an iron(III) metallacycle but also point to the importance of an iron(II) nitrile radical anion. For an aromatic isonitrile end-on coordination is observed, which is best described as an iron(I) complex with only minor unpaired spin transfer onto the isonitrile. For aliphatic isonitriles, the selective R-CN bond cleavage occurs and yields stoichiometric mixtures of alkyl iron(II) and cyanido iron(II) complexes. Attempts to isolate presumed (iso)nitrile radical anions void of 3d-metal coordination give for the reaction of an aromatic isonitrile with KC8 facile reductive coupling to the corresponding diamido acetylene.
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Affiliation(s)
- C Gunnar Werncke
- Chemistry Department, Philipps-University Marburg, Hans-Meerwein-Straße 4, D-35043 Marburg, Germany
| | - Igor Müller
- Chemistry Department, Philipps-University Marburg, Hans-Meerwein-Straße 4, D-35043 Marburg, Germany
| | - Kilian Weißer
- Institute of Chemistry, Humboldt-University Berlin, Brook-Taylor-Str. 2, D-13089 Berlin, Germany
| | - Christian Limberg
- Institute of Chemistry, Humboldt-University Berlin, Brook-Taylor-Str. 2, D-13089 Berlin, Germany
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2
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Brown AC, Suess DLM. Valence Localization in Alkyne and Alkene Adducts of Synthetic [Fe 4S 4] + Clusters. Inorg Chem 2023; 62:1911-1918. [PMID: 35704768 PMCID: PMC9751231 DOI: 10.1021/acs.inorgchem.2c01353] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Reported herein are alkyne and alkene adducts of synthetic [Fe4S4]+ clusters that model intermediates and inhibitor-bound states in enzymes involved in isoprenoid biosynthesis. Treatment of the N-heterocyclic carbene-ligated cluster [(IMes)3Fe4S4(OEt2)][BArF4] (IMes = 1,3-dimesitylimidazol-2-ylidene; [BArF4]- = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) with phenylacetylene (PhCCH) or cis-cyclooctene (COE) results in displacement of the Et2O ligand to yield the corresponding π complexes, [(IMes)3Fe4S4(PhCCH)][BArF4] and [(IMes)3Fe4S4(COE)][BArF4]. EPR spectroscopic analysis demonstrates that both clusters are doublets with giso > 2 and thus are spectroscopically faithful models of the analogous species characterized in the isoprenoid biosynthetic enzymes IspG and IspH. Structural and Mössbauer spectroscopic analysis reveals that both complexes are best described as [Fe4S4]+ clusters in which the unique Fe site engages in modest back-bonding to the π-acidic ligand. Paramagnetic NMR studies show that, even at room temperature, the alkyne/alkene-bound Fe centers harbor minority spin and therefore adopt an Fe2+ valence. We propose that such valence localization could likewise occur in Fe-S enzymes that interact with π-acidic molecules.
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3
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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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4
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Weller R, Müller I, Werncke CG. Catalytic 1,3‐H Atom Shift of a Terminal Benzylic Alkyne by Iron and Alkali Metal Silylamides – Switching between Allene and Internal Alkyne. Eur J Inorg Chem 2022. [DOI: 10.1002/ejic.202100955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Ruth Weller
- Department of Chemistry Philipps-University Marburg Hans-Meerwein-Straße 4 D-35032 Marburg Germany
| | - Igor Müller
- Department of Chemistry Philipps-University Marburg Hans-Meerwein-Straße 4 D-35032 Marburg Germany
| | - C. Gunnar Werncke
- Department of Chemistry Philipps-University Marburg Hans-Meerwein-Straße 4 D-35032 Marburg Germany
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5
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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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6
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Tarrago M, Römelt C, Nehrkorn J, Schnegg A, Neese F, Bill E, Ye S. Experimental and Theoretical Evidence for an Unusual Almost Triply Degenerate Electronic Ground State of Ferrous Tetraphenylporphyrin. Inorg Chem 2021; 60:4966-4985. [PMID: 33739093 DOI: 10.1021/acs.inorgchem.1c00031] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Iron porphyrins exhibit unrivalled catalytic activity for electrochemical CO2-to-CO conversion. Despite intensive experimental and computational studies in the last 4 decades, the exact nature of the prototypical square-planar [FeII(TPP)] complex (1; TPP2- = tetraphenylporphyrinate dianion) remained highly debated. Specifically, its intermediate-spin (S = 1) ground state was contradictorily assigned to either a nondegenerate 3A2g state with a (dxy)2(dz2)2(dxz,yz)2 configuration or a degenerate 3Egθ state with a (dxy)2(dxz,yz)3(dz2)1/(dz2)2(dxy)1(dxz,yz)3 configuration. To address this question, we present herein a comprehensive, spectroscopy-based theoretical and experimental electronic-structure investigation on complex 1. Highly correlated wave-function-based computations predicted that 3A2g and 3Egθ are well-isolated from other triplet states by ca. 4000 cm-1, whereas their splitting ΔA-E is on par with the effective spin-orbit coupling (SOC) constant of iron(II) (≈400 cm-1). Therfore, we invoked an effective Hamiltonian (EH) operating on the nine magnetic sublevels arising from SOC between the 3A2g and 3Egθ states. This approach enabled us to successfully simulate all spectroscopic data of 1 obtained by variable-temperature and variable-field magnetization, applied-field 57Fe Mössbauer, and terahertz electron paramagnetic resonance measurements. Remarkably, the EH contains only three adjustable parameters, namely, the energy gap without SOC, ΔA-E, an angle θ that describes the mixing of (dxy)2(dxz,yz)3(dz2)1 and (dz2)2(dxy)1(dxz,yz)3 configurations, and the ⟨rd-3⟩ expectation value of the iron d orbitals that is necessary to estimate the 57Fe magnetic hyperfine coupling tensor. The EH simulations revealed that the triplet ground state of 1 is genuinely multiconfigurational with substantial parentages of both 3A2g (<88%) and 3Eg (>12%), owing to their accidental near-triple degeneracy with ΔA-E = +950 cm-1. As a consequence of this peculiar electronic structure, 1 exhibits a huge effective magnetic moment (4.2 μB at 300 K), large temperature-independent paramagnetism, a large and positive axial zero-field splitting, strong easy-plane magnetization (g⊥ ≈ 3 and g∥ ≈ 1.7) and a large and positive internal field at the 57Fe nucleus aligned in the xy plane. Further in-depth analyses suggested that g⊥ ≫ g∥ is a general spectroscopic signature of near-triple orbital degeneracy with more than half-filled pseudodegenerate orbital sets. Implications of the unusual electronic structure of 1 for CO2 reduction are discussed.
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Affiliation(s)
- Maxime Tarrago
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - Christina Römelt
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Joscha Nehrkorn
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Alexander Schnegg
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Shengfa Ye
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany.,State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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7
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Ott JC, Wadepohl H, Gade LH. Metalloradical Reactivity, Charge Transfer, and Atom Abstractions in a T-Shaped Iron(I) Complex. Inorg Chem 2021; 60:3927-3938. [DOI: 10.1021/acs.inorgchem.0c03724] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Jonas C. Ott
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 276, 69120 Heidelberg, Germany
| | - Hubert Wadepohl
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 276, 69120 Heidelberg, Germany
| | - Lutz H. Gade
- Anorganisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 276, 69120 Heidelberg, Germany
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8
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In-beam Mössbauer spectra of 57Mn implanted into lithium aluminum hydride. Appl Radiat Isot 2021; 170:109582. [PMID: 33561749 DOI: 10.1016/j.apradiso.2020.109582] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 12/25/2020] [Accepted: 12/30/2020] [Indexed: 11/22/2022]
Abstract
In-beam Mössbauer spectra of 57Mn implanted into LiAlH4 were measured at different temperatures between 17 and 300 K. The Mössbauer spectrum measured at 17 K showed two sets of doublets, which were assigned to 57Fe atoms at substitutional sites at Al3+ and Li+ sites. The Debye temperatures θM for the 57Fe atoms at Al3+-substituted and Li+-substituted sites were estimated to be 194 K and 117 K, respectively. The assignments were confirmed by density functional theory calculations.
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9
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Isolation and electronic structures of derivatized manganocene, ferrocene and cobaltocene anions. Nat Chem 2020; 13:243-248. [PMID: 33318673 PMCID: PMC7610420 DOI: 10.1038/s41557-020-00595-w] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 10/27/2020] [Indexed: 11/08/2022]
Abstract
The discovery of ferrocene nearly 70 years ago marked the genesis of metallocene chemistry. Although the ferrocenium cation was discovered soon afterwards, a derivatized ferrocenium dication was only isolated in 2016 and the monoanion of ferrocene has only been observed in low-temperature electrochemical studies. Here we report the isolation of a derivatized ferrocene anion in the solid state as part of an isostructural family of 3d metallocenates, which consist of anionic complexes of a metal centre (manganese, iron or cobalt) sandwiched between two bulky Cpttt ligands (where Cpttt is {1,2,4-C5H2 tBu3}). These thermally and air-sensitive complexes decompose rapidly above -30 °C; however, we were able to characterize all metallocenates by a wide range of physical techniques and ab initio calculations. These data have allowed us to map the electronic structures of this metallocenate family, including an unexpected high-spin S = 3/2 ground state for the 19e- derivatized ferrocene anion.
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10
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Saber MR, Przyojski JA, Tonzetich ZJ, Dunbar KR. Slow magnetic relaxation in cobalt N-heterocyclic carbene complexes. Dalton Trans 2020; 49:11577-11582. [PMID: 32749418 DOI: 10.1039/d0dt02286a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The combined experimental and theoretical investigation of the magnetic properties of the cobalt(ii) NHC complexes (NHC = N-heterocyclic carbene); [Co(CH2SiMe3)2(IPr)] (1), [CoCl2(IMes)2] (2) and [Co(CH3)2(IMes)2] (3) revealed a large easy plane anisotropy for 1 (D = +73.7 cm-1) and a moderate easy axis anisotropy for 2 (D = -7.7 cm-1) due to significant out-of-state spin-orbit coupling. Dynamic magnetic measurements revealed slow relaxation of the magnetization for 1 (Ueff = 22.5 K, τ0 = 3 × 10-7 s, 1000 Oe) and for 2 (Ueff = 20.2 K, τ0 = 1.73 × 10-8 s, 1500 Oe). The molecular origin of the slow relaxation phenomena was further supported by the retention of AC signal in 10% solutions in 2-MeTHF which reveals a second zero field AC signal in 1 at higher frequencies. Compound 3 was found to be an S = 1/2 system.
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Affiliation(s)
- Mohamed R Saber
- Department of Chemistry, Texas A&M University, College Station, TX 77842-3012, USA. and Chemistry Department, Faculty of Science, Fayoum University, Fayoum 63514, Egypt
| | - Jacob A Przyojski
- Department of Chemistry, University of Texas at San Antonio (UTSA), San Antonio, TX 78249, USA
| | - Zachary J Tonzetich
- Department of Chemistry, University of Texas at San Antonio (UTSA), San Antonio, TX 78249, USA
| | - Kim R Dunbar
- Department of Chemistry, Texas A&M University, College Station, TX 77842-3012, USA.
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11
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Neumeier M, Chakraborty U, Schaarschmidt D, de la Pena O'Shea V, Perez‐Ruiz R, Jacobi von Wangelin A. Combined Photoredox and Iron Catalysis for the Cyclotrimerization of Alkynes. Angew Chem Int Ed Engl 2020; 59:13473-13478. [PMID: 32190960 PMCID: PMC7496134 DOI: 10.1002/anie.202000907] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Indexed: 11/11/2022]
Abstract
Successful combinations of visible-light photocatalysis with metal catalysis have recently enabled the development of hitherto unknown chemical reactions. Dual mechanisms from merging metal-free photocatalysts and earth-abundant metal catalysts are still in their infancy. We report a photo-organo-iron-catalyzed cyclotrimerization of alkynes by photoredox activation of a ligand-free Fe catalyst. The reaction operates under very mild conditions (visible light, 20 °C, 1 h) with 1-2 mol % loading of the three catalysts (dye, amine, FeCl2 ).
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Affiliation(s)
- Michael Neumeier
- Department of ChemistryUniversity of HamburgMartin Luther King Pl 620146HamburgGermany
| | - Uttam Chakraborty
- Department of ChemistryUniversity of HamburgMartin Luther King Pl 620146HamburgGermany
| | - Dieter Schaarschmidt
- Department of ChemistryUniversity of HamburgMartin Luther King Pl 620146HamburgGermany
| | | | - Raul Perez‐Ruiz
- Photoactivated ProcessesIMDEA Energy InstituteRamin de la Sagra 328935MistolesSpain
- Departamento de QuímicaUniversitat Politècnica de ValènciaCamino de Vera s/n46022ValenciaSpain
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12
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Guillet GL, Arpin KY, Boltin AM, Gordon JB, Rave JA, Hillesheim PC. Synthesis and Characterization of a Linear Triiron(II) Extended Metal Atom Chain Complex with Fe–Fe Bonds. Inorg Chem 2020; 59:11238-11243. [DOI: 10.1021/acs.inorgchem.0c01625] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gary L. Guillet
- Department of Chemistry and Biochemistry, Georgia Southern University, 11935 Abercorn Street, Savannah, Georgia 31419, United States
| | - Kathleen Y. Arpin
- Department of Chemistry and Biochemistry, Georgia Southern University, 11935 Abercorn Street, Savannah, Georgia 31419, United States
| | - Alan M. Boltin
- Department of Chemistry and Biochemistry, Georgia Southern University, 11935 Abercorn Street, Savannah, Georgia 31419, United States
| | - Jesse B. Gordon
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Justin A. Rave
- Department of Chemistry and Biochemistry, Georgia Southern University, 11935 Abercorn Street, Savannah, Georgia 31419, United States
| | - Patrick C. Hillesheim
- Department of Chemistry and Physics, Ave Maria University, 5050 Ave Maria Boulevard, Ave Maria, Florida 34142, United States
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13
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Müller I, Munz D, Werncke CG. Reactions of Alkynes with Quasi-Linear 3d Metal(I) Silylamides of Chromium to Cobalt: A Comparative Study. Inorg Chem 2020; 59:9521-9537. [DOI: 10.1021/acs.inorgchem.0c00365] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Igor Müller
- Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße 4, 35043 Marburg, Germany
| | - Dominik Munz
- Inorganic Chemistry: Coordination Chemistry, Saarland University, 66123 Saarbrücken Germany
- Inorganic and General Chemistry, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - C. Gunnar Werncke
- Department of Chemistry, Philipps-University Marburg, Hans-Meerwein-Straße 4, 35043 Marburg, Germany
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14
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Neumeier M, Chakraborty U, Schaarschmidt D, Pena O'Shea V, Perez‐Ruiz R, Jacobi von Wangelin A. Combined Photoredox and Iron Catalysis for the Cyclotrimerization of Alkynes. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202000907] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Michael Neumeier
- Department of Chemistry University of Hamburg Martin Luther King Pl 6 20146 Hamburg Germany
| | - Uttam Chakraborty
- Department of Chemistry University of Hamburg Martin Luther King Pl 6 20146 Hamburg Germany
| | - Dieter Schaarschmidt
- Department of Chemistry University of Hamburg Martin Luther King Pl 6 20146 Hamburg Germany
| | - Victor Pena O'Shea
- Photoactivated Processes IMDEA Energy Institute Ramin de la Sagra 3 28935 Mistoles Spain
| | - Raul Perez‐Ruiz
- Photoactivated Processes IMDEA Energy Institute Ramin de la Sagra 3 28935 Mistoles Spain
- Departamento de Química Universitat Politècnica de València Camino de Vera s/n 46022 Valencia Spain
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15
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Nagelski AL, Fataftah MS, Bollmeyer MM, McWilliams SF, MacMillan SN, Mercado BQ, Lancaster KM, Holland PL. The influences of carbon donor ligands on biomimetic multi-iron complexes for N 2 reduction. Chem Sci 2020; 11:12710-12720. [PMID: 34094466 PMCID: PMC8163302 DOI: 10.1039/d0sc03447a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The active site clusters of nitrogenase enzymes possess the only examples of carbides in biology. These are the only biological FeS clusters that are capable of reducing N2 to NH4+, implicating the central carbon and its interaction with Fe as important in the mechanism of N2 reduction. This biological question motivates study of the influence of carbon donors on the electronic structure and reactivity of unsaturated, high-spin iron centers. Here, we present functional and structural models that test the impacts of carbon donors and sulfide donors in simpler iron compounds. We report the first example of a diiron complex that is bridged by an alkylidene and a sulfide, which serves as a high-fidelity structural and spectroscopic model of a two-iron portion of the active-site cluster (FeMoco) in the resting state of Mo-nitrogenase. The model complexes have antiferromagnetically coupled pairs of high-spin iron centers, and sulfur K-edge X-ray absorption spectroscopy shows comparable covalency of the sulfide for C and S bridged species. The sulfur-bridged compound does not interact with N2 even upon reduction, but upon removal of the sulfide it becomes capable of reducing N2 to NH4+ with the addition of protons and electrons. This provides synthetic support for sulfide extrusion in the activation of nitrogenase cofactors. High-spin diiron alkylidenes give insight into the electronic structure and functional relevance of carbon in the FeMoco active site of nitrogenase.![]()
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Affiliation(s)
| | | | - Melissa M. Bollmeyer
- Department of Chemistry and Chemical Biology
- Baker Laboratory
- Cornell University
- Ithaca
- USA
| | | | - Samantha N. MacMillan
- Department of Chemistry and Chemical Biology
- Baker Laboratory
- Cornell University
- Ithaca
- USA
| | | | - Kyle M. Lancaster
- Department of Chemistry and Chemical Biology
- Baker Laboratory
- Cornell University
- Ithaca
- USA
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16
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MacLeod KC, DiMucci IM, Zovinka EP, McWilliams SF, Mercado BQ, Lancaster KM, Holland PL. Masked Radicals: Iron Complexes of Trityl, Benzophenone, and Phenylacetylene. Organometallics 2019; 38:4224-4232. [PMID: 34103782 DOI: 10.1021/acs.organomet.9b00534] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We report the first Fe─CPh3 complex, and show that the long Fe─C bond can be disrupted by neutral π-acceptor ligands (benzophenone and phenylacetylene) to release the triphenylmethyl radical. The products are formally iron(I) complexes, but X-ray absorption spectroscopy coupled with density functional and multireference ab initio calculations indicates that the best description of all the complexes is iron(II). In the formally iron(I) complexes, this does not imply that the π-acceptor ligand has radical character, because the iron(II) description arises from doubly-occupied frontier molecular orbitals that are shared equitably by the iron and the π-acceptor ligand, and the unpaired electrons lie on the metal. Despite the lack of substantial radical character on the ligands, alkyne and ketone fragments can couple to form a high-spin iron(III) complex with a cyclized metalladihydrofuran core.
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Affiliation(s)
- K Cory MacLeod
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511
| | - Ida M DiMucci
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca New York 14853
| | - Edward P Zovinka
- Department of Chemistry, Saint Francis University, Loretto, Pennsylvania 15940
| | - Sean F McWilliams
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511
| | - Brandon Q Mercado
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca New York 14853
| | - Patrick L Holland
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511
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17
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Citek C, Oyala PH, Peters JC. Mononuclear Fe(I) and Fe(II) Acetylene Adducts and Their Reductive Protonation to Terminal Fe(IV) and Fe(V) Carbynes. J Am Chem Soc 2019; 141:15211-15221. [PMID: 31430146 PMCID: PMC6800224 DOI: 10.1021/jacs.9b06987] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The activity of nitrogenase enzymes, which catalyze the conversion of atmospheric dinitrogen to bioavailable ammonia, is most commonly assayed by the reduction of acetylene gas to ethylene. Despite the practical importance of acetylene as a substrate, little is known concerning its binding or activation in the iron-rich active site. "Fischer-Tropsch" type coupling of non-native C1 substrates to higher-order C≥2 products is also known for nitrogenase, though potential metal-carbon multiply bonded intermediates remain underexplored. Here we report the activation of acetylene gas at a mononuclear tris(phosphino)silyl-iron center, (SiP3)Fe, to give Fe(I) and Fe(II) side-on adducts, including S = 1/2 FeI(η2-HCCH); the latter is characterized by pulse EPR spectroscopy and DFT calculations. Reductive protonation reactions with these compounds converge at stable examples of unusual, formally iron(IV) and iron(V) carbyne complexes, as in diamagnetic (SiP3)Fe≡CCH3 and the paramagnetic cation S = 1/2 [(SiP3)Fe≡CCH3]+. Both alkylcarbyne compounds possess short Fe-C triple bonds (approximately 1.7 Å) trans to the anchoring silane. Pulse EPR experiments, X-band ENDOR and HYSCORE, reveal delocalization of the iron-based spin onto the α-carbyne nucleus in carbon p-orbitals. Furthermore, isotropic coupling of the distal β-CH3 protons with iron indicates hyperconjugation with the spin/hole character on the Fe≡CCH3 unit. The electronic structures of (SiP3)Fe≡CCH3 and [(SiP3)Fe≡CCH3]+ are discussed in comparison to previously characterized, but heterosubstituted, iron carbynes, as well as a hypothetical nitride species, (SiP3)Fe≡N. Such comparisons are germane to the consideration of formally high-valent, multiply bonded Fe≡C and/or Fe≡N intermediates in synthetic or biological catalysis by iron.
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Affiliation(s)
- Cooper Citek
- 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
| | - Jonas C. Peters
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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18
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Cheng J, Chen Q, Leng X, Ye S, Deng L. Three-Coordinate Iron(0) Complexes with N-Heterocyclic Carbene and Vinyltrimethylsilane Ligation: Synthesis, Characterization, and Ligand Substitution Reactions. Inorg Chem 2019; 58:13129-13141. [PMID: 31536336 DOI: 10.1021/acs.inorgchem.9b02009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Low-coordinate iron(0) species are implicated as intermediates in a range of iron-catalyzed organic transformations. Isolable iron(0) complexes with coordination numbers of less than four, however, are rarely known. In continuing with our interests in three-coordinate iron(0) complexes with N-heterocyclic carbene (NHC) and alkene ligation, we report herein the synthesis and ligand substitution reactivity of three-coordinate iron(0) complexes featuring monodentate alkene ligands, [(NHC)Fe(η2-vtms)2] (vtms = vinyltrimethylsilane, NHC = 1,3-bis(2',6'-diisopropylphenyl)-imidazol-2-ylidene (IPr), 1; 1,3-bis(2',6'-diisopropylphenyl)-4,5-tetramethylene-imidazol-2-ylidene (cyIPr), 2; 1,3-bis(2',6'-diisopropylphenyl)-4,5,6,7-tetrahydro-1,3-diazepin-2-ylidene (7-IPr), 3). Complexes 1-3 were synthesized from the one-pot reactions of ferrous dihalides with the N-(2,6-diisopropylphenyl)-substituted NHC ligands, vtms, and KC8. Reactivity study of 1 revealed its facile ligand substitution reactions with terminal aryl alkynes, ketones, isocyanides, and CO, by which iron(0) complexes [(IPr)Fe(η2-HCCAr)] (Ar = Ph, 5; p-CH3C6H4, 6; 3,5-(CF3)2C6H3, 7), [(IPr)Fe(η2-OCPh2)2] (8), [(IPr)Fe(CNR)4] (R = 2,6-Me2C6H3, 9; But, 10), and (IPr)Fe(CO)4 (11) were prepared in good yields. These iron(0) complexes have been characterized by 1H NMR, solution magnetic susceptibility measurement, single-crystal X-ray diffraction study, 57Fe Mössbauer spectroscopy, and elemental analysis. Characterization data and computational studies suggest S = 1 ground-spin states for three-coordinate iron(0) complexes 1-3 and 5-8 and S = 0 ground states for 9-11. Theoretical studies on the three-coordinate complexes 1, 6, and 8 indicated pronounced metal-to-ligand backdonation from occupied Fe 3d orbitals to the π* orbitals of the C═C, C≡C, and C═O moieties of the π ligands. In addition, 1 proved an effective precatalyst for the cyclotrimerization reaction of alkynes.
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Affiliation(s)
- Jun Cheng
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road , Shanghai , 200032 , PR China
| | - Qi Chen
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road , Shanghai , 200032 , PR China
| | - Xuebing Leng
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road , Shanghai , 200032 , PR China
| | - Shengfa Ye
- Max-Planck Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1 , Mülheim an der Ruhr D-45470 , Germany
| | - Liang Deng
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road , Shanghai , 200032 , PR China
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19
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Kiernicki JJ, Shanahan JP, Zeller M, Szymczak NK. Tuning ligand field strength with pendent Lewis acids: access to high spin iron hydrides. Chem Sci 2019; 10:5539-5545. [PMID: 31293738 PMCID: PMC6553361 DOI: 10.1039/c9sc00561g] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 04/25/2019] [Indexed: 11/21/2022] Open
Abstract
Geometrically flexible 9-borabicyclo[3.3.1]nonyl units within the secondary coordination sphere enable isolation of high-spin Fe(ii)-dihydrides stabilized by boron-hydride interactions and a rare example of an isolable S = 3/2 reduction product. The borane-capped Fe(ii)-dihydride: (1) rapidly deprotonates E-H (E = N, O, P, S) bonds to afford borane-stabilized Fe adducts and (2) releases H2 upon exposure to π-acids. The Lewis acids provide an avenue for redox-leveling in analogy to the near constant operating potential for N2 reduction in nitrogenase.
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Affiliation(s)
- John J Kiernicki
- University of Michigan , 930 N. University , Ann Arbor , MI 48109 , USA .
| | - James P Shanahan
- University of Michigan , 930 N. University , Ann Arbor , MI 48109 , USA .
| | - Matthias Zeller
- H. C. Brown Laboratory , Purdue University , 560 Oval Dr , West Lafayette , IN 47907 , USA
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20
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Polezhaev AV, Liss CJ, Telser J, Chen C, Caulton KG. A PNNH Pincer Ligand Allows Access to Monovalent Iron. Chemistry 2017; 24:1330-1341. [DOI: 10.1002/chem.201703795] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Indexed: 12/21/2022]
Affiliation(s)
| | - Cameron J. Liss
- Department of Biological, Chemical, and Physical Sciences Roosevelt University 430 S. Michigan Ave Chicago Illinois 60605 USA
| | - Joshua Telser
- Department of Biological, Chemical, and Physical Sciences Roosevelt University 430 S. Michigan Ave Chicago Illinois 60605 USA
| | - Chun‐Hsing Chen
- Department of Chemistry Indiana University Bloomington 47405 Bloomington IN USA
| | - Kenneth G. Caulton
- Department of Chemistry Indiana University Bloomington 47405 Bloomington IN USA
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21
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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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22
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Horitani M, Grubel K, McWilliams SF, Stubbert BD, Mercado BQ, Yu Y, Gurubasavaraj PM, Lees NS, Holland PL, Hoffman BM. ENDOR characterization of an iron-alkene complex provides insight into a corresponding organometallic intermediate of nitrogenase. Chem Sci 2017; 8:5941-5948. [PMID: 28989623 PMCID: PMC5620524 DOI: 10.1039/c7sc01602f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 06/17/2017] [Indexed: 12/16/2022] Open
Abstract
Comparison of an iron(I)–alkene complex to a nitrogenase intermediate using ENDOR reveals details of the binding geometry.
A bio-organometallic intermediate, denoted PA, was previously trapped during the reduction of propargyl alcohol to allyl alcohol (AA) by nitrogenase, and a similar one was trapped during acetylene reduction, representing foundational examples of alkene binding to a metal center in biology. ENDOR spectroscopy led to the conclusion that these intermediates have η2 binding of the alkene, with the hydrogens on the terminal carbon structurally/magnetically equivalent and related by local mirror symmetry. However, our understanding of both the PA intermediate, and of the dependability of the ENDOR analysis on which this understanding was based, was constrained by the absence of reference iron–alkene complexes for EPR/ENDOR comparison. Here, we report an ENDOR study of the crystallographically characterized biomimetic iron(i) complex 1, which exhibits η2 coordination of styrene, thus connecting hyperfine and structural parameters of an Fe-bound alkene fragment for the first time. A tilt of the alkene plane of 1 from normal to the crystallographic Fe–C2–C1 plane causes substantial differences in the dipolar couplings of the two terminal vinylic protons. Comparison of the hyperfine couplings of 1 and PA confirms the proposed symmetry of PA, and that the η2 interaction forms a scalene Fe–C–C triangle, rather than an isosceles triangle. This spectroscopic study of a structurally characterized complex thus shows the exceptional sensitivity of ENDOR spectroscopy to structural details, while enhancing our understanding of the geometry of a key nitrogenase adduct.
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Affiliation(s)
- Masaki Horitani
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , USA . .,Department of Applied Biochemistry and Food Science , Saga University , Saga , 840-8502 , Japan
| | - Katarzyna Grubel
- Department of Chemistry , Yale University , New Haven , CT 06520 , USA .
| | - Sean F McWilliams
- Department of Chemistry , Yale University , New Haven , CT 06520 , USA .
| | - Bryan D Stubbert
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA
| | - Brandon Q Mercado
- Department of Chemistry , Yale University , New Haven , CT 06520 , USA .
| | - Ying Yu
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA
| | | | - Nicholas S Lees
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , USA .
| | - Patrick L Holland
- Department of Chemistry , Yale University , New Haven , CT 06520 , USA .
| | - Brian M Hoffman
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , USA .
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23
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Proppe J, Reiher M. Reliable Estimation of Prediction Uncertainty for Physicochemical Property Models. J Chem Theory Comput 2017; 13:3297-3317. [PMID: 28581746 DOI: 10.1021/acs.jctc.7b00235] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
One of the major challenges in computational science is to determine the uncertainty of a virtual measurement, that is the prediction of an observable based on calculations. As highly accurate first-principles calculations are in general unfeasible for most physical systems, one usually resorts to parameteric property models of observables, which require calibration by incorporating reference data. The resulting predictions and their uncertainties are sensitive to systematic errors such as inconsistent reference data, parametric model assumptions, or inadequate computational methods. Here, we discuss the calibration of property models in the light of bootstrapping, a sampling method that can be employed for identifying systematic errors and for reliable estimation of the prediction uncertainty. We apply bootstrapping to assess a linear property model linking the 57Fe Mössbauer isomer shift to the contact electron density at the iron nucleus for a diverse set of 44 molecular iron compounds. The contact electron density is calculated with 12 density functionals across Jacob's ladder (PWLDA, BP86, BLYP, PW91, PBE, M06-L, TPSS, B3LYP, B3PW91, PBE0, M06, TPSSh). We provide systematic-error diagnostics and reliable, locally resolved uncertainties for isomer-shift predictions. Pure and hybrid density functionals yield average prediction uncertainties of 0.06-0.08 mm s-1 and 0.04-0.05 mm s-1, respectively, the latter being close to the average experimental uncertainty of 0.02 mm s-1. Furthermore, we show that both model parameters and prediction uncertainty depend significantly on the composition and number of reference data points. Accordingly, we suggest that rankings of density functionals based on performance measures (e.g., the squared coefficient of correlation, r2, or the root-mean-square error, RMSE) should not be inferred from a single data set. This study presents the first statistically rigorous calibration analysis for theoretical Mössbauer spectroscopy, which is of general applicability for physicochemical property models and not restricted to isomer-shift predictions. We provide the statistically meaningful reference data set MIS39 and a new calibration of the isomer shift based on the PBE0 functional.
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Affiliation(s)
- Jonny Proppe
- Laboratorium für Physikalische Chemie, ETH Zürich , Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Markus Reiher
- Laboratorium für Physikalische Chemie, ETH Zürich , Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
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24
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Burcher B, Sanders KJ, Benda L, Pintacuda G, Jeanneau E, Danopoulos AA, Braunstein P, Olivier-Bourbigou H, Breuil PAR. A Straightforward Access to Stable, 16 Valence-electron Phosphine-Stabilized Fe 0 Olefin Complexes and their Reactivity. Organometallics 2017; 36:605-613. [PMID: 31031510 DOI: 10.1021/acs.organomet.6b00803] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The use of the dialkene divinyltetramethyldisiloxane (dvtms) allows easy access to the reactive 16 valence-electron complexes [Fe0(L-L)(dvtms)], (L-L) = dppe (1,2-bis(diphenylphosphino)ethane), (1), dppp (1,2-bis(diisopropylphosphino)propane), (2), pyNMeP(iPr)2 (N-(diisopropylphosphino)-N-methylpyridin-2-amine), (4), dipe (1,2-bis(diisopropylphosphino)ethane), (5), and [Fe0(L)2(dvtms)], L = PMe3, (3), by a mild reductive route using AlEt2(OEt) as reducing agent. In contrast, by the same methodology, the 18 valence-electron complexes [Fe0(L-L)2(ethylene)], (L-L) = dppm (1,2-bis(diphenylphosphino)methane), 6, (L-L) = dppa (1,2-bis(diphenylphosphino)amine) 7 or (L-L)=dppe, 8, were obtained, which do not contain dvtms. In addition, a combined DFT and solid-state paramagnetic NMR methodology is introduced for the structure determination of 5. A comparative study of the reactivity of 1,2,4-6 and 8 with 3-hexyne highlights emerging mechanistic implications for C-C coupling reactions using these complexes as catalysts.
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Affiliation(s)
- Benjamin Burcher
- IFP Energies nouvelles, Rond-point de l'échangeur de Solaize, BP 3, 69360 Solaize, France
| | - Kevin J Sanders
- Institut des Sciences Analytiques, UMR 5280 CNRS, Université de Lyon, École Normale Supérieure de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Ladislav Benda
- Institut des Sciences Analytiques, UMR 5280 CNRS, Université de Lyon, École Normale Supérieure de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Guido Pintacuda
- Institut des Sciences Analytiques, UMR 5280 CNRS, Université de Lyon, École Normale Supérieure de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Erwann Jeanneau
- Centre de Diffractométrie Henri Longchambon, Site CLEA - Bât. ISA, 3ème étage, 5 rue de La Doua, 69100 Villeurbanne, France
| | - Andreas A Danopoulos
- Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Chimie de Coordination, 4 rue Blaise Pascal, CS90032, 67081 Strasbourg, France
| | - Pierre Braunstein
- Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Chimie de Coordination, 4 rue Blaise Pascal, CS90032, 67081 Strasbourg, France
| | | | - Pierre-Alain R Breuil
- IFP Energies nouvelles, Rond-point de l'échangeur de Solaize, BP 3, 69360 Solaize, France
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25
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Damjanović M, Samuel PP, Roesky HW, Enders M. NMR analysis of an Fe(i)–carbene complex with strong magnetic anisotropy. Dalton Trans 2017; 46:5159-5169. [PMID: 28352888 DOI: 10.1039/c7dt00408g] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A paramagnetic, easy-plane anisotropic FeI complex, bearing cyclic-alkyl(amino) carbene (cAAC) ligands, is studied by means of NMR and DFT.
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Affiliation(s)
- Marko Damjanović
- Institute of Inorganic Chemistry
- Heidelberg University
- D-69120 Heidelberg
- Germany
| | - Prinson P. Samuel
- Universität Göttingen
- Institut für Anorganische Chemie
- Göttingen
- Germany
| | - Herbert W. Roesky
- Universität Göttingen
- Institut für Anorganische Chemie
- Göttingen
- Germany
| | - Markus Enders
- Institute of Inorganic Chemistry
- Heidelberg University
- D-69120 Heidelberg
- Germany
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26
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Espinal-Viguri M, Woof CR, Webster RL. Iron-Catalyzed Hydroboration: Unlocking Reactivity through Ligand Modulation. Chemistry 2016; 22:11605-8. [PMID: 27321704 DOI: 10.1002/chem.201602818] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Indexed: 11/09/2022]
Abstract
Iron-catalyzed hydroboration (HB) of alkenes and alkynes is reported. A simple change in ligand structure leads to an extensive change in catalyst activity. Reactions proceed efficiently over a wide range of challenging substrates including activated, unactivated and sterically encumbered motifs. Conditions are mild and do not require the use of reducing agents or other additives. Large excesses of borating reagent are not required, allowing control of chemo- and regioselectivity in the presence of multiple double bonds. Mechanistic insight reveals that the reaction is likely to proceed via a highly reactive iron hydride intermediate.
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Affiliation(s)
| | - Callum R Woof
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Ruth L Webster
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
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27
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Bellows SM, Brennessel WW, Holland PL. Effects of Ligand Halogenation on the Electron Localization, Geometry and Spin State of Low-Coordinate (β-Diketiminato)iron Complexes. Eur J Inorg Chem 2016; 2016:3344-3355. [PMID: 28835739 PMCID: PMC5563838 DOI: 10.1002/ejic.201600112] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Indexed: 11/05/2022]
Abstract
This contribution explores the influences of incorporating electron-withdrawing CF3 and halide groups into β-diketiminate iron complexes of tetrazene and isocyanide. The synthesis of a new halogenated β-diketimine (LCF3,ClH) was accomplished via two different methods, including a novel microwave-assisted synthesis that improves the yield of the difficult condensation. Treatment of an iron(II) complex of this ligand with reductant and azide gives two diiron complexes with novel tetrazenes as bridging ligands. Structural and Mössbauer data show that the bridging tetrazene is a radical anion. The halogenation of the supporting ligand also influences iron(I) complexes of the type LFe(CNtBu)2, which are low-spin and square-planar with alkyl substituents but high-spin and pseudotetrahedral with halogen substituents. DFT calculations suggest that the changes from halogenation come from a combination of steric and electronic effects, and that the electronic influence of ligand halogenation is minor.
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Affiliation(s)
- Sarina M Bellows
- Department of Chemistry, University of Rochester, 120 Trustee Rd, Rochester, NY 14627 USA
| | - William W Brennessel
- Department of Chemistry, University of Rochester, 120 Trustee Rd, Rochester, NY 14627 USA
| | - Patrick L Holland
- Department of Chemistry, Yale University 225, Prospect St, New Haven, CT 06520 USA, Homepage: http://holland.chem.yale.edu
- Department of Chemistry, University of Rochester, 120 Trustee Rd, Rochester, NY 14627 USA
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28
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Pascualini ME, Stoian SA, Ozarowski A, Abboud KA, Veige AS. Solid State Collapse of a High-Spin Square-Planar Fe(II) Complex, Solution Phase Dynamics, and Electronic Structure Characterization of an Fe(II)2 Dimer. Inorg Chem 2016; 55:5191-200. [DOI: 10.1021/acs.inorgchem.6b00075] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matias E. Pascualini
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, Florida 32611, United States
| | - Sebastian A. Stoian
- 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
| | - Khalil A. Abboud
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, Florida 32611, United States
| | - Adam S. Veige
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, Florida 32611, United States
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29
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Kaplan HZ, Mako TL, Wilding MJT, Li B, Byers JA. Electron-donating capabilities and evidence for redox activity in low oxidation state iron complexes bearing bis(amidine)pyrimidylidene ligands. J COORD CHEM 2016. [DOI: 10.1080/00958972.2016.1176158] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Hilan Z. Kaplan
- Department of Chemistry, Eugene F. Merkert Chemistry Center, Boston College, Chestnut Hill, MA, USA
| | - Teresa L. Mako
- Department of Chemistry, Eugene F. Merkert Chemistry Center, Boston College, Chestnut Hill, MA, USA
| | - Matthew J. T. Wilding
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Bo Li
- Department of Chemistry, Eugene F. Merkert Chemistry Center, Boston College, Chestnut Hill, MA, USA
| | - Jeffery A. Byers
- Department of Chemistry, Eugene F. Merkert Chemistry Center, Boston College, Chestnut Hill, MA, USA
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30
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Ouyang Z, Meng Y, Cheng J, Xiao J, Gao S, Deng L. Three- and Four-Coordinate Homoleptic Iron(I)–NHC Complexes: Synthesis and Characterization. Organometallics 2016. [DOI: 10.1021/acs.organomet.6b00047] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zhenwu Ouyang
- State
Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Yinshan Meng
- Beijing
National Laboratory for Molecular Sciences, State Key Laboratory of
Rare Earth Materials Chemistry and Applications, College of Chemistry
and Molecular Engineering, Peking University, Beijing 100871, China
| | - Jun Cheng
- State
Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Jie Xiao
- State
Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Song Gao
- Beijing
National Laboratory for Molecular Sciences, State Key Laboratory of
Rare Earth Materials Chemistry and Applications, College of Chemistry
and Molecular Engineering, Peking University, Beijing 100871, China
| | - Liang Deng
- State
Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
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31
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Pascualini ME, Stoian SA, Ozarowski A, Di Russo NV, Thuijs AE, Abboud KA, Christou G, Veige AS. Synthesis and characterization of a family of M(2+) complexes supported by a trianionic ONO(3-) pincer-type ligand: towards the stabilization of high-spin square-planar complexes. Dalton Trans 2015; 44:20207-15. [PMID: 26537572 DOI: 10.1039/c5dt03960f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High-spin square-planar molecular compounds are rare. In an effort to access this unique combination of geometry and spin state, we report the synthesis of a series of M(II) compounds stabilized by a trianionic pincer-type ligand, highlighting the formation of a high-spin square-planar Co(II) complex. Low-temperature, variable-frequency EPR measurements reveal that the ground electronic state of the Co(II) analogue is a highly anisotropic Kramers doublet (effective g values 7.35, 2.51, 1.48). This doublet can be identified with the lowest doublet of a quartet, S = 3/2 spin state that exhibits a very large ZFS, D ≥ 50 cm(-1). The observation of an effective g value considerably greater than the largest spin-only value 6, demonstrates that the orbital angular moment is essentially unquenched along one spatial direction. Density Functional Theory (DFT) and time-dependent DFT calculations reveal the electronic configurations of the ground and excited orbital states. A qualitative crystal field description of the geff tensor shows that it originates from the spin-orbit coupling acting on states obtained through the transfer of a β electron from the doubly occupied xy to the singly-occupied {xz/yz} orbitals.
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Affiliation(s)
- M E Pascualini
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - S A Stoian
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA.
| | - A Ozarowski
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA.
| | - N V Di Russo
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - A E Thuijs
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - K A Abboud
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - G Christou
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - A S Veige
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
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32
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Lichtenberg C, Viciu L, Vogt M, Rodríguez-Lugo RE, Adelhardt M, Sutter J, Khusniyarov MM, Meyer K, de Bruin B, Bill E, Grützmacher H. Low-valent iron: an Fe(I) ate compound as a building block for a linear trinuclear Fe cluster. Chem Commun (Camb) 2015. [PMID: 26221636 DOI: 10.1039/c5cc04908c] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
A low-valent trinuclear iron complex with an unusual linear Fe(I)-Fe(II)-Fe(I) unit is presented. It is accessed in a rational approach using a salt metathesis reaction between a new anionic Fe(I) containing heterocycle and FeCl2. Its electronic structure was studied by single crystal XRD analysis, EPR and Mössbauer spectroscopy, and magnetic susceptibility measurements.
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Affiliation(s)
- C Lichtenberg
- Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093, Switzerland.
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33
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Ouyang Z, Du J, Wang L, Kneebone JL, Neidig ML, Deng L. Linear and T-Shaped Iron(I) Complexes Supported by N-Heterocyclic Carbene Ligands: Synthesis and Structure Characterization. Inorg Chem 2015; 54:8808-16. [PMID: 26273996 PMCID: PMC4894307 DOI: 10.1021/acs.inorgchem.5b01522] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The use of the N-heterocyclic carbene (NHC) ligands 1,3-bis(2',6'-diethylphenyl)-4,5-(CH2)4-imidazol-2-ylidene (cyIDep), 1,3-bis(2',6'-diethylphenyl)-imidazolin-2-ylidene (sIDep), and its N-mesityl analogue sIMes enables the preparation of the two-coordinate homoleptic iron(I)-NHC complexes [(cyIDep)2Fe][BAr(F)4] (3, Ar(F) denoted for 3,5-di(trifluoromethyl)phenyl) and [(sIDep)2Fe][BAr(F)4] (4) and the T-shaped iron(I)-NHC complex [(sIMes)2Fe(THF)][BPh4] (5, THF = tetrahydrofuran). Complexes 3-5 were prepared via the sequential protocol of control reduction of iron(II) dihalides by KC8 in the presence of the corresponding NHC ligands followed by halide-abstraction with NaBAr4. Spectroscopic characterization, including single-crystal X-ray diffraction studies and (57)Fe Mössbauer spectroscopy, in combination with density functional theory calculations, suggest their high-spin nature. Solution property study (absorption spectroscopy and cyclic voltammetry) indicates that 3 and 5 keep their corresponding two- and three-coordinate nature in THF solution, and 4 might reversibly coordinate a THF molecule to form, presumably, the T-shaped species [(sIDep)2Fe(THF)][BAr(F)4]. The isolation of 3 and 4 demonstrates the accessibility of homoleptic two-coordinate iron(I)-NHC complexes.
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Affiliation(s)
- Zhenwu Ouyang
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Jingzhen Du
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Lei Wang
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Jared L. Kneebone
- Department of Chemistry, University of Rochester, New York 14627, United States
| | - Michael L. Neidig
- Department of Chemistry, University of Rochester, New York 14627, United States
| | - Liang Deng
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
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34
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Chen C, Bellows SM, Holland PL. Tuning steric and electronic effects in transition-metal β-diketiminate complexes. Dalton Trans 2015; 44:16654-70. [PMID: 26244489 DOI: 10.1039/c5dt02215k] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
β-Diketiminates are widely used supporting ligands for building a range of metal complexes with different oxidation states, structures, and reactivities. This Perspective summarizes the steric and electronic influences of ligand substituents on these complexes, with an eye toward informing the design of new complexes with optimized properties. The backbone and N-aryl substituents can give significant steric effects on structure, reactivity and selectivity of reactions. The electron density on the metal can be tuned by installation of electron withdrawing or donating groups on the β-diketiminate ligand as well. Examples are shown from throughout the transition metal series to demonstrate different types of effects attributable to systematic variation of β-diketiminate ligands.
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Affiliation(s)
- Chi Chen
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, USA.
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35
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Lichtenberg C, Viciu L, Adelhardt M, Sutter J, Meyer K, de Bruin B, Grützmacher H. Low-Valent Iron(I) Amido Olefin Complexes as Promotors for Dehydrogenation Reactions. Angew Chem Int Ed Engl 2015; 54:5766-71. [DOI: 10.1002/anie.201411365] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Indexed: 11/08/2022]
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36
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Lichtenberg C, Viciu L, Adelhardt M, Sutter J, Meyer K, de Bruin B, Grützmacher H. Niedervalente Eisen(I)-Amido-Olefinkomplexe als Promotoren von Dehydrierungsreaktionen. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201411365] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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37
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Werncke CG, Bunting PC, Duhayon C, Long JR, Bontemps S, Sabo‐Etienne S. Two‐Coordinate Iron(I) Complex [Fe{N(SiMe
3
)
2
}
2
]
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: Synthesis, Properties, and Redox Activity. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201408802] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- C. Gunnar Werncke
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, 31077 Toulouse (France) http://www.lcc‐toulouse.fr/lcc/spip.php?article433
- Université de Toulouse, UPS, INPT, 31077 Toulouse (France)
| | - Philip C. Bunting
- Department of Chemistry, University of California, Berkeley, CA 94720 (USA)
| | - Carine Duhayon
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, 31077 Toulouse (France) http://www.lcc‐toulouse.fr/lcc/spip.php?article433
- Université de Toulouse, UPS, INPT, 31077 Toulouse (France)
| | - Jeffrey R. Long
- Department of Chemistry, University of California, Berkeley, CA 94720 (USA)
| | - Sébastien Bontemps
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, 31077 Toulouse (France) http://www.lcc‐toulouse.fr/lcc/spip.php?article433
- Université de Toulouse, UPS, INPT, 31077 Toulouse (France)
| | - Sylviane Sabo‐Etienne
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, 31077 Toulouse (France) http://www.lcc‐toulouse.fr/lcc/spip.php?article433
- Université de Toulouse, UPS, INPT, 31077 Toulouse (France)
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38
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Werncke CG, Bunting PC, Duhayon C, Long JR, Bontemps S, Sabo‐Etienne S. Two‐Coordinate Iron(I) Complex [Fe{N(SiMe
3
)
2
}
2
]
−
: Synthesis, Properties, and Redox Activity. Angew Chem Int Ed Engl 2014; 54:245-8. [DOI: 10.1002/anie.201408802] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Indexed: 11/11/2022]
Affiliation(s)
- C. Gunnar Werncke
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, 31077 Toulouse (France) http://www.lcc‐toulouse.fr/lcc/spip.php?article433
- Université de Toulouse, UPS, INPT, 31077 Toulouse (France)
| | - Philip C. Bunting
- Department of Chemistry, University of California, Berkeley, CA 94720 (USA)
| | - Carine Duhayon
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, 31077 Toulouse (France) http://www.lcc‐toulouse.fr/lcc/spip.php?article433
- Université de Toulouse, UPS, INPT, 31077 Toulouse (France)
| | - Jeffrey R. Long
- Department of Chemistry, University of California, Berkeley, CA 94720 (USA)
| | - Sébastien Bontemps
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, 31077 Toulouse (France) http://www.lcc‐toulouse.fr/lcc/spip.php?article433
- Université de Toulouse, UPS, INPT, 31077 Toulouse (France)
| | - Sylviane Sabo‐Etienne
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, 31077 Toulouse (France) http://www.lcc‐toulouse.fr/lcc/spip.php?article433
- Université de Toulouse, UPS, INPT, 31077 Toulouse (France)
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39
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Lin YF, Ichihara N, Nakajima Y, Ozawa F. Disproportionation of Bis(phosphaethenyl)pyridine Iron(I) Bromide Induced by tBuNC. Organometallics 2014. [DOI: 10.1021/om500901a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Ya-Fan Lin
- International
Research Center for Elements Science (IRCELS), Institute for Chemical
Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Nobuko Ichihara
- International
Research Center for Elements Science (IRCELS), Institute for Chemical
Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Yumiko Nakajima
- International
Research Center for Elements Science (IRCELS), Institute for Chemical
Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Fumiyuki Ozawa
- International
Research Center for Elements Science (IRCELS), Institute for Chemical
Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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40
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Samuel PP, Mondal KC, Amin Sk N, Roesky HW, Carl E, Neufeld R, Stalke D, Demeshko S, Meyer F, Ungur L, Chibotaru LF, Christian J, Ramachandran V, van Tol J, Dalal NS. Electronic Structure and Slow Magnetic Relaxation of Low-Coordinate Cyclic Alkyl(amino) Carbene Stabilized Iron(I) Complexes. J Am Chem Soc 2014; 136:11964-71. [DOI: 10.1021/ja5043116] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Prinson P. Samuel
- Institut
für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077, Göttingen, Germany
| | - Kartik Chandra Mondal
- Institut
für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077, Göttingen, Germany
| | - Nurul Amin Sk
- Institut
für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077, Göttingen, Germany
| | - Herbert W. Roesky
- Institut
für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077, Göttingen, Germany
| | - Elena Carl
- Institut
für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077, Göttingen, Germany
| | - Roman Neufeld
- Institut
für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077, Göttingen, Germany
| | - Dietmar Stalke
- Institut
für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077, Göttingen, Germany
| | - Serhiy Demeshko
- Institut
für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077, Göttingen, Germany
| | - Franc Meyer
- Institut
für Anorganische Chemie, Georg-August-Universität, Tammannstrasse 4, D-37077, Göttingen, Germany
| | - Liviu Ungur
- KU Leuven, Celestijnenlaan,
200F, 3001, Leuven, Belgium
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41
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Zhang H, Ouyang Z, Liu Y, Zhang Q, Wang L, Deng L. (Aminocarbene)(Divinyltetramethyldisiloxane)Iron(0) Compounds: A Class of Low-Coordinate Iron(0) Reagents. Angew Chem Int Ed Engl 2014; 53:8432-6. [DOI: 10.1002/anie.201404677] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Indexed: 11/08/2022]
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42
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Zhang H, Ouyang Z, Liu Y, Zhang Q, Wang L, Deng L. (Aminocarbene)(Divinyltetramethyldisiloxane)Iron(0) Compounds: A Class of Low-Coordinate Iron(0) Reagents. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201404677] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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43
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Ung G, Rittle J, Soleilhavoup M, Bertrand G, Peters JC. Two-Coordinate Fe0and Co0Complexes Supported by Cyclic (alkyl)(amino)carbenes. Angew Chem Int Ed Engl 2014; 53:8427-31. [DOI: 10.1002/anie.201404078] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Indexed: 11/09/2022]
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44
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Ung G, Rittle J, Soleilhavoup M, Bertrand G, Peters JC. Two-Coordinate Fe0and Co0Complexes Supported by Cyclic (alkyl)(amino)carbenes. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201404078] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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45
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Mo Z, Ouyang Z, Wang L, Fillman KL, Neidig ML, Deng L. Two- and three-coordinate formal iron(i) compounds featuring monodentate aminocarbene ligands. Org Chem Front 2014. [DOI: 10.1039/c4qo00175c] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Monodentate aminocarbene ligands, both NHC and cAAC, are capable of stabilizing low-coordinate iron(i) compounds.
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Affiliation(s)
- Zhenbo Mo
- State Key Laboratory of Organometallic Chemistry
- Shanghai Institute of Organic Chemistry
- Chinese Academy of Sciences
- Shanghai 200032, China
| | - Zhenwu Ouyang
- State Key Laboratory of Organometallic Chemistry
- Shanghai Institute of Organic Chemistry
- Chinese Academy of Sciences
- Shanghai 200032, China
| | - Lei Wang
- State Key Laboratory of Organometallic Chemistry
- Shanghai Institute of Organic Chemistry
- Chinese Academy of Sciences
- Shanghai 200032, China
| | | | | | - Liang Deng
- State Key Laboratory of Organometallic Chemistry
- Shanghai Institute of Organic Chemistry
- Chinese Academy of Sciences
- Shanghai 200032, China
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46
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Hedström A, Lindstedt E, Norrby PO. On the oxidation state of iron in iron-mediated C–C couplings. J Organomet Chem 2013. [DOI: 10.1016/j.jorganchem.2013.04.024] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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47
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Zadrozny JM, Xiao DJ, Long JR, Atanasov M, Neese F, Grandjean F, Long GJ. Mössbauer Spectroscopy as a Probe of Magnetization Dynamics in the Linear Iron(I) and Iron(II) Complexes [Fe(C(SiMe3)3)2]1–/0. Inorg Chem 2013; 52:13123-31. [DOI: 10.1021/ic402013n] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | - Mihail Atanasov
- Max-Planck Institut fur Chemische Energiekonversion, Mulheim an der Ruhr, D-45470, Germany
- Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. Georgi Bontchev Str 11, 1113 Sofia, Bulgaria
| | - Frank Neese
- Max-Planck Institut fur Chemische Energiekonversion, Mulheim an der Ruhr, D-45470, Germany
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48
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Boynton JN, Guo JD, Fettinger JC, Melton CE, Nagase S, Power PP. Linear and nonlinear two-coordinate vanadium complexes: synthesis, characterization, and magnetic properties of V(II) amides. J Am Chem Soc 2013; 135:10720-8. [PMID: 23782062 DOI: 10.1021/ja403244w] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis and characterization of the first stable two-coordinate vanadium complexes are described. The vanadium(II) primary amido derivative V{N(H)Ar(iPr6)}2 [Ar(iPr6) = C6H3-2,6-(C6H2-2,4,6-iPr3)2] (1) was synthesized via the reaction of LiN(H)Ar(iPr6) with the V(III) complex VCl3·2NMe3 or the V(II) salt [V2Cl3(THF)6](+)I(-) in a 2:1 and 4:1 stoichiometry, respectively. Reaction of the less crowded LiN(H)Ar(Me6) with [V2Cl3(THF)6](+)I(-) afforded V{N(H)Ar(Me6)}2 [Ar(Me6) = C6H3-2,6-(C6H2-2,4,6-Me3)2] (2), which has a nonlinear [N-V-N = 123.47(9)°] vanadium coordination. Magnetometry studies showed that V{N(H)Ar(iPr6)}2 and V{N(H)Ar(Me6)}2 have ambient temperature magnetic moments of 3.41 and 2.77 μB, respectively, which are consistent with a high-spin d(3) electron configuration. These values suggest a significant spin orbital angular momentum contribution that leads to a magnetic moment that is lower than their spin-only value of 3.87 μB. DFT calculations showed that the major absorptions in their UV-vis spectra were due to ligand to metal charge transfer transitions. Exposure of the reaction mixture for 2 to dry O2 resulted in the formation of the diamagnetic V(V) oxocluster [V{N(H)Ar(Me6)}2]2(μ-O-Li-O)2 (3).
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Affiliation(s)
- Jessica N Boynton
- Department of Chemistry, University of California-Davis, 1 Shields Avenue, Davis, California 95616, USA
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49
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Stoian SA, Hsieh CH, Singleton ML, Casuras AF, Darensbourg MY, McNeely K, Sweely K, Popescu CV. Hyperfine interactions and electron distribution in FeIIFeI and FeIFeI models for the active site of the [FeFe] hydrogenases: Mössbauer spectroscopy studies of low-spin FeI. J Biol Inorg Chem 2013; 18:609-22. [DOI: 10.1007/s00775-013-1005-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 05/01/2013] [Indexed: 10/26/2022]
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50
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Zadrozny JM, Xiao DJ, Atanasov M, Long GJ, Grandjean F, Neese F, Long JR. Magnetic blocking in a linear iron(I) complex. Nat Chem 2013; 5:577-81. [PMID: 23787747 DOI: 10.1038/nchem.1630] [Citation(s) in RCA: 482] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 03/18/2013] [Indexed: 11/09/2022]
Abstract
Single-molecule magnets that contain one spin centre may represent the smallest possible unit for spin-based computational devices. Such applications, however, require the realization of molecules with a substantial energy barrier for spin inversion, achieved through a large axial magnetic anisotropy. Recently, significant progress has been made in this regard by using lanthanide centres such as terbium(III) and dysprosium(III), whose anisotropy can lead to extremely high relaxation barriers. We contend that similar effects should be achievable with transition metals by maintaining a low coordination number to restrict the magnitude of the d-orbital ligand-field splitting energy (which tends to hinder the development of large anisotropies). Herein we report the first two-coordinate complex of iron(I), [Fe(C(SiMe3)3)2](-), for which alternating current magnetic susceptibility measurements reveal slow magnetic relaxation below 29 K in a zero applied direct-current field. This S = complex exhibits an effective spin-reversal barrier of Ueff = 226(4) cm(-1), the largest yet observed for a single-molecule magnet based on a transition metal, and displays magnetic blocking below 4.5 K.
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Affiliation(s)
- Joseph M Zadrozny
- Department of Chemistry, University of California, Berkeley, California 94720-1460, USA
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