1
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Kumar R, Maji A, Biswas B, Draksharapu A. Amphoteric reactivity of a putative Cu(II)- mCPBA intermediate. Dalton Trans 2024; 53:5401-5406. [PMID: 38426906 DOI: 10.1039/d3dt03747a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
In copper-based enzymes, Cu-hydroperoxo/alkylperoxo species are proposed as key intermediates for their biological activity. A vast amount of literature is available on the functional and structural mimics of enzymatic systems with heme and non-heme ligand frameworks to stabilize high valent metal intermediates, mostly at low temperatures. Herein, we report a reaction between [CuI(NCCH3)4]+ and meta-chloroperoxybenzoic acid (mCPBA) in CH3CN that produces a putative CuII(mCPBA) species (1). 1 was characterized by UV/Vis, resonance Raman, and EPR spectroscopies. 1 can catalyze both electrophilic and nucleophilic reactions, demonstrating its amphoteric behavior. Additionally, 1 can also conduct electron transfer reactions with a weak reducing agent such as diacetyl ferrocene, making it one of the reactive copper-based intermediates. One of the most important aspects of the current work is the easy synthesis of a CuII(mCPBA) adduct with no complicated ligands for stabilization. Over time, 1 decays to form a CuII paddle wheel complex (2) and is found to be unreactive towards substrate oxidation.
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Affiliation(s)
- Rakesh Kumar
- Southern Laboratories - 208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Anweshika Maji
- Southern Laboratories - 208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Bhargab Biswas
- Southern Laboratories - 208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Apparao Draksharapu
- Southern Laboratories - 208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
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2
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Awasthi A, Mallojjala SC, Kumar R, Eerlapally R, Hirschi JS, Draksharapu A. Altering the Localization of an Unpaired Spin in a Formal Ni(V) Species. Chemistry 2024; 30:e202302824. [PMID: 37903027 PMCID: PMC10841873 DOI: 10.1002/chem.202302824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 10/28/2023] [Accepted: 10/30/2023] [Indexed: 11/01/2023]
Abstract
The participation of both ligand and the metal center in the redox events has been recognized as one of the ways to attain the formal high valent complexes for the late 3d metals, such as Ni and Cu. Such an approach has been employed successfully to stabilize a Ni(III) bisphenoxyl diradical species in which there exist an equilibrium between the ligand and the Ni localized resultant spin. The present work, however, broadens the scope of the previously reported three oxidized equivalent species by conveying the approaches that tend to affect the reported equilibrium in CH3 CN at 233 K. Various spectroscopic characterization revealed that employing exogenous N-donor ligands like 1-methyl imidazole and pyridine favors the formation of the Ni centered localized spin though axial binding. In contrast, due to its steric hinderance, quinoline favors an exclusive ligand localized radical species. DFT studies shed light on the novel intermediates' complex electronic structure. Further, the three oxidized equivalent species with the Ni centered spin was examined for its hydrogen atom abstraction ability stressing their key role in alike reactions.
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Affiliation(s)
- Ayushi Awasthi
- Southern Laboratories-208 A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | | | - Rakesh Kumar
- Southern Laboratories-208 A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Raju Eerlapally
- Southern Laboratories-208 A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Jennifer S Hirschi
- Department of Chemistry, Binghamton University, Binghamton, New York, 13902, USA
| | - Apparao Draksharapu
- Southern Laboratories-208 A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
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3
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Gupta S, Arora P, Kumar R, Awasthi A, Chandra B, Eerlapally R, Xiong J, Guo Y, Que L, Draksharapu A. Formation of a Reactive [Mn(III)-O-Ce(IV)] Species and its Facile Equilibrium with Related Mn(IV)(OX) (X = Sc or H) Complexes. Angew Chem Int Ed Engl 2024; 63:e202316378. [PMID: 37997195 PMCID: PMC10873046 DOI: 10.1002/anie.202316378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 11/22/2023] [Accepted: 11/23/2023] [Indexed: 11/25/2023]
Abstract
Lewis acid-bound high valent Mn-oxo species are of great importance due to their relevance to photosystem II. Here, we report the synthesis of a unique [(BnTPEN)Mn(III)-O-Ce(IV)(NO3 )4 ]+ adduct (2) by the reaction of (BnTPEN)Mn(II) (1) with 4 eq. ceric ammonium nitrate. 2 has been characterized using UV/Vis, NMR, resonance Raman spectroscopy, as well as by mass spectrometry. Treatment of 2 with Sc(III)(OTf)3 results in the formation of (BnTPEN)Mn(IV)-O-Sc(III) (3), while HClO4 addition to 2 forms (BnTPEN)Mn(IV)-OH (4), reverting to 2 upon Ce(III)(NO3 )3 addition. 2 can also be prepared by the oxidation of 1 eq. Ce(III)(NO3 )3 with [(BnTPEN)Mn(IV)=O]2+ (5). In addition, the EPR spectroscopy revealed the elegant temperature-dependent equilibria between 2 and Mn(IV) species. The binding of redox-active Ce(IV) boosts electron transfer efficiency of 2 towards ferrocenes. Remarkably, the newly characterized Mn(III)-O-Ce(IV) species can carry out O-atom and H-atom transfer reactions.
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Affiliation(s)
- Sikha Gupta
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Pragya Arora
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Rakesh Kumar
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Ayushi Awasthi
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Bittu Chandra
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Raju Eerlapally
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Jin Xiong
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Lawrence Que
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Apparao Draksharapu
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
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4
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Kumar R, Keshri R, Prodhan K, Shaikh K, Draksharapu A. A tetranuclear Mn-diamond core complex as a functional mimic of both catechol oxidase and phenoxazinone synthase enzymes. Dalton Trans 2023; 52:15412-15419. [PMID: 37226832 DOI: 10.1039/d3dt00761h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Through dioxygen activation, a tetranuclear Mn(II,III,III,II) diamond core, [Mn4(HPTP*)2(μ-O)2(H2O)4](ClO4)4 (1) complex, has been synthesised using a suitably designed septadentate ligand framework (HPTP*H = 1,3-bis(bis((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)amino)propan-2-ol). The newly prepared complex 1 was characterised using multiple spectroscopic techniques and X-ray crystallography. 1 exhibits excellent catalytic oxidation reactivity for the model substrates, namely, 3,5-di-tert-butylcatechol (3,5-DTBC) and 2-aminophenol, efficiently mimicking the enzymes catechol oxidase and phenoxazinone synthase, respectively. Remarkably, we employed aerial oxygen to catalyze the oxidation of these model substrates, 3,5-DTBC and 2-aminophenol, with turnover numbers of 835 and 14, respectively. A tetranuclear Mn-diamond core complex that mimics both catechol oxidase and phenoxazinone synthase could pave the way for further research into its potential as a multi-enzymatic functional mimic.
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Affiliation(s)
- Rakesh Kumar
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur - 208016, India.
| | - Rahul Keshri
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur - 208016, India.
| | - Koushik Prodhan
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur - 208016, India.
| | - Kanchan Shaikh
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur - 208016, India.
| | - Apparao Draksharapu
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur - 208016, India.
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Arora P, Gupta S, Kumari Vechalapu S, Kumar R, Awasthi A, Senthil S, Khanna S, Allimuthu D, Draksharapu A. Mn(II) Polypyridyl Complexes: Precursors to High Valent Mn(V)=O Species and Inhibitors of Cancer Cell Proliferation. Chemistry 2023; 29:e202301506. [PMID: 37415318 DOI: 10.1002/chem.202301506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 06/27/2023] [Accepted: 07/06/2023] [Indexed: 07/08/2023]
Abstract
The reaction of [(L)MnII ]2+ (L = neutral polypyridine ligand framework) in the presence of mCPBA (mCPBA = m-Chloroperoxybenzoic acid) generates a putative MnV =O species at RT. The proposed MnV =O species is capable of performing the aromatic hydroxylation of Cl-benzoic acid derived from mCPBA to give [(L)MnIII (m-Cl-salicylate)]+ , which in the presence of excess mCPBA generates a metastable [(L)MnV (O)(m-Cl-salicylate)]+ , characterized by UV/Vis absorption, EPR, resonance Raman spectroscopy, and ESI-MS studies. The current study highlights the fact that [(L)MnIII (m-Cl-salicylate)]+ formation may not be a dead end for catalysis. Further, a plausible mechanism has been proposed for the formation of [(L)MnV (O)-m-Cl-salicylate)]+ from [(L)MnIII (m-Cl-salicylate)]+ . The characterized transient [(L)MnV (O)-m-Cl-salicylate)]+ reported in the current work exhibits high reactivity for oxygen atom transfer reactions, supported by the electrophilic character depicted from Hammett studies using a series of para-substituted thioanisoles. The unprecedented study starting from a non-heme neutral polypyridine ligand framework paves a path for mimicking the natural active site of photosystem II under ambient conditions. Finally, evaluating the intracellular effect of Mn(II) complexes revealed an enhanced intracellular ROS and mitochondrial dysfunction to prevent the proliferation of hepatocellular carcinoma and breast cancer cells.
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Affiliation(s)
- Pragya Arora
- Southern Laboratories, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Sikha Gupta
- Southern Laboratories, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Sai Kumari Vechalapu
- Southern Laboratories, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Rakesh Kumar
- Southern Laboratories, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Ayushi Awasthi
- Southern Laboratories, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Sathyapriya Senthil
- Southern Laboratories, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Shweta Khanna
- Southern Laboratories, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Dharmaraja Allimuthu
- Southern Laboratories, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Apparao Draksharapu
- Southern Laboratories, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
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Kumar R, Ahsan F, Awasthi A, Swart M, Draksharapu A. Generation of Ru(III)-hypochlorite with resemblance to the heme-dependent haloperoxidase enzyme. Dalton Trans 2023; 52:12552-12559. [PMID: 37609762 DOI: 10.1039/d3dt02028b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
The reaction of [(Me/BnTPEN)RuII(NCCH3)]2+ (BnTPEN = N1-benzyl-N1,N2,N2-tris(pyridine-2-ylmethyl)ethane-1,2-diamine and MeTPEN = N1-methyl-N1,N2,N2-tris(pyridine-2-ylmethyl)ethane-1,2-diamine) with mCPBA in the presence of chloride ions in CH3CN : H2O generated a novel (Me/BnTPEN)RuIII-OCl species at room temperature. This hypochlorite adduct could also be obtained by the direct reaction of NaOCl and HClO4 with (L)RuII complexes. The current study mimics the synthesis of a metal hypochlorite adduct in a similar fashion as in the heme-dependent haloperoxidase enzyme. As an electrophilic oxidant, the ruthenium hypochlorite adduct catalyzes hydrogen atom abstraction reactions of phenols and their derivatives.
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Affiliation(s)
- Rakesh Kumar
- Southern Laboratories - 208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Faiza Ahsan
- IQCC & Departament de Química, Universitat de Girona, 17003 Girona, Spain
| | - Ayushi Awasthi
- Southern Laboratories - 208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Marcel Swart
- IQCC & Departament de Química, Universitat de Girona, 17003 Girona, Spain
- ICREA, 08010, Barcelona, Spain.
| | - Apparao Draksharapu
- Southern Laboratories - 208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
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7
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Eerlapally R, Gupta S, Awasthi A, Kumar R, Draksharapu A. Spectroscopic characterization and the reactivity of a high valent (L)Cu(III) species supported by a proline-based pseudopeptide. Dalton Trans 2023. [PMID: 37294205 DOI: 10.1039/d3dt00697b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Inspired by copper-based metalloenzymes, we aim to incorporate amino acids into our ligands to facilitate active copper intermediates that serve as functional and structural models for these enzymes. Herein, we report the synthesis of a Cu(II) complex with a C2 symmetric proline-based pseudopeptide LH2 (N,N'-(ethane-1,2-diyl)bis(pyrrolidine-2-carboxamide)), which is capable of supporting an [(L)Cu(III)]+ (3) intermediate in MeOH : CH3CN (1 : 20) at -30 °C. From comparative studies with the pyridine analog Cu(II) complex, it was demonstrated that the incorporation of amino acid in the ligand framework decreased the Cu(III)/Cu(II) redox potential significantly to react readily with mCPBA and CAN. The newly generated [(L)Cu(III)]+ can promote hydrogen atom abstraction reactions with phenolic substrates.
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Affiliation(s)
- Raju Eerlapally
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Sikha Gupta
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Ayushi Awasthi
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Rakesh Kumar
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Apparao Draksharapu
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
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8
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Awasthi A, Leach IF, Engbers S, Kumar R, Eerlapally R, Gupta S, Klein JEMN, Draksharapu A. Formation and Reactivity of a Fleeting Ni III Bisphenoxyl Diradical Species. Angew Chem Int Ed Engl 2022; 61:e202211345. [PMID: 35978531 PMCID: PMC9826141 DOI: 10.1002/anie.202211345] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Indexed: 01/11/2023]
Abstract
Cytochrome P450s and Galactose Oxidases exploit redox active ligands to form reactive high valent intermediates for oxidation reactions. This strategy works well for the late 3d metals where accessing high valent states is rather challenging. Herein, we report the oxidation of NiII (salen) (salen=N,N'-bis(3,5-di-tert-butyl-salicylidene)-1,2-cyclohexane-(1R,2R)-diamine) with mCPBA (meta-chloroperoxybenzoic acid) to form a fleeting NiIII bisphenoxyl diradical species, in CH3 CN and CH2 Cl2 at -40 °C. Electrochemical and spectroscopic analyses using UV/Vis, EPR, and resonance Raman spectroscopies revealed oxidation events both on the ligand and the metal centre to yield a NiIII bisphenoxyl diradical species. DFT calculations found the electronic structure of the ligand and the d-configuration of the metal center to be consistent with a NiIII bisphenoxyl diradical species. This three electron oxidized species can perform hydrogen atom abstraction and oxygen atom transfer reactions.
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Affiliation(s)
- Ayushi Awasthi
- Southern Laboratories-208 ADepartment of ChemistryIndian Institute of Technology KanpurKanpur208016India
| | - Isaac F. Leach
- Molecular Inorganic ChemistryStratingh Institute for ChemistryUniversity of Groningen9747 AGGroningenThe Netherlands
| | - Silène Engbers
- Molecular Inorganic ChemistryStratingh Institute for ChemistryUniversity of Groningen9747 AGGroningenThe Netherlands
| | - Rakesh Kumar
- Southern Laboratories-208 ADepartment of ChemistryIndian Institute of Technology KanpurKanpur208016India
| | - Raju Eerlapally
- Southern Laboratories-208 ADepartment of ChemistryIndian Institute of Technology KanpurKanpur208016India
| | - Sikha Gupta
- Southern Laboratories-208 ADepartment of ChemistryIndian Institute of Technology KanpurKanpur208016India
| | - Johannes E. M. N. Klein
- Molecular Inorganic ChemistryStratingh Institute for ChemistryUniversity of Groningen9747 AGGroningenThe Netherlands
| | - Apparao Draksharapu
- Southern Laboratories-208 ADepartment of ChemistryIndian Institute of Technology KanpurKanpur208016India
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9
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Kumar R, Awasthi A, Gupta S, Eerlapally R, Draksharapu A. Spectroscopic characterization of a Ru(III)-OCl intermediate: a structural mimic of haloperoxidase enzymes. Dalton Trans 2022; 51:12848-12854. [PMID: 35968730 DOI: 10.1039/d2dt01947g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Haloperoxidase enzymes utilize metal hypohalite species to halogenate aliphatic and aromatic C-H bonds to C-X (X = Cl, Br, I) in nature. In this work, we report the synthesis and spectroscopic characterization of a unique RuIII-OCl species as a structural mimic of haloperoxidase enzymes. The reaction of [(BnTPEN)RuII(NCCH3)]2+ (BnTPEN = N1-benzyl-N1,N2,N2-tris(pyridine-2-ylmethyl)ethane-1,2-diamine) with hypochlorite in the presence of an acid in CH3CN : H2O mixtures generated a novel [(BnTPEN)RuIII-OCl]2+ species that persists for 4.5 h at room temperature. This new species was characterized by UV-vis absorption, EPR, and resonance Raman spectroscopic techniques, and ESI-MS. The RuIII-OCl species is capable of performing oxygen atom transfer and hydrogen atom abstraction to various organic substrates.
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Affiliation(s)
- Rakesh Kumar
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Ayushi Awasthi
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Sikha Gupta
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Raju Eerlapally
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
| | - Apparao Draksharapu
- Southern Laboratories-208A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India.
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10
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Awasthi A, Leach IF, Engbers S, Kumar R, Eerlapally R, Gupta S, Klein JEMN, Draksharapu A. Formation and Reactivity of a Fleeting Ni(III) Bisphenoxyl Diradical Species. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202211345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - Isaac F. Leach
- University of Groningen Zernike Institute for Advanced Materials: Rijksuniversiteit Groningen Zernike Institute for Advanced Materials Stratingh Institute for Chemistry NETHERLANDS
| | - Silène Engbers
- University of Groningen Zernike Institute for Advanced Materials: Rijksuniversiteit Groningen Zernike Institute for Advanced Materials Stratingh Institute for Chemistry NETHERLANDS
| | - Rakesh Kumar
- Indian Institute of Technology Kanpur Chemistry INDIA
| | | | - Sikha Gupta
- Indian Institute of Technology Kanpur Chemistry INDIA
| | - Johannes E. M. N. Klein
- University of Groningen Zernike Institute for Advanced Materials: Rijksuniversiteit Groningen Zernike Institute for Advanced Materials Stratingh Institute for Chemistry NETHERLANDS
| | - Apparao Draksharapu
- IITK: Indian Institute of Technology Kanpur Chemistry SL-208A 208016 Kanpur INDIA
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11
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Aldous L, Comba P, DeBeer S, Dey A, Draksharapu A, Duboc C, Itoh S, Karlin K, Kundu S, López Domene R, Maréchal JD, Mazumdar S, Mukherjee R, Parker D, Pordea A, Que L, Rath SP, Sadler P, Sastri C, Schindler S, Schünemann V, Sen Gupta S, Solomon EI, P Stack TD. Small molecule activation and synthetic analogues: general discussion. Faraday Discuss 2022; 234:129-142. [PMID: 35531924 DOI: 10.1039/d2fd90012b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Anilkumar A, Ash P, Chakravarty AR, Comba P, DeBeer S, Dey A, Draksharapu A, Goswami D, Itoh S, Karlin K, Lakshmi KV, Mazumdar S, Pantazis D, Parker D, Que L, Rajaraman G, Rath SP, Sastri C, Sen Gupta S, Solomon EI. Electron transfer, spectroscopy and theory: general discussion. Faraday Discuss 2022; 234:245-263. [PMID: 35510729 DOI: 10.1039/d2fd90013k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Sheng Y, Abelson CS, Prakash J, Draksharapu A, Young VG, Que L. Unmasking Steps in Intramolecular Aromatic Hydroxylation by a Synthetic Nonheme Oxoiron(IV) Complex. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202108309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Yuan Sheng
- Department of Chemistry University of Minnesota Minneapolis MN 55455 USA
| | - Chase S. Abelson
- Department of Chemistry University of Minnesota Minneapolis MN 55455 USA
| | - Jai Prakash
- Department of Chemistry University of Minnesota Minneapolis MN 55455 USA
| | | | - Victor G. Young
- Department of Chemistry University of Minnesota Minneapolis MN 55455 USA
| | - Lawrence Que
- Department of Chemistry University of Minnesota Minneapolis MN 55455 USA
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14
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Sheng Y, Abelson CS, Prakash J, Draksharapu A, Young VG, Que L. Unmasking Steps in Intramolecular Aromatic Hydroxylation by a Synthetic Nonheme Oxoiron(IV) Complex. Angew Chem Int Ed Engl 2021; 60:20991-20998. [PMID: 34292639 DOI: 10.1002/anie.202108309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Indexed: 11/09/2022]
Abstract
In this study, a methyl group on the classic tetramethylcyclam (TMC) ligand framework is replaced with a benzylic group to form the metastable [FeIV (Osyn )(Bn3MC)]2+ (2-syn; Bn3MC=1-benzyl-4,8,11-trimethyl-1,4,8,11-tetraazacyclotetradecane) species at -40 °C. The decay of 2-syn with time at 25 °C allows the unprecedented monitoring of the steps involved in the intramolecular hydroxylation of the ligand phenyl ring to form the major FeIII -OAr product 3. At the same time, the FeII (Bn3MC)2+ (1) precursor to 2-syn is re-generated in a 1:2 molar ratio relative to 3, accounting for the first time for all the electrons involved and all the Fe species derived from 2-syn as shown in the following balanced equation: 3 [FeIV (O)(LPh )]2+ (2-syn)→2 [FeIII (LOAr )]2+ (3)+[FeII (LPh )]2+ (1)+H2 O. This system thus serves as a paradigm for aryl hydroxylation by FeIV =O oxidants described thus far. It is also observed that 2-syn can be intercepted by certain hydrocarbon substrates, thereby providing a means to assess the relative energetics of aliphatic and aromatic C-H hydroxylation in this system.
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Affiliation(s)
- Yuan Sheng
- Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Chase S Abelson
- Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Jai Prakash
- Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Apparao Draksharapu
- Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Victor G Young
- Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Lawrence Que
- Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USA
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15
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Draksharapu A, Xu S, Que L. Ce IV - and HClO 4 -Promoted Assembly of an Fe 2IV (μ-O) 2 Diamond Core from its Monomeric Fe IV =O Precursor at Room Temperature. Angew Chem Int Ed Engl 2020; 59:22484-22488. [PMID: 32902902 PMCID: PMC7708462 DOI: 10.1002/anie.202010027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Indexed: 11/06/2022]
Abstract
Diiron(IV)-oxo species are proposed to effect the cleavage of strong C-H bonds by nonheme diiron enzymes such as soluble methane monooxygenase (sMMO) and fatty acid desaturases. However, synthetic mimics of such diiron(IV) oxidants are rare. Herein we report the reaction of (TPA*)FeII (1) (TPA*=tris(3,5-dimethyl-4-methoxypyridyl-2-methyl)amine) in CH3 CN with 4 equiv CAN and 200 equiv HClO4 at 20 °C to form a complex with an [FeIV2 (μ-O)2 ]4+ core. CAN and HClO4 play essential roles in this unprecedented transformation, in which the comproportionation of FeIII -O-CeIV and FeIV =O/Ce4+ species is proposed to be involved in the assembly of the [FeIV2 (μ-O)2 ]4+ core.
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Affiliation(s)
- Apparao Draksharapu
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota, 55455, USA
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Shuangning Xu
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota, 55455, USA
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota, 55455, USA
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16
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Draksharapu A, Xu S, Que L. Ce
IV
‐ and HClO
4
‐Promoted Assembly of an Fe
2
IV
(μ‐O)
2
Diamond Core from its Monomeric Fe
IV
=O Precursor at Room Temperature. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202010027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Apparao Draksharapu
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis Minnesota 55455 USA
- Department of Chemistry Indian Institute of Technology Kanpur Kanpur 208016 India
| | - Shuangning Xu
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis Minnesota 55455 USA
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis Minnesota 55455 USA
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17
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Banerjee S, Draksharapu A, Crossland PM, Fan R, Guo Y, Swart M, Que L. Sc 3+-Promoted O-O Bond Cleavage of a (μ-1,2-Peroxo)diiron(III) Species Formed from an Iron(II) Precursor and O 2 to Generate a Complex with an Fe IV2(μ-O) 2 Core. J Am Chem Soc 2020; 142:4285-4297. [PMID: 32017545 DOI: 10.1021/jacs.9b12081] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Soluble methane monooxygenase (sMMO) carries out methane oxidation at 4 °C and under ambient pressure in a catalytic cycle involving the formation of a peroxodiiron(III) intermediate (P) from the oxygenation of the diiron(II) enzyme and its subsequent conversion to Q, the diiron(IV) oxidant that hydroxylates methane. Synthetic diiron(IV) complexes that can serve as models for Q are rare and have not been generated by a reaction sequence analogous to that of sMMO. In this work, we show that [FeII(Me3NTB)(CH3CN)](CF3SO3)2 (Me3NTB = tris((1-methyl-1H-benzo[d]imidazol-2-yl)methyl)amine) (1) reacts with O2 in the presence of base, generating a (μ-1,2-peroxo)diiron(III) adduct with a low O-O stretching frequency of 825 cm-1 and a short Fe···Fe distance of 3.07 Å. Even more interesting is the observation that the peroxodiiron(III) complex undergoes O-O bond cleavage upon treatment with the Lewis acid Sc3+ and transforms into a bis(μ-oxo)diiron(IV) complex, thus providing a synthetic precedent for the analogous conversion of P to Q in the catalytic cycle of sMMO.
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Affiliation(s)
- Saikat Banerjee
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Apparao Draksharapu
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Patrick M Crossland
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Ruixi Fan
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Marcel Swart
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain.,IQCC and Department of Chemistry, University of Girona, 17003 Girona, Spain
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
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18
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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19
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Dantignana V, Serrano-Plana J, Draksharapu A, Magallón C, Banerjee S, Fan R, Gamba I, Guo Y, Que L, Costas M, Company A. Spectroscopic and Reactivity Comparisons between Nonheme Oxoiron(IV) and Oxoiron(V) Species Bearing the Same Ancillary Ligand. J Am Chem Soc 2019; 141:15078-15091. [PMID: 31469954 DOI: 10.1021/jacs.9b05758] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This work directly compares the spectroscopic and reactivity properties of an oxoiron(IV) and an oxoiron(V) complex that are supported by the same neutral tetradentate N-based PyNMe3 ligand. A complete spectroscopic characterization of the oxoiron(IV) species (2) reveals that this compound exists as a mixture of two isomers. The reactivity of the thermodynamically more stable oxoiron(IV) isomer (2b) is directly compared to that exhibited by the previously reported 1e--oxidized analogue [FeV(O)(OAc)(PyNMe3)]2+ (3). Our data indicates that 2b is 4 to 5 orders of magnitude slower than 3 in hydrogen atom transfer (HAT) from C-H bonds. The origin of this huge difference lies in the strength of the O-H bond formed after HAT by the oxoiron unit, the O-H bond derived from 3 being about 20 kcal·mol-1 stronger than that from 2b. The estimated bond strength of the FeIVO-H bond of 100 kcal·mol-1 is very close to the reported values for highly active synthetic models of compound I of cytochrome P450. In addition, this comparative study provides direct experimental evidence that the lifetime of the carbon-centered radical that forms after the initial HAT by the high valent oxoiron complex depends on the oxidation state of the nascent Fe-OH complex. Complex 2b generates long-lived carbon-centered radicals that freely diffuse in solution, while 3 generates short-lived caged radicals that rapidly form product C-OH bonds, so only 3 engages in stereoretentive hydroxylation reactions. Thus, the oxidation state of the iron center modulates not only the rate of HAT but also the rate of ligand rebound.
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Affiliation(s)
- Valeria Dantignana
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química , Universitat de Girona , C/M. Aurèlia Capmany 69 , 17003 Girona , Catalonia , Spain
| | - Joan Serrano-Plana
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química , Universitat de Girona , C/M. Aurèlia Capmany 69 , 17003 Girona , Catalonia , Spain
| | - Apparao Draksharapu
- Department of Chemistry and Center for Metals in Biocatalysis , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Carla Magallón
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química , Universitat de Girona , C/M. Aurèlia Capmany 69 , 17003 Girona , Catalonia , Spain
| | - Saikat Banerjee
- Department of Chemistry and Center for Metals in Biocatalysis , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Ruixi Fan
- Department of Chemistry , Carnegie Mellon University , 4400 Fifth Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Ilaria Gamba
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química , Universitat de Girona , C/M. Aurèlia Capmany 69 , 17003 Girona , Catalonia , Spain
| | - Yisong Guo
- Department of Chemistry , Carnegie Mellon University , 4400 Fifth Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Miquel Costas
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química , Universitat de Girona , C/M. Aurèlia Capmany 69 , 17003 Girona , Catalonia , Spain
| | - Anna Company
- 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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20
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Banerjee S, Rasheed W, Fan R, Draksharapu A, Oloo WN, Guo Y, Que L. NMR Reveals That a Highly Reactive Nonheme Fe IV =O Complex Retains Its Six-Coordinate Geometry and S=1 State in Solution. Chemistry 2019; 25:9608-9613. [PMID: 31059593 DOI: 10.1002/chem.201902048] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Indexed: 01/08/2023]
Abstract
The [FeIV (O)(Me3 NTB)]2+ (Me3 NTB=tris[(1-methyl-benzimidazol-2-yl)methyl]amine) complex 1 has been shown by Mössbauer spectroscopy to have an S=1 ground state at 4 K, but is proposed to become an S=2 trigonal-bipyramidal species at higher temperatures based on a DFT model to rationalize its very high C-H bond-cleavage reactivity. In this work, 1 H NMR spectroscopy was used to determine that 1 does not have C3 -symmetry in solution and is not an S=2 species. Our results show that 1 is unique among nonheme FeIV =O complexes in retaining its S=1 spin state and high reactivity at 193 K, providing evidence that S=1 FeIV =O complexes can be as reactive as their S=2 counterparts. This result emphasizes the need to identify factors besides the ground spin state of the FeIV =O center to rationalize nonheme oxoiron(IV) reactivity.
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Affiliation(s)
- Saikat Banerjee
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Waqas Rasheed
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Ruixi Fan
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Apparao Draksharapu
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA.,Current address: Southern Laboratories, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Williamson N Oloo
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
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21
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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22
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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] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [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 1H NMR and Raman spectroscopy. Indeed, when H218O is introduced to 2, the nascent 1 becomes 18O‐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 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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23
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Chen J, Draksharapu A, Angelone D, Unjaroen D, Padamati SK, Hage R, Swart M, Duboc C, Browne WR. H 2O 2 Oxidation by Fe III-OOH Intermediates and Its Effect on Catalytic Efficiency. ACS Catal 2018; 8:9665-9674. [PMID: 30319886 PMCID: PMC6179451 DOI: 10.1021/acscatal.8b02326] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 08/30/2018] [Indexed: 11/28/2022]
Abstract
![]()
The
oxidation of the C–H and C=C bonds of hydrocarbons with
H2O2 catalyzed by non-heme iron complexes with
pentadentate ligands is widely accepted as involving a reactive FeIV=O species such as [(N4Py)FeIV=O]2+ formed by homolytic cleavage of the O–O bond of an
FeIII–OOH intermediate (where N4Py is 1,1-bis(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)methanamine).
We show here that at low H2O2 concentrations
the FeIV=O species formed is detectable in methanol.
Furthermore, we show that the decomposition of H2O2 to water and O2 is an important competing pathway
that limits efficiency in the terminal oxidant and indeed dominates
reactivity except where only sub-/near-stoichiometric amounts of H2O2 are present. Although independently prepared
[(N4Py)FeIV=O]2+ oxidizes stoichiometric
H2O2 rapidly, the rate of formation of FeIV=O from the FeIII–OOH intermediate
is too low to account for the rate of H2O2 decomposition
observed under catalytic conditions. Indeed, with excess H2O2, disproportionation to O2 and H2O is due to reaction with the FeIII–OOH intermediate
and thereby prevents formation of the FeIV=O species.
These data rationalize that the activity of these catalysts with respect
to hydrocarbon/alkene oxidation is maximized by maintaining sub-/near-stoichiometric
steady-state concentrations of H2O2, which ensure
that the rate of the H2O2 oxidation by the FeIII–OOH intermediate is less than the rate of the O–O
bond homolysis and the subsequent reaction of the FeIV=O
species with a substrate.
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Affiliation(s)
- Juan Chen
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Apparao Draksharapu
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Davide Angelone
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus Montilivi, E17003 Girona, Catalonia, Spain
| | - Duenpen Unjaroen
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Sandeep K. Padamati
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Ronald Hage
- Catexel BV, BioPartner Center, Galileiweg 8, 2333BD Leiden, The Netherlands
| | - Marcel Swart
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus Montilivi, E17003 Girona, Catalonia, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Carole Duboc
- Departement de Chimie Moleculaire, Univ. Grenoble Alpes/CNRS, UMR-5250, BP-53, 38041 Grenoble Cedex 9, France
| | - Wesley R. Browne
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
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24
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Rasheed W, Draksharapu A, Banerjee S, Young VG, Fan R, Guo Y, Ozerov M, Nehrkorn J, Krzystek J, Telser J, Que L. Crystallographic Evidence for a Sterically Induced Ferryl Tilt in a Non‐Heme Oxoiron(IV) Complex that Makes it a Better Oxidant. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201804836] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Waqas Rasheed
- 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
| | - Saikat Banerjee
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis MN 55455 USA
| | - Victor G. Young
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis MN 55455 USA
| | - Ruixi Fan
- Department of Chemistry Carnegie Mellon University Pittsburgh PA 15213 USA
| | - Yisong Guo
- Department of Chemistry Carnegie Mellon University Pittsburgh PA 15213 USA
| | - M. Ozerov
- National High Magnetic Field Laboratory (NHMFL) Florida State University Tallahassee FL 32310 USA
| | - Joscha Nehrkorn
- National High Magnetic Field Laboratory (NHMFL) Florida State University Tallahassee FL 32310 USA
| | - J. Krzystek
- National High Magnetic Field Laboratory (NHMFL) Florida State University Tallahassee FL 32310 USA
| | - Joshua Telser
- Department of Biological Chemical and Physical Sciences Roosevelt University Chicago IL 60605 USA
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis MN 55455 USA
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25
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Rasheed W, Draksharapu A, Banerjee S, Young VG, Fan R, Guo Y, Ozerov M, Nehrkorn J, Krzystek J, Telser J, Que L. Crystallographic Evidence for a Sterically Induced Ferryl Tilt in a Non-Heme Oxoiron(IV) Complex that Makes it a Better Oxidant. Angew Chem Int Ed Engl 2018; 57:9387-9391. [PMID: 29882390 DOI: 10.1002/anie.201804836] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Indexed: 11/06/2022]
Abstract
Oxoiron(IV) units are often implicated as intermediates in the catalytic cycles of non-heme iron oxygenases and oxidases. The most reactive synthetic analogues of these intermediates are supported by tetradentate tripodal ligands with N-methylbenzimidazole or quinoline donors, but their instability precludes structural characterization. Herein we report crystal structures of two [FeIV (O)(L)]2+ complexes supported by pentadentate ligands incorporating these heterocycles, which show longer average Fe-N distances than the complex with only pyridine donors. These longer distances correlate linearly with log k2 ' values for O- and H-atom transfer rates, suggesting that weakening the ligand field increases the electrophilicity of the Fe=O center. The sterically bulkier quinoline donors are also found to tilt the Fe=O unit away from a linear N-Fe=O arrangement by 10°.
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Affiliation(s)
- Waqas Rasheed
- 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
| | - Saikat Banerjee
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Victor G Young
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Ruixi Fan
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA
| | - M Ozerov
- National High Magnetic Field Laboratory (NHMFL), Florida State University, Tallahassee, FL, 32310, USA
| | - Joscha Nehrkorn
- National High Magnetic Field Laboratory (NHMFL), Florida State University, Tallahassee, FL, 32310, USA
| | - J Krzystek
- National High Magnetic Field Laboratory (NHMFL), Florida State University, Tallahassee, FL, 32310, USA
| | - Joshua Telser
- Department of Biological, Chemical and Physical Sciences, Roosevelt University, Chicago, IL, 60605, USA
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
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26
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Kal S, Draksharapu A, Que L. Sc 3+ (or HClO 4) Activation of a Nonheme Fe III-OOH Intermediate for the Rapid Hydroxylation of Cyclohexane and Benzene. J Am Chem Soc 2018; 140:5798-5804. [PMID: 29618199 DOI: 10.1021/jacs.8b01435] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[Fe(β-BPMCN)(CH3CN)2]2+ (1, BPMCN = N,N' -bis(pyridyl-2-methyl)- N,N' -dimethyl- trans-1,2-diaminocyclo-hexane) is a relatively poor catalyst for cyclohexane oxidation by H2O2 and cannot perform benzene hydroxylation. However, addition of Sc3+ activates the 1/H2O2 reaction mixture to be able to hydroxylate cyclohexane and benzene within seconds at -40 °C. A metastable S = 1/2 FeIII-(η1-OOH) intermediate 2 is trapped at -40 °C, which undergoes rapid decay upon addition of Sc3+ at rates independent of [substrate] but linearly dependent on [Sc3+]. HClO4 elicits comparable reactivity as Sc3+ at the same concentration. We thus postulate that these additives both facilitate O-O bond heterolysis of 2 to form a common highly electrophilic FeV═O oxidant that is comparably reactive to the fastest nonheme high-valent iron-oxo oxidants found to date.
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Affiliation(s)
- Subhasree Kal
- 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
| | - 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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27
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Fan R, Serrano-Plana J, Oloo WN, Draksharapu A, Delgado-Pinar E, Company A, Martin-Diaconescu V, Borrell M, Lloret-Fillol J, García-España E, Guo Y, Bominaar EL, Que L, Costas M, Münck E. Spectroscopic and DFT Characterization of a Highly Reactive Nonheme Fe V-Oxo Intermediate. J Am Chem Soc 2018; 140:3916-3928. [PMID: 29463085 DOI: 10.1021/jacs.7b11400] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The reaction of [(PyNMe3)FeII(CF3SO3)2], 1, with excess peracetic acid at -40 °C generates a highly reactive intermediate, 2b(PAA), that has the fastest rate to date for oxidizing cyclohexane by a nonheme iron species. It exhibits an intense 490 nm chromophore associated with an S = 1/2 EPR signal having g-values at 2.07, 2.01, and 1.94. This species was shown to be in a fast equilibrium with a second S = 1/2 species, 2a(PAA), assigned to a low-spin acylperoxoiron(III) center. Unfortunately, contaminants accompanying the 2(PAA) samples prevented determination of the iron oxidation state by Mössbauer spectroscopy. Use of MeO-PyNMe3 (an electron-enriched version of PyNMe3) and cyclohexyl peroxycarboxylic acid as oxidant affords intermediate 3b(CPCA) with a Mössbauer isomer shift δ = -0.08 mm/s that indicates an iron(V) oxidation state. Analysis of the Mössbauer and EPR spectra, combined with DFT studies, demonstrates that the electronic ground state of 3b(CPCA) is best described as a quantum mechanical mixture of [(MeO-PyNMe3)FeV(O)(OC(O)R)]2+ (∼75%) with some FeIV(O)(•OC(O)R) and FeIII(OOC(O)R) character. DFT studies of 3b(CPCA) reveal that the unbound oxygen of the carboxylate ligand, O2, is only 2.04 Å away from the oxo group, O1, corresponding to a Wiberg bond order for the O1-O2 bond of 0.35. This unusual geometry facilitates reversible O1-O2 bond formation and cleavage and accounts for the high reactivity of the intermediate when compared to the rates of hydrogen atom transfer and oxygen atom transfer reactions of FeIII(OC(O)R) ferric acyl peroxides and FeIV(O) complexes. The interaction of O2 with O1 leads to a significant downshift of the Fe-O1 Raman frequency (815 cm-1) relative to the 903 cm-1 value predicted for the hypothetical [(MeO-PyNMe3)FeV(O)(NCMe)]3+ complex.
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Affiliation(s)
- Ruixi Fan
- Department of Chemistry , Carnegie Mellon University , 4400 Fifth Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Joan Serrano-Plana
- 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
| | - Williamson N Oloo
- 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
| | - Estefanía Delgado-Pinar
- Grup de Química Supramolecular, Institut de Ciència Molecular, Departament de Química Inorgànica , Universitat de València , 46980 Paterna , Valencia , 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
| | - Vlad Martin-Diaconescu
- 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
| | - Margarida Borrell
- 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
| | - Julio Lloret-Fillol
- Institute of Chemical Research of Catalonia (ICIQ) , The Barcelona Institute of Science and Technology , Avinguda Països Catalans 16 , 43007 Tarragona , Spain
| | - Enrique García-España
- Grup de Química Supramolecular, Institut de Ciència Molecular, Departament de Química Inorgànica , Universitat de València , 46980 Paterna , Valencia , Spain
| | - Yisong Guo
- Department of Chemistry , Carnegie Mellon University , 4400 Fifth Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Emile L Bominaar
- Department of Chemistry , Carnegie Mellon University , 4400 Fifth Avenue , Pittsburgh , Pennsylvania 15213 , 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
| | - 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
| | - Eckard Münck
- Department of Chemistry , Carnegie Mellon University , 4400 Fifth Avenue , Pittsburgh , Pennsylvania 15213 , United States
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28
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Chen J, Stepanovic S, Draksharapu A, Gruden M, Browne WR. A Non-Heme Iron Photocatalyst for Light-Driven Aerobic Oxidation of Methanol. Angew Chem Int Ed Engl 2018; 57:3207-3211. [PMID: 29334586 PMCID: PMC5887871 DOI: 10.1002/anie.201712678] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Indexed: 11/29/2022]
Abstract
Non‐heme (L)FeIII and (L)FeIII‐O‐FeIII(L) complexes (L=1,1‐di(pyridin‐2‐yl)‐N,N‐bis(pyridin‐2‐ylmethyl)ethan‐1‐amine) underwent reduction under irradiation to the FeII state with concomitant oxidation of methanol to methanal, without the need for a secondary photosensitizer. Spectroscopic and DFT studies support a mechanism in which irradiation results in charge‐transfer excitation of a FeIII−μ‐O−FeIII complex to generate [(L)FeIV=O]2+ (observed transiently during irradiation in acetonitrile), and an equivalent of (L)FeII. Under aerobic conditions, irradiation accelerates reoxidation from the FeII to the FeIII state with O2, thus closing the cycle of methanol oxidation to methanal.
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Affiliation(s)
- Juan Chen
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Stepan Stepanovic
- Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, 11000, Belgrade, Serbia
| | - Apparao Draksharapu
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands.,Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN, 55455, USA
| | - Maja Gruden
- Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, 11000, Belgrade, Serbia
| | - Wesley R Browne
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
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29
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Chen J, Stepanovic S, Draksharapu A, Gruden M, Browne WR. A Non-Heme Iron Photocatalyst for Light-Driven Aerobic Oxidation of Methanol. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201712678] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Juan Chen
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry; Faculty of Science and Engineering; University of Groningen; Nijenborgh 4 9747AG Groningen The Netherlands
| | - Stepan Stepanovic
- Faculty of Chemistry; University of Belgrade; Studentski trg 12-16 11000 Belgrade Serbia
| | - Apparao Draksharapu
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry; Faculty of Science and Engineering; University of Groningen; Nijenborgh 4 9747AG Groningen The Netherlands
- Department of Chemistry and Center for Metals in Biocatalysis; University of Minnesota; 207 Pleasant Street SE Minneapolis MN 55455 USA
| | - Maja Gruden
- Faculty of Chemistry; University of Belgrade; Studentski trg 12-16 11000 Belgrade Serbia
| | - Wesley R. Browne
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry; Faculty of Science and Engineering; University of Groningen; Nijenborgh 4 9747AG Groningen The Netherlands
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30
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Serrano-Plana J, Acuña-Parés F, Dantignana V, Oloo WN, Castillo E, Draksharapu A, Whiteoak CJ, Martin-Diaconescu V, Basallote MG, Luis JM, Que L, Costas M, Company A. Acid-Triggered O-O Bond Heterolysis of a Nonheme Fe III (OOH) Species for the Stereospecific Hydroxylation of Strong C-H Bonds. Chemistry 2018; 24:5331-5340. [PMID: 29193378 DOI: 10.1002/chem.201704851] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Indexed: 12/11/2022]
Abstract
A novel hydroperoxoiron(III) species [FeIII (OOH)(MeCN)(PyNMe3 )]2+ (3) has been generated by reaction of its ferrous precursor [FeII (CF3 SO3 )2 (PyNMe3 )] (1) with hydrogen peroxide at low temperatures. This species has been characterized by several spectroscopic techniques and cryospray mass spectrometry. Similar to most of the previously described low-spin hydroperoxoiron(III) compounds, 3 behaves as a sluggish oxidant and it is not kinetically competent for breaking weak C-H bonds. However, triflic acid addition to 3 causes its transformation into a much more reactive compound towards organic substrates that is capable of oxidizing unactivated C-H bonds with high stereospecificity. Stopped-flow kinetic analyses and theoretical studies provide a rationale for the observed chemistry, a triflic-acid-assisted heterolytic cleavage of the O-O bond to form a putative strongly oxidizing oxoiron(V) species. This mechanism is reminiscent to that observed in heme systems, where protonation of the hydroperoxo intermediate leads to the formation of the high-valent [(Porph. )FeIV (O)] (Compound I).
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Affiliation(s)
- Joan Serrano-Plana
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/ M. Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Ferran Acuña-Parés
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/ M. Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain.,Institute of Chemical Research of Catalonia (ICIQ), Avinguda Països Catalans 16, 43007, Tarragona, Spain
| | - Valeria Dantignana
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/ M. Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Williamson N Oloo
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Esther Castillo
- Departamento de Ciencia de los Materiales e Ingeniería MetalúrgicayQuímica Inorgánica, Universidad de Cádiz, Facultad de Ciencias, Apdo. 40, 11510, Puerto Real, Cádiz, Spain
| | - Apparao Draksharapu
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Christopher J Whiteoak
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/ M. Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Vlad Martin-Diaconescu
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/ M. Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Manuel G Basallote
- Departamento de Ciencia de los Materiales e Ingeniería MetalúrgicayQuímica Inorgánica, Universidad de Cádiz, Facultad de Ciencias, Apdo. 40, 11510, Puerto Real, Cádiz, Spain
| | - Josep M Luis
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/ M. Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Miquel Costas
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/ M. Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Anna Company
- 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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31
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Klein JEMN, Draksharapu A, Shokri A, Cramer CJ, Que L. On the Lewis Acidity of the Oxoiron(IV) Unit in a Tetramethylcyclam Complex. Chemistry 2017; 24:5373-5378. [PMID: 29205555 DOI: 10.1002/chem.201704977] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Indexed: 11/08/2022]
Abstract
The correlation between oxidation state and Lewis acidity is well established for hexaquairon complexes in the +II and +III oxidation state, in which the higher oxidation state leads to a lower pKa for the bound H2 O ligand. This article addresses the Lewis acidity of the oxoiron(IV) complex [FeIV (O)(TMC)(OH2 )]2+ (1-OH2 ; TMC=1,4,8,11-tetramethylcyclam) by determining the pKa of the H2 O ligand. We establish that 1-OH2 has a pKa of 6.9±0.5, a value that falls in between those found for [FeIII (OH2 )6 ]3+ and [FeII (OH2 )6 ]2+ . This intermediate value can be readily rationalized by the presence of the highly basic oxide ligand that mitigates the Lewis acidity of the iron(IV) center. Although the oxo ligand occupies only one position in 1-OH2 , anti to all four methyl groups that protrude from the same face of the nonplanar TMC ligand, its conjugate base 1-OH exists as a mixture of syn and anti tautomers, which are related by proton transfer between the oxo and the hydroxo ligands.
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Affiliation(s)
- Johannes E M N Klein
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. S.E., Minneapolis, Minnesota, 55455, USA.,Present Address: Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747, AG Groningen, The Netherlands
| | - Apparao Draksharapu
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. S.E., Minneapolis, Minnesota, 55455, USA
| | - Alireza Shokri
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. S.E., Minneapolis, Minnesota, 55455, USA
| | - Christopher J Cramer
- Department of Chemistry, Supercomputing Institute, and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota, 55455, USA
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. S.E., Minneapolis, Minnesota, 55455, USA
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32
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Padamati S, Angelone D, Draksharapu A, Primi G, Martin DJ, Tromp M, Swart M, Browne WR. Transient Formation and Reactivity of a High-Valent Nickel(IV) Oxido Complex. J Am Chem Soc 2017; 139:8718-8724. [PMID: 28581745 PMCID: PMC5492195 DOI: 10.1021/jacs.7b04158] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Indexed: 12/15/2022]
Abstract
A reactive high-valent dinuclear nickel(IV) oxido bridged complex is reported that can be formed at room temperature by reaction of [(L)2Ni(II)2(μ-X)3]X (X = Cl or Br) with NaOCl in methanol or acetonitrile (where L = 1,4,7-trimethyl-1,4,7-triazacyclononane). The unusual Ni(IV) oxido species is stabilized within a dinuclear tris-μ-oxido-bridged structure as [(L)2Ni(IV)2(μ-O)3]2+. Its structure and its reactivity with organic substrates are demonstrated through a combination of UV-vis absorption, resonance Raman, 1H NMR, EPR, and X-ray absorption (near-edge) spectroscopy, ESI mass spectrometry, and DFT methods. The identification of a Ni(IV)-O species opens opportunities to control the reactivity of NaOCl for selective oxidations.
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Affiliation(s)
- Sandeep
K. Padamati
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of
Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Davide Angelone
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of
Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
- IQCC
& Departament de Química, Universitat
de Girona, Campus Montilivi
(Ciències), 17003 Girona, Spain
| | - Apparao Draksharapu
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of
Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Gloria Primi
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of
Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - David J. Martin
- Sustainable
Materials Characterisation, Van’t Hoff Institute for Molecular
Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Moniek Tromp
- Sustainable
Materials Characterisation, Van’t Hoff Institute for Molecular
Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Marcel Swart
- IQCC
& Departament de Química, Universitat
de Girona, Campus Montilivi
(Ciències), 17003 Girona, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Wesley R. Browne
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of
Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
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33
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Draksharapu A, Rasheed W, Klein JEMN, Que L. Facile and Reversible Formation of Iron(III)–Oxo–Cerium(IV) Adducts from Nonheme Oxoiron(IV) Complexes and Cerium(III). Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201704322] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Apparao Draksharapu
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis MN 55455 USA
| | - Waqas Rasheed
- 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
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis MN 55455 USA
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34
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Draksharapu A, Rasheed W, Klein JEMN, Que L. Facile and Reversible Formation of Iron(III)-Oxo-Cerium(IV) Adducts from Nonheme Oxoiron(IV) Complexes and Cerium(III). Angew Chem Int Ed Engl 2017; 56:9091-9095. [PMID: 28598024 DOI: 10.1002/anie.201704322] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Indexed: 11/09/2022]
Abstract
Ceric ammonium nitrate (CAN) or CeIV (NH4 )2 (NO3 )6 is often used in artificial water oxidation and generally considered to be an outer-sphere oxidant. Herein we report the spectroscopic and crystallographic characterization of [(N4Py)FeIII -O-CeIV (OH2 )(NO3 )4 ]+ (3), a complex obtained from the reaction of [(N4Py)FeII (NCMe)]2+ with 2 equiv CAN or [(N4Py)FeIV =O]2+ (2) with CeIII (NO3 )3 in MeCN. Surprisingly, the formation of 3 is reversible, the position of the equilibrium being dependent on the MeCN/water ratio of the solvent. These results suggest that the FeIV and CeIV centers have comparable reduction potentials. Moreover, the equilibrium entails a change in iron spin state, from S=1 FeIV in 2 to S=5/2 in 3, which is found to be facile despite the formal spin-forbidden nature of this process. This observation suggests that FeIV =O complexes may avail of reaction pathways involving multiple spin states having little or no barrier.
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Affiliation(s)
- Apparao Draksharapu
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Waqas Rasheed
- 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
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
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35
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Pattanayak S, Jasniewski AJ, Rana A, Draksharapu A, Singh KK, Weitz A, Hendrich M, Que L, Dey A, Sen Gupta S. Spectroscopic and Reactivity Comparisons of a Pair of bTAML Complexes with Fe V═O and Fe IV═O Units. Inorg Chem 2017; 56:6352-6361. [PMID: 28481521 DOI: 10.1021/acs.inorgchem.7b00448] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In this report we compare the geometric and electronic structures and reactivities of [FeV(O)]- and [FeIV(O)]2- species supported by the same ancillary nonheme biuret tetraamido macrocyclic ligand (bTAML). Resonance Raman studies show that the Fe═O vibration of the [FeIV(O)]2- complex 2 is at 798 cm-1, compared to 862 cm-1 for the corresponding [FeV(O)]- species 3, a 64 cm-1 frequency difference reasonably reproduced by density functional theory calculations. These values are, respectively, the lowest and the highest frequencies observed thus far for nonheme high-valent Fe═O complexes. Extended X-ray absorption fine structure analysis of 3 reveals an Fe═O bond length of 1.59 Å, which is 0.05 Å shorter than that found in complex 2. The redox potentials of 2 and 3 are 0.44 V (measured at pH 12) and 1.19 V (measured at pH 7) versus normal hydrogen electrode, respectively, corresponding to the [FeIV(O)]2-/[FeIII(OH)]2- and [FeV(O)]-/[FeIV(O)]2- couples. Consistent with its higher potential (even after correcting for the pH difference), 3 oxidizes benzyl alcohol at pH 7 with a second-order rate constant that is 2500-fold bigger than that for 2 at pH 12. Furthermore, 2 exhibits a classical kinteic isotope effect (KIE) of 3 in the oxidation of benzyl alcohol to benzaldehyde versus a nonclassical KIE of 12 for 3, emphasizing the reactivity differences between 2 and 3.
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Affiliation(s)
- Santanu Pattanayak
- Chemical Engineering Division, CSIR-National Chemical Laboratory , Pune 411008, India
| | - Andrew J Jasniewski
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Atanu Rana
- Department of Inorganic Chemistry, Indian Association for the Cultivation of Science , Kolkata 700032, India
| | - Apparao Draksharapu
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Kundan K Singh
- Chemical Engineering Division, CSIR-National Chemical Laboratory , Pune 411008, India
| | - Andrew Weitz
- Department of Chemistry, Carnegie Mellon University , 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Michael Hendrich
- Department of Chemistry, Carnegie Mellon University , 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, United States
| | - Abhishek Dey
- Department of Inorganic Chemistry, Indian Association for the Cultivation of Science , Kolkata 700032, India
| | - Sayam Sen Gupta
- Department of Chemical Sciences, Indian Institute of Science Education and Research-Kolkata , Mohanpur, West Bengal 741246, India
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Chen J, Draksharapu A, Harvey E, Rasheed W, Que L, Browne WR. Direct photochemical activation of non-heme Fe(iv)O complexes. Chem Commun (Camb) 2017; 53:12357-12360. [DOI: 10.1039/c7cc07452b] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Near-UV light accelerates alcohol and aliphatic C–H oxidation by non-heme Fe(iv)O complexes.
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Affiliation(s)
- Juan Chen
- Stratingh Institute for Chemistry, Faculty of Science and Engineering
- Groningen
- The Netherlands
| | - Apparao Draksharapu
- Stratingh Institute for Chemistry, Faculty of Science and Engineering
- Groningen
- The Netherlands
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. SE, University of Minnesota
- Minneapolis
| | - Emma Harvey
- Stratingh Institute for Chemistry, Faculty of Science and Engineering
- Groningen
- The Netherlands
| | - Waqas Rasheed
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. SE, University of Minnesota
- Minneapolis
- USA
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St. SE, University of Minnesota
- Minneapolis
- USA
| | - Wesley R. Browne
- Stratingh Institute for Chemistry, Faculty of Science and Engineering
- Groningen
- The Netherlands
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37
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Zhou A, Prakash J, Rohde GT, Klein JEMN, Kleespies ST, Draksharapu A, Fan R, Guo Y, Cramer CJ, Que L. The Two Faces of Tetramethylcyclam in Iron Chemistry: Distinct Fe-O-M Complexes Derived from [Fe IV(O anti/syn)(TMC)] 2+ Isomers. Inorg Chem 2016; 56:518-527. [PMID: 28001379 DOI: 10.1021/acs.inorgchem.6b02417] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Tetramethylcyclam (TMC, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) exhibits two faces in supporting an oxoiron(IV) moiety, as exemplified by the prototypical [(TMC)FeIV(Oanti)(NCCH3)](OTf)2, where anti indicates that the O atom is located on the face opposite all four methyl groups, and the recently reported syn isomer [(TMC)FeIV(Osyn)(OTf)](OTf). The ability to access two isomers of [(TMC)FeIV(Oanti/syn)] raises the fundamental question of how ligand topology can affect the properties of the metal center. Previously, we have reported the formation of [(CH3CN)(TMC)FeIII-Oanti-CrIII(OTf)4(NCCH3)] (1) by inner-sphere electron transfer between Cr(OTf)2 and [(TMC)FeIV(Oanti)(NCCH3)](OTf)2. Herein we demonstrate that a new species 2 is generated from the reaction between Cr(OTf)2 and [(TMC)FeIV(Osyn)(NCCH3)](OTf)2, which is formulated as [(TMC)FeIII-Osyn-CrIII(OTf)4(NCCH3)] based on its characterization by UV-vis, resonance Raman, Mössbauer, and X-ray absorption spectroscopic methods, as well as electrospray mass spectrometry. Its pre-edge area (30 units) and Fe-O distance (1.77 Å) determined by X-ray absorption spectroscopy are distinctly different from those of 1 (11-unit pre-edge area and 1.81 Å Fe-O distance) but more closely resemble the values reported for [(TMC)FeIII-Osyn-ScIII(OTf)4(NCCH3)] (3, 32-unit pre-edge area and 1.75 Å Fe-O distance). This comparison suggests that 2 has a square pyramidal iron center like 3, rather than the six-coordinate center deduced for 1. Density functional theory calculations further validate the structures for 1 and 2. The influence of the distinct TMC topologies on the coordination geometries is further confirmed by the crystal structures of [(Cl)(TMC)FeIII-Oanti-FeIIICl3] (4Cl) and [(TMC)FeIII-Osyn-FeIIICl3](OTf) (5). Complexes 1-5 thus constitute a set of complexes that shed light on ligand topology effects on the coordination chemistry of the oxoiron moiety.
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Affiliation(s)
| | | | | | | | | | | | - Ruixi Fan
- Department of Chemistry, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
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38
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Corona T, Draksharapu A, Padamati SK, Gamba I, Martin-Diaconescu V, Acuña-Parés F, Browne WR, Company A. Rapid Hydrogen and Oxygen Atom Transfer by a High-Valent Nickel-Oxygen Species. J Am Chem Soc 2016; 138:12987-12996. [PMID: 27598293 DOI: 10.1021/jacs.6b07544] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Terminal high-valent metal-oxygen species are key reaction intermediates in the catalytic cycle of both enzymes (e.g., oxygenases) and synthetic oxidation catalysts. While tremendous efforts have been directed toward the characterization of the biologically relevant terminal manganese-oxygen and iron-oxygen species, the corresponding analogues based on late-transition metals such as cobalt, nickel or copper are relatively scarce. This scarcity is in part related to the "Oxo Wall" concept, which predicts that late transition metals cannot support a terminal oxido ligand in a tetragonal environment. Here, the nickel(II) complex (1) of the tetradentate macrocyclic ligand bearing a 2,6-pyridinedicarboxamidate unit is shown to be an effective catalyst in the chlorination and oxidation of C-H bonds with sodium hypochlorite as terminal oxidant in the presence of acetic acid (AcOH). Insight into the active species responsible for the observed reactivity was gained through the study of the reaction of 1 with ClO- at low temperature by UV-vis absorption, resonance Raman, EPR, ESI-MS, and XAS analyses. DFT calculations aided the assignment of the trapped chromophoric species (3) as a nickel-hypochlorite species. Despite the fact that the formal oxidation state of the nickel in 3 is +4, experimental and computational analysis indicate that 3 is best formulated as a NiIII complex with one unpaired electron delocalized in the ligands surrounding the metal center. Most remarkably, 3 reacts rapidly with a range of substrates including those with strong aliphatic C-H bonds, indicating the direct involvement of 3 in the oxidation/chlorination reactions observed in the 1/ClO-/AcOH catalytic system.
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Affiliation(s)
- Teresa Corona
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 69 , E17003 Girona, Catalonia, Spain
| | - Apparao Draksharapu
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Sandeep K Padamati
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Ilaria Gamba
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 69 , E17003 Girona, Catalonia, Spain
| | - Vlad Martin-Diaconescu
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 69 , E17003 Girona, Catalonia, Spain
| | - Ferran Acuña-Parés
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 69 , E17003 Girona, Catalonia, Spain
| | - Wesley R Browne
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Anna Company
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 69 , E17003 Girona, Catalonia, Spain
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39
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Padamati SK, Draksharapu A, Unjaroen D, Browne WR. Conflicting Role of Water in the Activation of H2O2 and the Formation and Reactivity of Non-Heme FeIII–OOH and FeIII–O–FeIII Complexes at Room Temperature. Inorg Chem 2016; 55:4211-22. [DOI: 10.1021/acs.inorgchem.5b02976] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Sandeep K. Padamati
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of
Mathematics and Natural Sciences, University of Groningen, Nijenborgh
4, 9747AG, Groningen, The Netherlands
| | - Apparao Draksharapu
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of
Mathematics and Natural Sciences, University of Groningen, Nijenborgh
4, 9747AG, Groningen, The Netherlands
| | - Duenpen Unjaroen
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of
Mathematics and Natural Sciences, University of Groningen, Nijenborgh
4, 9747AG, Groningen, The Netherlands
| | - Wesley R. Browne
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of
Mathematics and Natural Sciences, University of Groningen, Nijenborgh
4, 9747AG, Groningen, The Netherlands
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40
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Draksharapu A, Codolà Z, Gómez L, Lloret-Fillol J, Browne WR, Costas M. Spectroscopic Analyses on Reaction Intermediates Formed during Chlorination of Alkanes with NaOCl Catalyzed by a Nickel Complex. Inorg Chem 2015; 54:10656-66. [PMID: 26540133 DOI: 10.1021/acs.inorgchem.5b01463] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The spectroscopic, electrochemical, and crystallographic characterization of [((Me,H)PyTACN)Ni(II)(CH3CN)2](OTf)2 (1) ((Me,H)PyTACN = 1-(2-pyridylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane, OTf = CF3SO3) is described together with its reactivity with NaOCl. 1 catalyzes the chlorination of alkanes with NaOCl, producing only a trace amount of oxygenated byproducts. The reaction was monitored spectroscopically and by high resolution electrospray-mass spectrometry (ESI-MS) with the aim to elucidate mechanistic aspects. NaOCl reacts with 1 in acetonitrile to form the transient species [(L)Ni(II)-OCl(S)](+) (A) (L = (Me,H)PyTACN, S = solvent), which was identified by ESI-MS. UV/vis absorption, electron paramagnetic resonance, and resonance Raman spectroscopy indicate that intermediate A decays to the complex [(L)Ni(III)-OH(S)](2+) (B) presumably through homolytic cleavage of the O-Cl bond, which liberates a Cl(•) atom. Hydrolysis of acetonitrile to acetic acid under the applied conditions results in the formation of [(L)Ni(III)-OOCCH3(S)](2+) (C), which undergoes subsequent reduction to [(L)Ni(II)-OOCCH3(S)](2+) (D), presumably via reaction with OCl(-) or ClO2(-). Subsequent addition of NaOCl to [(L)Ni(II)-OOCCH3(S)](+) (D) regenerates [(L)Ni(III)-OH(S)](2+) (B) to a much greater extent and at a faster rate. Addition of acids such as acetic and triflic acid enhances the rate and extent of formation of [(L)Ni(III)-OH(S)](2+) (B) from 1, suggesting that O-Cl homolytic cleavage is accelerated by protonation. Overall, these reactions generate Cl(•) atoms and ClO2 in a catalytic cycle where the nickel center alternates between Ni(II) and Ni(III). Chlorine atoms in turn react with the C-H bonds of alkanes, forming alkyl radicals that are trapped by Cl(•) to form alkyl chlorides.
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Affiliation(s)
- Apparao Draksharapu
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen , Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Zoel Codolà
- Institut de Química Computacional i Catalisi (IQCC) and Departament de Química, University of Girona , Campus de Montilivi, Girona 17071, Spain
| | - Laura Gómez
- Institut de Química Computacional i Catalisi (IQCC) and Departament de Química, University of Girona , Campus de Montilivi, Girona 17071, Spain.,Serveis Tècnics de Recerca (STR), Universitat de Girona, Parc Cientı́fic i Tecnològic de la UdG , Pic de Peguera 15, E17003 Girona, Catalonia, Spain
| | - Julio Lloret-Fillol
- Institut de Química Computacional i Catalisi (IQCC) and Departament de Química, University of Girona , Campus de Montilivi, Girona 17071, Spain
| | - Wesley R Browne
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen , Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Miquel Costas
- Institut de Química Computacional i Catalisi (IQCC) and Departament de Química, University of Girona , Campus de Montilivi, Girona 17071, Spain
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41
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Draksharapu A, Boersma AJ, Leising M, Meetsma A, Browne WR, Roelfes G. Binding of copper(II) polypyridyl complexes to DNA and consequences for DNA-based asymmetric catalysis. Dalton Trans 2015; 44:3647-55. [PMID: 25476597 DOI: 10.1039/c4dt02733g] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The interaction between salmon testes DNA (st-DNA) and a series of Cu(II) polypyridyl complexes, i.e. [Cu(dmbpy)(NO3)2] (1) (dmbpy = 4,4'-dimethyl-2,2'-bipyridine), [Cu(bpy)(NO3)2] (2) (bpy = 2,2'-bipyridine), [Cu(phen)(NO3)2] (3) (phen = phenanthroline), [Cu(terpy)(NO3)2]·H2O (4) (terpy = 2,2':6',2″-terpyridine), [Cu(dpq)(NO3)2] (5) (dpq = dipyrido-[3,2-d:2',3'-f]-quinoxaline) and [Cu(dppz)(NO3)2] (6) (dppz = dipyrido[3,2-a:2',3'-c]phenazine) was studied by UV/Vis absorption, Circular Dichroism, Linear Dichroism, EPR, Raman and (UV and vis) resonance Raman spectroscopies and viscometry. These complexes catalyse enantioselective C-C bond forming reactions in water with DNA as the source of chirality. Complex 1 crystallizes as an inorganic polymer with nitrate ligands bridging the copper ions, which adopt essentially a distorted square pyramidal structure with a fifth bridging nitrate ligand at the axial position. Raman spectroscopy indicates that in solution the nitrate ligands in 1, 2, 3 and 4 are displaced by solvent (H2O). For complex 1, multiple supramolecular species are observed in the presence of st-DNA in contrast to the other complexes, which appear to interact relatively uniformly as a single species predominantly, when st-DNA is present. Overall the data suggest that complexes 1 and 2 engage primarily through groove binding with st-DNA while 5 and 6 undergo intercalation. For complexes 3 and 4 the data indicates that both groove binding and intercalation takes place, albeit primarily intercalation. Although it is tempting to conclude that the groove binders give highest ee and rate acceleration, it is proposed that the flexibility and dynamics in binding of Cu(II) complexes to DNA are key parameters that determine the outcome of the reaction. These findings provide insight into the complex supramolecular structure of these DNA-based catalysts.
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Affiliation(s)
- Apparao Draksharapu
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
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42
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Corona T, Pfaff FF, Acuña-Parés F, Draksharapu A, Whiteoak CJ, Martin-Diaconescu V, Lloret-Fillol J, Browne WR, Ray K, Company A. Reactivity of a Nickel(II) Bis(amidate) Complex with meta-Chloroperbenzoic Acid: Formation of a Potent Oxidizing Species. Chemistry 2015; 21:15029-38. [PMID: 26311073 DOI: 10.1002/chem.201501841] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Indexed: 12/14/2022]
Abstract
Herein, we report the formation of a highly reactive nickel-oxygen species that has been trapped following reaction of a Ni(II) precursor bearing a macrocyclic bis(amidate) ligand with meta-chloroperbenzoic acid (HmCPBA). This compound is only detectable at temperatures below 250 K and is much more reactive toward organic substrates (i.e., C-H bonds, C=C bonds, and sulfides) than previously reported well-defined nickel-oxygen species. Remarkably, this species is formed by heterolytic O-O bond cleavage of a Ni-HmCPBA precursor, which is concluded from experimental and computational data. On the basis of spectroscopy and DFT calculations, this reactive species is proposed to be a Ni(III) -oxyl compound.
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Affiliation(s)
- Teresa Corona
- Group de Química Bioinorgànica, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona (Spain), Fax: (+34) 972-41-81-50
| | - Florian F Pfaff
- Humboldt Universität zu Berlin, Department of Chemistry, Brook-Taylor Strasse 2, 12489 Berlin (Germany)
| | - Ferran Acuña-Parés
- Group de Química Bioinorgànica, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona (Spain), Fax: (+34) 972-41-81-50
| | - Apparao Draksharapu
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands)
| | - Christopher J Whiteoak
- Group de Química Bioinorgànica, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona (Spain), Fax: (+34) 972-41-81-50
| | - Vlad Martin-Diaconescu
- Group de Química Bioinorgànica, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona (Spain), Fax: (+34) 972-41-81-50
| | - Julio Lloret-Fillol
- Group de Química Bioinorgànica, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona (Spain), Fax: (+34) 972-41-81-50.,Current address: Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans 16, 43007 Tarragona (Spain)
| | - Wesley R Browne
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands)
| | - Kallol Ray
- Humboldt Universität zu Berlin, Department of Chemistry, Brook-Taylor Strasse 2, 12489 Berlin (Germany)
| | - Anna Company
- Group de Química Bioinorgànica, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona (Spain), Fax: (+34) 972-41-81-50.
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43
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Draksharapu A, Angelone D, Quesne MG, Padamati SK, Gómez L, Hage R, Costas M, Browne WR, de Visser SP. Identification and spectroscopic characterization of nonheme iron(III) hypochlorite intermediates. Angew Chem Int Ed Engl 2015; 54:4357-61. [PMID: 25663379 PMCID: PMC4670478 DOI: 10.1002/anie.201411995] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 01/10/2015] [Indexed: 11/18/2022]
Abstract
Fe(III)-hypohalite complexes have been implicated in a wide range of important enzyme-catalyzed halogenation reactions including the biosynthesis of natural products and antibiotics and post-translational modification of proteins. The absence of spectroscopic data on such species precludes their identification. Herein, we report the generation and spectroscopic characterization of nonheme Fe(III)-hypohalite intermediates of possible relevance to iron halogenases. We show that Fe(III)-OCl polypyridylamine complexes can be sufficiently stable at room temperature to be characterized by UV/Vis absorption, resonance Raman and EPR spectroscopies, and cryo-ESIMS. DFT methods rationalize the pathways to the formation of the Fe(III)-OCl, and ultimately Fe(IV)=O, species and provide indirect evidence for a short-lived Fe(II)-OCl intermediate. The species observed and the pathways involved offer insight into and, importantly, a spectroscopic database for the investigation of iron halogenases.
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Affiliation(s)
- Apparao Draksharapu
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of GroningenNijenborgh 4, 9747 AG Groningen (The Netherlands) E-mail:
| | - Davide Angelone
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of GroningenNijenborgh 4, 9747 AG Groningen (The Netherlands) E-mail:
| | - Matthew G Quesne
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester131 Princess Street, Manchester M1 7DN (UK) E-mail:
| | - Sandeep K Padamati
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of GroningenNijenborgh 4, 9747 AG Groningen (The Netherlands) E-mail:
| | - Laura Gómez
- Departament de Química and Institute of Computational Chemistry and Catalysis (IQCC), University of GironaCampus de Montilivi, Girona 17071 (Spain)
- Serveis Tècnics de Recerca (STR), Universitat de GironaParc Científic i Tecnològic, E-17003 Girona, Spain
| | - Ronald Hage
- Catexel Ltd., BioPartner Center LeidenGalileiweg 8, 2333 BD Leiden (The Netherlands)
| | - Miquel Costas
- Departament de Química and Institute of Computational Chemistry and Catalysis (IQCC), University of GironaCampus de Montilivi, Girona 17071 (Spain)
| | - Wesley R Browne
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of GroningenNijenborgh 4, 9747 AG Groningen (The Netherlands) E-mail:
| | - Sam P de Visser
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester131 Princess Street, Manchester M1 7DN (UK) E-mail:
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44
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Draksharapu A, Angelone D, Quesne MG, Padamati SK, Gómez L, Hage R, Costas M, Browne WR, de Visser SP. Identification and Spectroscopic Characterization of Nonheme Iron(III) Hypochlorite Intermediates. Angew Chem Weinheim Bergstr Ger 2015; 127:4431-4435. [PMID: 27478260 PMCID: PMC4955228 DOI: 10.1002/ange.201411995] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 01/10/2015] [Indexed: 11/07/2022]
Abstract
FeIII-hypohalite complexes have been implicated in a wide range of important enzyme-catalyzed halogenation reactions including the biosynthesis of natural products and antibiotics and post-translational modification of proteins. The absence of spectroscopic data on such species precludes their identification. Herein, we report the generation and spectroscopic characterization of nonheme FeIII-hypohalite intermediates of possible relevance to iron halogenases. We show that FeIII-OCl polypyridylamine complexes can be sufficiently stable at room temperature to be characterized by UV/Vis absorption, resonance Raman and EPR spectroscopies, and cryo-ESIMS. DFT methods rationalize the pathways to the formation of the FeIII-OCl, and ultimately FeIV=O, species and provide indirect evidence for a short-lived FeII-OCl intermediate. The species observed and the pathways involved offer insight into and, importantly, a spectroscopic database for the investigation of iron halogenases.
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Affiliation(s)
- Apparao Draksharapu
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands)
| | - Davide Angelone
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands)
| | - Matthew G. Quesne
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN (UK)
| | - Sandeep K. Padamati
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands)
| | - Laura Gómez
- Departament de Química and Institute of Computational Chemistry and Catalysis (IQCC), University of Girona, Campus de Montilivi, Girona 17071 (Spain)
- Serveis Tècnics de Recerca (STR), Universitat de Girona, Parc Científic i Tecnològic, E‐17003 Girona, Spain
| | - Ronald Hage
- Catexel Ltd., BioPartner Center Leiden, Galileiweg 8, 2333 BD Leiden (The Netherlands)
| | - Miquel Costas
- Departament de Química and Institute of Computational Chemistry and Catalysis (IQCC), University of Girona, Campus de Montilivi, Girona 17071 (Spain)
| | - Wesley R. Browne
- Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands)
| | - Sam P. de Visser
- 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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45
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Draksharapu A, Boersma AJ, Browne WR, Roelfes G. Characterisation of the interactions between substrate, copper(ii) complex and DNA and their role in rate acceleration in DNA-based asymmetric catalysis. Dalton Trans 2015; 44:3656-63. [DOI: 10.1039/c4dt02734e] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High effective molarity is responsible for the significant increase of binding of substrates to copper(ii) complexes in DNA-based catalysis.
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Affiliation(s)
- Apparao Draksharapu
- Stratingh Institute for Chemistry
- Faculty of Mathematics and Natural Sciences
- University of Groningen
- Groningen
- The Netherlands
| | - Arnold J. Boersma
- Stratingh Institute for Chemistry
- Faculty of Mathematics and Natural Sciences
- University of Groningen
- Groningen
- The Netherlands
| | - Wesley R. Browne
- Stratingh Institute for Chemistry
- Faculty of Mathematics and Natural Sciences
- University of Groningen
- Groningen
- The Netherlands
| | - Gerard Roelfes
- Stratingh Institute for Chemistry
- Faculty of Mathematics and Natural Sciences
- University of Groningen
- Groningen
- The Netherlands
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46
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Angelone D, Draksharapu A, Browne WR, Choudhuri M, Crutchley RJ, Xu X, Xu X, Doyle MP. Dinuclear compounds without a metal–metal bond. Dirhodium(III,III) carboxamidates. Inorganica Chim Acta 2015. [DOI: 10.1016/j.ica.2014.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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47
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Drienovská I, Rioz-Martínez A, Draksharapu A, Roelfes G. Novel artificial metalloenzymes by in vivo incorporation of metal-binding unnatural amino acids. Chem Sci 2015; 6:770-776. [PMID: 28936318 PMCID: PMC5590542 DOI: 10.1039/c4sc01525h] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 10/09/2014] [Indexed: 12/21/2022] Open
Abstract
Artificial metalloenzymes have emerged as an attractive new approach to enantioselective catalysis. Herein, we introduce a novel strategy for preparation of artificial metalloenzymes utilizing amber stop codon suppression methodology for the in vivo incorporation of metal-binding unnatural amino acids. The resulting artificial metalloenzymes were applied in catalytic asymmetric Friedel-Crafts alkylation reactions and up to 83% ee for the product was achieved.
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Affiliation(s)
- Ivana Drienovská
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands . ; http://roelfesgroup.nl
| | - Ana Rioz-Martínez
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands . ; http://roelfesgroup.nl
| | - Apparao Draksharapu
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands . ; http://roelfesgroup.nl
| | - Gerard Roelfes
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands . ; http://roelfesgroup.nl
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48
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Pap JS, Draksharapu A, Giorgi M, Browne WR, Kaizer J, Speier G. Stabilisation of μ-peroxido-bridged Fe(III) intermediates with non-symmetric bidentate N-donor ligands. Chem Commun (Camb) 2014; 50:1326-9. [PMID: 24343416 DOI: 10.1039/c3cc48196d] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The spectroscopic characterisation of the (μ-1,2-peroxido)diiron(iii) species formed transiently upon reaction of [Fe(ii)(NN)3](2+) complexes with H2O2 by UV/vis absorption and resonance Raman spectroscopy is reported. The intermediacy of such species in the disproportionation of H2O2 is demonstrated.
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Affiliation(s)
- József S Pap
- Department of Chemistry, University of Pannonia, H-8200 Veszprém, Hungary.
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49
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Halpin Y, Logtenberg H, Cleary L, Schenk S, Schulz M, Draksharapu A, Browne WR, Vos JG. An Electrochemical and Raman Spectroscopy Study of the Surface Behaviour of Mononuclear Ruthenium and Osmium Polypyridyl Complexes Based on Pyridyl‐ and Thiophene‐Based Linkers. Eur J Inorg Chem 2013. [DOI: 10.1002/ejic.201300366] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Yvonne Halpin
- Solar Energy Conversion SRC, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland, Fax: +353‐1‐7005503
| | - Hella Logtenberg
- Stratingh Institute for Chemistry and Zernike Institute for Advanced Materials, Faculty of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands, http://www.rug.nl/stratingh,
| | - Laura Cleary
- Solar Energy Conversion SRC, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland, Fax: +353‐1‐7005503
| | - Stephan Schenk
- BASF SE, Material Physics and Analytics, Carl‐Bosch‐Str. 38, 67056 Ludwigshafen, Germany
| | - Martin Schulz
- Pharmaceutical Radiochemistry, Technical University, Munich, Walther‐Meißner‐Str. 3, 85748 Garching, Germany
| | - Apparao Draksharapu
- Stratingh Institute for Chemistry and Zernike Institute for Advanced Materials, Faculty of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands, http://www.rug.nl/stratingh,
| | - Wesley R. Browne
- Stratingh Institute for Chemistry and Zernike Institute for Advanced Materials, Faculty of Mathematics and Natural Sciences, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands, http://www.rug.nl/stratingh,
| | - Johannes G. Vos
- Solar Energy Conversion SRC, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland, Fax: +353‐1‐7005503
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50
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Brennan C, Draksharapu A, Browne WR, McGarvey JJ, Vos JG, Pryce MT. Unexpected reversible pyrazine based methylation in a Ru(ii) complex bearing a pyrazin-2′-yl-1,2,4-triazolato ligand and its effect on acid/base and photophysical properties. Dalton Trans 2013; 42:2546-55. [DOI: 10.1039/c2dt31589k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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