1
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Rydel-Ciszek K, Sobkowiak A. The [(Bn-tpen)Fe II] 2+ Complex as a Catalyst for the Oxidation of Cyclohexene and Limonene with Dioxygen. Molecules 2024; 29:3755. [PMID: 39202835 PMCID: PMC11357577 DOI: 10.3390/molecules29163755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Revised: 08/05/2024] [Accepted: 08/06/2024] [Indexed: 09/03/2024] Open
Abstract
[(Bn-tpen)FeII(MeCN)](ClO4)2, containing the pentadentate Bn-tpen-N-benzyl-N,N',N'-tris(2-pyridylmethyl)-1,2-diaminoethane ligand, was studied in the oxygenation of cyclohexene and limonene using low-pressure dioxygen (0.2 atm air or 1 atm pure O2) in acetonitrile. 2-Cyclohexen-1-one and 2-cyclohexen-1-ol are the main products of cyclohexene oxidations, with cyclohexene oxide as a minor product. Limonene is oxidized to limonene oxide, carvone, and carveol. Other oxidation products such as perillaldehyde and perillyl alcohol are found in trace amounts. This catalyst is slightly less active than the previously reported [(N4Py)FeII(MeCN)](ClO4)2 (N4Py-N,N-bis(2-pyridylmethyl)-N-(bis-2-pyridylmethyl)amine). Based on cyclic voltammetry experiments, it is postulated that [(Bn-tpen)FeIV=O]2+ is the active species. The induction period of approx. 3 h during cyclohexene oxygenation is probably caused by deactivation of the reactive Fe(IV)=O species by the parent Fe(II) complex. Equimolar mixtures of Fe(II) salt and the ligand (in situ-formed catalyst) gave catalytic performance similar to that of the synthesized catalyst.
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Affiliation(s)
- Katarzyna Rydel-Ciszek
- Department of Physical Chemistry, Faculty of Chemistry, Rzeszów University of Technology, Al. Powstańców Warszawy 6, 35-959 Rzeszów, Poland
| | - Andrzej Sobkowiak
- Department of Physical Chemistry, Faculty of Chemistry, Rzeszów University of Technology, Al. Powstańców Warszawy 6, 35-959 Rzeszów, Poland
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2
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Josephy T, Kumar R, Bleher K, Röhs F, Glaser T, Rajaraman G, Comba P. Synthesis, Characterization, and Reactivity of Bispidine-Iron(IV)-Tosylimido Species. Inorg Chem 2024; 63:12109-12119. [PMID: 38875304 DOI: 10.1021/acs.inorgchem.4c01237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2024]
Abstract
Reported are the synthesis and detailed studies of the iron(IV)-tosylimido complexes of two isomeric pentadentate bispidine ligands (bispidines are 3,7-diazabicyclo[3.3.1]nonane derivatives). This completes a series of five tosylimido complexes with comparable pentadentate amine/pyridine ligands, where the corresponding [(L)FeIV═O]2+ oxidants have been studied in detail. The characterization of the two new complexes in solution (UV-vis-NIR, Mössbauer, HR-ESI-MS) shows that these oxidants have an intermediate spin (S = 1) electronic ground state. The reactivities have been studied as oxidants in C-H activation at 1,3-cyclohexadiene and nitrogen atom transfer to thioanisole. For the latter substrate, the entire set of data for the five ligands and for both nitrogen and oxygen atom transfer is now available and the interesting observation is that oxygen atom transfer is, as expected, generally faster than nitrogen atom transfer, with the exception of the two ligands that have four and three pyridine groups oriented parallel to the Fe-O and Fe-N axes. A thorough DFT analysis indicates that this is due to steric effects in the case of the [(L)FeIV═O]2+ species, which are less important in the [(L)FeIV═NTs]2+ compounds due to partial electron transfer from the thioanisole substrate to the iron(IV)-tosylimido oxidant.
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Affiliation(s)
- Thomas Josephy
- Anorganisch-Chemisches Institut, Universität Heidelberg, INF 270,Heidelberg D-69120, Germany
| | - Ravi Kumar
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Katharina Bleher
- Anorganisch-Chemisches Institut, Universität Heidelberg, INF 270,Heidelberg D-69120, Germany
- Institute of Functional Interfaces, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen 76344, Germany
| | - Fridolin Röhs
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Thorsten Glaser
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Gopalan Rajaraman
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Peter Comba
- Anorganisch-Chemisches Institut, Universität Heidelberg, INF 270,Heidelberg D-69120, Germany
- Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), Universität Heidelberg, Heidelberg 69120, Germany
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3
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Fagnano A, Frateloreto F, Paoloni R, Sappino C, Lanzalunga O, Costas M, Di Stefano S, Olivo G. Proximity Effects on the Reactivity of a Nonheme Iron (IV) Oxo Complex in C-H Oxidation. Angew Chem Int Ed Engl 2024; 63:e202401694. [PMID: 38478739 DOI: 10.1002/anie.202401694] [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: 01/24/2024] [Indexed: 04/05/2024]
Abstract
Precise control of substrate positioning and orientation (its proximity to the reactive unit) is often invoked to rationalize the superior enzymatic reaction rates and selectivities when compared to synthetic models. Artificial nonheme iron (IV) oxo (Fe(IV)=O) complexes react with C(sp3)-H bonds via a biomimetic Hydrogen Atom Transfer/Hydroxyl Rebound mechanism, but rates, site-selectivity and even hydroxyl rebound efficiency (ligand rebound versus substrate radical diffusion) are smaller than in oxygenases. Herein, we quantitatively analyze how substrate binding modulates nonheme Fe(IV)=O reactivity by comparing rates and outcomes of C-H oxidation by a pair of Fe(IV)=O complexes that share the same first coordination sphere but only one contains a crown ether receptor that recognizes the substrate. Substrate binding makes the reaction intramolecular, exhibiting Michaelis-Menten kinetics and increased reaction rates. In addition, C-H oxidation occurs with high site selectivity for remote sites. Analysis of Effective Molarity reveals that the system operates at its maximal theoretical capability for the oxidation of these remote sites. Remarkably, substrate positioning also affects Hydroxyl Rebound, whose efficiency only increases on the sites placed in proximity by recognition. Overall, these observations provide evidence that supramolecular control of substrate positioning can effectively modulate the reactivity of oxygenases and its models.
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Affiliation(s)
- Alessandro Fagnano
- Dipartimento di Chimica and Istituto CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione, c/o Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro, 5 I-00185, Rome, Italy
| | - Federico Frateloreto
- Dipartimento di Chimica and Istituto CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione, c/o Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro, 5 I-00185, Rome, Italy
| | - Roberta Paoloni
- Dipartimento di Chimica and Istituto CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione, c/o Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro, 5 I-00185, Rome, Italy
| | - Carla Sappino
- Dipartimento di Chimica and Istituto CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione, c/o Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro, 5 I-00185, Rome, Italy
| | - Osvaldo Lanzalunga
- Dipartimento di Chimica and Istituto CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione, c/o Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro, 5 I-00185, Rome, Italy
| | - Miquel Costas
- QBIS-Cat, Institut de Química Computacional i Catàlisi (IQCC), Departament de Quimica, Universitat de Girona Campus Montilivi, 17071, Girona, Catalonia, Spain
| | - Stefano Di Stefano
- Dipartimento di Chimica and Istituto CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione, c/o Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro, 5 I-00185, Rome, Italy
| | - Giorgio Olivo
- Dipartimento di Chimica and Istituto CNR per i Sistemi Biologici (ISB-CNR), Sezione Meccanismi di Reazione, c/o Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro, 5 I-00185, Rome, Italy
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4
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Chandra B, Ahsan F, Sheng Y, Swart M, Que L. A tale of two topological isomers: Uptuning [Fe IV(O)(Me 4cyclam)] 2+ for olefin epoxidation. Proc Natl Acad Sci U S A 2024; 121:e2319799121. [PMID: 38478690 PMCID: PMC10962992 DOI: 10.1073/pnas.2319799121] [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: 11/15/2023] [Accepted: 01/30/2024] [Indexed: 03/27/2024] Open
Abstract
TMC-anti and TMC-syn, the two topological isomers of [FeIV(O)(TMC)(CH3CN)]2+ (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, or Me4cyclam), differ in the orientations of their FeIV=O units relative to the four methyl groups of the TMC ligand framework. The FeIV=O unit of TMC-anti points away from the four methyl groups, while that of TMC-syn is surrounded by the methyl groups, resulting in differences in their oxidative reactivities. TMC-syn reacts with HAT (hydrogen atom transfer) substrates at 1.3- to 3-fold faster rates than TMC-anti, but the reactivity difference increases dramatically in oxygen-atom transfer reactions. R2S substrates are oxidized into R2S=O products at rates 2-to-3 orders of magnitude faster by TMC-syn than TMC-anti. Even more remarkably, TMC-syn epoxidizes all the olefin substrates in this study, while TMC-anti reacts only with cis-cyclooctene but at a 100-fold slower rate. Comprehensive quantum chemical calculations have uncovered the key factors governing such reactivity differences found between these two topological isomers.
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Affiliation(s)
- Bittu Chandra
- Department of Chemistry, University of Minnesota, Minneapolis, MN55455
| | - Faiza Ahsan
- Institut de Química Computacional i Catàlisi and Department of Chemistry, University of Girona, 17003Girona, Spain
| | - Yuan Sheng
- Department of Chemistry, University of Minnesota, Minneapolis, MN55455
| | - Marcel Swart
- Institut de Química Computacional i Catàlisi and Department of Chemistry, University of Girona, 17003Girona, Spain
- ICREA, 08010Barcelona, Spain
| | - Lawrence Que
- Department of Chemistry, University of Minnesota, Minneapolis, MN55455
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5
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Kumar R, Ansari A, Comba P, Rajaraman G. Rebound or Cage Escape? The Role of the Rebound Barrier for the Reactivity of Non-Heme High-Valent Fe IV =O Species. Chemistry 2024; 30:e202303300. [PMID: 37929771 DOI: 10.1002/chem.202303300] [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: 10/09/2023] [Revised: 11/03/2023] [Accepted: 11/06/2023] [Indexed: 11/07/2023]
Abstract
Owing to their high reactivity and selectivity, variations in the spin ground state and a range of possible pathways, high-valent FeIV =O species are popular models with potential bioinspired applications. An interesting example of a structure-reactivity pattern is the detailed study with five nonheme amine-pyridine pentadentate ligand FeIV =O species, including N4py: [(L1 )FeIV =O]2+ (1), bntpen: [(L2 )FeIV =O]2+ (2), py2 tacn: [(L3 )FeIV =O]2+ (3), and two isomeric bispidine derivatives: [(L4 )FeIV =O]2+ (4) and [(L5 )FeIV =O]2+ (5). In this set, the order of increasing reactivity in the hydroxylation of cyclohexane differs from that with cyclohexadiene as substrate. A comprehensive DFT, ab initio CASSCF/NEVPT2 and DLPNO-CCSD(T) study is presented to untangle the observed patterns. These are well reproduced when both activation barriers for the C-H abstraction and the OH rebound are taken into account. An MO, NBO and deformation energy analysis reveals the importance of π(pyr) → π*xz (FeIII -OH) electron donation for weakening the FeIII -OH bond and thus reducing the rebound barrier. This requires that pyridine rings are oriented perpendicularly to the FeIII -OH bond and this is a subtle but crucial point in ligand design for non-heme iron alkane hydroxylation.
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Affiliation(s)
- Ravi Kumar
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, Powai, 400076, India
| | - Azaj Ansari
- Department of Chemistry, Central University of Haryana, Haryana, 123031, India
| | - Peter Comba
- Institute of Inorganic Chemistry &, Interdisciplinary Center for Scientific Computing, Heidelberg University, 69120, Heidelberg, Germany
| | - Gopalan Rajaraman
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, Powai, 400076, India
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6
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Mukherjee G, Velmurugan G, Kerscher M, Kumar Satpathy J, Sastri CV, Comba P. Mechanistic Insights into Amphoteric Reactivity of an Iron-Bispidine Complex. Chemistry 2024; 30:e202303127. [PMID: 37942658 DOI: 10.1002/chem.202303127] [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: 09/26/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 11/10/2023]
Abstract
The reactivity of FeIII -alkylperoxido complexes has remained a riddle to inorganic chemists owing to their thermal instability and impotency towards organic substrates. These iron-oxygen adducts have been known as sluggish oxidants towards oxidative electrophilic and nucleophilic reactions. Herein, we report the synthesis and spectroscopic characterization of a relatively stable mononuclear high-spin FeIII -alkylperoxido complex supported by an engineered bispidine framework. Against the notion, this FeIII -alkylperoxido complex serves as a rare example of versatile reactivity in both electrophilic and nucleophilic reactions. Detailed mechanistic studies and computational calculations reveal a novel reaction mechanism, where a putative superoxido intermediate orchestrates the amphoteric property of the oxidant. The design of the backbone is pivotal to convey stability and reactivity to alkylperoxido and superoxido intermediates. Contrary to the well-known O-O bond cleavage that generates an FeIV -oxido species, the FeIII -alkylperoxido complex reported here undergoes O-C bond scission to generate a superoxido moiety that is responsible for the amphiphilic reactivity.
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Affiliation(s)
- Gourab Mukherjee
- Department of Catalysis & Fine Chemicals, CSIR-Indian Institute of Chemical Technology Tarnaka, Hyderabad, 500007, India
| | - Gunasekaran Velmurugan
- Anorganisch-Chemisches Institut and, Interdisciplinary Center for Scientific Computing (IWR), Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany)
| | - Marion Kerscher
- Anorganisch-Chemisches Institut and, Interdisciplinary Center for Scientific Computing (IWR), Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany)
| | - Jagnyesh Kumar Satpathy
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam, 781039, India
| | - Chivukula V Sastri
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam, 781039, India
| | - Peter Comba
- Anorganisch-Chemisches Institut and, Interdisciplinary Center for Scientific Computing (IWR), Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany)
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7
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Li Y, Singh R, Sinha A, Lisensky GC, Haukka M, Nilsson J, Yiga S, Demeshko S, Gross SJ, Dechert S, Gonzalez A, Farias G, Wendt OF, Meyer F, Nordlander E. Nonheme Fe IV═O Complexes Supported by Four Pentadentate Ligands: Reactivity toward H- and O- Atom Transfer Processes. Inorg Chem 2023; 62:18338-18356. [PMID: 37913548 PMCID: PMC10647104 DOI: 10.1021/acs.inorgchem.3c02526] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 10/06/2023] [Accepted: 10/11/2023] [Indexed: 11/03/2023]
Abstract
Four new pentadentate N5-donor ligands, [N-(1-methyl-2-imidazolyl)methyl-N-(2-pyridyl)-methyl-N-(bis-2-pyridylmethyl)-amine] (L1), [N-bis(1-methyl-2-imidazolyl)methyl-N-(bis-2-pyridylmethyl)amine] (L2), (N-(isoquinolin-3-ylmethyl)-1,1-di(pyridin-2-yl)-N-(pyridin-2-ylmethyl)methanamine (L3), and N,N-bis(isoquinolin-3-ylmethyl)-1,1-di(pyridin-2-yl)methanamine (L4), have been synthesized based on the N4Py ligand framework, where one or two pyridyl arms of the N4Py parent are replaced by (N-methyl)imidazolyl or N-(isoquinolin-3-ylmethyl) moieties. Using these four pentadentate ligands, the mononuclear complexes [FeII(CH3CN)(L1)]2+ (1a), [FeII(CH3CN)(L2)]2+ (2a), [FeII(CH3CN)(L3)]2+ (3a), and [FeII(CH3CN)(L4)]2+ (4a) have been synthesized and characterized. The half-wave potentials (E1/2) of the complexes become more positive in the order: 2a < 1a < 4a ≤ 3a ≤ [Fe(N4Py)(CH3CN)]2+. The order of redox potentials correlates well with the Fe-Namine distances observed by crystallography, which are 2a > 1a ≥ 4a > 3a ≥ [Fe(N4Py)(CH3CN)]2+. The corresponding ferryl complexes [FeIV(O)(L1)]2+ (1b), [FeIV(O)(L2)]2+ (2b), [FeIV(O)(L3)]2+ (3b), and [FeIV(O)(L4)]2+ (4b) were prepared by the reaction of the ferrous complexes with isopropyl 2-iodoxybenzoate (IBX ester) in acetonitrile. The greenish complexes 3b and 4b were also isolated in the solid state by the reaction of the ferrous complexes in CH3CN with ceric ammonium nitrate in water. Mössbauer spectroscopy and magnetic measurements (using superconducting quantum interference device) show that the four complexes 1b, 2b, 3b, and 4b are low-spin (S = 1) FeIV═O complexes. UV/vis spectra of the four FeIV═O complexes in acetonitrile show typical long-wavelength absorptions of around 700 nm, which are expected for FeIV═O complexes with N4Py-type ligands. The wavelengths of these absorptions decrease in the following order: 721 nm (2b) > 706 nm (1b) > 696 nm (4b) > 695 nm (3b) = 695 nm ([FeIV(O) (N4Py)]2+), indicating that the replacement of the pyridyl arms with (N-methyl) imidazolyl moieties makes L1 and L2 exert weaker ligand fields than the parent N4Py ligand, while the ligand field strengths of L3 and L4 are similar to the N4Py parent despite the replacement of the pyridyl arms with N-(isoquinolin-3-ylmethyl) moieties. Consequently, complexes 1b and 2b tend to be less stable than the parent [FeIV(O)(N4Py)]2+ complex: the half-life sequence at room temperature is 1.67 h (2b) < 16 h (1b) < 45 h (4b) < 63 h (3b) ≈ 60 h ([FeIV(O)(N4Py)]2+). Compared to the parent complex, 1b and 2b exhibit enhanced reactivity in both the oxidation of thioanisole in the oxygen atom transfer (OAT) reaction and the oxygenation of C-H bonds of aromatic and aliphatic substrates, presumed to occur via an oxygen rebound process. Furthermore, the second-order rate constants for hydrogen atom transfer (HAT) reactions affected by the ferryl complexes can be directly related to the C-H bond dissociation energies of a range of substrates that have been studied. Using either IBX ester or H2O2 as an oxidant, all four new FeII complexes display good performance in catalytic reactions involving both HAT and OAT reactions.
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Affiliation(s)
- Yong Li
- Chemical
Physics, Department of Chemistry, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Reena Singh
- Chemical
Physics, Department of Chemistry, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Arup Sinha
- Chemical
Physics, Department of Chemistry, Lund University, Box 124, Lund SE-221 00, Sweden
| | - George C. Lisensky
- Department
of Chemistry, Beloit College, 700 College Street, Beloit, Wisconsin 53511, United States
| | - Matti Haukka
- Department
of Chemistry, University of Jyväskylä, P.O. Box-35, Jyväskylä FI-40014, Finland
| | - Justin Nilsson
- Chemical
Physics, Department of Chemistry, Lund University, Box 124, Lund SE-221 00, Sweden
| | - Solomon Yiga
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, Lund SE-22100, Sweden
| | - Serhiy Demeshko
- Georg-August
Universität Göttingen, Institut
für Anorganische Chemie, Tammanstrasse 4, Göttingen D-37077, Germany
| | - Sophie Jana Gross
- Georg-August
Universität Göttingen, Institut
für Anorganische Chemie, Tammanstrasse 4, Göttingen D-37077, Germany
| | - Sebastian Dechert
- Georg-August
Universität Göttingen, Institut
für Anorganische Chemie, Tammanstrasse 4, Göttingen D-37077, Germany
| | - Ana Gonzalez
- MAX IV Laboratory, Lund University, P.O.
Box 118, Lund SE-221 00, Sweden
| | - Giliandro Farias
- Department
of Chemistry, Federal University of Santa
Catarina, Florianópolis 88040900, Santa Catarina, Brazil
| | - Ola F. Wendt
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, Lund SE-22100, Sweden
| | - Franc Meyer
- Georg-August
Universität Göttingen, Institut
für Anorganische Chemie, Tammanstrasse 4, Göttingen D-37077, Germany
| | - Ebbe Nordlander
- Chemical
Physics, Department of Chemistry, Lund University, Box 124, Lund SE-221 00, Sweden
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8
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Schneider JE, Anderson JS. Reconciling Imbalanced and Nonadiabatic Reactivity in Transition Metal-Oxo-Mediated Concerted Proton Electron Transfer (CPET). J Phys Chem Lett 2023; 14:9548-9555. [PMID: 37856336 DOI: 10.1021/acs.jpclett.3c02318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
Recently, there have been several experimental demonstrations of how the rates of concerted proton electron transfer (CPET) are affected by stepwise thermodynamic parameters of only proton (ΔG°PT) or electron (ΔG°ET) transfer. Semiclassical structure-activity relationships have been invoked to rationalize these linear free energy relationships, but it is not clear how they would manifest in a nonadiabatic reaction. Using density functional theory calculations, we demonstrate how a decrease in ΔG°PT can lead to transition state imbalance in a nonadiabatic framework. We then use these calculations to anchor a theoretical model that reproduces experimental trends with ΔG°PT and ΔG°ET. Our results reconcile predictions from semiclassical transition state theory with models that treat proton transfer quantum mechanically in CPET reactivity, make new predictions about the importance of basicity for uphill CPET reactions, and suggest similar treatments may be possible for other nonadiabatic reactions.
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Affiliation(s)
- Joseph E Schneider
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - John S Anderson
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
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9
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Follmer AH, Borovik AS. The role of basicity in selective C-H bond activation by transition metal-oxidos. Dalton Trans 2023; 52:11005-11016. [PMID: 37497779 PMCID: PMC10619463 DOI: 10.1039/d3dt01781h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
The development of (bio)catalysts capable of selectively activating strong C-H bonds is a continuing challenge in modern chemistry. In both metalloenzymes and synthetic systems capable of activating C-H bonds, transition metal-oxido intermediates serve as the active species for reactivity whose thermodynamic properties influence the bond strengths they are capable of activating. In this Frontier article, we present current ideas of how the basicity of transition metal-oxidos impacts their reactivity with C-H bonds and present new opportunities within this field. We highlight recent insights into the role basicity plays in the activation process and its influence on mechanism, as well as the important role that secondary coordination sphere effects, such as hydrogen bonds, in tuning the basicity of the metal-oxido species is discussed.
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Affiliation(s)
- Alec H Follmer
- Department of Chemistry, University of California-Irvine, Irvine, CA 92697-3900, USA.
| | - A S Borovik
- Department of Chemistry, University of California-Irvine, Irvine, CA 92697-3900, USA.
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10
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Sun C, Jaimes JL, Follmer AH, Ziller JW, Borovik AS. Selective C-H Bond Cleavage with a High-Spin Fe IV-Oxido Complex. Molecules 2023; 28:4755. [PMID: 37375309 DOI: 10.3390/molecules28124755] [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: 03/10/2023] [Revised: 05/23/2023] [Accepted: 06/03/2023] [Indexed: 06/29/2023] Open
Abstract
Non-heme Fe monooxygenases activate C-H bonds using intermediates with high-spin FeIV-oxido centers. To mimic these sites, a new tripodal ligand [pop]3- was prepared that contains three phosphoryl amido groups that are capable of stabilizing metal centers in high oxidation states. The ligand was used to generate [FeIVpop(O)]-, a new FeIV-oxido complex with an S = 2 spin ground state. Spectroscopic measurements, which included low-temperature absorption and electron paramagnetic resonance spectroscopy, supported the assignment of a high-spin FeIV center. The complex showed reactivity with benzyl alcohol as the external substrate but not with related compounds (e.g., ethyl benzene and benzyl methyl ether), suggesting the possibility that hydrogen bonding interaction(s) between the substrate and [FeIVpop(O)]- was necessary for reactivity. These results exemplify the potential role of the secondary coordination sphere in metal-mediated processes.
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Affiliation(s)
- Chen Sun
- Department of Chemistry, University of California-Irvine, Irvine, CA 92697, USA
| | - Jennifer L Jaimes
- Department of Chemistry, University of California-Irvine, Irvine, CA 92697, USA
| | - Alec H Follmer
- Department of Chemistry, University of California-Irvine, Irvine, CA 92697, USA
| | - Joseph W Ziller
- Department of Chemistry, University of California-Irvine, Irvine, CA 92697, USA
| | - Andrew S Borovik
- Department of Chemistry, University of California-Irvine, Irvine, CA 92697, USA
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11
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Imran M, Khan AR, Husin MN, Tchier F, Ghani MU, Hussain S. Computation of Entropy Measures for Metal-Organic Frameworks. Molecules 2023; 28:4726. [PMID: 37375281 DOI: 10.3390/molecules28124726] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 06/04/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023] Open
Abstract
Entropy is a thermodynamic function used in chemistry to determine the disorder and irregularities of molecules in a specific system or process. It does this by calculating the possible configurations for each molecule. It is applicable to numerous issues in biology, inorganic and organic chemistry, and other relevant fields. Metal-organic frameworks (MOFs) are a family of molecules that have piqued the curiosity of scientists in recent years. They are extensively researched due to their prospective applications and the increasing amount of information about them. Scientists are constantly discovering novel MOFs, which results in an increasing number of representations every year. Furthermore, new applications for MOFs continue to arise, illustrating the materials' adaptability. This article investigates the characterisation of the metal-organic framework of iron(III) tetra-p-tolyl porphyrin (FeTPyP) and CoBHT (CO) lattice. By constructing these structures with degree-based indices such as the K-Banhatti, redefined Zagreb, and the atom-bond sum connectivity indices, we also employ the information function to compute entropies.
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Affiliation(s)
- Muhammad Imran
- Department of Mathematical Sciences, United Arab Emirates University, Al Ain P. O. Box 15551, United Arab Emirates
| | - Abdul Rauf Khan
- Department of Mathematics, Faculty of Science, Ghazi University, Dera Ghazi Khan 32200, Pakistan
| | - Mohamad Nazri Husin
- Special Interest Group on Modelling, Data Analytics (SIGMDA) Faculty of Ocean Engineering Technology, Informatics Universiti Malaysia Terengganu, Kuala Nerus 21030, Terengganu, Malaysia
| | - Fairouz Tchier
- Mathematics Department, College of Science, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia
| | - Muhammad Usman Ghani
- Institute of Mathematics, Khawaja Fareed University of Engineering & Information Technology, Abu Dhabi Road, Rahim Yar Khan 64200, Pakistan
| | - Shahid Hussain
- Energy Engineering Division, Department of Engineering Science and Mathematics, Lulea University of Technology, 97187 Lulea, Sweden
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12
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Bleher K, Comba P, Kass D, Ray K, Wadepohl H. Reactivities of iron(IV)-oxido compounds with pentadentate bispidine ligands. J Inorg Biochem 2023; 241:112123. [PMID: 36701984 DOI: 10.1016/j.jinorgbio.2023.112123] [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: 08/30/2022] [Revised: 01/05/2023] [Accepted: 01/05/2023] [Indexed: 01/11/2023]
Abstract
The FeIVO complexes of bispidines (3,7-diazabicyclo[3.3.1]nonane derivatives) are known to be highly reactive oxidants - with the tetradentate bispidine, the so far most reactive ferryl complex has been reported and two isomeric pentadentate ligands also lead to very reactive high-valent oxidants. With a series of 4 new bispidine derivatives we now try to address the question why the bispidine scaffold in general leads to very reactive oxidants and how this can be tuned by ligand modifications. The study is based on a full structural, spectroscopic and electrochemical analysis of the iron(II) precursors, spectroscopic data of the iron(IV)-oxido complexes, a kinetic analysis of the stoichiometric oxidation of thioanisole by five different bispidine‑iron(IV)-oxido complexes and on product analyses of reactions by the five ferryl oxidants with thioanisole, β-methylstyrene and cis-stilbene as substrates.
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Affiliation(s)
- Katharina Bleher
- Universität Heidelberg, Anorganisch-Chemisches Institut, INF 270, D-69120 Heidelberg, Germany
| | - Peter Comba
- Universität Heidelberg, Anorganisch-Chemisches Institut, INF 270, D-69120 Heidelberg, Germany; Universität Heidelberg, Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), Germany.
| | - Dustin Kass
- Humboldt-Universität zu Berlin, Department of Chemistry, Brook-Taylor Strasse 2, D-12489 Berlin, Germany
| | - Kallol Ray
- Humboldt-Universität zu Berlin, Department of Chemistry, Brook-Taylor Strasse 2, D-12489 Berlin, Germany
| | - Hubert Wadepohl
- Universität Heidelberg, Anorganisch-Chemisches Institut, INF 270, D-69120 Heidelberg, Germany
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13
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Dantignana V, Pérez-Segura MC, Besalú-Sala P, Delgado-Pinar E, Martínez-Camarena Á, Serrano-Plana J, Álvarez-Núñez A, Castillo CE, García-España E, Luis JM, Basallote MG, Costas M, Company A. Characterization of a Ferryl Flip in Electronically Tuned Nonheme Complexes. Consequences in Hydrogen Atom Transfer Reactivity. Angew Chem Int Ed Engl 2023; 62:e202211361. [PMID: 36305539 PMCID: PMC10107328 DOI: 10.1002/anie.202211361] [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: 08/02/2022] [Indexed: 12/04/2022]
Abstract
Two oxoiron(IV) isomers (R 2a and R 2b) of general formula [FeIV (O)(R PyNMe3 )(CH3 CN)]2+ are obtained by reaction of their iron(II) precursor with NBu4 IO4 . The two isomers differ in the position of the oxo ligand, cis and trans to the pyridine donor. The mechanism of isomerization between R 2a and R 2b has been determined by kinetic and computational analyses uncovering an unprecedented path for interconversion of geometrical oxoiron(IV) isomers. The activity of the two oxoiron(IV) isomers in hydrogen atom transfer (HAT) reactions shows that R 2a reacts one order of magnitude faster than R 2b, which is explained by a repulsive noncovalent interaction between the ligand and the substrate in R 2b. Interestingly, the electronic properties of the R substituent in the ligand pyridine ring do not have a significant effect on reaction rates. Overall, the intrinsic structural aspects of each isomer define their relative HAT reactivity, overcoming changes in electronic properties of the ligand.
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Affiliation(s)
- Valeria Dantignana
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - M Carmen Pérez-Segura
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias, Instituto de Biomoléculas (INBIO), Universidad de Cádiz, Puerto Real, 11510, Cádiz, Spain
| | - Pau Besalú-Sala
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Estefanía Delgado-Pinar
- Departamento de Química Inorgánica, Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, C/Catedrático José Beltrán, Paterna, 46980, Valencia 2, Spain
| | - Álvaro Martínez-Camarena
- Departamento de Química Inorgánica, Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, C/Catedrático José Beltrán, Paterna, 46980, Valencia 2, Spain
| | - Joan Serrano-Plana
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Andrea Álvarez-Núñez
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - 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, 11510, Cádiz, Spain
| | - Enrique García-España
- Departamento de Química Inorgánica, Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, C/Catedrático José Beltrán, Paterna, 46980, Valencia 2, Spain
| | - Josep M Luis
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, 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, 11510, Cádiz, Spain
| | - Miquel Costas
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Anna Company
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
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14
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Bagha UK, Satpathy JK, Mukherjee G, Barman P, Kumar D, de Visser SP, Sastri CV. Oxidative dehalogenation of halophenols by high-valent nonheme iron(IV)-oxo intermediates. Faraday Discuss 2022; 234:58-69. [PMID: 35170590 DOI: 10.1039/d1fd00064k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mononuclear high-valent iron(IV)-oxo intermediates are excellent oxidants towards oxygenation reactions by heme and nonheme metalloenzymes and their model systems. One of the most important functions of these intermediates in nature is to detoxify various environmental pollutants. Organic substrates, such as halogenated phenols, are known to be water pollutants which can be degraded to their less hazardous forms through an oxidation reaction by iron(IV)-oxo complexes. Metalloproteins in nature utilize various types of second-coordination sphere interactions to anchor the substrate in the vicinity of the active site. This concept of substrate-binding is well-known for natural enzymes, but is elusive for the relevant biomimetic model systems. Herein, we report the oxidative reactivity patterns of an iron(IV)-oxo intermediate, [FeIV(O)(2PyN2Q)]2+, (2PyN2Q = 1,1-di(pyridin-2yl)-N,N-bis(quinolin-2-ylmethyl)methanamine) with a series of mono-, di- and tri-halophenols. A detailed experimental study shows that the dehalogenation reactions of the halophenols by such iron(IV)-oxo intermediates proceed via an initial hydrogen atom abstraction from the phenolic O-H group. Furthermore, based on the size and nucleophilicity of the halophenol, an intermediate substrate-bound species forms that is a phenolate adduct to the ferric species, which thereafter leads to the formation of the corresponding products.
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Affiliation(s)
- Umesh Kumar Bagha
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, India.
| | | | - Gourab Mukherjee
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, India. .,Department of Chemical Science, Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai, 400005, India
| | - Prasenjit Barman
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, India. .,Department of Chemistry, Kaliyaganj College, West Bengal, 733129, India
| | - Devesh Kumar
- Department of Applied Physics, School for Physical Sciences, Babasaheb Bhimrao Ambedkar University, Lucknow, 226025, India.
| | - Sam P de Visser
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, India. .,The Manchester Institute of Biotechnology, Department of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.
| | - Chivukula V Sastri
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, India.
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15
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Comba P, Nunn G, Scherz F, Walton PH. Intermediate-spin iron(IV)-oxido species with record reactivity. Faraday Discuss 2022; 234:232-244. [PMID: 35156976 DOI: 10.1039/d1fd00073j] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The nonheme iron(IV)-oxido complex trans-N3-[(L1)FeIVO(Cl)]+, where L1 is a derivative of the tetradentate bispidine 2,4-di(pyridine-2-yl)-3,7-diazabicyclo[3.3.1]nonane-1-one, has an S = 1 electronic ground state and is the most reactive nonheme iron model system known so far, of a similar order of reactivity as nonheme iron enzymes (C-H abstraction of cyclohexane, -90 °C (propionitrile), t1/2 = 3.5 s). The reaction with cyclohexane selectively leads to chlorocyclohexane, but "cage escape" at the [(L1)FeIII(OH)(Cl)]+/cyclohexyl radical intermediate lowers the productivity. Ligand field theory is used herein to analyze the d-d transitions of [(L1)FeIVO(X)]n+ (X = Cl-, Br-, MeCN) in comparison with the thoroughly characterized ferryl complex of tetramethylcyclam (TMC = L2; [(L2)FeIVO(MeCN)]2+). The ligand field parameters and d-d transition energies are shown to provide important information on the triplet-quintet gap and its correlation with oxidation reactivity.
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Affiliation(s)
- Peter Comba
- Universität Heidelberg, Anorganisch-Chemisches Institut, INF 270, D-69120 Heidelberg, Germany. .,Universität Heidelberg, Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), Germany
| | - George Nunn
- Department of Chemistry, University of York, Heslington, YORK, YO10 5DD, UK
| | - Frederik Scherz
- Universität Heidelberg, Anorganisch-Chemisches Institut, INF 270, D-69120 Heidelberg, Germany.
| | - Paul H Walton
- Department of Chemistry, University of York, Heslington, YORK, YO10 5DD, UK
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16
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Bleher K, Comba P, Faltermeier D, Gupta A, Kerscher M, Krieg S, Martin B, Velmurugan G, Yang S. Non-Heme-Iron-Mediated Selective Halogenation of Unactivated Carbon-Hydrogen Bonds. Chemistry 2022; 28:e202103452. [PMID: 34792224 PMCID: PMC9300152 DOI: 10.1002/chem.202103452] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Indexed: 12/23/2022]
Abstract
Oxidation of the iron(II) precursor [(L1 )FeII Cl2 ], where L1 is a tetradentate bispidine, with soluble iodosylbenzene (s PhIO) leads to the extremely reactive ferryl oxidant [(L1 )(Cl)FeIV =O]+ with a cis disposition of the chlorido and oxido coligands, as observed in non-heme halogenase enzymes. Experimental data indicate that, with cyclohexane as substrate, there is selective formation of chlorocyclohexane, the halogenation being initiated by C-H abstraction and the result of a rebound of the ensuing radical to an iron-bound Cl- . The time-resolved formation of the halogenation product indicates that this primarily results from s PhIO oxidation of an initially formed oxido-bridged diiron(III) resting state. The high yield of up to >70 % (stoichiometric reaction) as well as the differing reactivities of free Fe2+ and Fe3+ in comparison with [(L1 )FeII Cl2 ] indicate a high complex stability of the bispidine-iron complexes. DFT analysis shows that, due to a large driving force and small triplet-quintet gap, [(L1 )(Cl)FeIV =O]+ is the most reactive small-molecule halogenase model, that the FeIII /radical rebound intermediate has a relatively long lifetime (as supported by experimentally observed cage escape), and that this intermediate has, as observed experimentally, a lower energy barrier to the halogenation than the hydroxylation product; this is shown to primarily be due to steric effects.
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Affiliation(s)
- Katharina Bleher
- Universität HeidelbergAnorganisch-Chemisches Institut und Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), INF 27069120HeidelbergGermany
| | - Peter Comba
- Universität HeidelbergAnorganisch-Chemisches Institut und Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), INF 27069120HeidelbergGermany
| | - Dieter Faltermeier
- Universität HeidelbergAnorganisch-Chemisches Institut und Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), INF 27069120HeidelbergGermany
| | - Ashutosh Gupta
- Universität HeidelbergAnorganisch-Chemisches Institut und Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), INF 27069120HeidelbergGermany
| | - Marion Kerscher
- Universität HeidelbergAnorganisch-Chemisches Institut und Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), INF 27069120HeidelbergGermany
| | - Saskia Krieg
- Universität HeidelbergAnorganisch-Chemisches Institut und Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), INF 27069120HeidelbergGermany
| | - Bodo Martin
- Universität HeidelbergAnorganisch-Chemisches Institut und Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), INF 27069120HeidelbergGermany
| | - Gunasekaran Velmurugan
- Universität HeidelbergAnorganisch-Chemisches Institut und Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), INF 27069120HeidelbergGermany
| | - Shuyi Yang
- Universität HeidelbergAnorganisch-Chemisches Institut und Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), INF 27069120HeidelbergGermany
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17
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Lee JL, Ross DL, Barman SK, Ziller JW, Borovik AS. C-H Bond Cleavage by Bioinspired Nonheme Metal Complexes. Inorg Chem 2021; 60:13759-13783. [PMID: 34491738 DOI: 10.1021/acs.inorgchem.1c01754] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The functionalization of C-H bonds is one of the most challenging transformations in synthetic chemistry. In biology, these processes are well-known and are achieved with a variety of metalloenzymes, many of which contain a single metal center within their active sites. The most well studied are those with Fe centers, and the emerging experimental data show that high-valent iron oxido species are the intermediates responsible for cleaving the C-H bond. This Forum Article describes the state of this field with an emphasis on nonheme Fe enzymes and current experimental results that provide insights into the properties that make these species capable of C-H bond cleavage. These parameters are also briefly considered in regard to manganese oxido complexes and Cu-containing metalloenzymes. Synthetic iron oxido complexes are discussed to highlight their utility as spectroscopic and mechanistic probes and reagents for C-H bond functionalization. Avenues for future research are also examined.
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Affiliation(s)
- Justin L Lee
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Dolores L Ross
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Suman K Barman
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Joseph W Ziller
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - A S Borovik
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
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18
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Gardner JG, Schneider JE, Anderson JS. Two, Three, or Not to Be? Elucidating Multiple Bonding in d 6 Pseudotetrahedral Oxo and Imide Complexes. Inorg Chem 2021; 60:13854-13860. [PMID: 34197705 DOI: 10.1021/acs.inorgchem.1c01022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Late-transition-metal oxo and imide complexes play an important role in the catalytic functionalization and activation of small molecules. An emerging theme in this area over the past few decades has been the use of lower coordination numbers, and pseudotetrahedral geometries in particular, to stabilize what would otherwise be highly reactive species. However, the bonding structure in d6 oxo and imide complexes in this geometry is ambiguous. These species are typically depicted with a triple bond; however, recent experimental evidence suggests significant empirical differences between these complexes and other triply bonded complexes with lower d counts. Here we use a suite of computational orbital localization methods and electron density analyses to probe the bonding structure of isoelectronic d6 CoIII oxo and imide complexes. These analyses suggest that a triple-bond description is inaccurate because of a dramatically weakened σ interaction. While the exact bond order in these cases is necessarily dependent on the model used, several metrics suggest that the strength of the metal-O/N bond is most similar to that of other formally doubly bonded complexes.
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Affiliation(s)
- Joel G Gardner
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Joseph E Schneider
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - John S Anderson
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
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19
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Abu‐Odeh M, Bleher K, Johnee Britto N, Comba P, Gast M, Jaccob M, Kerscher M, Krieg S, Kurth M. Pathways of the Extremely Reactive Iron(IV)-oxido complexes with Tetradentate Bispidine Ligands. Chemistry 2021; 27:11377-11390. [PMID: 34121233 PMCID: PMC8456976 DOI: 10.1002/chem.202101045] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Indexed: 11/07/2022]
Abstract
The nonheme iron(IV)-oxido complex trans-N3-[(L1 )FeIV =O(Cl)]+ , where L1 is a derivative of the tetradentate bispidine 2,4-di(pyridine-2-yl)-3,7-diazabicyclo[3.3.1]nonane-1-one, is known to have an S=1 electronic ground state and to be an extremely reactive oxidant for oxygen atom transfer (OAT) and hydrogen atom abstraction (HAA) processes. Here we show that, in spite of this ferryl oxidant having the "wrong" spin ground state, it is the most reactive nonheme iron model system known so far and of a similar order of reactivity as nonheme iron enzymes (C-H abstraction of cyclohexane, -90 °C (propionitrile), t1/2 =3.5 sec). Discussed are spectroscopic and kinetic data, supported by a DFT-based theoretical analysis, which indicate that substrate oxidation is significantly faster than self-decay processes due to an intramolecular demethylation pathway and formation of an oxido-bridged diiron(III) intermediate. It is also shown that the iron(III)-chlorido-hydroxido/cyclohexyl radical intermediate, resulting from C-H abstraction, selectively produces chlorocyclohexane in a rebound process. However, the life-time of the intermediate is so long that other reaction channels (known as cage escape) become important, and much of the C-H abstraction therefore is unproductive. In bulk reactions at ambient temperature and at longer time scales, there is formation of significant amounts of oxidation product - selectively of chlorocyclohexane - and it is shown that this originates from oxidation of the oxido-bridged diiron(III) resting state.
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Affiliation(s)
- Mahmud Abu‐Odeh
- Anorganisch-Chemisches InstitutUniversität HeidelbergINF 27069120HeidelbergGermany
| | - Katharina Bleher
- Anorganisch-Chemisches InstitutUniversität HeidelbergINF 27069120HeidelbergGermany
| | | | - Peter Comba
- Anorganisch-Chemisches InstitutUniversität HeidelbergINF 27069120HeidelbergGermany
- Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR) MathematikonIm Neuenheimer Feld 20569120HeidelbergGermany
| | - Michael Gast
- Anorganisch-Chemisches InstitutUniversität HeidelbergINF 27069120HeidelbergGermany
| | | | - Marion Kerscher
- Anorganisch-Chemisches InstitutUniversität HeidelbergINF 27069120HeidelbergGermany
| | - Saskia Krieg
- Anorganisch-Chemisches InstitutUniversität HeidelbergINF 27069120HeidelbergGermany
| | - Marius Kurth
- Anorganisch-Chemisches InstitutUniversität HeidelbergINF 27069120HeidelbergGermany
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20
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Warm K, Paskin A, Kuhlmann U, Bill E, Swart M, Haumann M, Dau H, Hildebrandt P, Ray K. A Pseudotetrahedral Terminal Oxoiron(IV) Complex: Mechanistic Promiscuity in C-H Bond Oxidation Reactions. Angew Chem Int Ed Engl 2021; 60:6752-6756. [PMID: 33348460 PMCID: PMC7985879 DOI: 10.1002/anie.202015896] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Indexed: 11/12/2022]
Abstract
S=2 oxoiron(IV) species act as reactive intermediates in the catalytic cycle of nonheme iron oxygenases. The few available synthetic S=2 FeIV =O complexes known to date are often limited to trigonal bipyramidal and very rarely to octahedral geometries. Herein we describe the generation and characterization of an S=2 pseudotetrahedral FeIV =O complex 2 supported by the sterically demanding 1,4,7-tri-tert-butyl-1,4,7-triazacyclononane ligand. Complex 2 is a very potent oxidant in hydrogen atom abstraction (HAA) reactions with large non-classical deuterium kinetic isotope effects, suggesting hydrogen tunneling contributions. For sterically encumbered substrates, direct HAA is impeded and an alternative oxidative asynchronous proton-coupled electron transfer mechanism prevails, which is unique within the nonheme oxoiron community. The high reactivity and the similar spectroscopic parameters make 2 one of the best electronic and functional models for a biological oxoiron(IV) intermediate of taurine dioxygenase (TauD-J).
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Affiliation(s)
- Katrin Warm
- Institut für ChemieHumboldt-Universität zu BerlinBrook-Taylor-Str. 212489BerlinGermany
| | - Alice Paskin
- Institut für ChemieHumboldt-Universität zu BerlinBrook-Taylor-Str. 212489BerlinGermany
| | - Uwe Kuhlmann
- Institut für ChemieTechnische Universität Berlin, Fakultät IIStraße des 17. Juni 13510623BerlinGermany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion (CEC)Stiftstraße 34–3645470MülheimGermany
| | - Marcel Swart
- Institut de Química Computacional i CatàlisiUniversitat de GironaCampus Montilivi (Ciències)Maria Aurèlia Capmany i Farnés, 6917003GironaSpain
- ICREAPg. Lluís Companys 2308010BarcelonaSpain
| | - Michael Haumann
- Institut für PhysikFreie Universität BerlinArnimallee 1414195BerlinGermany
| | - Holger Dau
- Institut für PhysikFreie Universität BerlinArnimallee 1414195BerlinGermany
| | - Peter Hildebrandt
- Institut für ChemieTechnische Universität Berlin, Fakultät IIStraße des 17. Juni 13510623BerlinGermany
| | - Kallol Ray
- Institut für ChemieHumboldt-Universität zu BerlinBrook-Taylor-Str. 212489BerlinGermany
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21
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Warm K, Paskin A, Kuhlmann U, Bill E, Swart M, Haumann M, Dau H, Hildebrandt P, Ray K. A Pseudotetrahedral Terminal Oxoiron(IV) Complex: Mechanistic Promiscuity in C−H Bond Oxidation Reactions. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202015896] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Katrin Warm
- Institut für Chemie Humboldt-Universität zu Berlin Brook-Taylor-Str. 2 12489 Berlin Germany
| | - Alice Paskin
- Institut für Chemie Humboldt-Universität zu Berlin Brook-Taylor-Str. 2 12489 Berlin Germany
| | - Uwe Kuhlmann
- Institut für Chemie Technische Universität Berlin, Fakultät II Straße des 17. Juni 135 10623 Berlin Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion (CEC) Stiftstraße 34–36 45470 Mülheim Germany
| | - Marcel Swart
- Institut de Química Computacional i Catàlisi Universitat de Girona Campus Montilivi (Ciències) Maria Aurèlia Capmany i Farnés, 69 17003 Girona Spain
- ICREA Pg. Lluís Companys 23 08010 Barcelona Spain
| | - Michael Haumann
- Institut für Physik Freie Universität Berlin Arnimallee 14 14195 Berlin Germany
| | - Holger Dau
- Institut für Physik Freie Universität Berlin Arnimallee 14 14195 Berlin Germany
| | - Peter Hildebrandt
- Institut für Chemie Technische Universität Berlin, Fakultät II Straße des 17. Juni 135 10623 Berlin Germany
| | - Kallol Ray
- Institut für Chemie Humboldt-Universität zu Berlin Brook-Taylor-Str. 2 12489 Berlin Germany
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22
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D’Agostini S, Kottrup KG, Casadevall C, Gamba I, Dantignana V, Bucci A, Costas M, Lloret-Fillol J, Hetterscheid DG. Electrocatalytic Water Oxidation with α-[Fe(mcp)(OTf) 2] and Analogues. ACS Catal 2021; 11:2583-2595. [PMID: 33815893 PMCID: PMC8016111 DOI: 10.1021/acscatal.0c05439] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/26/2021] [Indexed: 12/02/2022]
Abstract
![]()
The complex α-[Fe(mcp)(OTf)2] (mcp = N,N′-dimethyl-N,N′-bis(pyridin-2-ylmethyl)-cyclohexane-1,2-diamine
and OTf
= trifluoromethanesulfonate anion) was reported in 2011 by some of
us as an active water oxidation (WO) catalyst in the presence of sacrificial
oxidants. However, because chemical oxidants are likely to take part
in the reaction mechanism, mechanistic electrochemical studies are
critical in establishing to what extent previous studies with sacrificial
reagents have actually been meaningful. In this study, the complex
α-[Fe(mcp)(OTf)2] and its analogues were investigated
electrochemically under both acidic and neutral conditions. All the
systems under investigation proved to be electrochemically active
toward the WO reaction, with no major differences in activity despite
the structural changes. Our findings show that WO-catalyzed by mcp–iron
complexes proceeds via homogeneous species, whereas the analogous
manganese complex forms a heterogeneous deposit on the electrode surface.
Mechanistic studies show that the reaction proceeds with a different
rate-determining step (rds) than what was previously proposed in the
presence of chemical oxidants. Moreover, the different kinetic isotope
effect (KIE) values obtained electrochemically at pH 7 (KIE ∼
10) and at pH 1 (KIE = 1) show that the reaction conditions have a
remarkable effect on the rds and on the mechanism. We suggest a proton-coupled
electron transfer (PCET) as the rds under neutral conditions, whereas
at pH 1 the rds is most likely an electron transfer (ET).
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Affiliation(s)
- Silvia D’Agostini
- Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands
| | | | - Carla Casadevall
- Institute of Chemical Research of Catalonia, Spain (ICIQ), The Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, 43007 Tarragona, Spain
| | - Ilaria Gamba
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus de Montilivi, 17003 Girona, Spain
| | - Valeria Dantignana
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus de Montilivi, 17003 Girona, Spain
| | - Alberto Bucci
- Institute of Chemical Research of Catalonia, Spain (ICIQ), The Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, 43007 Tarragona, Spain
| | - Miquel Costas
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus de Montilivi, 17003 Girona, Spain
| | - Julio Lloret-Fillol
- Institute of Chemical Research of Catalonia, Spain (ICIQ), The Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, 43007 Tarragona, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluïs Companys 23, 08010 Barcelona, Spain
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23
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Monkcom EC, de Bruin D, de Vries AJ, Lutz M, Ye S, Klein Gebbink RJM. Structurally Modelling the 2-His-1-Carboxylate Facial Triad with a Bulky N,N,O Phenolate Ligand. Chemistry 2021; 27:5191-5204. [PMID: 33326655 PMCID: PMC8048785 DOI: 10.1002/chem.202004633] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Indexed: 11/25/2022]
Abstract
We present the synthesis and coordination chemistry of a bulky, tripodal N,N,O ligand, ImPh2NNOtBu (L), designed to model the 2‐His‐1‐carboxylate facial triad (2H1C) by means of two imidazole groups and an anionic 2,4‐di‐tert‐butyl‐subtituted phenolate. Reacting K‐L with MCl2 (M = Fe, Zn) affords the isostructural, tetrahedral non‐heme complexes [Fe(L)(Cl)] (1) and [Zn(L)(Cl)] (2) in high yield. The tridentate N,N,O ligand coordination observed in their X‐ray crystal structures remains intact and well‐defined in MeCN and CH2Cl2 solution. Reacting 2 with NaSPh affords a tetrahedral zinc thiolate complex, [Zn(L)(SPh)] (4), that is relevant to isopenicillin N synthase (IPNS) biomimicry. Cyclic voltammetry studies demonstrate the ligand's redox non‐innocence, where phenolate oxidation is the first electrochemical response observed in K‐L, 2 and 4. However, the first electrochemical oxidation in 1 is iron‐centred, the assignment of which is supported by DFT calculations. Overall, ImPh2NNOtBu provides access to well‐defined mononuclear, monoligated, N,N,O‐bound metal complexes, enabling more accurate structural modelling of the 2H1C to be achieved.
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Affiliation(s)
- Emily C Monkcom
- Organic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584, CG, Utrecht, The Netherlands
| | - Daniël de Bruin
- Organic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584, CG, Utrecht, The Netherlands
| | - Annemiek J de Vries
- Organic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584, CG, Utrecht, The Netherlands
| | - Martin Lutz
- Crystal and Structural Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, Padualaan 8, 3584, CH, Utrecht, The Netherlands
| | - Shengfa Ye
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023, P. R. China.,Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Robertus J M Klein Gebbink
- Organic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584, CG, Utrecht, The Netherlands
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24
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Schneider JE, Goetz MK, Anderson JS. Statistical analysis of C-H activation by oxo complexes supports diverse thermodynamic control over reactivity. Chem Sci 2021; 12:4173-4183. [PMID: 34163690 PMCID: PMC8179456 DOI: 10.1039/d0sc06058e] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 01/28/2021] [Indexed: 01/29/2023] Open
Abstract
Transition metal oxo species are key intermediates for the activation of strong C-H bonds. As such, there has been interest in understanding which structural or electronic parameters of metal oxo complexes determine their reactivity. Factors such as ground state thermodynamics, spin state, steric environment, oxygen radical character, and asynchronicity have all been cited as key contributors, yet there is no consensus on when each of these parameters is significant or the relative magnitude of their effects. Herein, we present a thorough statistical analysis of parameters that have been proposed to influence transition metal oxo mediated C-H activation. We used density functional theory (DFT) to compute parameters for transition metal oxo complexes and analyzed their ability to explain and predict an extensive data set of experimentally determined reaction barriers. We found that, in general, only thermodynamic parameters play a statistically significant role. Notably, however, there are independent and significant contributions from the oxidation potential and basicity of the oxo complexes which suggest a more complicated thermodynamic picture than what has been shown previously.
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Affiliation(s)
| | - McKenna K Goetz
- Department of Chemistry, University of Chicago Chicago IL 60637 USA
| | - John S Anderson
- Department of Chemistry, University of Chicago Chicago IL 60637 USA
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25
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Tavani F, Capocasa G, Martini A, Sessa F, Di Stefano S, Lanzalunga O, D'Angelo P. Activation of C-H bonds by a nonheme iron(IV)-oxo complex: mechanistic evidence through a coupled EDXAS/UV-Vis multivariate analysis. Phys Chem Chem Phys 2021; 23:1188-1196. [PMID: 33355324 DOI: 10.1039/d0cp04304d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The understanding of reactive processes involving organic substrates is crucial to chemical knowledge and requires multidisciplinary efforts for its advancement. Herein, we apply a combined multivariate, statistical and theoretical analysis of coupled time-resolved X-ray absorption (XAS)/UV-Vis data to obtain detailed mechanistic information for on the C-H bond activation of 9,10-dihydroanthracene (DHA) and diphenylmethane (Ph2CH2) by the nonheme FeIV-oxo complex [N4Py·FeIV(O)]2+ (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine) in CH3CN at room temperature. Within this approach, we determine the number of key chemical species present in the reaction mixtures and derive spectral and concentration profiles for the reaction intermediates. From the quantitative analysis of the XAS spectra the transient intermediate species are structurally determined. As a result, it is suggested that, while DHA is oxidized by [N4Py·FeIV(O)]2+ with a hydrogen atom transfer-electron transfer (HAT-ET) mechanism, Ph2CH2 is oxidized by the nonheme iron-oxo complex through a HAT-radical dissociation pathway. In the latter process, we prove that the intermediate FeIII complex [N4Py·FeIII(OH)]2+ is not able to oxidize the diphenylmethyl radical and we provide its structural characterization in solution. The employed combined experimental and theoretical strategy is promising for the spectroscopic characterization of transient intermediates as well as for the mechanistic investigation of redox chemical transformations on the second to millisecond time scales.
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Affiliation(s)
- Francesco Tavani
- Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro 5, 00185 Roma, Italy.
| | - Giorgio Capocasa
- Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro 5, 00185 Roma, Italy.
| | - Andrea Martini
- Dipartimento di Chimica, Università degli Studi di Torino, Via P. Giuria 7, 10125 Torino, Italy and The Smart Materials Research Institute, Southern Federal University, 344090 Sladkova 178/24 Rostov-on-Don, Russia
| | - Francesco Sessa
- Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro 5, 00185 Roma, Italy.
| | - Stefano Di Stefano
- Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro 5, 00185 Roma, Italy.
| | - Osvaldo Lanzalunga
- Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro 5, 00185 Roma, Italy.
| | - Paola D'Angelo
- Dipartimento di Chimica, Università di Roma "La Sapienza", P.le A. Moro 5, 00185 Roma, Italy.
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26
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Tavani F, Capocasa G, Martini A, Sessa F, Di Stefano S, Lanzalunga O, D'Angelo P. Direct structural and mechanistic insights into fast bimolecular chemical reactions in solution through a coupled XAS/UV–Vis multivariate statistical analysis. Dalton Trans 2021; 50:131-142. [DOI: 10.1039/d0dt03083j] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A combined multivariate and theoretical analysis of coupled XAS/UV–Vis data was proven to be an innovative method to obtain direct structural and mechanistic evidence for bimolecular reactions in solution involving organic substrates.
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Affiliation(s)
- Francesco Tavani
- Dipartimento di Chimica
- Università di Roma “La Sapienza”
- 00185 Roma
- Italy
| | - Giorgio Capocasa
- Dipartimento di Chimica
- Università di Roma “La Sapienza”
- 00185 Roma
- Italy
| | - Andrea Martini
- Dipartimento di Chimica
- Università degli Studi di Torino
- 10125 Torino
- Italy
- The Smart Materials Research Institute
| | - Francesco Sessa
- Dipartimento di Chimica
- Università di Roma “La Sapienza”
- 00185 Roma
- Italy
| | | | | | - Paola D'Angelo
- Dipartimento di Chimica
- Università di Roma “La Sapienza”
- 00185 Roma
- Italy
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27
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Comba P, Faltermeier D, Martin B. Computational Approaches for Redox Potentials of Iron(IV)‐oxido Complexes. Z Anorg Allg Chem 2020. [DOI: 10.1002/zaac.202000355] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Peter Comba
- Anorganisch‐Chemisches Institut, INF 270und Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR) Universität Heidelberg 69120 Heidelberg Germany
| | - Dieter Faltermeier
- Anorganisch‐Chemisches Institut, INF 270und Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR) Universität Heidelberg 69120 Heidelberg Germany
| | - Bodo Martin
- Anorganisch‐Chemisches Institut, INF 270und Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR) Universität Heidelberg 69120 Heidelberg Germany
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28
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Kumar R, Pandey B, Sen A, Ansari M, Sharma S, Rajaraman G. Role of oxidation state, ferryl-oxygen, and ligand architecture on the reactivity of popular high-valent FeIV=O species: A theoretical perspective. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213397] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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29
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Specht P, Oßberger M, Klüfers P, Schindler S. Kinetic studies on the reaction of NO with iron(ii) complexes using low temperature stopped-flow techniques. Dalton Trans 2020; 49:9480-9486. [PMID: 32608457 DOI: 10.1039/d0dt01764g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Low temperature stopped-flow techniques were used to investigate the reaction of three different iron(ii) complexes with nitrogen monoxide. The kinetic studies allowed calculation of the activation parameters from the corresponding Eyring plots for all three systems. The reaction of iron(ii) chloride with NO leading to the formation of MNIC (mononitrosyl-iron-complex) and DNIC (dinitrosyl-iron-complex) led to activation parameters of ΔH‡ = 55.4 ± 0.4 kJ mol-1 and ΔS‡ = 13 ± 2 J K-1 mol-1 for MNIC and ΔH‡ = 32 ± 6 kJ mol-1 and ΔS‡ = -193 ± 21 J K-1 mol-1 for DNIC. Formation of MNIC turned out to be much faster in comparison with DNIC. In contrast, activation parameters for the formation of monoculear [Fe(bztpen)(NO)](OTf)2 (bztpen = N-benzyl-N,N',N'-tris(2-pyridylmethyl)-ethylenediamine) ΔH‡ = 17.8 ± 0.8 kJ mol-1 and ΔS‡ = -181 ± 3 J K-1 mol-1 supported an associative mechanism. Interestingly, [Fe(bztpen)(CH3CN)](OTf)2 does not react with dioxygen at all. Furthermore, activation parameters of ΔH‡ = 37.7 ± 0.7 kJ mol-1 and ΔS‡ = -66 ± 3 J K-1 mol-1 were obtained for the reaction of NO with the dinuclear iron(ii) H-HPTB complex (H-HPTB = N,N,N',N'-tetrakis(2-benzimidazolylmethyl)-2-hydroxy-1,3-diaminopropane), [Fe2(H-HPTB)(Cl)3]. The kinetic data allowed postulation of the mechanisms for all of these reactions.
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Affiliation(s)
- Pascal Specht
- Institut für Anorganische und Analytische Chemie, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 17, 35392 Gießen, Germany.
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30
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Mukherjee G, Sastri CV. Eccentricities in Spectroscopy and Reactivity of Non‐Heme Metal Intermediates Contained in Bispidine Scaffolds. Isr J Chem 2020. [DOI: 10.1002/ijch.202000045] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Gourab Mukherjee
- Department of Chemistry Indian Institute of Technology Guwahati Guwahati, Assam 781039 India
| | - Chivukula V. Sastri
- Department of Chemistry Indian Institute of Technology Guwahati Guwahati, Assam 781039 India
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31
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Larson VA, Battistella B, Ray K, Lehnert N, Nam W. Iron and manganese oxo complexes, oxo wall and beyond. Nat Rev Chem 2020; 4:404-419. [PMID: 37127969 DOI: 10.1038/s41570-020-0197-9] [Citation(s) in RCA: 139] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2020] [Indexed: 11/09/2022]
Abstract
High-valent metal-oxo species with multiply-bonded M-O groups have been proposed as key intermediates in many biological and abiological catalytic oxidation reactions. These intermediates are implicated as active oxidants in alkane hydroxylation, olefin epoxidation and other oxidation reactions. For example, [FeivO(porphyrinato•-)]+ cofactors bearing π-radical porphyrinato•- ligands oxidize organic substrates in cytochrome P450 enzymes, which are common to many life forms. Likewise, high-valent Mn-oxo species are active for H2O oxidation in photosystem II. The chemistry of these native reactive species has inspired chemists to prepare highly oxidized transition-metal complexes as functional mimics. Although many synthetic Fe-O and Mn-O complexes now exist, the analogous oxo complexes of the late transition metals (groups 9-11) are rare. Indeed, late-transition-metal-oxo complexes of tetragonal (fourfold) symmetry should be electronically unstable, a rule commonly referred to as the 'oxo wall'. A few late metal-oxos have been prepared by targeting other symmetries or unusual spin states. These complexes have been studied using spectroscopic and theoretical methods. This Review describes mononuclear non-haem Fe-O and Mn-O species, the nature of the oxo wall and recent advances in the preparation of oxo complexes of Co, Ni and Cu beyond the oxo wall.
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32
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Oswald VF, Lee JL, Biswas S, Weitz AC, Mittra K, Fan R, Li J, Zhao J, Hu MY, Alp EE, Bominaar EL, Guo Y, Green MT, Hendrich MP, Borovik AS. Effects of Noncovalent Interactions on High-Spin Fe(IV)-Oxido Complexes. J Am Chem Soc 2020; 142:11804-11817. [PMID: 32489096 DOI: 10.1021/jacs.0c03085] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
High-valent nonheme FeIV-oxido species are key intermediates in biological oxidation, and their properties are proposed to be influenced by the unique microenvironments present in protein active sites. Microenvironments are regulated by noncovalent interactions, such as hydrogen bonds (H-bonds) and electrostatic interactions; however, there is little quantitative information about how these interactions affect crucial properties of high valent metal-oxido complexes. To address this knowledge gap, we introduced a series of FeIV-oxido complexes that have the same S = 2 spin ground state as those found in nature and then systematically probed the effects of noncovalent interactions on their electronic, structural, and vibrational properties. The key design feature that provides access to these complexes is the new tripodal ligand [poat]3-, which contains phosphinic amido groups. An important structural aspect of [FeIVpoat(O)]- is the inclusion of an auxiliary site capable of binding a Lewis acid (LAII); we used this unique feature to further modulate the electrostatic environment around the Fe-oxido unit. Experimentally, studies confirmed that H-bonds and LAII s can interact directly with the oxido ligand in FeIV-oxido complexes, which weakens the Fe═O bond and has an impact on the electronic structure. We found that relatively large vibrational changes in the Fe-oxido unit correlate with small structural changes that could be difficult to measure, especially within a protein active site. Our work demonstrates the important role of noncovalent interactions on the properties of metal complexes, and that these interactions need to be considered when developing effective oxidants.
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Affiliation(s)
- Victoria F Oswald
- Department of Chemistry, 1102 Natural Sciences II, University of California at Irvine, Irvine, California 92697, United States
| | - Justin L Lee
- Department of Chemistry, 1102 Natural Sciences II, University of California at Irvine, Irvine, California 92697, United States
| | - Saborni Biswas
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Andrew C Weitz
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Kaustuv Mittra
- Department of Molecular Biosciences and Biochemistry, University of California at Irvine, Irvine, California 92697, United States
| | - Ruixi Fan
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Jikun Li
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Jiyong Zhao
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Michael Y Hu
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Esen E Alp
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Emile L Bominaar
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Michael T Green
- Department of Chemistry, 1102 Natural Sciences II, University of California at Irvine, Irvine, California 92697, United States.,Department of Molecular Biosciences and Biochemistry, University of California at Irvine, Irvine, California 92697, United States
| | - Michael P Hendrich
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - A S Borovik
- Department of Chemistry, 1102 Natural Sciences II, University of California at Irvine, Irvine, California 92697, United States
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33
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Comba P, Löhr A, Pfaff F, Ray K. Redox Potentials of High‐Valent Iron‐, Cobalt‐, and Nickel‐Oxido Complexes: Evidence for Exchange Enhanced Reactivity. Isr J Chem 2020. [DOI: 10.1002/ijch.202000038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Peter Comba
- Universität Heidelberg Anorganisch-Chemisches Institut, INF 270 D-69120 Heidelberg Germany
- Universität Heidelberg Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR) D-69120 Heidelberg Germany
| | - Anna‐Maria Löhr
- Universität Heidelberg Anorganisch-Chemisches Institut, INF 270 D-69120 Heidelberg Germany
| | - Florian Pfaff
- Department of Chemistry Humboldt-Universität zu Berlin Brook-Taylor-Strasse 2 Berlin Germany 12489
| | - Kallol Ray
- Department of Chemistry Humboldt-Universität zu Berlin Brook-Taylor-Strasse 2 Berlin Germany 12489
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34
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Ye YX, Wen C, Wang JW, Pan J, Huang S, Liang S, Zhou M, Tong Q, Zhu F, Xu J, Ouyang G. Valence-dependent catalytic activities of iron terpyridine complexes for pollutant degradation. Chem Commun (Camb) 2020; 56:5476-5479. [PMID: 32391821 DOI: 10.1039/d0cc00824a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein, iron-terpyridine complexes with the iron centers at different initial valence states were utilized as homogeneous catalysts for the degradation of phenol in water. The iron(iii)-terpyridine complex induced the formation of more high-valent iron-oxo centers and hydroxyl radicals than the iron(ii)-terpyridine complex, leading to a higher catalytic activity.
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Affiliation(s)
- Yu-Xin Ye
- KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, Guangdong, China.
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35
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Kass D, Corona T, Warm K, Braun-Cula B, Kuhlmann U, Bill E, Mebs S, Swart M, Dau H, Haumann M, Hildebrandt P, Ray K. Stoichiometric Formation of an Oxoiron(IV) Complex by a Soluble Methane Monooxygenase Type Activation of O 2 at an Iron(II)-Cyclam Center. J Am Chem Soc 2020; 142:5924-5928. [PMID: 32168447 DOI: 10.1021/jacs.9b13756] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In soluble methane monooxygenase enzymes (sMMO), dioxygen (O2) is activated at a diiron(II) center to form an oxodiiron(IV) intermediate Q that performs the challenging oxidation of methane to methanol. An analogous mechanism of O2 activation at mono- or dinuclear iron centers is rare in the synthetic chemistry. Herein, we report a mononuclear non-heme iron(II)-cyclam complex, 1-trans, that activates O2 to form the corresponding iron(IV)-oxo complex, 2-trans, via a mechanism reminiscent of the O2 activation process in sMMO. The conversion of 1-trans to 2-trans proceeds via the intermediate formation of an iron(III)-superoxide species 3, which could be trapped and spectroscopically characterized at -50 °C. Surprisingly, 3 is a stronger oxygen atom transfer (OAT) agent than 2-trans; 3 performs OAT to 1-trans or PPh3 to yield 2-trans quantitatively. Furthermore, 2-trans oxidizes the aromatic C-H bonds of 2,6-di-tert-butylphenol, which, together with the strong OAT ability of 3, represents new domains of oxoiron(IV) and superoxoiron(III) reactivities.
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Affiliation(s)
- Dustin Kass
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Teresa Corona
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Katrin Warm
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Beatrice Braun-Cula
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Uwe Kuhlmann
- Department of Chemistry, Technische Universität Berlin, Straβe des 17. Juni 135, 10623 Berlin, Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Stefan Mebs
- Department of Physics, Freie Universität Berlin, Arminallee 14, 14195 Berlin, Germany
| | - Marcel Swart
- ICREA, Lluis Companys 23, 08010 Barcelona, Spain.,IQCC, Universitat de Girona, Campus Montilivi, 17003 Girona, Spain
| | - Holger Dau
- Department of Physics, Freie Universität Berlin, Arminallee 14, 14195 Berlin, Germany
| | - Michael Haumann
- Department of Physics, Freie Universität Berlin, Arminallee 14, 14195 Berlin, Germany
| | - Peter Hildebrandt
- Department of Chemistry, Technische Universität Berlin, Straβe des 17. Juni 135, 10623 Berlin, Germany
| | - Kallol Ray
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
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36
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Park H, Lee D. Ligand Taxonomy for Bioinorganic Modeling of Dioxygen-Activating Non-Heme Iron Enzymes. Chemistry 2020; 26:5916-5926. [PMID: 31909506 DOI: 10.1002/chem.201904975] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/04/2020] [Indexed: 12/15/2022]
Abstract
Novel functions emerge from novel structures. To develop efficient catalytic systems for challenging chemical transformations, chemists often seek inspirations from enzymatic catalysis. A large number of iron complexes supported by nitrogen-rich multidentate ligands have thus been developed to mimic oxo-transfer reactivity of dioxygen-activating metalloenzymes. Such efforts have significantly advanced our understanding of the reaction mechanisms by trapping key intermediates and elucidating their geometric and electronic properties. Critical to the success of this biomimetic approach is the design and synthesis of elaborate ligand systems to balance the thermodynamic stability, structural adaptability, and chemical reactivity. In this Concept article, representative design strategies for biomimetic atom-transfer chemistry are discussed from the perspectives of "ligand builders". Emphasis is placed on how the primary coordination sphere is constructed, and how it can be elaborated further by rational design for desired functions.
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Affiliation(s)
- Hyunchang Park
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Korea
| | - Dongwhan Lee
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Korea
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37
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Dantignana V, Company A, Costas M. Oxoiron(V) Complexes of Relevance in Oxidation Catalysis of Organic Substrates. Isr J Chem 2020. [DOI: 10.1002/ijch.201900161] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Valeria Dantignana
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química Universitat de Girona C/M. Aurèlia Capmany 69 17003 Girona, Catalonia Spain
| | - Anna Company
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química Universitat de Girona C/M. Aurèlia Capmany 69 17003 Girona, Catalonia Spain
| | - Miquel Costas
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química Universitat de Girona C/M. Aurèlia Capmany 69 17003 Girona, Catalonia Spain
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38
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Comba P, Faltermeier D, Krieg S, Martin B, Rajaraman G. Spin state and reactivity of iron(iv)oxido complexes with tetradentate bispidine ligands. Dalton Trans 2020; 49:2888-2894. [DOI: 10.1039/c9dt04578c] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The iron(iv)oxido complex [(bispidine)FeIVO(Cl)]+is shown by experiment and high-level DLPNO-CCSD(T) quantum-chemical calculations to be an extremely short-lived and very reactive intermediate-spin (S= 1) species.
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Affiliation(s)
- Peter Comba
- Universität Heidelberg
- Anorganisch-Chemisches Institut
- D-69120 Heidelberg
- Germany
- Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR)
| | - Dieter Faltermeier
- Universität Heidelberg
- Anorganisch-Chemisches Institut
- D-69120 Heidelberg
- Germany
- Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR)
| | - Saskia Krieg
- Universität Heidelberg
- Anorganisch-Chemisches Institut
- D-69120 Heidelberg
- Germany
| | - Bodo Martin
- Universität Heidelberg
- Anorganisch-Chemisches Institut
- D-69120 Heidelberg
- Germany
- Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR)
| | - Gopalan Rajaraman
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai-400076
- India
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39
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Mukherjee G, Reinhard FGC, Bagha UK, Sastri CV, de Visser SP. Sluggish reactivity by a nonheme iron(iv)-tosylimido complex as compared to its oxo analogue. Dalton Trans 2020; 49:5921-5931. [DOI: 10.1039/d0dt00018c] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A comparative spectroscopic and computational study of reactivity between ferryl-tosylimido and ferryl-oxo complexes of two biomimetic model systems. The Fe(iv)-tosylimido complex was found to be sluggish in comparison to its fellow oxo counterpart.
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Affiliation(s)
- Gourab Mukherjee
- Department of Chemistry
- Indian Institute of Technology Guwahati
- India
| | - Fabián G. Cantú Reinhard
- The Manchester Institute of Biotechnology and Department of Chemical Engineering and Analytical Science
- The University of Manchester
- Manchester M1 7DN
- UK
| | | | | | - Sam P. de Visser
- The Manchester Institute of Biotechnology and Department of Chemical Engineering and Analytical Science
- The University of Manchester
- Manchester M1 7DN
- UK
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40
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Sabenya G, Gamba I, Gómez L, Clémancey M, Frisch JR, Klinker EJ, Blondin G, Torelli S, Que L, Martin-Diaconescu V, Latour JM, Lloret-Fillol J, Costas M. Octahedral iron(iv)-tosylimido complexes exhibiting single electron-oxidation reactivity. Chem Sci 2019; 10:9513-9529. [PMID: 32055323 PMCID: PMC6979323 DOI: 10.1039/c9sc02526j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 08/17/2019] [Indexed: 11/28/2022] Open
Abstract
High valent iron species are very reactive molecules involved in oxidation reactions of relevance to biology and chemical synthesis. Herein we describe iron(iv)-tosylimido complexes [FeIV(NTs)(MePy2tacn)](OTf)2 (1(IV)[double bond, length as m-dash]NTs) and [FeIV(NTs)(Me2(CHPy2)tacn)](OTf)2 (2(IV)[double bond, length as m-dash]NTs), (MePy2tacn = N-methyl-N,N-bis(2-picolyl)-1,4,7-triazacyclononane, and Me2(CHPy2)tacn = 1-(di(2-pyridyl)methyl)-4,7-dimethyl-1,4,7-triazacyclononane, Ts = Tosyl). 1(IV)[double bond, length as m-dash]NTs and 2(IV)[double bond, length as m-dash]NTs are rare examples of octahedral iron(iv)-imido complexes and are isoelectronic analogues of the recently described iron(iv)-oxo complexes [FeIV(O)(L)]2+ (L = MePy2tacn and Me2(CHPy2)tacn, respectively). 1(IV)[double bond, length as m-dash]NTs and 2(IV)[double bond, length as m-dash]NTs are metastable and have been spectroscopically characterized by HR-MS, UV-vis, 1H-NMR, resonance Raman, Mössbauer, and X-ray absorption (XAS) spectroscopy as well as by DFT computational methods. Ferric complexes [FeIII(HNTs)(L)]2+, 1(III)-NHTs (L = MePy2tacn) and 2(III)-NHTs (L = Me2(CHPy2)tacn) have been isolated after the decay of 1(IV)[double bond, length as m-dash]NTs and 2(IV)[double bond, length as m-dash]NTs in solution, spectroscopically characterized, and the molecular structure of [FeIII(HNTs)(MePy2tacn)](SbF6)2 determined by single crystal X-ray diffraction. Reaction of 1(IV)[double bond, length as m-dash]NTs and 2(IV)[double bond, length as m-dash]NTs with different p-substituted thioanisoles results in the transfer of the tosylimido moiety to the sulphur atom producing sulfilimine products. In these reactions, 1(IV)[double bond, length as m-dash]NTs and 2(IV)[double bond, length as m-dash]NTs behave as single electron oxidants and Hammett analyses of reaction rates evidence that tosylimido transfer is more sensitive than oxo transfer to charge effects. In addition, reaction of 1(IV)[double bond, length as m-dash]NTs and 2(IV)[double bond, length as m-dash]NTs with hydrocarbons containing weak C-H bonds results in the formation of 1(III)-NHTs and 2(III)-NHTs respectively, along with the oxidized substrate. Kinetic analyses indicate that reactions proceed via a mechanistically unusual HAT reaction, where an association complex precedes hydrogen abstraction.
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Affiliation(s)
- Gerard Sabenya
- Institut de Química Computacional i Catàlisi (IQCC) , Departament de Química , Universitat de Girona , Campus Montilivi , E17071 Girona , Spain .
| | - Ilaria Gamba
- Institut de Química Computacional i Catàlisi (IQCC) , Departament de Química , Universitat de Girona , Campus Montilivi , E17071 Girona , Spain .
| | - Laura Gómez
- Institut de Química Computacional i Catàlisi (IQCC) , Departament de Química , Universitat de Girona , Campus Montilivi , E17071 Girona , Spain .
| | - Martin Clémancey
- Univ. Grenoble-Alpes , CNRS , CEA , IRIG , DIESE , CBM , Grenoble 38000 , France
| | - Jonathan R Frisch
- Department of Chemistry , University of Minnesota , Pleasant Str 207 , Minneapolis , Minnesota , USA
| | - Eric J Klinker
- Department of Chemistry , University of Minnesota , Pleasant Str 207 , Minneapolis , Minnesota , USA
| | - Geneviève Blondin
- Univ. Grenoble-Alpes , CNRS , CEA , IRIG , DIESE , CBM , Grenoble 38000 , France
| | - Stéphane Torelli
- Univ. Grenoble-Alpes , CNRS , CEA , IRIG , DIESE , CBM , Grenoble 38000 , France
| | - Lawrence Que
- Department of Chemistry , University of Minnesota , Pleasant Str 207 , Minneapolis , Minnesota , USA
| | - Vlad Martin-Diaconescu
- Institut de Química Computacional i Catàlisi (IQCC) , Departament de Química , Universitat de Girona , Campus Montilivi , E17071 Girona , Spain .
- Institute of Chemical Research of Catalonia (ICIQ) , The Barcelona Institute of Science and Technology , Avinguda Països Catalans 16 , 43007 Tarragona , Spain .
| | - Jean-Marc Latour
- Univ. Grenoble-Alpes , CNRS , CEA , IRIG , DIESE , CBM , Grenoble 38000 , France
| | - Julio Lloret-Fillol
- Institut de Química Computacional i Catàlisi (IQCC) , Departament de Química , Universitat de Girona , Campus Montilivi , E17071 Girona , Spain .
- Institute of Chemical Research of Catalonia (ICIQ) , The Barcelona Institute of Science and Technology , Avinguda Països Catalans 16 , 43007 Tarragona , Spain .
- Catalan Institution for Research and Advanced Studies (ICREA) , Passeig Lluïs Companys, 23 , 08010 , Barcelona , Spain
| | - Miquel Costas
- Institut de Química Computacional i Catàlisi (IQCC) , Departament de Química , Universitat de Girona , Campus Montilivi , E17071 Girona , Spain .
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41
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Kroll N, Speckmann I, Schoknecht M, Gülzow J, Diekmann M, Pfrommer J, Stritt A, Schlangen M, Grohmann A, Hörner G. O−O Bond Formation and Liberation of Dioxygen Mediated by N 5‐Coordinate Non‐Heme Iron(IV) Complexes. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201903902] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Nicole Kroll
- Institut für ChemieTechnische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Ina Speckmann
- Institut für ChemieTechnische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Marc Schoknecht
- Institut für ChemieTechnische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Jana Gülzow
- Institut für ChemieTechnische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Marek Diekmann
- Institut für ChemieTechnische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Johannes Pfrommer
- Institut für ChemieTechnische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Anika Stritt
- Institut für ChemieTechnische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Maria Schlangen
- Institut für ChemieTechnische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Andreas Grohmann
- Institut für ChemieTechnische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
| | - Gerald Hörner
- Institut für ChemieTechnische Universität Berlin Straße des 17. Juni 135 10623 Berlin Germany
- Permanent address: Institut für Anorganische Chemie IVUniversität Bayreuth Universitätsstraße 30, NW I 95540 Bayreuth Germany
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42
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Kroll N, Speckmann I, Schoknecht M, Gülzow J, Diekmann M, Pfrommer J, Stritt A, Schlangen M, Grohmann A, Hörner G. O-O Bond Formation and Liberation of Dioxygen Mediated by N 5 -Coordinate Non-Heme Iron(IV) Complexes. Angew Chem Int Ed Engl 2019; 58:13472-13478. [PMID: 31271694 PMCID: PMC6772150 DOI: 10.1002/anie.201903902] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 06/07/2019] [Indexed: 01/04/2023]
Abstract
Formation of the O-O bond is considered the critical step in oxidative water cleavage to produce dioxygen. High-valent metal complexes with terminal oxo (oxido) ligands are commonly regarded as instrumental for oxygen evolution, but direct experimental evidence is lacking. Herein, we describe the formation of the O-O bond in solution, from non-heme, N5 -coordinate oxoiron(IV) species. Oxygen evolution from oxoiron(IV) is instantaneous once meta-chloroperbenzoic acid is administered in excess. Oxygen-isotope labeling reveals two sources of dioxygen, pointing to mechanistic branching between HAT (hydrogen atom transfer)-initiated free-radical pathways of the peroxides, which are typical of catalase-like reactivity, and iron-borne O-O coupling, which is unprecedented for non-heme/peroxide systems. Interpretation in terms of [FeIV (O)] and [FeV (O)] being the resting and active principles of the O-O coupling, respectively, concurs with fundamental mechanistic ideas of (electro-) chemical O-O coupling in water oxidation catalysis (WOC), indicating that central mechanistic motifs of WOC can be mimicked in a catalase/peroxidase setting.
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Affiliation(s)
- Nicole Kroll
- Institut für ChemieTechnische Universität BerlinStraße des 17. Juni 13510623BerlinGermany
| | - Ina Speckmann
- Institut für ChemieTechnische Universität BerlinStraße des 17. Juni 13510623BerlinGermany
| | - Marc Schoknecht
- Institut für ChemieTechnische Universität BerlinStraße des 17. Juni 13510623BerlinGermany
| | - Jana Gülzow
- Institut für ChemieTechnische Universität BerlinStraße des 17. Juni 13510623BerlinGermany
| | - Marek Diekmann
- Institut für ChemieTechnische Universität BerlinStraße des 17. Juni 13510623BerlinGermany
| | - Johannes Pfrommer
- Institut für ChemieTechnische Universität BerlinStraße des 17. Juni 13510623BerlinGermany
| | - Anika Stritt
- Institut für ChemieTechnische Universität BerlinStraße des 17. Juni 13510623BerlinGermany
| | - Maria Schlangen
- Institut für ChemieTechnische Universität BerlinStraße des 17. Juni 13510623BerlinGermany
| | - Andreas Grohmann
- Institut für ChemieTechnische Universität BerlinStraße des 17. Juni 13510623BerlinGermany
| | - Gerald Hörner
- Institut für ChemieTechnische Universität BerlinStraße des 17. Juni 13510623BerlinGermany
- Permanent address: Institut für Anorganische Chemie IVUniversität BayreuthUniversitätsstraße 30, NW I95540BayreuthGermany
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43
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Xu S, Draksharapu A, Rasheed W, Que L. Acid pKa Dependence in O–O Bond Heterolysis of a Nonheme FeIII–OOH Intermediate To Form a Potent FeV═O Oxidant with Heme Compound I-Like Reactivity. J Am Chem Soc 2019; 141:16093-16107. [DOI: 10.1021/jacs.9b08442] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Shuangning Xu
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Apparao Draksharapu
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Waqas Rasheed
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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44
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Das A, Nutting JE, Stahl SS. Electrochemical C-H oxygenation and alcohol dehydrogenation involving Fe-oxo species using water as the oxygen source. Chem Sci 2019; 10:7542-7548. [PMID: 31588305 PMCID: PMC6761876 DOI: 10.1039/c9sc02609f] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 06/25/2019] [Indexed: 11/30/2022] Open
Abstract
High-valent iron-oxo complexes are key intermediates in C-H functionalization reactions. Herein, we report the generation of a (TAML)Fe-oxo species (TAML = tetraamido macrocyclic ligand) via electrochemical proton-coupled oxidation of the corresponding (TAML)FeIII-OH2 complex. Cyclic voltammetry (CV) and spectroelectrochemical studies are used to elucidate the relevant (TAML)Fe redox processes and determine the predominant (TAML)Fe species present in solution during bulk electrolysis. Evidence for iron(iv) and iron(v) species is presented, and these species are used in the electrochemical oxygenation of benzylic C-H bonds and dehydrogenation of alcohols to ketones.
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Affiliation(s)
- Amit Das
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , USA .
| | - Jordan E Nutting
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , USA .
| | - Shannon S Stahl
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , USA .
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45
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Das B, Al-Hunaiti A, Sánchez-Eguía BN, Zeglio E, Demeshko S, Dechert S, Braunger S, Haukka M, Repo T, Castillo I, Nordlander E. Di- and Tetrairon(III) μ-Oxido Complexes of an N3S-Donor Ligand: Catalyst Precursors for Alkene Oxidations. Front Chem 2019; 7:97. [PMID: 30881952 PMCID: PMC6405480 DOI: 10.3389/fchem.2019.00097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 02/04/2019] [Indexed: 12/03/2022] Open
Abstract
The new di- and tetranuclear Fe(III) μ-oxido complexes [Fe4(μ-O)4(PTEBIA)4](CF3SO3)4(CH3CN)2] (1a), [Fe2(μ-O)Cl2(PTEBIA)2](CF3SO3)2 (1b), and [Fe2(μ-O)(HCOO)2(PTEBIA)2](ClO4)2 (MeOH) (2) were prepared from the sulfur-containing ligand (2-((2,4-dimethylphenyl)thio)-N,N-bis ((1-methyl-benzimidazol-2-yl)methyl)ethanamine (PTEBIA). The tetrairon complex 1a features four μ-oxido bridges, while in dinuclear 1b, the sulfur moiety of the ligand occupies one of the six coordination sites of each Fe(III) ion with a long Fe-S distance of 2.814(6) Å. In 2, two Fe(III) centers are bridged by one oxido and two formate units, the latter likely formed by methanol oxidation. Complexes 1a and 1b show broad sulfur-to-iron charge transfer bands around 400–430 nm at room temperature, consistent with mononuclear structures featuring Fe-S interactions. In contrast, acetonitrile solutions of 2 display a sulfur-to-iron charge transfer band only at low temperature (228 K) upon addition of H2O2/CH3COOH, with an absorption maximum at 410 nm. Homogeneous oxidative catalytic activity was observed for 1a and 1b using H2O2 as oxidant, but with low product selectivity. High valent iron-oxo intermediates could not be detected by UV-vis spectroscopy or ESI mass spectrometry. Rather, evidence suggest preferential ligand oxidation, in line with the relatively low selectivity and catalytic activity observed in the reactions.
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Affiliation(s)
- Biswanath Das
- Chemical Physics, Department of Chemistry, Lund University, Lund, Sweden
| | - Afnan Al-Hunaiti
- Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, Helsinki, Finland
| | | | - Erica Zeglio
- Chemical Physics, Department of Chemistry, Lund University, Lund, Sweden
| | - Serhiy Demeshko
- Institute for Inorganic Chemistry, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Sebastian Dechert
- Institute for Inorganic Chemistry, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Steffen Braunger
- Institute for Inorganic Chemistry, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Matti Haukka
- Department of Chemistry, University of Jyväskylä, Jyväskylä, Finland
| | - Timo Repo
- Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, Helsinki, Finland
| | - Ivan Castillo
- Instituto de Química, Universidad Nacional Autónoma de México, Mexico, Mexico
| | - Ebbe Nordlander
- Chemical Physics, Department of Chemistry, Lund University, Lund, Sweden
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46
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Mukherjee G, Alili A, Barman P, Kumar D, Sastri CV, de Visser SP. Interplay Between Steric and Electronic Effects: A Joint Spectroscopy and Computational Study of Nonheme Iron(IV)-Oxo Complexes. Chemistry 2019; 25:5086-5098. [PMID: 30720909 DOI: 10.1002/chem.201806430] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Indexed: 01/05/2023]
Abstract
Iron is an essential element in nonheme enzymes that plays a crucial role in many vital oxidative transformations and metabolic reactions in the human body. Many of those reactions are regio- and stereospecific and it is believed that the selectivity is guided by second-coordination sphere effects in the protein. Here, results are shown of a few engineered biomimetic ligand frameworks based on the N4Py (N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine) scaffold and the second-coordination sphere effects are studied. For the first time, selective substitutions in the ligand framework have been shown to tune the catalytic properties of the iron(IV)-oxo complexes by regulating the steric and electronic factors. In particular, a better positioning of the oxidant and substrate in the rate-determining transition state lowers the reaction barriers. Therefore, an optimum balance between steric and electronic factors mediates the ideal positioning of oxidant and substrate in the rate-determining transition state that affects the reactivity of high-valent reaction intermediates.
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Affiliation(s)
- Gourab Mukherjee
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Aligulu Alili
- The Manchester Institute of Biotechnology and School of Chemical, Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Prasenjit Barman
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Devesh Kumar
- Department of Applied Physics, Babasaheb Bhimrao Ambedkar University, School for Physical Sciences, Vidya Vihar, Rae Bareilly Road, Lucknow, 226025, UP, India
| | - Chivukula V Sastri
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India
| | - Sam P de Visser
- The Manchester Institute of Biotechnology and School of Chemical, Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
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47
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Prakash J, Sheng Y, Draksharapu A, Klein JEMN, Cramer CJ, Que L. Facile Conversion of
syn
‐[Fe
IV
(O)(TMC)]
2+
into the
anti
Isomer via Meunier's Oxo–Hydroxo Tautomerism Mechanism. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201811454] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Jai Prakash
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis MN 55455 USA
- Current address: Department of Physical and Environmental Sciences Texas A & M University-Corpus Christi Corpus Christi TX 78412 USA
| | - Yuan Sheng
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis MN 55455 USA
| | - Apparao Draksharapu
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis MN 55455 USA
| | - Johannes E. M. N. Klein
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis MN 55455 USA
- Molecular Inorganic Chemistry Stratingh Institute for Chemistry Faculty of Science and Engineering University of Groningen Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Christopher J. Cramer
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis MN 55455 USA
- Chemical Theory Center and Minnesota Supercomputing Institute University of Minnesota Minneapolis MN 55455-0431 USA
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis MN 55455 USA
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48
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Prakash J, Sheng Y, Draksharapu A, Klein JEMN, Cramer CJ, Que L. Facile Conversion of syn-[Fe IV (O)(TMC)] 2+ into the anti Isomer via Meunier's Oxo-Hydroxo Tautomerism Mechanism. Angew Chem Int Ed Engl 2019; 58:1995-1999. [PMID: 30556289 PMCID: PMC6470793 DOI: 10.1002/anie.201811454] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 11/27/2018] [Indexed: 12/05/2022]
Abstract
The syn and anti isomers of [FeIV (O)(TMC)]2+ (TMC=tetramethylcyclam) represent the first isolated pair of synthetic non-heme oxoiron(IV) complexes with identical ligand topology, differing only in the position of the oxo unit bound to the iron center. Both isomers have previously been characterized. Reported here is that the syn isomer [FeIV (Osyn )(TMC)(NCMe)]2+ (2) converts into its anti form [FeIV (Oanti )(TMC)(NCMe)]2+ (1) in MeCN, an isomerization facilitated by water and monitored most readily by 1 H NMR and Raman spectroscopy. Indeed, when H218 O is introduced to 2, the nascent 1 becomes 18 O-labeled. These results provide compelling evidence for a mechanism involving direct binding of a water molecule trans to the oxo atom in 2 with subsequent oxo-hydroxo tautomerism for its incorporation as the oxo atom of 1. The nonplanar nature of the TMC supporting ligand makes this isomerization an irreversible transformation, unlike for their planar heme counterparts.
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Affiliation(s)
- Jai Prakash
- Department of Chemistry and Center for Metals in BiocatalysisUniversity of MinnesotaMinneapolisMN55455USA
- Current address: Department of Physical and Environmental SciencesTexas A & M University-Corpus ChristiCorpus ChristiTX78412USA
| | - Yuan Sheng
- Department of Chemistry and Center for Metals in BiocatalysisUniversity of MinnesotaMinneapolisMN55455USA
| | - Apparao Draksharapu
- Department of Chemistry and Center for Metals in BiocatalysisUniversity of MinnesotaMinneapolisMN55455USA
| | - Johannes E. M. N. Klein
- Department of Chemistry and Center for Metals in BiocatalysisUniversity of MinnesotaMinneapolisMN55455USA
- Molecular Inorganic ChemistryStratingh Institute for ChemistryFaculty of Science and Engineering University of GroningenNijenborgh 49747AGGroningenThe Netherlands
| | - Christopher J. Cramer
- Department of Chemistry and Center for Metals in BiocatalysisUniversity of MinnesotaMinneapolisMN55455USA
- Chemical Theory Center and Minnesota Supercomputing InstituteUniversity of MinnesotaMinneapolisMN55455-0431USA
| | - Lawrence Que
- Department of Chemistry and Center for Metals in BiocatalysisUniversity of MinnesotaMinneapolisMN55455USA
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49
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Singh R, Ganguly G, Malinkin SO, Demeshko S, Meyer F, Nordlander E, Paine TK. A Mononuclear Nonheme Iron(IV)-Oxo Complex of a Substituted N4Py Ligand: Effect of Ligand Field on Oxygen Atom Transfer and C–H Bond Cleavage Reactivity. Inorg Chem 2019; 58:1862-1876. [DOI: 10.1021/acs.inorgchem.8b02577] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Reena Singh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Gaurab Ganguly
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Sergey O. Malinkin
- Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Serhiy Demeshko
- Universität
Göttingen, Institut für Anorganische Chemie, Tammanstrasse 4, D-37077 Göttingen, Germany
| | - Franc Meyer
- Universität
Göttingen, Institut für Anorganische Chemie, Tammanstrasse 4, D-37077 Göttingen, Germany
| | - Ebbe Nordlander
- Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Tapan Kanti Paine
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
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50
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Nag SS, Mukherjee G, Barman P, Sastri CV. Influence of induced steric on the switchover reactivity of mononuclear Cu(II)-alkylperoxo complexes. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2018.09.087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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