1
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Liu L, Johnson SI, Appel AM, Bullock RM. Oxidation of Ammonia Catalyzed by a Molecular Iron Complex: Translating Chemical Catalysis to Mediated Electrocatalysis. Angew Chem Int Ed Engl 2024; 63:e202402635. [PMID: 38981858 DOI: 10.1002/anie.202402635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 07/08/2024] [Accepted: 07/09/2024] [Indexed: 07/11/2024]
Abstract
Ammonia is a promising candidate in the quest for sustainable, clean energy. With its capacity to serve as an energy carrier, the oxidation of ammonia opens avenues for carbon-neutral approaches to address worldwide growing energy needs. We report the catalytic chemical oxidation of ammonia by an Earth-abundant transition metal complex, trans-[LFeII(MeCN)2][PF6]2, where L is a macrocyclic ligand bearing four N-heterocyclic carbene (NHC) donors. Using triarylaminium radical cations in MeCN, up to 182 turnovers of N2 per Fe were obtained from chemical catalysis with an extremely low loading of the Fe catalyst (0.043 mM, 0.004 mol % catalyst). This chemical catalysis was successfully transitioned to mediated electrocatalysis for the oxidation of ammonia. Molecular electrocatalysis by the Fe catalyst and the mediator (p-MeOC6H4)3N exhibited a catalytic half-wave potential (Ecat/2) of 0.18 V vs [Cp2Fe]+/0 in MeCN, and achieved 9.3 turnovers of N2 at an applied potential of 0.20 V vs [Cp2Fe]+/0 at -20 °C in controlled-potential electrolysis, with a Faradaic efficiency of 75 %. Based on computational results, the catalyst undergoes sequential oxidation and deprotonation steps to form [LFeIV(NH2)2]2+, and thereafter bimetallic coupling to form an N-N bond.
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Affiliation(s)
- Liang Liu
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington, 99352, USA
- Current address: College of Chemistry, Central China Normal University, Wuhan, Hubei, 430079, P. R. China
| | - Samantha I Johnson
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington, 99352, USA
| | - Aaron M Appel
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington, 99352, USA
| | - R Morris Bullock
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington, 99352, USA
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2
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Hüppe HM, Iffland-Mühlhaus L, Heck J, Eilers M, Gildenast H, Schönfeld S, Dürrmann A, Hoffmann A, Weber B, Apfel UP, Herres-Pawlis S. Triflate vs Acetonitrile: Understanding the Iron(II)-Based Coordination Chemistry of Tri(quinolin-8-yl)amine. Inorg Chem 2023; 62:4435-4455. [PMID: 36888965 DOI: 10.1021/acs.inorgchem.2c03890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/10/2023]
Abstract
In this study, a synthesis route of tri(quinolin-8-yl)amine (L), a recent member of the tetradentate tris(2-pyridylmethyl)amine (TPA) ligand family, is reported. With the neutral ligand L bound to an iron(II) center in κ4 mode, two cis-oriented coordination sites remain vacant. These can be occupied by coligands such as counterions and solvent molecules. How sensitive this equilibrium can be is most evident if both triflate anions and acetonitrile molecules are available. All three combinations─bis(triflato), bis(acetonitrile), and mixed coligand species─could be characterized by single-crystal X-ray diffraction (SCXRD), which is unique so far for this class of ligand. While at room temperature, the three compounds tend to crystallize concomitantly, the equilibrium can be shifted in favor of the bis(acetonitrile) species by lowering the crystallization temperature. Removed from their mother liquor, the latter is very sensitive to evaporation of the residual solvent, which was observed by powder X-ray diffraction (PXRD) and Mössbauer spectroscopy. The solution behavior of the triflate and acetonitrile species was studied in detail using time- and temperature-resolved UV/vis spectroscopy, Mössbauer spectroscopy of frozen solution, NMR spectroscopy, and magnetic susceptibility measurements. The results indicate a bis(acetonitrile) species in acetonitrile showing a temperature-dependent spin-switching behavior between high- and low-spin. In dichloromethane, the results reveal a high-spin bis(triflato) species. In pursuit of understanding the coordination environment equilibria of the [Fe(L)]2+ complex, a series of compounds with different coligands was prepared and analyzed with SCXRD. The crystal structures indicate that the spin state can be controlled by changing the coordination environment─all of the {N6}-coordinated complexes display geometries expected for low-spin species, while any other donor atom in the coligand position induces a shift to the high-spin state. This fundamental study sheds light on the coligand competition of triflate and acetonitrile, and the high number of crystal structures allows further insights into the influence of different coligands on the geometry and spin state of the complexes.
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Affiliation(s)
- Henrika M Hüppe
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany
| | - Linda Iffland-Mühlhaus
- Inorganic Chemistry I, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | - Joshua Heck
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany
| | - Maverick Eilers
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany
| | - Hans Gildenast
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany
| | - Sophie Schönfeld
- Department of Chemistry, Inorganic Chemistry IV, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany
| | - Andreas Dürrmann
- Department of Chemistry, Inorganic Chemistry IV, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany
| | - Alexander Hoffmann
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany
| | - Birgit Weber
- Department of Chemistry, Inorganic Chemistry IV, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany
| | - Ulf-Peter Apfel
- Inorganic Chemistry I, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany.,Fraunhofer UMSICHT, Osterfelder Straße 3, 46047 Oberhausen, Germany
| | - Sonja Herres-Pawlis
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany
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3
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Livesay BN, Shores MP. Influence of Coordinated Triflate Anions on the Solution Magnetic Properties of a Neutral Iron(II) Complex. Inorg Chem 2021; 60:15445-15455. [PMID: 34596394 DOI: 10.1021/acs.inorgchem.1c02112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In an effort to probe the impacts of speciation on spin-state switching, the synthesis and unique solution-phase magnetic properties of [((TIPSC≡C)3tren)Fe(OTf)2] (1) are described. Analysis of the single-crystal X-ray diffraction data shows that the tris(iminoalkyne) ligand coordinates to the iron(II) center through all four nitrogen atoms, while the other two coordination sites are filled by the oxygen atoms from triflate anions. Solid-state variable-temperature (VT) magnetic studies show that 1 remains high-spin (HS) at all temperatures. In the presence of moderately strong coordinating solvents, solvent replaces the two bound triflate counteranions, as observed by 19F NMR spectroscopy and supported by conductivity measurements. VT solution measurements show 1 to be in the HS state when this solvent is oxygen-donating but low-spin (LS) with a nitrogen-donating solvent. In the noncoordinating solvent dichloromethane, both triflates are bound to the iron(II) center at room temperature, but upon cooling, 1 undergoes a coordination change, resulting in the loss of one triflate, as shown by 19F NMR. With the moderately coordinating solvent acetone, triflate dissociation upon cooling results in a spin-switching species with a T1/2 value of 171 K, characterized via 19F NMR, Evans' method, and solution magnetometry measurements. Solution magnetic measurements collected in structurally similar cyclopentanone suggest that the spin-state switching event is exclusive to the acetone environment, suggesting the influence of both the local coordination environment and aggregation. Additionally, a comparison of the solvodoynamic diameters via dynamic light scattering suggests that aggregation of 1 is significantly different in (CH3)2CO and (CD3)2CO, leading to the observation of spin-switching behavior in the former and fully HS behavior in the latter. This study highlights the sensitivity of solution magnetic properties to solvent choice.
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Affiliation(s)
- Brooke N Livesay
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Matthew P Shores
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
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4
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Castillo CE, Gamba I, Vicens L, Clémancey M, Latour JM, Costas M, Basallote MG. Spin State Tunes Oxygen Atom Transfer towards Fe IV O Formation in Fe II Complexes. Chemistry 2021; 27:4946-4954. [PMID: 33350013 DOI: 10.1002/chem.202004921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Indexed: 11/08/2022]
Abstract
Oxoiron(IV) complexes bearing tetradentate ligands have been extensively studied as models for the active oxidants in non-heme iron-dependent enzymes. These species are commonly generated by oxidation of their ferrous precursors. The mechanisms of these reactions have seldom been investigated. In this work, the reaction kinetics of complexes [FeII (CH3 CN)2 L](SbF6 )2 ([1](SbF6 )2 and [2](SbF6 )2 ) and [FeII (CF3 SO3 )2 L] ([1](OTf)2 and [2](OTf)2 (1, L=Me,H Pytacn; 2, L=nP,H Pytacn; R,R' Pytacn=1-[(6-R'-2-pyridyl)methyl]-4,7- di-R-1,4,7-triazacyclononane) with Bu4 NIO4 to form the corresponding [FeIV (O)(CH3 CN)L]2+ (3, L=Me,H Pytacn; 4, L=nP,H Pytacn) species was studied in acetonitrile/acetone at low temperatures. The reactions occur in a single kinetic step with activation parameters independent of the nature of the anion and similar to those obtained for the substitution reaction with Cl- as entering ligand, which indicates that formation of [FeIV (O)(CH3 CN)L]2+ is kinetically controlled by substitution in the starting complex to form [FeII (IO4 )(CH3 CN)L]+ intermediates that are converted rapidly to oxo complexes 3 and 4. The kinetics of the reaction is strongly dependent on the spin state of the starting complex. A detailed analysis of the magnetic susceptibility and kinetic data for the triflate complexes reveals that the experimental values of the activation parameters for both complexes are the result of partial compensation of the contributions from the thermodynamic parameters for the spin-crossover equilibrium and the activation parameters for substitution. The observation of these opposite and compensating effects by modifying the steric hindrance at the ligand illustrates so far unconsidered factors governing the mechanism of oxygen atom transfer leading to high-valent iron oxo species.
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Affiliation(s)
- Carmen E Castillo
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica, y Química Inorgánica, Facultad de Ciencias, Instituto de Biomoléculas (INBIO), Universidad de Cádiz, Puerto Real, Cádiz, 11510, Spain
| | - Ilaria Gamba
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus de Montilivi, Girona, 17071, Catalonia, Spain
| | - Laia Vicens
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus de Montilivi, Girona, 17071, Catalonia, Spain
| | - Martin Clémancey
- CEA, CNRS, IRIG, DIESE, LCBM, Université Grenoble Alpes, pmb, 38000, Grenoble, France
| | - Jean-Marc Latour
- CEA, CNRS, IRIG, DIESE, LCBM, Université Grenoble Alpes, pmb, 38000, Grenoble, France
| | - Miquel Costas
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus de Montilivi, Girona, 17071, Catalonia, Spain
| | - Manuel G Basallote
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica, y Química Inorgánica, Facultad de Ciencias, Instituto de Biomoléculas (INBIO), Universidad de Cádiz, Puerto Real, Cádiz, 11510, Spain
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5
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Keisers K, Hüppe HM, Iffland-Mühlhaus L, Hoffmann A, Göbel C, Apfel UP, Weber B, Herres-Pawlis S. Interplay of Spin Crossover and Coordination-Induced Spin State Switch for Iron Bis(pyrazolyl)methanes in Solution. Inorg Chem 2020; 59:15343-15354. [PMID: 33002361 DOI: 10.1021/acs.inorgchem.0c02306] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Bis(pyrazolyl)bipyridinylmethane iron(II) complexes show a versatile spin state switching behavior in different solvents. In the solid, the magnetic properties of the compounds have been characterized by X-ray diffraction, Mößbauer spectroscopy, and SQUID magnetometry and point toward a high spin state. For nitrilic solvents, the solvation of the complexes leads to a change of the coordination environment from {N5O} to {N6} and results in a temperature-dependent SCO behavior. Thermodynamic properties of this transformation are obtained via UV/vis spectroscopy, SQUID measurements, and the Evans NMR method. Moreover, a coordination-induced spin state switch (CISSS) to low spin is observed by using methanol as solvent, triggered through a rearrangement of the coordination sphere. The same behavior can be observed by changing the stoichiometry of the ligand-to-metal ratio in MeCN, where the process is reversible. This transformation is monitored via UV/vis spectroscopy, and the resulting new bis-meridional coordination motif, first described for bis(pyrazolyl)methanes, is characterized in the solid state via X-ray diffraction, Mößbauer spectroscopy, and SQUID measurements. The sophisticated correlation of these switchable properties in dependence on different types of solvents reveals that the influence of the solvent on the coordination environment and magnetic properties should not be underestimated. Furthermore, careful investigation is necessary to differentiate between a thermally-induced spin crossover and a coordination-induced spin state switch.
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Affiliation(s)
- Kristina Keisers
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany
| | - Henrika M Hüppe
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany
| | - Linda Iffland-Mühlhaus
- Inorganic Chemistry I, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | - Alexander Hoffmann
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany
| | - Christoph Göbel
- Department of Chemistry, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany
| | - Ulf-Peter Apfel
- Inorganic Chemistry I, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany.,Fraunhofer UMSICHT, Osterfelder Straße 3, 46047 Oberhausen, Germany
| | - Birgit Weber
- Department of Chemistry, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany
| | - Sonja Herres-Pawlis
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany
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6
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Abstract
We report herein on five new Fe(II) complexes of general formula [Fe(L)2(NCCH3)2](BF4)2•xCH3CN (L = substituted 2-pyridylimine-based ligands). The influence of proximally located electron withdrawing groups (e.g., NO2, CN, CF3, Cl, Br) bound to coordinated pyridylimine ligands has been studied for the effect on spin crossover in their Fe(II) complexes. Variable-temperature UV-visible spectroscopic studies performed on complexes with more strongly electronegative ligand substituents revealed spin crossover (SCO) in the solution, and thermodynamic parameters associated with the spin crossover were estimated.
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7
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Khusniyarov MM. How to Switch Spin-Crossover Metal Complexes at Constant Room Temperature. Chemistry 2016; 22:15178-15191. [DOI: 10.1002/chem.201601140] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Indexed: 12/27/2022]
Affiliation(s)
- Marat M. Khusniyarov
- Department of Chemistry and Pharmacy; Friedrich-Alexander University Erlangen-Nürnberg (FAU); Egerlandstr. 1 91058 Erlangen Germany
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8
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Petzold H, Djomgoue P, Hörner G, Speck JM, Rüffer T, Schaarschmidt D. (1)H NMR spectroscopic elucidation in solution of the kinetics and thermodynamics of spin crossover for an exceptionally robust Fe(2+) complex. Dalton Trans 2016; 45:13798-809. [PMID: 27506162 DOI: 10.1039/c6dt01895e] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of Fe(2+) spin crossover (SCO) complexes [Fe(5/6)](2+) employing hexadentate ligands (5/6) with cis/trans-1,2-diamino cyclohexanes (4) as central building blocks were synthesised. The ligands were obtained by reductive amination of 4 with 2,2'-bipyridyl-6-carbaldehyde or 1,10-phenanthroline-2-carbaldehyde 3. The chelating effect and the rigid structure of the ligands 5/6 lead to exceptionally robust Fe(2+) and Zn(2+) complexes conserving their structure even in coordinating solvents like dmso at high temperatures. Their solution behavior was investigated using variable temperature (VT) (1)H NMR spectroscopy and VT Vis spectroscopy. SCO behavior was found for all Fe(2+) complexes in this series centred around and far above room temperature. For the first time we have demonstrated that the thermodynamics as well as kinetics for SCO can be deduced by using VT (1)H NMR spectroscopy. An alternative scheme using a linear correction term C(1) to model chemical shifts for Fe(2+) SCO complexes is presented. The rate constant for the SCO of [Fe(rac-trans-5)](2+) obtained by VT (1)H NMR was validated by Laser Flash Photolysis (LFP), with excellent agreement (1/(kHL + kLH) = 33.7/35.8 ns for NMR/LFP). The solvent dependence of the transition temperature T1/2 and the solvatochromism of complex [Fe(rac-trans-5)](2+) were ascribed to hydrogen bond formation of the secondary amine to the solvent. Enantiomerically pure complexes can be prepared starting with R,R- or S,S-1,2-diaminocyclohexane (R,R-trans-4 or S,S-trans-4). The high robustness of the complexes reduces a possible ligand scrambling and allows preparation of quasiracemic crystals of [Zn(R,R-5)][Fe(S,S-5)](ClO4)4·(CH3CN) composed of a 1 : 1 mixture of the Zn and Fe complexes with inverse chirality.
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Affiliation(s)
- Holm Petzold
- TU Chemnitz, Institut für Chemie, Anorganische Chemie, Straße der Nationen 62, 09111 Chemnitz, Germany.
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9
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England J, Prakash J, Cranswick MA, Mandal D, Guo Y, Münck E, Shaik S, Que L. Oxoiron(IV) Complex of the Ethylene-Bridged Dialkylcyclam Ligand Me2EBC. Inorg Chem 2015; 54:7828-39. [PMID: 26244657 DOI: 10.1021/acs.inorgchem.5b00861] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We report herein the first example of an oxoiron(IV) complex of an ethylene-bridged dialkylcyclam ligand, [Fe(IV)(O)(Me2EBC)(NCMe)](2+) (2; Me2EBC = 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane). Complex 2 has been characterized by UV-vis, (1)H NMR, resonance Raman, Mössbauer, and X-ray absorption spectroscopy as well as electrospray ionization mass spectrometry, and its properties have been compared with those of the closely related [Fe(IV)(O)(TMC)(NCMe)](2+) (3; TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), the intensively studied prototypical oxoiron(IV) complex of the macrocyclic tetramethylcyclam ligand. Me2EBC has an N4 donor set nearly identical with that of TMC but possesses an ethylene bridge in place of the 1- and 8-methyl groups of TMC. As a consequence, Me2EBC is forced to deviate from the trans-I configuration typically found for Fe(IV)(O)(TMC) complexes and instead adopts a folded cis-V stereochemistry that requires the MeCN ligand to coordinate cis to the Fe(IV)═O unit in 2 rather than in the trans arrangement found in 3. However, switching from the trans geometry of 3 to the cis geometry of 2 did not significantly affect their ground-state electronic structures, although a decrease in ν(Fe═O) was observed for 2. Remarkably, despite having comparable Fe(IV/III) reduction potentials, 2 was found to be significantly more reactive than 3 in both oxygen-atom-transfer (OAT) and hydrogen-atom-transfer (HAT) reactions. A careful analysis of density functional theory calculations on the HAT reactivity of 2 and 3 revealed the root cause to be the higher oxyl character of 2, leading to a stronger O---H bond specifically in the quintet transition state.
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Affiliation(s)
- Jason England
- †Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Jai Prakash
- †Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Matthew A Cranswick
- †Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Debasish Mandal
- §Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Yisong Guo
- ‡Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Eckard Münck
- ‡Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Sason Shaik
- §Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Lawrence Que
- †Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
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10
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Borgogno A, Rastrelli F, Bagno A. Characterization of Paramagnetic Reactive Intermediates: Predicting the NMR Spectra of Iron(IV)-Oxo Complexes by DFT. Chemistry 2015; 21:12960-70. [PMID: 26235229 DOI: 10.1002/chem.201500864] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Indexed: 11/06/2022]
Abstract
The relative energies of spin states of several iron(IV)-oxo complexes and related species have been calculated with DFT methods by employing the B3LYP* functional. We show that such calculations can predict the correct ground spin state of Fe(IV) complexes and can then be used to determine the (1) H NMR spectra of all spin states; the spectral features are remarkably different, hence calculated paramagnetic (1) H NMR spectra can be used to support the structure elucidation of numerous paramagnetic complexes. Applications to a number of stable and reactive iron(IV)-oxo species are described.
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Affiliation(s)
- Andrea Borgogno
- Department of Chemical Sciences, University of Padova via Marzolo 1, 35131 Padova (Italy)
| | - Federico Rastrelli
- Department of Chemical Sciences, University of Padova via Marzolo 1, 35131 Padova (Italy).
| | - Alessandro Bagno
- Department of Chemical Sciences, University of Padova via Marzolo 1, 35131 Padova (Italy)
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11
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Spin state behavior of iron(II)/dipyrazolylpyridine complexes. New insights from crystallographic and solution measurements. Coord Chem Rev 2015. [DOI: 10.1016/j.ccr.2014.08.006] [Citation(s) in RCA: 152] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Samanta S, Demesko S, Dechert S, Meyer F. A two-in-one pincer ligand and its diiron(II) complex showing spin state switching in solution through reversible ligand exchange. Angew Chem Int Ed Engl 2015; 54:583-7. [PMID: 25412962 DOI: 10.1002/anie.201408966] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Indexed: 11/09/2022]
Abstract
A novel pyrazolate-bridged ligand providing two {PNN} pincer-type compartments has been synthesized. Its diiron(II) complex LFe2(OTf)3(CH3CN) (1; Tf = triflate) features, in solid state, two bridging triflate ligands, with a terminal triflate and a MeCN ligand completing the octahedral coordination spheres of the two high-spin metal ions. In MeCN solution, 1 is shown to undergo a sequential, reversible, and complete spin transition to the low-spin state upon cooling. Detailed UV/Vis and (19)F NMR spectroscopic studies as well as magnetic measurements have unraveled that spin state switching correlates with a rapid multistep triflate/MeCN ligand exchange equilibrium. The spin transition temperature can be continuously tuned by varying the triflate concentration in solution.
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Affiliation(s)
- Subhas Samanta
- Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstrasse 4, 37077 Göttingen (Germany) http://www.meyer.chemie.uni-goettingen.de
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13
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Roux Y, Ghattas W, Avenier F, Guillot R, Simaan AJ, Mahy JP. Synthesis and characterization of [Fe(BPMEN)ACC]SbF6: a structural and functional mimic of ACC-oxidase. Dalton Trans 2015; 44:5966-8. [DOI: 10.1039/c5dt00347d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Miming plants: an original synthesis led to the preparation of the first model of the active site of the ethylene-forming enzyme ACC-oxidase. The prepared complex is a structural and a functional model as it reacts with hydrogen peroxide to produce the phytohormone ethylene.
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Affiliation(s)
- Y. Roux
- Institut de Chimie Moléculaire et des Matériaux d'Orsay
- Université Paris Sud
- Orsay 91405 CEDEX
- France
| | - W. Ghattas
- Institut de Chimie Moléculaire et des Matériaux d'Orsay
- Université Paris Sud
- Orsay 91405 CEDEX
- France
| | - F. Avenier
- Institut de Chimie Moléculaire et des Matériaux d'Orsay
- Université Paris Sud
- Orsay 91405 CEDEX
- France
| | - R. Guillot
- Institut de Chimie Moléculaire et des Matériaux d'Orsay
- Université Paris Sud
- Orsay 91405 CEDEX
- France
| | - A. J. Simaan
- Aix Marseille Université
- Centrale Marseille
- 13397, Marseille
- France
| | - J.-P. Mahy
- Institut de Chimie Moléculaire et des Matériaux d'Orsay
- Université Paris Sud
- Orsay 91405 CEDEX
- France
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Samanta S, Demesko S, Dechert S, Meyer F. A Two-in-one Pincer Ligand and its Diiron(II) Complex Showing Spin State Switching in Solution through Reversible Ligand Exchange. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201408966] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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15
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Grau M, Kyriacou A, Cabedo Martinez F, de Wispelaere IM, White AJP, Britovsek GJP. Unraveling the origins of catalyst degradation in non-heme iron-based alkane oxidation. Dalton Trans 2014; 43:17108-19. [DOI: 10.1039/c4dt02067g] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of iron(ii) complexes with tetradentate and pentadentate pyridyl amine ligands has been used for the oxidation of cyclohexane with hydrogen peroxide. Ligand degradation is observed under oxidising conditions via oxidative N-dealkylation.
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Affiliation(s)
- Michaela Grau
- Department of Chemistry
- Imperial College London
- London, UK
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16
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Hasserodt J, Kolanowski JL, Touti F. Magnetogenese in Wasser, ausgelöst durch einen chemischen Analyten. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201305662] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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17
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Hasserodt J, Kolanowski JL, Touti F. Magnetogenesis in Water Induced by a Chemical Analyte. Angew Chem Int Ed Engl 2013; 53:60-73. [DOI: 10.1002/anie.201305662] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Indexed: 11/12/2022]
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18
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Prat I, Company A, Corona T, Parella T, Ribas X, Costas M. Assessing the Impact of Electronic and Steric Tuning of the Ligand in the Spin State and Catalytic Oxidation Ability of the FeII(Pytacn) Family of Complexes. Inorg Chem 2013; 52:9229-44. [DOI: 10.1021/ic4004033] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Irene Prat
- Grup de Química Bioinorgànica
i Supramolecular (QBIS), Institut de Química Computacional
i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, E17071 Girona,
Catalonia, Spain
| | - Anna Company
- Grup de Química Bioinorgànica
i Supramolecular (QBIS), Institut de Química Computacional
i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, E17071 Girona,
Catalonia, Spain
| | - Teresa Corona
- Grup de Química Bioinorgànica
i Supramolecular (QBIS), Institut de Química Computacional
i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, E17071 Girona,
Catalonia, Spain
| | - Teodor Parella
- Servei
de Ressonància
Magnètica Nuclear, Universitat Autònoma de Barcelona, Bellaterra, E08193 Barcelona, Catalonia,
Spain
| | - Xavi Ribas
- Grup de Química Bioinorgànica
i Supramolecular (QBIS), Institut de Química Computacional
i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, E17071 Girona,
Catalonia, Spain
| | - Miquel Costas
- Grup de Química Bioinorgànica
i Supramolecular (QBIS), Institut de Química Computacional
i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, E17071 Girona,
Catalonia, Spain
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Kolanowski JL, Jeanneau E, Steinhoff R, Hasserodt J. Bispidine Platform Grants Full Control over Magnetic State of Ferrous Chelates in Water. Chemistry 2013; 19:8839-49. [DOI: 10.1002/chem.201300604] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Indexed: 11/11/2022]
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20
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Knight JC, Prabaharan R, Amoroso AJ, Edwards PG, Ooi LL. Synthesis and co-ordination chemistry of tris(picolyl-2-carboxyamido-6-pyridyl) methanol: A ligand with a strong preference for trigonal prismatic geometries. Polyhedron 2012. [DOI: 10.1016/j.poly.2011.09.040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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21
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Shejwalkar P, Rath NP, Bauer EB. New iron(ii) α-iminopyridine complexes and their catalytic activity in the oxidation of activated methylene groups and secondary alcohols to ketones. Dalton Trans 2011; 40:7617-31. [DOI: 10.1039/c1dt10387c] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Ni Z, Shores MP. Supramolecular Effects on Anion-Dependent Spin-State Switching Properties in Heteroleptic Iron(II) Complexes. Inorg Chem 2010; 49:10727-35. [DOI: 10.1021/ic102004c] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zhaoping Ni
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, United States
| | - Matthew P. Shores
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, United States
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Ni Z, McDaniel AM, Shores MP. Ambient temperature anion-dependent spin state switching observed in “mostly low spin” heteroleptic iron(ii) diimine complexes. Chem Sci 2010. [DOI: 10.1039/c0sc00303d] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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24
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England J, Gondhia R, Bigorra-Lopez L, Petersen AR, White AJP, Britovsek GJP. Towards robust alkane oxidation catalysts: electronic variations in non-heme iron(ii) complexes and their effect in catalytic alkane oxidation. Dalton Trans 2009:5319-34. [DOI: 10.1039/b901390c] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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25
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Duban EA, Brylyakov KP, Talsi EP. The nature of active species in catalytic systems based on non-heme iron complexes, hydrogen peroxide, and acetic acid for selective olefin epoxidation. KINETICS AND CATALYSIS 2008. [DOI: 10.1134/s0023158408030099] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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26
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England J, Davies C, Banaru M, White AJ, Britovsek GJ. Catalyst Stability Determines the Catalytic Activity of Non-Heme Iron Catalysts in the Oxidation of Alkanes. Adv Synth Catal 2008. [DOI: 10.1002/adsc.200700462] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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27
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Halcrow MA. The spin-states and spin-transitions of mononuclear iron(II) complexes of nitrogen-donor ligands. Polyhedron 2007. [DOI: 10.1016/j.poly.2007.03.033] [Citation(s) in RCA: 270] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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28
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Duban EA, Bryliakov KP, Talsi EP. The Active Intermediates of Non-Heme-Iron-Based Systems for Catalytic Alkene Epoxidation with H2O2/CH3COOH. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200600895] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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29
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Mas-Ballesté R, Costas M, van den Berg T, Que L. Ligand Topology Effects on Olefin Oxidations by Bio-Inspired [FeII(N2Py2)] Catalysts. Chemistry 2006; 12:7489-500. [PMID: 16871511 DOI: 10.1002/chem.200600453] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Linear tetradentate N2Py2 ligands can coordinate to an octahedral FeII center in three possible topologies (cis-alpha, cis-beta, and trans). While for the N,N'-bis(2-pyridylmethyl)-1,2-diaminoethane (bpmen) complex, only the cis-alpha topology has been observed, for N,N'-bis(2-pyridylmethyl)-1,2-diaminocyclohexane (bpmcn) both cis-alpha and cis-beta isomers have been reported. To date, no facile interconversion between cis-alpha and cis-beta topologies has been observed for ironII complexes even at high temperatures. However, this work provides evidence for facile interconversion in solution of cis-alpha, cis-beta, and trans topologies for [Fe(bpmpn)X2] (bpmpn=N,N'-bis(2-pyridylmethyl)-1,3-diaminopropane; X=triflate, CH3CN) complexes. As reported previously, the catalytic behavior of cis-alpha and cis-beta isomers of [Fe(bpmcn)(OTf)2] with respect to olefin oxidation depends dramatically on the geometry adopted by the iron complex. To establish a general pattern of the catalysis/topology dependence, this work presents an extended comparison of the catalytic behavior for oxidation of olefins of a family of [Fe(N2py2)] complexes that present different topologies. 18O labeling experiments provide evidence for a complex mechanistic landscape in which several pathways should be considered. Complexes with a trans topology catalyze only non-water-assisted epoxidation. In contrast, complexes with a cis-alpha topology, such as [Fe(bpmen)X2] and [Fe(alpha-bpmcn)(OTf)2], can catalyze both epoxidation and cis-dihydroxylation through a water-assisted mechanism. Surprisingly, [Fe(bpmpn)X2] and [Fe(beta-bpmcn)(OTf)2] catalyze epoxidation via a water-assisted pathway and cis-dihydroxylation via a non-water-assisted mechanism, a result that requires two independent and distinct oxidants.
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Affiliation(s)
- Rubén Mas-Ballesté
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, USA
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