51
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Yang J, Dong HT, Seo MS, Larson VA, Lee YM, Shearer J, Lehnert N, Nam W. The Oxo-Wall Remains Intact: A Tetrahedrally Distorted Co(IV)-Oxo Complex. J Am Chem Soc 2021; 143:16943-16959. [PMID: 34609879 DOI: 10.1021/jacs.1c04919] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In this paper, we report the preparation, spectroscopic and theoretical characterization, and reactivity studies of a Co(IV)-oxo complex bearing an N4-macrocyclic coligand, 12-TBC (12-TBC = 1,4,7,10-tetrabenzyl-1,4,7,10-tetraazacyclododecane). On the basis of the ligand and the structure of the Co(II) precursor, [CoII(12-TBC)(CF3SO3)2], one would assume that this species corresponds to a tetragonal Co(IV)-oxo complex, but the spectroscopic data do not support this notion. Co K-edge XAS data show that the treatment of the Co(II) precursor with iodosylbenzene (PhIO) as an oxidant at -40 °C in the presence of a proton source leads to a distinct shift in the Co K-edge, in agreement with the formation of a Co(IV) intermediate. The presence of the oxo group is further demonstrated by resonance Raman (rRaman) spectroscopy. Interestingly, the EPR data of this complex show a high degree of rhombicity, indicating structural distortion. This is further supported by the EXAFS data. Using DFT calculations, a structural model is developed for this complex with a ligand-protonated structure that features a Co═O···HN hydrogen bond and a four-coordinate Co center in a seesaw-shaped coordination geometry. Magnetic circular dichroism (MCD) spectroscopy further supports this finding. The hydrogen bond leads to an interesting polarization of the Co-oxo π-bonds, where one O(p) lone-pair is stabilized and leads to a regular Co(d) interaction, whereas the other π-bond shows an inverted ligand field. The reactivity of this complex in hydrogen atom and oxygen atom transfer reactions is discussed as well.
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Affiliation(s)
- Jindou Yang
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Hai T Dong
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Mi Sook Seo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Virginia A Larson
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Jason Shearer
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
| | - Nicolai Lehnert
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.,School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, China
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52
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Ma Z, Nakatani N, Hada M. Insights into the electronic structure and mechanism of norcarane hydroxylation by OxoMn(V) porphyrin complexes: A density functional theory study. J Comput Chem 2021; 42:1920-1928. [PMID: 34448235 DOI: 10.1002/jcc.26715] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 06/12/2021] [Accepted: 06/15/2021] [Indexed: 11/05/2022]
Abstract
Norcarane hydroxylation by neutral [PorMn(V)O-L] (L═OH- , F- ) and cationic [PorMn(V)O-L]+ (L═H2 O, imidazole) oxoMn(V) porphyrin complex models has been investigated by density functional theory calculations to better understand the reaction mechanism and electronic structure. We found that the energy barriers of norcarane hydroxylation by cationic oxoMn(V) porphyrin complexes are lower than those by neutral oxoMn(V) porphyrin complexes. This indicates that cationic oxoMn(V) porphyrin complexes enhance norcarane hydroxylation compared with neutral oxoMn(V) porphyrin complexes. According to electronic structure analysis, in the C─H activation step, electron transfer occurs through initial interaction between the σCH and rich-oxygen π(Mn═O) orbitals to form real donor orbitals, followed by transfer to the acceptor π*(Mn═O) orbitals. Moreover, single electron shifts from norcarane (CH) to Mn atom during C─H activation. The positive charge of the cationic complex stabilizes the acceptor orbital more than the donor orbital, reducing the energy gap between these orbitals, thus lowering the reaction barrier.
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Affiliation(s)
- Zhifeng Ma
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Japan
| | - Naoki Nakatani
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Japan
| | - Masahiko Hada
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Japan
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53
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Opalade AA, Hessefort L, Day VW, Jackson TA. Controlling the Reactivity of a Metal-Hydroxo Adduct with a Hydrogen Bond. J Am Chem Soc 2021; 143:15159-15175. [PMID: 34494835 DOI: 10.1021/jacs.1c06199] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The enzymes manganese lipoxygenase (MnLOX) and manganese superoxide dismutase (MnSOD) utilize mononuclear Mn centers to effect their catalytic reactions. In the oxidized MnIII state, the active site of each enzyme contains a hydroxo ligand, and X-ray crystal structures imply a hydrogen bond between this hydroxo ligand and a cis carboxylate ligand. While hydrogen bonding is a common feature of enzyme active sites, the importance of this particular hydroxo-carboxylate interaction is relatively unexplored. In this present study, we examined a pair of MnIII-hydroxo complexes that differ by a single functional group. One of these complexes, [MnIII(OH)(PaPy2N)]+, contains a naphthyridinyl moiety capable of forming an intramolecular hydrogen bond with the hydroxo ligand. The second complex, [MnIII(OH)(PaPy2Q)]+, contains a quinolinyl moiety that does not permit any intramolecular hydrogen bonding. Spectroscopic characterization of these complexes supports a common structure, but with perturbations to [MnIII(OH)(PaPy2N)]+, consistent with a hydrogen bond. Kinetic studies using a variety of substrates with activated O-H bonds, revealed that [MnIII(OH)(PaPy2N)]+ is far more reactive than [MnIII(OH)(PaPy2Q)]+, with rate enhancements of 15-100-fold. A detailed analysis of the thermodynamic contributions to these reactions using DFT computations reveals that the former complex is significantly more basic. This increased basicity counteracts the more negative reduction potential of this complex, leading to a stronger O-H BDFE in the [MnII(OH2)(PaPy2N)]+ product. Thus, the differences in reactivity between [MnIII(OH)(PaPy2Q)]+ and [MnIII(OH)(PaPy2N)]+ can be understood on the basis of thermodynamic considerations, which are strongly influenced by the ability of the latter complex to form an intramolecular hydrogen bond.
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Affiliation(s)
- Adedamola A Opalade
- The University of Kansas, Department of Chemistry and Center for Environmentally Beneficial Catalysis, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Logan Hessefort
- The University of Kansas, Department of Chemistry and Center for Environmentally Beneficial Catalysis, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Victor W Day
- The University of Kansas, Department of Chemistry and Center for Environmentally Beneficial Catalysis, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Timothy A Jackson
- The University of Kansas, Department of Chemistry and Center for Environmentally Beneficial Catalysis, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
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54
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Li X, Cho K, Nam W. Electronic properties and reactivity patterns of
high‐valent metal‐oxo
species of Mn, Fe, Co, and Ni. B KOREAN CHEM SOC 2021. [DOI: 10.1002/bkcs.12389] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Xiao‐Xi Li
- Department of Chemistry and Nano Science Ewha Womans University Seoul Korea
| | - Kyung‐Bin Cho
- Department of Chemistry Jeonbuk National University Jeonju Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science Ewha Womans University Seoul Korea
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55
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Lee JL, Ross DL, Barman SK, Ziller JW, Borovik AS. C-H Bond Cleavage by Bioinspired Nonheme Metal Complexes. Inorg Chem 2021; 60:13759-13783. [PMID: 34491738 DOI: 10.1021/acs.inorgchem.1c01754] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The functionalization of C-H bonds is one of the most challenging transformations in synthetic chemistry. In biology, these processes are well-known and are achieved with a variety of metalloenzymes, many of which contain a single metal center within their active sites. The most well studied are those with Fe centers, and the emerging experimental data show that high-valent iron oxido species are the intermediates responsible for cleaving the C-H bond. This Forum Article describes the state of this field with an emphasis on nonheme Fe enzymes and current experimental results that provide insights into the properties that make these species capable of C-H bond cleavage. These parameters are also briefly considered in regard to manganese oxido complexes and Cu-containing metalloenzymes. Synthetic iron oxido complexes are discussed to highlight their utility as spectroscopic and mechanistic probes and reagents for C-H bond functionalization. Avenues for future research are also examined.
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Affiliation(s)
- Justin L Lee
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Dolores L Ross
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Suman K Barman
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Joseph W Ziller
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - A S Borovik
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
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56
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Choi Y, Pandey B, Li X, Lee Y, Cho K, Nam W. How does Lewis acid affect the reactivity of mononuclear
high‐valent chromium–oxo
species? A theoretical study. B KOREAN CHEM SOC 2021. [DOI: 10.1002/bkcs.12397] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Yunhee Choi
- Department of Chemistry Jeonbuk National University Jeonju Republic of Korea
| | - Bhawana Pandey
- Department of Chemistry and Nano Science Ewha Womans University Seoul Republic of Korea
| | - Xiao‐Xi Li
- Department of Chemistry and Nano Science Ewha Womans University Seoul Republic of Korea
| | - Yong‐Min Lee
- Department of Chemistry and Nano Science Ewha Womans University Seoul Republic of Korea
| | - Kyung‐Bin Cho
- Department of Chemistry Jeonbuk National University Jeonju Republic of Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science Ewha Womans University Seoul Republic of Korea
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57
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Barman SK, Yang MY, Parsell TH, Green MT, Borovik AS. Semiempirical method for examining asynchronicity in metal-oxido-mediated C-H bond activation. Proc Natl Acad Sci U S A 2021; 118:e2108648118. [PMID: 34465626 PMCID: PMC8433561 DOI: 10.1073/pnas.2108648118] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The oxidation of substrates via the cleavage of thermodynamically strong C-H bonds is an essential part of mammalian metabolism. These reactions are predominantly carried out by enzymes that produce high-valent metal-oxido species, which are directly responsible for cleaving the C-H bonds. While much is known about the identity of these transient intermediates, the mechanistic factors that enable metal-oxido species to accomplish such difficult reactions are still incomplete. For synthetic metal-oxido species, C-H bond cleavage is often mechanistically described as synchronous, proton-coupled electron transfer (PCET). However, data have emerged that suggest that the basicity of the M-oxido unit is the key determinant in achieving enzymatic function, thus requiring alternative mechanisms whereby proton transfer (PT) has a more dominant role than electron transfer (ET). To bridge this knowledge gap, the reactivity of a monomeric MnIV-oxido complex with a series of external substrates was studied, resulting in a spread of over 104 in their second-order rate constants that tracked with the acidity of the C-H bonds. Mechanisms that included either synchronous PCET or rate-limiting PT, followed by ET, did not explain our results, which led to a proposed PCET mechanism with asynchronous transition states that are dominated by PT. To support this premise, we report a semiempirical free energy analysis that can predict the relative contributions of PT and ET for a given set of substrates. These findings underscore why the basicity of M-oxido units needs to be considered in C-H functionalization.
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Affiliation(s)
- Suman K Barman
- Department of Chemistry, University of California Irvine, CA 92697;
| | - Meng-Yin Yang
- Department of Chemistry, University of California Irvine, CA 92697
| | | | - Michael T Green
- Department of Chemistry, University of California Irvine, CA 92697;
- Department of Molecular Biosciences and Biochemistry, University of California Irvine, CA 92697
| | - A S Borovik
- Department of Chemistry, University of California Irvine, CA 92697;
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58
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Wolff N, Rivada‐Wheelaghan O, Tocqueville D. Molecular Electrocatalytic Hydrogenation of Carbonyls and Dehydrogenation of Alcohols. ChemElectroChem 2021. [DOI: 10.1002/celc.202100617] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Niklas Wolff
- Laboratoire d'Électrochimie Moléculaire Université de Paris, CNRS F-75006 Paris France
| | | | - Damien Tocqueville
- Laboratoire d'Électrochimie Moléculaire Université de Paris, CNRS F-75006 Paris France
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59
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Amtawong J, Skjelstad BB, Handford RC, Suslick BA, Balcells D, Tilley TD. C-H Activation by RuCo 3O 4 Oxo Cubanes: Effects of Oxyl Radical Character and Metal-Metal Cooperativity. J Am Chem Soc 2021; 143:12108-12119. [PMID: 34318666 DOI: 10.1021/jacs.1c04069] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
High-valent multimetallic-oxo/oxyl species have been implicated as intermediates in oxidative catalysis involving proton-coupled electron transfer (PCET) reactions, but the reactive nature of these oxo species has hindered the development of an in-depth understanding of their mechanisms and multimetallic character. The mechanism of C-H oxidation by previously reported RuCo3O4 cubane complexes bearing a terminal RuV-oxo ligand, with significant oxyl radical character, was investigated. The rate-determining step involves H atom abstraction (HAA) from an organic substrate to generate a Ru-OH species and a carbon-centered radical. Radical intermediates are subsequently trapped by another equivalent of the terminal oxo to afford isolable radical-trapped cubane complexes. Density functional theory (DFT) reveals a barrierless radical combination step that is more favorable than an oxygen-rebound mechanism by 12.3 kcal mol-1. This HAA reactivity to generate organic products is influenced by steric congestion and the C-H bond dissociation energy of the substrate. Tuning the electronic properties of the cubane (i.e., spin density localized on terminal oxo, basicity, and redox potential) by varying the donor ability of ligands at the Co sites modulates C-H activations by the RuV-oxo fragment and enables construction of structure-activity relationships. These results reveal a mechanistic pathway for C-H activation by high-valent metal-oxo species with oxyl radical character and provide insights into cooperative effects of multimetallic centers in tuning PCET reactivity.
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Affiliation(s)
- Jaruwan Amtawong
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Bastian Bjerkem Skjelstad
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway
| | - Rex C Handford
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, United States
| | - Benjamin A Suslick
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - David Balcells
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway
| | - T Don Tilley
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720-1460, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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60
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Bakas NJ, Neidig ML. Additive and Counterion Effects in Iron-Catalyzed Reactions Relevant to C-C Bond Formation. ACS Catal 2021; 11:8493-8503. [PMID: 35664726 DOI: 10.1021/acscatal.1c00928] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The use of iron catalysts in carbon-carbon bond forming reactions is of interest as an alternative to precious metal catalysts, offering reduced cost, lower toxicity, and different reactivity. While well-defined ligands such as N-heterocyclic carbenes (NHCs) and phosphines can be highly effective in these reactions, additional additives such as N-methylpyrrolidone (NMP), N,N,N',N'-tetramethylethylenediamine (TMEDA), and iron salts that alter speciation can also be employed to achieve high product yields. However, in contrast to well-defined iron ligands, the roles of these additives are often ambiguous, and molecular-level insights into how they achieve effective catalysis are not well-defined. Using a unique physical-inorganic in situ spectroscopic approach, detailed insights into the effect of additives on iron speciation, mechanism, and catalysis can inform further reaction development. In this Perspective, recent advances will be discussed as well as ongoing challenges and potential opportunities in iron-catalyzed reactions.
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Affiliation(s)
- Nikki J Bakas
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Michael L Neidig
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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61
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Zhang R, Zhou W, Warren JJ. Photo-initiated oxidation of C-H bonds by diimine complexes of vanadium(V). Chem Commun (Camb) 2021; 57:4007-4010. [PMID: 33885690 DOI: 10.1039/d1cc00649e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The photochemical activation of carbon-hydrogen bonds by vanadium(v)-dioxo and vanadium(v)-oxo-peroxo diimine complexes is described. Reactions were carried out using a selection of organic substrates with C-H bond dissociation free energy values between 70 and 97 kcal mol-1. The ability to activate C-H bonds using vanadium(v)-dioxo and vanadium(v)-oxo-peroxo diimine complexes varies with different bond dissociation free energy. Compounds with weaker C-H bonds are oxidized in minutes, rather than in days for thermal oxidations by the corresponding complexes. Dioxygen is necessary for substrate consumption, which suggests that the electronically excited V complexes are radical reaction initiators via H-atom abstraction from the organic substrate.
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Affiliation(s)
- Rui Zhang
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby BC V5A 1S6, Canada.
| | - Wen Zhou
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby BC V5A 1S6, Canada.
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby BC V5A 1S6, Canada.
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62
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Singh P, Stewart-Jones E, Denler MC, Jackson TA. Mechanistic insight into oxygen atom transfer reactions by mononuclear manganese(IV)-oxo adducts. Dalton Trans 2021; 50:3577-3585. [PMID: 33616141 PMCID: PMC8075156 DOI: 10.1039/d0dt04436a] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High-valent metal-oxo intermediates are well known to facilitate oxygen-atom transfer (OAT) reactions both in biological and synthetic systems. These reactions can occur by a single-step OAT mechanism or by a stepwise process initiated by rate-limiting electron transfer between the substrate and the metal-oxo unit. Several recent reports have demonstrated that changes in the metal reduction potential, caused by the addition of Brønsted or Lewis acids, cause a change in sulfoxidation mechanism of MnIV-oxo complexes from single-step OAT to the multistep process. In this work, we sought to determine if ca. 4000-fold rate variations observed for sulfoxidation reactions by a series of MnIV-oxo complexes supported by neutral, pentadentate ligands could arise from a change in sulfoxidation mechanism. We examined the basis for this rate variation by performing variable-temperature kinetic studies to determine activation parameters for the reactions of the MnIV-oxo complexes with thioanisole. These data reveal activation barriers predominantly controlled by activation enthalpy, with unexpectedly small contributions from the activation entropy. We also compared the reactivity of these MnIV-oxo complexes by a Hammett analysis using para-substituted thioanisole derivatives. Similar Hammett ρ values from this analysis suggest a common sulfoxidation mechanism for these complexes. Because the rates of oxidation of the para-substituted thioanisole derivatives by the MnIV-oxo adducts are much faster than that expected from the Marcus theory of outer-sphere electron-transfer, we conclude that these reactions proceed by a single-step OAT mechanism. Thus, large variations in sulfoxidation by this series of MnIV-oxo centers occur without a change in reaction mechanism.
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Affiliation(s)
- Priya Singh
- The University of Kansas, Department of Chemistry and Center for Environmentally Beneficial Catalysis, 1567 Irving Hill Road, Lawrence, KS 66045, USA.
| | - Eleanor Stewart-Jones
- The University of Kansas, Department of Chemistry and Center for Environmentally Beneficial Catalysis, 1567 Irving Hill Road, Lawrence, KS 66045, USA.
| | - Melissa C Denler
- The University of Kansas, Department of Chemistry and Center for Environmentally Beneficial Catalysis, 1567 Irving Hill Road, Lawrence, KS 66045, USA.
| | - Timothy A Jackson
- The University of Kansas, Department of Chemistry and Center for Environmentally Beneficial Catalysis, 1567 Irving Hill Road, Lawrence, KS 66045, USA.
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63
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Kim S, Jeong HY, Kim S, Kim H, Lee S, Cho J, Kim C, Lee D. Proton Switch in the Secondary Coordination Sphere to Control Catalytic Events at the Metal Center: Biomimetic Oxo Transfer Chemistry of Nickel Amidate Complex. Chemistry 2021; 27:4700-4708. [PMID: 33427344 DOI: 10.1002/chem.202005183] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Indexed: 11/11/2022]
Abstract
High-valent metal-oxo species are key intermediates for the oxygen atom transfer step in the catalytic cycles of many metalloenzymes. While the redox-active metal centers of such enzymes are typically supported by anionic amino acid side chains or porphyrin rings, peptide backbones might function as strong electron-donating ligands to stabilize high oxidation states. To test the feasibility of this idea in synthetic settings, we have prepared a nickel(II) complex of new amido multidentate ligand. The mononuclear nickel complex of this N5 ligand catalyzes epoxidation reactions of a wide range of olefins by using mCPBA as a terminal oxidant. Notably, a remarkably high catalytic efficiency and selectivity were observed for terminal olefin substrates. We found that protonation of the secondary coordination sphere serves as the entry point to the catalytic cycle, in which high-valent nickel species is subsequently formed to carry out oxo-transfer reactions. A conceptually parallel process might allow metalloenzymes to control the catalytic cycle in the primary coordination sphere by using proton switch in the secondary coordination sphere.
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Affiliation(s)
- Soohyung Kim
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Korea
| | - Ha Young Jeong
- Department of Fine Chemistry, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul, 01811, Korea
| | - Seonghan Kim
- Department of Emerging Materials Science, DGIST, Daegu, 42988, Korea
| | - Hongsik Kim
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Korea
| | - Sojeong Lee
- Department of Fine Chemistry, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul, 01811, Korea
| | - Jaeheung Cho
- Department of Emerging Materials Science, DGIST, Daegu, 42988, Korea.,Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Korea
| | - Cheal Kim
- Department of Fine Chemistry, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul, 01811, Korea
| | - Dongwhan Lee
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Korea
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64
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Karuppasamy P, Thiruppathi D, Sundar JV, Ganesan M, Rajendran T, Meena SS, Rajagopal S, Sivasubramanian VK, Rajapandian V. Insight into structural aspects and study of reaction kinetics of model [oxo(salen)iron(IV)] complexes with dipeptides. Polyhedron 2021. [DOI: 10.1016/j.poly.2020.114952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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65
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Oohora K, Hayashi T. Myoglobins engineered with artificial cofactors serve as artificial metalloenzymes and models of natural enzymes. Dalton Trans 2021; 50:1940-1949. [PMID: 33433532 DOI: 10.1039/d0dt03597a] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Metalloenzymes naturally achieve various reactivities by assembling limited types of cofactors with endogenous amino acid residues. Enzymes containing metal porphyrinoid cofactors such as heme, cobalamin and F430 exert precise control over the reactivities of the cofactors with protein matrices. This perspective article focuses on our recent efforts to assemble metal complexes of non-natural porphyrinoids within the protein matrix of myoglobin, an oxygen storage hemoprotein. Engineered myoglobins with suitable metal complexes as artificial cofactors demonstrate unique reactivities toward C-H bond hydroxylation, olefin cyclopropanation, methyl group transfer and methane generation. In these cases, the protein matrix enhances the catalytic activities of the cofactors and allows us to monitor the active intermediates. The present findings indicate that placing artificial cofactors in protein matrices provides a useful strategy for creating artificial metalloenzymes that catalyse otherwise unfavourable reactions and providing enzyme models for elucidating the complicated reaction mechanisms of natural enzymes.
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Affiliation(s)
- Koji Oohora
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, 565-0871, Japan.
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66
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Pachisia S, Kishan R, Yadav S, Gupta R. Half-Sandwich Ruthenium Complexes of Amide-Phosphine Based Ligands: H-Bonding Cavity Assisted Binding and Reduction of Nitro-substrates. Inorg Chem 2021; 60:2009-2022. [PMID: 33459009 DOI: 10.1021/acs.inorgchem.0c03505] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present synthesis and characterization of two half-sandwich Ru(II) complexes supported with amide-phosphine based ligands. These complexes presented a pyridine-2,6-dicarboxamide based pincer cavity, decorated with hydrogen bonds, that participated in the binding of nitro-substrates closer to the Ru(II) centers, which is further supported with binding and docking studies. These ruthenium complexes functioned as the noteworthy catalysts for the borohydride mediated reduction of assorted nitro-substrates. Mechanistic studies not only confirmed the intermediacy of [Ru-H] in the reduction but also asserted the involvement of several organic intermediates during the course of the catalysis. A similar Ru(II) complex that lacked pyridine-2,6-dicarboxamide based pincer cavity substantiated its unique role both in the substrate binding and the subsequent catalysis.
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Affiliation(s)
- Sanya Pachisia
- Department of Chemistry, University of Delhi, Delhi 110007, India
| | - Ram Kishan
- Department of Chemistry, University of Delhi, Delhi 110007, India
| | - Samanta Yadav
- Department of Chemistry, University of Delhi, Delhi 110007, India
| | - Rajeev Gupta
- Department of Chemistry, University of Delhi, Delhi 110007, India
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Keshari K, Bera M, Velasco L, Munshi S, Gupta G, Moonshiram D, Paria S. Characterization and reactivity study of non-heme high-valent iron-hydroxo complexes. Chem Sci 2021; 12:4418-4424. [PMID: 34163706 PMCID: PMC8179568 DOI: 10.1039/d0sc07054h] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A terminal FeIIIOH complex, [FeIII(L)(OH)]2− (1), has been synthesized and structurally characterized (H4L = 1,2-bis(2-hydroxy-2-methylpropanamido)benzene). The oxidation reaction of 1 with one equiv. of tris(4-bromophenyl)ammoniumyl hexachloroantimonate (TBAH) or ceric ammonium nitrate (CAN) in acetonitrile at −45 °C results in the formation of a FeIIIOH ligand radical complex, [FeIII(L˙)(OH)]− (2), which is hereby characterized by UV-visible, 1H nuclear magnetic resonance, electron paramagnetic resonance, and X-ray absorption spectroscopy techniques. The reaction of 2 with a triphenylcarbon radical further gives triphenylmethanol and mimics the so-called oxygen rebound step of Cpd II of cytochrome P450. Furthermore, the reaction of 2 was explored with different 4-substituted-2,6-di-tert-butylphenols. Based on kinetic analysis, a hydrogen atom transfer (HAT) mechanism has been established. A pKa value of 19.3 and a BDFE value of 78.2 kcal/mol have been estimated for complex 2. One-electron oxidation of an FeIII–OH complex (1) results in the formation of a FeIII–OH ligand radical complex (2). Its reaction with (C6H5)3C˙ results in the formation of (C6H5)3COH, which is a functional mimic of compound II of cytochrome P450.![]()
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Affiliation(s)
- Kritika Keshari
- Department of Chemistry, Indian Institute of Technology Delhi Hauz Khas New Delhi 110016 India
| | - Moumita Bera
- Department of Chemistry, Indian Institute of Technology Delhi Hauz Khas New Delhi 110016 India
| | - Lucía Velasco
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia Calle Faraday, 9 28049 Madrid Spain
| | - Sandip Munshi
- School of Chemical Sciences, Indian Association for the Cultivation of Science 2A & 2B Raja S. C. Mullick Road, Jadavpur Kolkata 700032 India
| | - Geetika Gupta
- Department of Chemistry, Indian Institute of Technology Delhi Hauz Khas New Delhi 110016 India
| | - Dooshaye Moonshiram
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia Calle Faraday, 9 28049 Madrid Spain
| | - Sayantan Paria
- Department of Chemistry, Indian Institute of Technology Delhi Hauz Khas New Delhi 110016 India
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68
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Ledray AP, Krest CM, Yosca TH, Mittra K, Green MT. Ascorbate Peroxidase Compound II Is an Iron(IV) Oxo Species. J Am Chem Soc 2020; 142:10.1021/jacs.0c09108. [PMID: 33170000 PMCID: PMC8107191 DOI: 10.1021/jacs.0c09108] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The protonation state of the iron(IV) oxo (or ferryl) form of ascorbate peroxidase compound II (APX-II) is a subject of debate. It has been reported that this intermediate is best described as an iron(IV) hydroxide species. Neutron diffraction data obtained from putative APX-II crystals indicate a protonated oxygenic ligand at 1.88 Å from the heme iron. This finding, if correct, would be unprecedented. A basic iron(IV) oxo species has yet to be spectroscopically observed in a histidine-ligated heme enzyme. The importance of ferryl basicity lies in its connection to our fundamental understanding of C-H bond activation. Basic ferryl species have been proposed to facilitate the oxidation of inert C-H bonds, reactions that are unknown for histidine-ligated hemes enzymes. To provide further insight into the protonation status of APX-II, we examined the intermediate using a combination of Mössbauer and X-ray absorption spectroscopies. Our data indicate that APX-II is an iron(IV) oxo species with an Fe-O bond distance of 1.68 Å, a K-edge pre-edge absorption of 18 units, and Mössbauer parameters of ΔEq = 1.65 mm/s and δ = 0.03 mm/s.
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Affiliation(s)
- Aaron P Ledray
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Courtney M Krest
- Roach & Associates, Limited Liability Company, Seymour, Wisconsin 54942, United States
| | - Timothy H Yosca
- Department of Chemistry, University of California, Irvine, California 92697, United States
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Kaustuv Mittra
- Department of Chemistry, University of California, Irvine, California 92697, United States
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Michael T Green
- Department of Chemistry, University of California, Irvine, California 92697, United States
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
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69
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Kannan N, Patil AR, Sinha A. Direct C-H bond halogenation and pseudohalogenation of hydrocarbons mediated by high-valent 3d metal-oxo species. Dalton Trans 2020; 49:14344-14360. [PMID: 33057538 DOI: 10.1039/d0dt02533j] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Late-stage direct functionalization of the C-H bond is synthetically desirable. Metalloenzymes having metal-oxo active sites are well known to selectively catalyze hydroxylation and halogenation reactions with high efficiency. This review highlights the recent developments in the field of direct C-H halogenation and pseudohalogenation reactions catalyzed by the functional models of metalloenzymes.
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Affiliation(s)
- Neppoliyan Kannan
- Department of Chemistry, School of Advanced Science, Vellore Institute of Technology, Vellore-632014, Tamil Nadu, India.
| | - Akshay R Patil
- Department of Chemistry, School of Advanced Science, Vellore Institute of Technology, Vellore-632014, Tamil Nadu, India.
| | - Arup Sinha
- Department of Chemistry, School of Advanced Science, Vellore Institute of Technology, Vellore-632014, Tamil Nadu, India.
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Kotani H, Shimomura H, Ikeda K, Ishizuka T, Shiota Y, Yoshizawa K, Kojima T. Mechanistic Insight into Concerted Proton-Electron Transfer of a Ru(IV)-Oxo Complex: A Possible Oxidative Asynchronicity. J Am Chem Soc 2020; 142:16982-16989. [PMID: 32924508 DOI: 10.1021/jacs.0c05738] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have thoroughly investigated the oxidation of benzyl alcohol (BA) derivatives by a RuIV(O) complex (RuIV(O)) in the absence or presence of Brønsted acids in order to elucidate the proton-coupled electron-transfer (PCET) mechanisms in C-H oxidation on the basis of a kinetic analysis. Oxidation of BA derivatives by RuIV(O) without acids proceeded through concerted proton-electron transfer (CPET) with a large kinetic isotope effect (KIE). In contrast, the oxidation of 3,4,5-trimethoxy-BA ((MeO)3-BA) by RuIV(O) was accelerated by the addition of acids, in which the KIE value reached 1.1 with TFA (550 mM), indicating an alteration of the PCET mechanism from CPET to stepwise electron transfer (ET) followed by proton transfer (PT). Although the oxidized products of BA derivatives were confirmed to be the corresponding benzaldehydes in the range of acid concentrations (0-550 mM), a one-electron-reduction potential of RuIV(O) was positively shifted with increases in the concentrations of acids. The elevated reduction potential of RuIV(O) strongly influenced the PCET mechanisms in the oxidation of (MeO)3-BA, changing the mechanism from CPET to ET/PT, as evidenced by the driving-force dependence of logarithms of reaction rate constants in light of the Marcus theory of ET. In addition, dependence of activation parameters on acid concentrations suggested that an oxidative asynchronous CPET, which is not an admixture of the CPET and ET/PT mechanisms, is probably operative in the boundary region (0 mM < [TFA] < 50 mM) involving a one-proton-interacted RuIV(O)···H+ as a dominant reactive species.
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Affiliation(s)
- Hiroaki Kotani
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba and CREST (JST), 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
| | - Hinatsu Shimomura
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba and CREST (JST), 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
| | - Kei Ikeda
- Institute for Materials Chemistry and Engineering, Kyushu University and CREST (JST), Motooka, Nishi-Ku, Fukuoka 819-0395, Japan
| | - Tomoya Ishizuka
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba and CREST (JST), 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
| | - Yoshihito Shiota
- Institute for Materials Chemistry and Engineering, Kyushu University and CREST (JST), Motooka, Nishi-Ku, Fukuoka 819-0395, Japan
| | - Kazunari Yoshizawa
- Institute for Materials Chemistry and Engineering, Kyushu University and CREST (JST), Motooka, Nishi-Ku, Fukuoka 819-0395, Japan
| | - Takahiko Kojima
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba and CREST (JST), 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
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Mondal P, McDonald AR. Phenol Oxidation by a Nickel(III)-Fluoride Complex: Exploring the Influence of the Proton Accepting Ligand in PCET Oxidation. Chemistry 2020; 26:10083-10089. [PMID: 32567726 DOI: 10.1002/chem.202002135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/15/2020] [Indexed: 11/05/2022]
Abstract
In order to gain insight into the influence of the H+ -accepting terminal ligand in high-valent oxidant mediated proton coupled electron transfer (PCET) reactions, the reactivity of a high valent nickel-fluoride complex [NiIII (F)(L)] (2, L=N,N'-(2,6-dimethylphenyl)-2,6-pyridinecarboxamidate) with substituted phenols was explored. Analysis of kinetic data from these reactions (Evans-Polanyi, Hammett, and Marcus plots, and KIE measurements) and the formed products show that 2 reacted with electron rich phenols through a hydrogen atom transfer (HAT, or concerted PCET) mechanism and with electron poor phenols through a stepwise proton transfer/electron transfer (PT/ET) reaction mechanism. The analogous complexes [NiIII (Z)(L)] (Z=Cl, OCO2 H, O2 CCH3 , ONO2 ) reacted with all phenols through a HAT mechanism. We explore the reason for a change in mechanism with the highly basic fluoride ligand in 2. Complex 2 was also found to react one to two orders of magnitude faster than the corresponding analogous [NiIII (Z)(L)] complexes. This was ascribed to a high bond dissociation free energy value associated with H-F (135 kcal mol-1 ), which is postulated to be the product formed from PCET oxidation by 2 and is believed to be the driving force for the reaction. Our findings show that high-valent metal-fluoride complexes represent a class of highly reactive PCET oxidants.
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Affiliation(s)
- Prasenjit Mondal
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin, 2, Ireland
| | - Aidan R McDonald
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin, 2, Ireland
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72
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Larson VA, Battistella B, Ray K, Lehnert N, Nam W. Iron and manganese oxo complexes, oxo wall and beyond. Nat Rev Chem 2020; 4:404-419. [PMID: 37127969 DOI: 10.1038/s41570-020-0197-9] [Citation(s) in RCA: 139] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2020] [Indexed: 11/09/2022]
Abstract
High-valent metal-oxo species with multiply-bonded M-O groups have been proposed as key intermediates in many biological and abiological catalytic oxidation reactions. These intermediates are implicated as active oxidants in alkane hydroxylation, olefin epoxidation and other oxidation reactions. For example, [FeivO(porphyrinato•-)]+ cofactors bearing π-radical porphyrinato•- ligands oxidize organic substrates in cytochrome P450 enzymes, which are common to many life forms. Likewise, high-valent Mn-oxo species are active for H2O oxidation in photosystem II. The chemistry of these native reactive species has inspired chemists to prepare highly oxidized transition-metal complexes as functional mimics. Although many synthetic Fe-O and Mn-O complexes now exist, the analogous oxo complexes of the late transition metals (groups 9-11) are rare. Indeed, late-transition-metal-oxo complexes of tetragonal (fourfold) symmetry should be electronically unstable, a rule commonly referred to as the 'oxo wall'. A few late metal-oxos have been prepared by targeting other symmetries or unusual spin states. These complexes have been studied using spectroscopic and theoretical methods. This Review describes mononuclear non-haem Fe-O and Mn-O species, the nature of the oxo wall and recent advances in the preparation of oxo complexes of Co, Ni and Cu beyond the oxo wall.
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73
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Ikeda K, Mahyuddin MH, Shiota Y, Yoshizawa K. Active Catalyst for Methane Hydroxylation by an Iridium–Oxo Complex. ACS Catal 2020. [DOI: 10.1021/acscatal.0c01610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Kei Ikeda
- Institute for Materials Chemistry and Engineering and Integrated Research Consortium on Chemical Science (IRCCS), Kyushu University, Fukuoka 819-0395, Japan
| | - Muhammad Haris Mahyuddin
- Research Group of Advanced Functional Materials, Faculty of Industrial Technology, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132, Indonesia
- Research Center for Nanoscience and Nanotechnology, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132, Indonesia
| | - Yoshihito Shiota
- Institute for Materials Chemistry and Engineering and Integrated Research Consortium on Chemical Science (IRCCS), Kyushu University, Fukuoka 819-0395, Japan
| | - Kazunari Yoshizawa
- Institute for Materials Chemistry and Engineering and Integrated Research Consortium on Chemical Science (IRCCS), Kyushu University, Fukuoka 819-0395, Japan
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74
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Oswald VF, Lee JL, Biswas S, Weitz AC, Mittra K, Fan R, Li J, Zhao J, Hu MY, Alp EE, Bominaar EL, Guo Y, Green MT, Hendrich MP, Borovik AS. Effects of Noncovalent Interactions on High-Spin Fe(IV)-Oxido Complexes. J Am Chem Soc 2020; 142:11804-11817. [PMID: 32489096 DOI: 10.1021/jacs.0c03085] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
High-valent nonheme FeIV-oxido species are key intermediates in biological oxidation, and their properties are proposed to be influenced by the unique microenvironments present in protein active sites. Microenvironments are regulated by noncovalent interactions, such as hydrogen bonds (H-bonds) and electrostatic interactions; however, there is little quantitative information about how these interactions affect crucial properties of high valent metal-oxido complexes. To address this knowledge gap, we introduced a series of FeIV-oxido complexes that have the same S = 2 spin ground state as those found in nature and then systematically probed the effects of noncovalent interactions on their electronic, structural, and vibrational properties. The key design feature that provides access to these complexes is the new tripodal ligand [poat]3-, which contains phosphinic amido groups. An important structural aspect of [FeIVpoat(O)]- is the inclusion of an auxiliary site capable of binding a Lewis acid (LAII); we used this unique feature to further modulate the electrostatic environment around the Fe-oxido unit. Experimentally, studies confirmed that H-bonds and LAII s can interact directly with the oxido ligand in FeIV-oxido complexes, which weakens the Fe═O bond and has an impact on the electronic structure. We found that relatively large vibrational changes in the Fe-oxido unit correlate with small structural changes that could be difficult to measure, especially within a protein active site. Our work demonstrates the important role of noncovalent interactions on the properties of metal complexes, and that these interactions need to be considered when developing effective oxidants.
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Affiliation(s)
- Victoria F Oswald
- Department of Chemistry, 1102 Natural Sciences II, University of California at Irvine, Irvine, California 92697, United States
| | - Justin L Lee
- Department of Chemistry, 1102 Natural Sciences II, University of California at Irvine, Irvine, California 92697, United States
| | - Saborni Biswas
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Andrew C Weitz
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Kaustuv Mittra
- Department of Molecular Biosciences and Biochemistry, University of California at Irvine, Irvine, California 92697, United States
| | - Ruixi Fan
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Jikun Li
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Jiyong Zhao
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Michael Y Hu
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Esen E Alp
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Emile L Bominaar
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Michael T Green
- Department of Chemistry, 1102 Natural Sciences II, University of California at Irvine, Irvine, California 92697, United States.,Department of Molecular Biosciences and Biochemistry, University of California at Irvine, Irvine, California 92697, United States
| | - Michael P Hendrich
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - A S Borovik
- Department of Chemistry, 1102 Natural Sciences II, University of California at Irvine, Irvine, California 92697, United States
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75
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Vibbert HB, Filatov AS, Hopkins MD. Synthesis, Structure, and Bonding of d
3
Molybdenum–Oxo Complexes. Angew Chem Int Ed Engl 2020; 59:10581-10586. [DOI: 10.1002/anie.202001379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/09/2020] [Indexed: 11/05/2022]
Affiliation(s)
- Hunter B. Vibbert
- Department of Chemistry The University of Chicago Chicago IL 60637 USA
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76
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Vibbert HB, Filatov AS, Hopkins MD. Synthesis, Structure, and Bonding of d
3
Molybdenum–Oxo Complexes. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202001379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Hunter B. Vibbert
- Department of Chemistry The University of Chicago Chicago IL 60637 USA
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77
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Mondal P, Lovisari M, Twamley B, McDonald AR. Fast Hydrocarbon Oxidation by a High‐Valent Nickel–Fluoride Complex. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202004639] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Prasenjit Mondal
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
| | - Marta Lovisari
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
| | - Brendan Twamley
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
| | - Aidan R. McDonald
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
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78
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Mondal P, Lovisari M, Twamley B, McDonald AR. Fast Hydrocarbon Oxidation by a High‐Valent Nickel–Fluoride Complex. Angew Chem Int Ed Engl 2020; 59:13044-13050. [DOI: 10.1002/anie.202004639] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Indexed: 11/11/2022]
Affiliation(s)
- Prasenjit Mondal
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
| | - Marta Lovisari
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
| | - Brendan Twamley
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
| | - Aidan R. McDonald
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
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79
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Rosen AS, Notestein JM, Snurr RQ. High‐Valent Metal–Oxo Species at the Nodes of Metal–Triazolate Frameworks: The Effects of Ligand Exchange and Two‐State Reactivity for C−H Bond Activation. Angew Chem Int Ed Engl 2020; 59:19494-19502. [DOI: 10.1002/anie.202004458] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Indexed: 01/18/2023]
Affiliation(s)
- Andrew S. Rosen
- Department of Chemical and Biological Engineering Northwestern University 2145 Sheridan Rd. Evanston IL 60208 USA
| | - Justin M. Notestein
- Department of Chemical and Biological Engineering Northwestern University 2145 Sheridan Rd. Evanston IL 60208 USA
| | - Randall Q. Snurr
- Department of Chemical and Biological Engineering Northwestern University 2145 Sheridan Rd. Evanston IL 60208 USA
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80
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Rosen AS, Notestein JM, Snurr RQ. High‐Valent Metal–Oxo Species at the Nodes of Metal–Triazolate Frameworks: The Effects of Ligand Exchange and Two‐State Reactivity for C−H Bond Activation. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202004458] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Andrew S. Rosen
- Department of Chemical and Biological Engineering Northwestern University 2145 Sheridan Rd. Evanston IL 60208 USA
| | - Justin M. Notestein
- Department of Chemical and Biological Engineering Northwestern University 2145 Sheridan Rd. Evanston IL 60208 USA
| | - Randall Q. Snurr
- Department of Chemical and Biological Engineering Northwestern University 2145 Sheridan Rd. Evanston IL 60208 USA
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81
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Das A, Ren Y, Hessin C, Desage-El Murr M. Copper catalysis with redox-active ligands. Beilstein J Org Chem 2020; 16:858-870. [PMID: 32461767 PMCID: PMC7214867 DOI: 10.3762/bjoc.16.77] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 04/08/2020] [Indexed: 01/15/2023] Open
Abstract
Copper catalysis finds applications in various synthetic fields by utilizing the ability of copper to sustain mono- and bielectronic elementary steps. Further to the development of well-defined copper complexes with classical ligands such as phosphines and N-heterocyclic carbenes, a new and fast-expanding area of research is exploring the possibility of a complementing metal-centered reactivity with electronic participation by the coordination sphere. To achieve this electronic flexibility, redox-active ligands can be used to engage in a fruitful “electronic dialogue” with the metal center, and provide additional venues for electron transfer. This review aims to present the latest results in the area of copper-based cooperative catalysis with redox-active ligands.
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Affiliation(s)
- Agnideep Das
- Université de Strasbourg, Institut de Chimie, UMR CNRS 7177, 67000 Strasbourg, France
| | - Yufeng Ren
- Sorbonne Université, Institut Parisien de Chimie Moléculaire, UMR CNRS 8232, 75005 Paris, France
| | - Cheriehan Hessin
- Université de Strasbourg, Institut de Chimie, UMR CNRS 7177, 67000 Strasbourg, France
| | - Marine Desage-El Murr
- Université de Strasbourg, Institut de Chimie, UMR CNRS 7177, 67000 Strasbourg, France
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82
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Biswas JP, Guin S, Maiti D. Highvalent 3d metal-oxo mediated C–H halogenation: Biomimetic approaches. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2019.213174] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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83
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Abstract
AuIII-oxygen adducts have been implicated as intermediates in homogeneous and heterogeneous Au oxidation catalysis, but their reactivity is under-explored. Complex 1, ([AuIII(OH)(terpy)](ClO4)2, (terpy = 2,2':6',2-terpyridine), readily oxidized substrates bearing C-H and O-H bonds. Kinetic analysis revealed that the oxidation occurred through a hydrogen atom transfer (HAT) mechanism. Stable radicals were detected and quantified as products of almost quantitative HAT oxidation of alcohols by 1. Our findings highlight the possible role of AuIII-oxygen adducts in oxidation catalysis and the capability of late transition metal-oxygen adducts to perform proton coupled electron transfer.
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Affiliation(s)
- Marta Lovisari
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Aidan R McDonald
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
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84
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Stuyver T, Ramanan R, Mallick D, Shaik S. Oriented (Local) Electric Fields Drive the Millionfold Enhancement of the H-Abstraction Catalysis Observed for Synthetic Metalloenzyme Analogues. Angew Chem Int Ed Engl 2020; 59:7915-7920. [PMID: 32097514 DOI: 10.1002/anie.201916592] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 01/29/2020] [Indexed: 01/01/2023]
Abstract
This contribution follows the recent remarkable catalysis observed by Groves et al. in hydrogen-abstraction reactions by a) an oxoferryl porphyrin radical-cation complex [Por⋅+ FeIV (O)Lax ] and b) a hydroxoiron porphyrazine ferric complex [PyPzFeIII (OH)Lax ], both of which involve positively charged substituents on the outer circumference of the respective macrocyclic ligands. These charge-coronated complexes are analogues of the biologically important Compound I (Cpd I) and synthetic hydroxoferric species, respectively. We demonstrate that the observed enhancement of the H-abstraction catalysis for these systems is a purely electrostatic effect, elicited by the local charges embedded on the peripheries of the respective macrocyclic ligands. Our findings provide new insights into how electrostatics can be employed to tune the catalytic activity of metalloenzymes and can thus contribute to the future design of new and highly efficient hydrogen-abstraction catalysts.
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Affiliation(s)
- Thijs Stuyver
- Department of Organic Chemistry, The Hebrew Unviersity of Jerusalem, Jerusalem, 91904, Israel.,Algemene Chemie, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
| | - Rajeev Ramanan
- Department of Organic Chemistry, The Hebrew Unviersity of Jerusalem, Jerusalem, 91904, Israel.,Department of Chemistry, Michigan Technological University, Houghton, MI, USA
| | - Dibyendu Mallick
- Department of Organic Chemistry, The Hebrew Unviersity of Jerusalem, Jerusalem, 91904, Israel.,Department of Chemistry, Presidency University, Kolkata, 700073, India
| | - Sason Shaik
- Department of Organic Chemistry, The Hebrew Unviersity of Jerusalem, Jerusalem, 91904, Israel
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85
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Stuyver T, Ramanan R, Mallick D, Shaik S. Oriented (Local) Electric Fields Drive the Millionfold Enhancement of the H‐Abstraction Catalysis Observed for Synthetic Metalloenzyme Analogues. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201916592] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Thijs Stuyver
- Department of Organic Chemistry The Hebrew Unviersity of Jerusalem Jerusalem 91904 Israel
- Algemene Chemie Vrije Universiteit Brussel Pleinlaan 2 1050 Brussels Belgium
| | - Rajeev Ramanan
- Department of Organic Chemistry The Hebrew Unviersity of Jerusalem Jerusalem 91904 Israel
- Department of Chemistry Michigan Technological University Houghton MI USA
| | - Dibyendu Mallick
- Department of Organic Chemistry The Hebrew Unviersity of Jerusalem Jerusalem 91904 Israel
- Department of Chemistry Presidency University Kolkata 700073 India
| | - Sason Shaik
- Department of Organic Chemistry The Hebrew Unviersity of Jerusalem Jerusalem 91904 Israel
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86
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Stimple SD, Smith MD, Tessier PM. Directed evolution methods for overcoming trade-offs between protein activity and stability. AIChE J 2020; 66. [PMID: 32719568 DOI: 10.1002/aic.16814] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Engineered proteins are being widely developed and employed in applications ranging from enzyme catalysts to therapeutic antibodies. Directed evolution, an iterative experimental process composed of mutagenesis and library screening, is a powerful technique for enhancing existing protein activities and generating entirely new ones not observed in nature. However, the process of accumulating mutations for enhanced protein activity requires chemical and structural changes that are often destabilizing, and low protein stability is a significant barrier to achieving large enhancements in activity during multiple rounds of directed evolution. Here we highlight advances in understanding the origins of protein activity/stability trade-offs for two important classes of proteins (enzymes and antibodies) as well as innovative experimental and computational methods for overcoming such trade-offs. These advances hold great potential for improving the generation of highly active and stable proteins that are needed to address key challenges related to human health, energy and the environment.
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Affiliation(s)
- Samuel D. Stimple
- Department of Pharmaceutical Sciences Biointerfaces Institute, University of Michigan Ann Arbor Michigan
- Department of Chemical Engineering Biointerfaces Institute, University of Michigan Ann Arbor Michigan
| | - Matthew D. Smith
- Department of Chemical Engineering Biointerfaces Institute, University of Michigan Ann Arbor Michigan
| | - Peter M. Tessier
- Department of Pharmaceutical Sciences Biointerfaces Institute, University of Michigan Ann Arbor Michigan
- Department of Chemical Engineering Biointerfaces Institute, University of Michigan Ann Arbor Michigan
- Department of Biomedical Engineering Biointerfaces Institute, University of Michigan Ann Arbor Michigan
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87
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Sen A, Vyas N, Pandey B, Jaccob M, Rajaraman G. Mechanistic Insights on the Formation of High‐Valent Mn
III/IV
=O Species Using Oxygen as Oxidant: A Theoretical Perspective. Isr J Chem 2020. [DOI: 10.1002/ijch.201900142] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Asmita Sen
- Department of Chemistry Indian Institute of Technology Bombay Mumbai 400076 India
| | - Nidhi Vyas
- Department of Chemistry Indian Institute of Technology Bombay Mumbai 400076 India
- School of Biotechnology Jawaharlal Nehru University New Delhi 110067 India
| | - Bhawana Pandey
- Department of Chemistry Indian Institute of Technology Bombay Mumbai 400076 India
| | - Madhavan Jaccob
- Department of Chemistry Indian Institute of Technology Bombay Mumbai 400076 India
- Department of chemistry Loyola College Chennai 600 034
| | - Gopalan Rajaraman
- Department of Chemistry Indian Institute of Technology Bombay Mumbai 400076 India
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88
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Chambers RK, Zhao J, Delaney CP, White MC. Chemoselective Tertiary C-H Hydroxylation for Late-Stage Functionalization with Mn(PDP)/Chloroacetic Acid Catalysis. Adv Synth Catal 2020; 362:417-423. [PMID: 32165875 DOI: 10.1002/adsc.201901472] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Aromatic and heterocyclic functionality are ubiquitous in pharmaceuticals. Herein, we disclose a new Mn(PDP)catalyst system using chloroacetic acid additive capable of chemoselectively oxidizing remote tertiary C(sp 3)-H bonds in the presence of a broad range of aromatic and heterocyclic moieties. Although catalyst loadings can be lowered to 0.1 mol% under a Mn(PDP)/acetic acid system for aromatic and non-basic nitrogen heterocycle substrates, the Mn(PDP)/chloroacetic acid system generally affords 10-15% higher isolated yields on these substrates and is uniquely effective for remote C(sp 3)-H hydroxylations in substrates housing basic nitrogen heterocycles. The demonstrated ability to perform Mn(PDP)/chloroacetic acid C(sp 3)-H oxidations in pharmaceutically relevant complex molecules on multi-gram scales will facilitate drug discovery processes via late-stage functionalization.
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Affiliation(s)
- Rachel K Chambers
- Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States.,These authors contributed equally to this work
| | - Jinpeng Zhao
- Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States.,These authors contributed equally to this work.,Current address: Corteva Agriscience, 9330 Zionsville Road, Indianapolis, Indiana, 46268
| | - Connor P Delaney
- Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States
| | - M Christina White
- Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States
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89
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Rice DB, Massie AA, Jackson TA. Experimental and Multireference ab Initio Investigations of Hydrogen-Atom-Transfer Reactivity of a Mononuclear MnIV-oxo Complex. Inorg Chem 2019; 58:13902-13916. [DOI: 10.1021/acs.inorgchem.9b01761] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Derek B. Rice
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, The University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Allyssa A. Massie
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, The University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Timothy A. Jackson
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, The University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
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90
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Pap LG, Couldridge A, Arulsamy N, Hulley E. Electrostatic polarization of nonpolar substrates: a study of interactions between simple cations and Mo-bound N 2. Dalton Trans 2019; 48:11004-11017. [PMID: 31232399 DOI: 10.1039/c9dt01606f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Although a great deal of catalytic studies have focused on covalent interactions between substrates and catalyst centers, recognition of the importance of noncovalent and ionic interactions is driving new approaches to catalyst design. Electrostatic interactions with simple cations (those with little covalency, such as alkali metals) play crucial roles in many catalytic processes, but these effects are challenging to study due to their complicated solvation and speciation behaviour. These effects are particularly difficult to study during cation-mediated reactions with weakly-polar or non-polar substrates. Dinitrogen is one of the most nonpolar substrates known to be affected by electrostatic interactions in both heterogeneous and homogeneous reactions but understanding the significance of these effects requires further exploration. To examine these effects systematically, a new multidentate ligand framework bearing pendent crown ethers has been developed and incorporated into a series of Mo(0)-based dinitrogen complexes. Prepared via both reduction and ligand substitution routes, the strength and impact of cation-N2 interactions have been studied experimentally (IR spectroscopy) and computationally. Although the smallest cation (Li+) has the largest impact on the ground-state heterobimetallic activation of N2, solvation interactions are highly competitive and result in low Li+-(N2)Mo binding affinities. Thus, although smaller cations can have the largest electronic impact on substrates, these interactions are also the least persistent.
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Affiliation(s)
- Levente G Pap
- Department of Chemistry, University of Wyoming, Dept. 3838, 1000 E. University Avenue, Laramie, Wyoming 82071, USA.
| | - Adam Couldridge
- Department of Chemistry, University of Wyoming, Dept. 3838, 1000 E. University Avenue, Laramie, Wyoming 82071, USA.
| | - Navamoney Arulsamy
- Department of Chemistry, University of Wyoming, Dept. 3838, 1000 E. University Avenue, Laramie, Wyoming 82071, USA.
| | - Elliott Hulley
- Department of Chemistry, University of Wyoming, Dept. 3838, 1000 E. University Avenue, Laramie, Wyoming 82071, USA.
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91
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Nandy A, Zhu J, Janet JP, Duan C, Getman RB, Kulik HJ. Machine Learning Accelerates the Discovery of Design Rules and Exceptions in Stable Metal–Oxo Intermediate Formation. ACS Catal 2019. [DOI: 10.1021/acscatal.9b02165] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
| | - Jiazhou Zhu
- Department of Chemical & Biomolecular Engineering, Clemson University, Clemson, South Carolina 29634, United States
| | | | | | - Rachel B. Getman
- Department of Chemical & Biomolecular Engineering, Clemson University, Clemson, South Carolina 29634, United States
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92
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Barman SK, Jones JR, Sun C, Hill EA, Ziller JW, Borovik AS. Regulating the Basicity of Metal-Oxido Complexes with a Single Hydrogen Bond and Its Effect on C-H Bond Cleavage. J Am Chem Soc 2019; 141:11142-11150. [PMID: 31274298 DOI: 10.1021/jacs.9b03688] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The functionalization of C-H bonds is an essential reaction in biology and chemistry. Metalloenzymes that often exhibit this type of reactivity contain metal-oxido intermediates that are directly involved in the initial cleavage of the C-H bonds. Regulation of the cleavage process is achieved, in part, by hydrogen bonds that are proximal to the metal-oxido units, yet our understanding of their exact role(s) is still emerging. To gain further information into the role of H-bonds on C-H bond activation, a hybrid set of urea-containing tripodal ligands has been developed in which a single H-bond can be adjusted through changes in the properties of one ureayl N-H bond. This modularity is achieved by appending a phenyl ring with different para-substituents from one ureayl NH group. The ligands have been used to prepare a series of MnIII-oxido complexes, and a Hammett correlation was found between the pKa values of the complexes and the substituents on the phenyl ring that was explained within the context of changes to the H-bonds involving the MnIII-oxido unit. The complexes were tested for their reactivity toward 9,10-dihydroanthracene (DHA), and a Hammett correlation was found between the second-order rate constants for the reactions and the pKa values. Studies to determine activation parameters and the kinetic isotope effects are consistent with a mechanism in which rate-limiting proton transfer is an important contributor. However, additional reactivity studies with xanthene found a significant increase in the rate constant compared to DHA, even though the substrates have the same pKa(C-H) values. These results do not support a discrete proton-transfer/electron-transfer process, but rather an asynchronous mechanism in which the proton and electron are transferred unequally at the transition state.
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Affiliation(s)
- Suman K Barman
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , United States
| | - Jason R Jones
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , United States
| | - Chen Sun
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , United States
| | - Ethan A Hill
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , United States
| | - Joseph W Ziller
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , United States
| | - A S Borovik
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , United States
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93
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Ricciarelli D, Phung QM, Belpassi L, Harvey JN, Belanzoni P. Understanding the Reactivity of Mn-Oxo Porphyrins for Substrate Hydroxylation: Theoretical Predictions and Experimental Evidence Reconciled. Inorg Chem 2019; 58:7345-7356. [PMID: 31117625 DOI: 10.1021/acs.inorgchem.9b00476] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Mn-oxo porphyrin (MnOP) mechanism for substrate hydroxylation is computationally studied with the aim to better understand reactivity in these systems. Theoretical studies suggest Mn(V)OP species to be very reactive intermediates with thermally accessible reaction barriers represented by low-spin/high-spin-crossover occurring in the Mn(V)OP oxidant, and kinetics for selected Mn(V)OP species indeed find high reactivity. On the other hand, MnOP complexes lead to modest yields in hydroxylation reactions of several different substrates, implying low rate constants and high reaction barriers. The resolution of this inconsistency is very important to understand the reactivity of Mn-oxo porphyrins and to improve the catalytic conditions. In this work we use the toluene hydroxylation by the Mn(V)OP(H2O)+ complex as a case study to gain deep insight into the reaction mechanism. Minimum energy crossing point (MECP) results on the H-abstraction process from toluene indicate a first crossover from a singlet to a triplet spin state of the Mn(V)OP(H2O)+ species with a thermally accessible barrier, followed by a very facile H-abstraction by the triplet complex. Issues concerning (i) the validation of the level of the density functional theory employed (BP86) to describe the singlet-triplet energy gap in the Mn(V)OP(H2O)+ system versus highly accurate DMRG-CASPT2/CC calculations, and (ii) the influence of the axial ligand (X = none, Cl-, CH3CN, OH-, and O2-) on MnOP reactivity, which models the different experimental conditions, are addressed. The ligand trans influence mainly controls the reactivity through the singlet-triplet energy gap modulation, with the porphyrin ruffling distortion also finely tuning it. Finally, a stepwise model for the H-abstraction process is proposed which allows a direct comparison between the calculated and experimentally measured Gibbs free activation energy barriers ( Zhang et al. J. Am. Chem. Soc. 2005 , 127 , 6573 - 6582 ). The low yields in catalysis are shown not to be due to low reactivity of Mn(V).
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Affiliation(s)
| | - Quan Manh Phung
- Department of Chemistry , KU Leuven , Celestijnenlaan 200F , B-3001 Leuven , Belgium.,Institute of Transformative Bio-Molecules (WPI-ITbM) , Nagoya University , Chikusa , Nagoya 464-8602 , Japan
| | - Leonardo Belpassi
- Consortium for Computational Molecular and Materials Sciences (CMS)2 , via Elce di Sotto 8 , 06123 Perugia , Italy
| | - Jeremy N Harvey
- Department of Chemistry , KU Leuven , Celestijnenlaan 200F , B-3001 Leuven , Belgium
| | - Paola Belanzoni
- Consortium for Computational Molecular and Materials Sciences (CMS)2 , via Elce di Sotto 8 , 06123 Perugia , Italy
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94
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Rajpurohit J, Shukla P, Kumar P, Das C, Vaidya S, Sundararajan M, Shanmugam M, Shanmugam M. Stabilizing Terminal Ni(III)-Hydroxide Complex Using NNN-Pincer Ligands: Synthesis and Characterization. Inorg Chem 2019; 58:6257-6267. [PMID: 31009214 DOI: 10.1021/acs.inorgchem.9b00466] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reaction of [Ni(COD)2] (COD; cyclooctadiene) in THF with the NNN-pincer ligand bis(imino)pyridyl (L1) reveals a susceptibility to oxidation in an inert atmosphere ([O2] level <0.5 ppm), resulting in a transient Ni:dioxygen adduct. This reactive intermediate abstracts a hydrogen atom from THF and stabilizes an uncommon Ni(III) complex. The complex is crystallographically characterized by a molecular formula of [NiIII(L1··)2-(OH)] (1). Various isotopically labeled experiments (16O/18O) assertively endorse the origin of terminal oxygen based ligand in 1 due to the activation of molecular dioxygen. The presence of proton bound to the terminal oxygen in 1 is well supported by NMR, IR spectroscopy, DFT calculations, and hydrogen atom transfer (HAT) reactions promoted by 1. The observation of shakeup satellite peaks for the primary photoelectron lines of Ni(2p) in the X-ray photoelectron spectroscopy (XPS) unambiguously confirms the paramagnetic signature associated with the distorted square planar nickel ion, which is consistent with the trivalent oxidation state assigned for the nickel ion in 1. The variable temperature magnetic susceptibility data of 1 shows dominant antiferromagnetic interactions exist among the paramagnetic centers, resulting in an overall S = 1/2 ground state. Variable temperature X-band EPR studies performed on 1 show evidence for the S = 1/2 ground state, which is consistent with magnetic data. The unusual g-tensor extracted for the ground state S = 1/2 is analyzed under a strong exchange limit of spin-coupled centers. The electronic structure predicted for 1 is in good agreement with theoretical calculations.
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Affiliation(s)
- Jitendrasingh Rajpurohit
- Department of Chemistry , Indian Institute of Technology Bombay , Powai - 400076 , Mumbai , Maharashtra , India
| | - Pragya Shukla
- Department of Chemistry , Indian Institute of Technology Bombay , Powai - 400076 , Mumbai , Maharashtra , India
| | - Pardeep Kumar
- Department of Chemistry , Indian Institute of Technology Bombay , Powai - 400076 , Mumbai , Maharashtra , India
| | - Chinmoy Das
- Department of Chemistry , Indian Institute of Technology Bombay , Powai - 400076 , Mumbai , Maharashtra , India
| | - Shefali Vaidya
- Department of Chemistry , Indian Institute of Technology Bombay , Powai - 400076 , Mumbai , Maharashtra , India
| | - Mahesh Sundararajan
- Theoretical Chemistry Section , Bhabha Atomic Research Centre , Mumbai - 400 085 , India
| | - Muralidharan Shanmugam
- Manchester Institute of Biotechnology , The University of Manchester , 131 Princes Street , Manchester - M1 7DN , U.K
| | - Maheswaran Shanmugam
- Department of Chemistry , Indian Institute of Technology Bombay , Powai - 400076 , Mumbai , Maharashtra , India
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95
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Chevallot-Beroux E, Ako AM, Schmitt W, Twamley B, Moran J, Corinne B, Ruhlmann L, Mameri S. Synthesis of new Mn 19 analogues and their structural, electrochemical and catalytic properties. Dalton Trans 2019; 48:4830-4836. [PMID: 30778455 DOI: 10.1039/c8dt04807j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the synthesis and structural characterisation of new Mn19 and Mn18M analogues, [MnIII12MnII7(μ4-O)8(μ3-OCH3)2(μ3-Br)6(HLMe)12(MeOH)6]Br2 (2) and [MnIII12MnII6Sr(μ4-O8(μ3-Cl)8(HLMe)12(MeCN)6]Cl2 cluster (3), where H3LMe is 2,6-bis(hydroxymethyl)-p-cresol. The electrochemistry of 2 and 3 has been investigated and their activity as catalysts in the oxidation of benzyl alcohol has been evaluated. Selective oxidation of benzyl alcohol to benzaldehyde by O2 was achieved using 1 mol% of catalyst with conversions of 74% (2) and 60% (3) at 140 °C using TEMPO as a co-catalyst. No partial conversion of benzaldehyde to benzoic acid was observed. The results obtained revealed that different operative parameters - such as catalyst loading, temperature, time, solvent and the presence of molecular oxygen - played an important role in the selective oxidation of benzyl alcohol.
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Affiliation(s)
- Elodie Chevallot-Beroux
- Laboratory of Chemical Catalysis, University of Strasbourg, ISIS UMR 7006, 8 allée Gaspard Monge, Strasbourg 67083, France
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96
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Photochemical nitrogenation of alkanes and arenes by a strongly luminescent osmium(VI) nitrido complex. Commun Chem 2019. [DOI: 10.1038/s42004-019-0142-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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97
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McManus C, Mondal P, Lovisari M, Twamley B, McDonald AR. Carboxamidate Ligand Noninnocence in Proton Coupled Electron Transfer. Inorg Chem 2019; 58:4515-4523. [PMID: 30864788 DOI: 10.1021/acs.inorgchem.9b00055] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Caitilín McManus
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Prasenjit Mondal
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Marta Lovisari
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Brendan Twamley
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Aidan R. McDonald
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
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98
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Kadassery KJ, Sethi K, Fanara PM, Lacy DC. CO-Photolysis-Induced H-Atom Transfer from MnIO–H Bonds. Inorg Chem 2019; 58:4679-4685. [DOI: 10.1021/acs.inorgchem.9b00322] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Karthika J. Kadassery
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - Komal Sethi
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - Paul M. Fanara
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - David C. Lacy
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
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99
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Liu Y, Lau TC. Activation of Metal Oxo and Nitrido Complexes by Lewis Acids. J Am Chem Soc 2019; 141:3755-3766. [DOI: 10.1021/jacs.8b13100] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Yingying Liu
- Department of Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong 999077, China
| | - Tai-Chu Lau
- Department of Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong 999077, China
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100
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Iron(III)–salen ion catalyzed s-oxidation of l-cysteine and s-alkyl-l-cysteines by H2O2: Spectral, kinetic and electrochemical study. Polyhedron 2019. [DOI: 10.1016/j.poly.2018.11.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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