1
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Chan SC, Palone A, Bietti M, Costas M. tert-Butyl as a Functional Group: Non-Directed Catalytic Hydroxylation of Sterically Congested Primary C-H Bonds. Angew Chem Int Ed Engl 2024; 63:e202402858. [PMID: 38688859 DOI: 10.1002/anie.202402858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/29/2024] [Accepted: 04/30/2024] [Indexed: 05/02/2024]
Abstract
The tert-butyl group is a common aliphatic motif extensively employed to implement steric congestion and conformational rigidity in organic and organometallic molecules. Because of the combination of a high bond dissociation energy (~100 kcal mol-1) and limited accessibility, in the absence of directing groups, neither radical nor organometallic approaches are effective for the chemical modification of tert-butyl C-H bonds. Herein we overcome these limits by employing a highly electrophilic manganese catalyst, [Mn(CF3bpeb)(OTf)2], that operates in the strong hydrogen bond donor solvent nonafluoro-tert-butyl alcohol (NFTBA) and catalytically activates hydrogen peroxide to generate a powerful manganese-oxo species that effectively oxidizes tert-butyl C-H bonds. Leveraging on the interplay of steric, electronic, medium and torsional effects, site-selective and product chemoselective hydroxylation of the tert-butyl group is accomplished with broad reaction scope, delivering primary alcohols as largely dominant products in preparative yields. Late-stage hydroxylation at tert-butyl sites is demonstrated on 6 densely functionalized molecules of pharmaceutical interest. This work uncovers a novel disconnection approach, harnessing tert-butyl as a potential functional group in strategic synthetic planning for complex molecular architectures.
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Affiliation(s)
- Siu-Chung Chan
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus Montilivi, Girona, E-17071, Catalonia, Spain
| | - Andrea Palone
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus Montilivi, Girona, E-17071, Catalonia, Spain
| | - Massimo Bietti
- Dipartimento di Scienze e Tecnologie Chimiche, Università "Tor Vergata"; Via della Ricerca Scientifica, 1, I-00133, Rome, Italy
| | - Miquel Costas
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, Campus Montilivi, Girona, E-17071, Catalonia, Spain
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2
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Ćorović M, Milinkovic A, Stix N, Dupé A, Mösch-Zanetti NC. Nucleophiles Target the Tungsten Center Over Acetylene in Biomimetic Models. Inorg Chem 2024; 63:11953-11962. [PMID: 38877603 PMCID: PMC11220757 DOI: 10.1021/acs.inorgchem.4c00286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 05/23/2024] [Accepted: 06/10/2024] [Indexed: 06/16/2024]
Abstract
Inspired by the first shell mechanism proposed for the tungstoenzyme acetylene hydratase, the electrophilic reactivity of tungsten-acetylene complexes [W(CO)(C2H2)(6-MePyS)2] (1) and [WO(C2H2)(6-MePyS)2] (2) was investigated. The biological nucleophile water/hydroxide and tert-butyl isocyanide were employed. Our findings consistently show that, regardless of the nucleophile used, both tungsten centers W(II) and W(IV), respectively, are the preferred targets over the coordinated acetylene. Treatment of 2 with aqueous NaOH led to protonation of coordinated acetylene to ethylene, pointing toward the Brønsted basic character of the coordinated alkyne instead of the anticipated electrophilic behavior. In cases involving isocyanides as nucleophiles, the attack on the W(II) center of 1 took place first, whereas the W(IV) complex 2 remained unchanged. These experiments indicate that the direct nucleophilic attack of W-coordinated acetylene by water, as some computational studies of acetylene hydratase propose, is unlikely to occur.
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Affiliation(s)
- Miljan
Z. Ćorović
- Institute of Chemistry, Inorganic
Chemistry, University of Graz, 8010 Graz, Austria
| | - Angela Milinkovic
- Institute of Chemistry, Inorganic
Chemistry, University of Graz, 8010 Graz, Austria
| | - Niklas Stix
- Institute of Chemistry, Inorganic
Chemistry, University of Graz, 8010 Graz, Austria
| | - Antoine Dupé
- Institute of Chemistry, Inorganic
Chemistry, University of Graz, 8010 Graz, Austria
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3
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Malik DD, Ryu W, Kim Y, Singh G, Kim JH, Sankaralingam M, Lee YM, Seo MS, Sundararajan M, Ocampo D, Roemelt M, Park K, Kim SH, Baik MH, Shearer J, Ray K, Fukuzumi S, Nam W. Identification, Characterization, and Electronic Structures of Interconvertible Cobalt-Oxygen TAML Intermediates. J Am Chem Soc 2024; 146:13817-13835. [PMID: 38716885 PMCID: PMC11216523 DOI: 10.1021/jacs.3c14346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2024]
Abstract
The reaction of Li[(TAML)CoIII]·3H2O (TAML = tetraamido macrocyclic tetraanionic ligand) with iodosylbenzene at 253 K in acetone in the presence of redox-innocent metal ions (Sc(OTf)3 and Y(OTf)3) or triflic acid affords a blue species 1, which is converted reversibly to a green species 2 upon cooling to 193 K. The electronic structures of 1 and 2 have been determined by combining advanced spectroscopic techniques (X-band electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR), X-ray absorption spectroscopy/extended X-ray absorption fine structure (XAS/EXAFS), and magnetic circular dichroism (MCD)) with ab initio theoretical studies. Complex 1 is best represented as an S = 1/2 [(Sol)(TAML•+)CoIII---OH(LA)]- species (LA = Lewis/Brønsted acid and Sol = solvent), where an S = 1 Co(III) center is antiferromagnetically coupled to S = 1/2 TAML•+, which represents a one-electron oxidized TAML ligand. In contrast, complex 2, also with an S = 1/2 ground state, is found to be multiconfigurational with contributions of both the resonance forms [(H-TAML)CoIV═O(LA)]- and [(H-TAML•+)CoIII═O(LA)]-; H-TAML and H-TAML•+ represent the protonated forms of TAML and TAML•+ ligands, respectively. Thus, the interconversion of 1 and 2 is associated with a LA-associated tautomerization event, whereby H+ shifts from the terminal -OH group to TAML•+ with the concomitant formation of a terminal cobalt-oxo species possessing both singlet (SCo = 0) Co(III) and doublet (SCo = 1/2) Co(IV) characters. The reactivities of 1 and 2 at different temperatures have been investigated in oxygen atom transfer (OAT) and hydrogen atom transfer (HAT) reactions to compare the activation enthalpies and entropies of 1 and 2.
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Affiliation(s)
- Deesha D Malik
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Wooyeol Ryu
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Yujeong Kim
- Western Seoul Center, Korea Basic Science Institute, Seoul 03759, Korea
| | - Gurjot Singh
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Jun-Hyeong Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science, Daejeon 34141, Korea
| | | | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Mi Sook Seo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Mahesh Sundararajan
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science, Daejeon 34141, Korea
- Theoretical Chemistry Section, Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Daniel Ocampo
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
| | - Michael Roemelt
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Kiyoung Park
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Sun Hee Kim
- Western Seoul Center, Korea Basic Science Institute, Seoul 03759, Korea
- Department of Chemistry, Chung-Ang University, Seoul 06974, Korea
| | - Mu-Hyun Baik
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science, Daejeon 34141, Korea
| | - Jason Shearer
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
| | - Kallol Ray
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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4
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Shoji Y, Terashima Y, Ohkubo K, Ito H, Maruyama K, Fukuzumi S, Nakanishi I. Scandium Ion-Promoted Electron-Transfer Disproportionation of 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-Oxide (PTIO •) in Acetonitrile and Its Regeneration Induced by Water. Int J Mol Sci 2024; 25:4417. [PMID: 38674002 PMCID: PMC11050215 DOI: 10.3390/ijms25084417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 04/09/2024] [Accepted: 04/16/2024] [Indexed: 04/28/2024] Open
Abstract
2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO•), a persistent nitronyl nitroxide radical, has been used for the detection and trapping of nitric oxide, as a redox mediator for batteries, for the activity estimation of antioxidants, and so on. However, there is no report on the reactivity of PTIO• in the presence of redox-inactive metal ions. In this study, it is demonstrated that the addition of scandium triflate, Sc(OTf)3 (OTf = OSO2CF3), to an acetonitrile (MeCN) solution of PTIO• resulted in an electron-transfer disproportionation to generate the corresponding cation (PTIO+) and anion (PTIO-), the latter of which is suggested to be stabilized by Sc3+ to form [(PTIO)Sc]2+. The decay of the absorption band at 361 nm due to PTIO•, monitored using a stopped-flow technique, obeyed second-order kinetics. The second-order rate constant for the disproportionation, thus determined, increased with increasing the Sc(OTf)3 concentration to reach a constant value. A drastic change in the cyclic voltammogram recorded for PTIO• in deaerated MeCN containing 0.10 M Bu4NClO4 was also observed upon addition of Sc(OTf)3, suggesting that the large positive shift of the one-electron reduction potential of PTIO• (equivalent to the one-electron oxidation potential of PTIO-) in the presence of Sc(OTf)3 may result in the disproportionation. When H2O was added to the PTIO•-Sc(OTf)3 system in deaerated MeCN, PTIO• was completely regenerated. It is suggested that the complex formation of Sc3+ with H2O may weaken the interaction between PTIO- and Sc3+, leading to electron-transfer comproportionation to regenerate PTIO•. The reversible disproportionation of PTIO• was also confirmed by electron paramagnetic resonance (EPR) spectroscopy.
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Grants
- JP18K06620 Ministry of Education, Culture, Sports, Science and Technology
- JP20H02779 Ministry of Education, Culture, Sports, Science and Technology
- JP20H04819 Ministry of Education, Culture, Sports, Science and Technology
- JP18H04650 Ministry of Education, Culture, Sports, Science and Technology
- JP17H03010 Ministry of Education, Culture, Sports, Science and Technology
- JP16H02268 Ministry of Education, Culture, Sports, Science and Technology
- JP23K04686 Ministry of Education, Culture, Sports, Science and Technology
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Affiliation(s)
- Yoshimi Shoji
- Quantum RedOx Chemistry Team, Institute for Quantum Life Science (iQLS), Quantum Life and Medical Science Directorate (QLMS), National Institutes for Quantum Science and Technology (QST), Chiba-shi 263-8555, Chiba, Japan; (Y.S.); (H.I.)
| | - Yuri Terashima
- Environmental Radiation Effects Research Group, Department of Radiation Measurement and Dose Assessment, Institute for Radiological Science (NIRS), Quantum Life and Medical Science Directorate (QLMS), National Institutes for Quantum Science and Technology (QST), Chiba-shi 263-8555, Chiba, Japan; (Y.T.); (K.M.)
| | - Kei Ohkubo
- Institute for Advanced Co-Creation Studies, Open and Transdisciplinary Research Initiatives, Osaka University, Suita 565-0871, Osaka, Japan;
| | - Hiromu Ito
- Quantum RedOx Chemistry Team, Institute for Quantum Life Science (iQLS), Quantum Life and Medical Science Directorate (QLMS), National Institutes for Quantum Science and Technology (QST), Chiba-shi 263-8555, Chiba, Japan; (Y.S.); (H.I.)
| | - Kouichi Maruyama
- Environmental Radiation Effects Research Group, Department of Radiation Measurement and Dose Assessment, Institute for Radiological Science (NIRS), Quantum Life and Medical Science Directorate (QLMS), National Institutes for Quantum Science and Technology (QST), Chiba-shi 263-8555, Chiba, Japan; (Y.T.); (K.M.)
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Republic of Korea;
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Ibaraki, Japan
| | - Ikuo Nakanishi
- Quantum RedOx Chemistry Team, Institute for Quantum Life Science (iQLS), Quantum Life and Medical Science Directorate (QLMS), National Institutes for Quantum Science and Technology (QST), Chiba-shi 263-8555, Chiba, Japan; (Y.S.); (H.I.)
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5
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Buil ML, Esteruelas MA, Oñate E, Picazo NR. Unequivocal Characterization of an Osmium Complex with a Terminal Sulfide Ligand and Its Transformation into Hydrosulfide and Methylsulfide. Inorg Chem 2024; 63:5779-5782. [PMID: 38488723 DOI: 10.1021/acs.inorgchem.4c00596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Deprotonation of the thioamidate group of [OsH{κ2-N,S-[NHC(CH3)S]}(≡CPh)(IPr)(PiPr3)]OTf [1; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolylidene; OTf = CF3SO3] results in the release of acetonitrile and formation of the terminal sulfide complex OsH(S)(≡CPh)(IPr)(PiPr3) (2), which has been transformed into the hydrosulfide [OsH(SH)(≡CPh)(IPr)(PiPr3)]OTf (3) and the methylsulfide [OsH(SMe)(≡CPh)(IPr)(PiPr3)]OTf (4) through protonation and methylation reactions, respectively. The structure, spectroscopic characteristics, and reactivity of these compounds are compared. Reactions of 3 and 4 with 2-hydroxypyridine and 2-mercaptopyridine afford [OsH{κ2-X,N-[X-py]}(≡CPh)(IPr)(PiPr3)]OTf [X = O (5), S(6)].
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Affiliation(s)
- María L Buil
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, Centro de Innovación en Química Avanzada, Universidad de Zaragoza-CSIC, Zaragoza 50009, Spain
| | - Miguel A Esteruelas
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, Centro de Innovación en Química Avanzada, Universidad de Zaragoza-CSIC, Zaragoza 50009, Spain
| | - Enrique Oñate
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, Centro de Innovación en Química Avanzada, Universidad de Zaragoza-CSIC, Zaragoza 50009, Spain
| | - Nieves R Picazo
- Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, Centro de Innovación en Química Avanzada, Universidad de Zaragoza-CSIC, Zaragoza 50009, Spain
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6
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Lionetti D, Suseno S, Shiau AA, de Ruiter G, Agapie T. Redox Processes Involving Oxygen: The Surprising Influence of Redox-Inactive Lewis Acids. JACS AU 2024; 4:344-368. [PMID: 38425928 PMCID: PMC10900226 DOI: 10.1021/jacsau.3c00675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 03/02/2024]
Abstract
Metalloenzymes with heteromultimetallic active sites perform chemical reactions that control several biogeochemical cycles. Transformations catalyzed by such enzymes include dioxygen generation and reduction, dinitrogen reduction, and carbon dioxide reduction-instrumental transformations for progress in the context of artificial photosynthesis and sustainable fertilizer production. While the roles of the respective metals are of interest in all these enzymatic transformations, they share a common factor in the transfer of one or multiple redox equivalents. In light of this feature, it is surprising to find that incorporation of redox-inactive metals into the active site of such an enzyme is critical to its function. To illustrate, the presence of a redox-inactive Ca2+ center is crucial in the Oxygen Evolving Complex, and yet particularly intriguing given that the transformation catalyzed by this cluster is a redox process involving four electrons. Therefore, the effects of redox inactive metals on redox processes-electron transfer, oxygen- and hydrogen-atom transfer, and O-O bond cleavage and formation reactions-mediated by transition metals have been studied extensively. Significant effects of redox inactive metals have been observed on these redox transformations; linear free energy correlations between Lewis acidity and the redox properties of synthetic model complexes are observed for several reactions. In this Perspective, these effects and their relevance to multielectron processes will be discussed.
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Affiliation(s)
| | - Sandy Suseno
- Division of Chemistry and
Chemical Engineering, California Institute
of Technology, 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
| | - Angela A. Shiau
- Division of Chemistry and
Chemical Engineering, California Institute
of Technology, 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
| | - Graham de Ruiter
- Division of Chemistry and
Chemical Engineering, California Institute
of Technology, 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
| | - Theodor Agapie
- Division of Chemistry and
Chemical Engineering, California Institute
of Technology, 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
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7
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Wang R, Pan Y, Feng S, Liang C, Xie J, Lau TC, Liu Y. Structure and reactivity of a seven-coordinate ruthenium acylperoxo complex. Chem Commun (Camb) 2024; 60:312-315. [PMID: 38063010 DOI: 10.1039/d3cc04751b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
The use of metal-acylperoxo complexes as oxidants has been little explored. Herein we report the synthesis and characterization of the first seven-coordinate Ru-acylperoxo complex, [RuIV(bdpm)(pic)2(mCPBA)]+ (H2bdpm = [2,2'-bipyridine]-6,6'-diylbis(diphenylmethanol); pic = 4-picoline; HmCPBA = m-chloroperbenzoic acid). This complex is a highly reactive oxidant for C-H bond activation and O-atom transfer reactions.
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Affiliation(s)
- Rui Wang
- Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, P. R. China.
- Science Island Branch, Graduate School of USTC, Hefei 230026, P. R. China
| | - Yunling Pan
- Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, P. R. China.
- Anhui Province Key Laboratory of Advanced Catalytic Materials and Reaction Engineering, School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009, P. R. China
| | - Sushan Feng
- Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, P. R. China.
- Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, P. R. China
| | - Chenyi Liang
- Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, P. R. China.
- Science Island Branch, Graduate School of USTC, Hefei 230026, P. R. China
| | - Jianhui Xie
- Anhui Province Key Laboratory of Advanced Catalytic Materials and Reaction Engineering, School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009, P. R. China
| | - Tai-Chu Lau
- Department of Chemistry, City University of Hong Kong, Kowloon Tong, Hong Kong, P. R. China
| | - Yingying Liu
- Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, P. R. China.
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8
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Yang J, Tripodi GL, Derks MTGM, Seo MS, Lee YM, Southwell KW, Shearer J, Roithová J, Nam W. Generation, Spectroscopic Characterization, and Computational Analysis of a Six-Coordinate Cobalt(III)-Imidyl Complex with an Unusual S = 3/2 Ground State that Promotes N-Group and Hydrogen Atom-Transfer Reactions with Exogenous Substrates. J Am Chem Soc 2023; 145:26106-26121. [PMID: 37997643 PMCID: PMC11175169 DOI: 10.1021/jacs.3c08117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
We report the synthesis and characterization of a mononuclear nonheme cobalt(III)-imidyl complex, [Co(NTs)(TQA)(OTf)]+ (1), with an S = 3/2 spin state that is capable of facilitating exogenous substrate modifications. Complex 1 was generated from the reaction of CoII(TQA)(OTf)2 with PhINTs at -20 °C. A flow setup with ESI-MS detection was used to explore the kinetics of the formation, stability, and degradation pathway of 1 in solution by treating the Co(II) precursor with PhINTs. Co K-edge XAS data revealed a distinct shift in the Co K-edge compared to the Co(II) precursor, in agreement with the formation of a Co(III) intermediate. The unusual S = 3/2 spin state was proposed based on EPR, DFT, and CASSCF calculations and Co Kβ XES results. Co K-edge XAS and IR photodissociation (IRPD) spectroscopies demonstrate that 1 is a six-coordinate species, and IRPD and resonance Raman spectroscopies are consistent with 1 being exclusively the isomer with the NT ligand occupying the vacant site trans to the TQA aliphatic amine nitrogen atom. Electronic structure calculations (broken symmetry DFT and CASSCF/NEVPT2) demonstrate an S = 3/2 oxidation state resulting from the strong antiferromagnetic coupling of an •NTs spin to the high-spin S = 2 Co(III) center. Reactivity studies of 1 with PPh3 derivatives revealed its electrophilic characteristic in the nitrene-transfer reaction. While the activation of C-H bonds by 1 was proved to be kinetically challenging, 1 could oxidize weak O-H and N-H bonds. Complex 1 is, therefore, a rare example of a Co(III)-imidyl complex capable of exogenous substrate transformations.
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Affiliation(s)
- Jindou Yang
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Guilherme L. Tripodi
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Max T. G. M. Derks
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Mi Sook Seo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Kendal W. Southwell
- Department of Chemistry, Trinity University, San Antonio, Texas 78212, United States
| | - Jason Shearer
- Department of Chemistry, Trinity University, San Antonio, Texas 78212, United States
| | - Jana Roithová
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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9
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Lv H, Zhang XP, Guo K, Han J, Guo H, Lei H, Li X, Zhang W, Apfel UP, Cao R. Coordination Tuning of Metal Porphyrins for Improved Oxygen Evolution Reaction. Angew Chem Int Ed Engl 2023; 62:e202305938. [PMID: 37550259 DOI: 10.1002/anie.202305938] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 08/06/2023] [Accepted: 08/07/2023] [Indexed: 08/09/2023]
Abstract
The nucleophilic attack of water or hydroxide on metal-oxo units forms an O-O bond in the oxygen evolution reaction (OER). Coordination tuning to improve this attack is intriguing but has been rarely realized. We herein report on improved OER catalysis by metal porphyrin 1-M (M=Co, Fe) with a coordinatively unsaturated metal ion. We designed and synthesized 1-M by sterically blocking one porphyrin side with a tethered tetraazacyclododecane unit. With this protection, the metal-oxo species generated in OER can maintain an unoccupied trans axial site. Importantly, 1-M displays a higher OER activity in alkaline solutions than analogues lacking such an axial protection by decreasing up to 150-mV overpotential to achieve 10 mA/cm2 current density. Theoretical studies suggest that with an unoccupied trans axial site, the metal-oxo unit becomes more positively charged and thus is more favoured for the hydroxide nucleophilic attack as compared to metal-oxo units bearing trans axial ligands.
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Affiliation(s)
- Haoyuan Lv
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Xue-Peng Zhang
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Kai Guo
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Jinxiu Han
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Hongbo Guo
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Haitao Lei
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Xialiang Li
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Wei Zhang
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
| | - Ulf-Peter Apfel
- Ruhr-Universität Bochum, Fakultät für Chemie und Biochemie, Anorganische Chemie I, Universitätsstrasse 150, 44801, Bochum, Germany
- Fraunhofer UMSICHT, Osterfelder Strasse 3, 46047, Oberhausen, Germany
| | - Rui Cao
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 710119, Xi'an, China
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10
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Pan Y, Zhou M, Wang R, Song D, Yiu SM, Xie J, Lau KC, Lau TC, Liu Y. Structure and Reactivity of a Seven-Coordinate Ruthenium Iodosylbenzene Complex. Inorg Chem 2023; 62:7772-7778. [PMID: 37146252 DOI: 10.1021/acs.inorgchem.3c00417] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Seven-coordinate (CN7) ruthenium-oxo species have attracted much attention as highly reactive intermediates in both organic and water oxidation. Apart from metal-oxo, other metal-oxidant adducts, such as metal-iodosylarenes, have also recently emerged as active oxidants. We reported herein the first example of a CN7 Ru-iodosylbenzene complex, [RuIV(bdpm)(pic)2(O)I(Cl)Ph]+ (H2bdpm = [2,2'-bipyridine]-6,6'-diylbis(diphenylmethanol); pic = 4-picoline). The X-ray crystal structure of this complex shows that it adopts a distorted pentagonal bipyramidal geometry with Ru-O(I) and O-I distances of 2.0451(39) and 1.9946(40) Å, respectively. This complex is highly reactive, and it readily undergoes O-atom transfer (OAT) and C-H bond activation reactions with various organic substrates. This work should provide insights for the development of new highly reactive oxidizing agents based on CN7 geometry.
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Affiliation(s)
- Yunling Pan
- Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, P. R. China
- Anhui Province Key Laboratory of Advanced Catalytic Materials and Reaction Engineering, School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009, P. R. China
| | - Miaomiao Zhou
- Department of Chemistry, City University of Hong Kong, Kowloon Tong 999077, Hong Kong, P. R. China
| | - Rui Wang
- Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, P. R. China
| | - Dan Song
- Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, P. R. China
- Anhui Province Key Laboratory of Advanced Catalytic Materials and Reaction Engineering, School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009, P. R. China
| | - Shek-Man Yiu
- Department of Chemistry, City University of Hong Kong, Kowloon Tong 999077, Hong Kong, P. R. China
| | - Jianhui Xie
- Anhui Province Key Laboratory of Advanced Catalytic Materials and Reaction Engineering, School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009, P. R. China
| | - Kai-Chung Lau
- Department of Chemistry, City University of Hong Kong, Kowloon Tong 999077, Hong Kong, P. R. China
| | - Tai-Chu Lau
- Department of Chemistry, City University of Hong Kong, Kowloon Tong 999077, Hong Kong, P. R. China
- Research Center for Eco-environmental Engineering, Dongguan University of Technology, Dongguan 523808, P. R. China
| | - Yingying Liu
- Institute of Intelligent Machines, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, P. R. China
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11
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Hong YH, Lee YM, Nam W, Fukuzumi S. Reaction Intermediates in Artificial Photosynthesis with Molecular Catalysts. ACS Catal 2022. [DOI: 10.1021/acscatal.2c05033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Young Hyun Hong
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul03760, Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul03760, Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul03760, Korea
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul03760, Korea
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12
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Zhang J, Lee YM, Seo MS, Nilajakar M, Fukuzumi S, Nam W. A Contrasting Effect of Acid in Electron Transfer, Oxygen Atom Transfer, and Hydrogen Atom Transfer Reactions of a Nickel(III) Complex. Inorg Chem 2022; 61:19735-19747. [PMID: 36445726 DOI: 10.1021/acs.inorgchem.2c02504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
There have been many examples of the accelerating effects of acids in electron transfer (ET), oxygen atom transfer (OAT), and hydrogen atom transfer (HAT) reactions. Herein, we report a contrasting effect of acids in the ET, OAT, and HAT reactions of a nickel(III) complex, [NiIII(PaPy3*)]2+ (1) in acetone/CH3CN (v/v 19:1). 1 was synthesized by reacting [NiII(PaPy3*)]+ (2) with magic blue or iodosylbenzene in the absence or presence of triflic acid (HOTf), respectively. Sulfoxidation of thioanisole by 1 and H2O occurred in the presence of HOTf, and the reaction rate increased proportionally with increasing concentration of HOTf ([HOTf]). The rate of ET from diacetylferrocene to 1 also increased linearly with increasing [HOTf]. In contrast, HAT from 9,10-dihydroanthracene (DHA) to 1 slowed down with increasing [HOTf], exhibiting an inversely proportional relation to [HOTf]. The accelerating effect of HOTf in the ET and OAT reactions was ascribed to the binding of H+ to the PaPy3* ligand of 2; the one-electron reduction potential (Ered) of 1 was positively shifted with increasing [HOTf]. Such a positive shift in the Ered value resulted in accelerating the ET and OAT reactions that proceeded via the rate-determining ET step. On the other hand, the decelerating effect of HOTf on HAT from DHA to 1 resulted from the inhibition of proton transfer from DHA•+ to 2 due to the binding of H+ to the PaPy3* ligand of 2. The ET reactions of 1 in the absence and presence of HOTf were well analyzed in light of the Marcus theory of ET in comparison with the HAT reactions.
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Affiliation(s)
- Jisheng Zhang
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Mi Sook Seo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Madhuri Nilajakar
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
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13
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Kaur S, Bera M, Santra A, Munshi S, Sterbinsky GE, Wu T, Moonshiram D, Paria S. Effect of Redox-Inactive Metal Ion-Nickel(III) Interactions on the Redox Properties and Proton-Coupled Electron Transfer Reactivity. Inorg Chem 2022; 61:14252-14266. [PMID: 36041064 DOI: 10.1021/acs.inorgchem.2c01472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mononuclear nickel(II) and nickel(III) complexes of a bisamidate-bisalkoxide ligand, (NMe4)2[NiII(HMPAB)] (1) and (NMe4)[NiIII(HMPAB)] (2), respectively, have been synthesized and characterized by various spectroscopic techniques including X-ray crystallography. The reaction of redox-inactive metal ions (Mn+ = Ca2+, Mg2+, Zn2+, Y3+, and Sc3+) with 2 resulted in 2-Mn+ adducts, which was assessed by an array of spectroscopic techniques including X-ray absorption spectroscopy (XAS), electron paramagnetic resonance (EPR), and reactivity studies. The X-ray structure of Ca2+ coordinated to Ni(III) complexes, 2-Ca2+T, was determined and exhibited an average Ni-Ca distance of 3.1253 Å, close to the metal ions' covalent radius. XAS analysis of 2-Ca2+ and 2-Y3+ in solution further revealed an additional coordination to Ca and Y in the 2-Mn+ adducts with shortened Ni-M distances of 2.15 and 2.11 Å, respectively, implying direct bonding interactions between Ni and Lewis acids (LAs). Such a short interatomic distance between Ni(III) and M is unprecedented and was not observed before. EPR analysis of 2 and 2-Mn+ species, moreover, displayed rhombic signals with gav > 2.12 for all complexes, supporting the +III oxidation state of Ni. The NiIII/NiII redox potential of 2 and 2-Mn+ species was determined, and a plot of E1/2 of 2-Mn+ versus pKa of [M(H2O)n]m+ exhibited a linear relationship, implying that the NiIII/NiII potential of 2 can be tuned with different redox-inactive metal ions. Reactivity studies of 2 and 2-Mn+ with different 4-X-2,6-ditert-butylphenol (4-X-DTBP) and other phenol derivatives were performed, and based on kinetic studies, we propose the involvement of a proton-coupled electron transfer (PCET) pathway. Analysis of the reaction products after the reaction of 2 with 4-OMe-DTBP showed the formation of a Ni(II) complex (1a) where one of the alkoxide arms of the ligand is protonated. A pKa value of 24.2 was estimated for 1a. The reaction of 2-Mn+ species was examined with 4-OMe-DTBP, and it was observed that the k2 values of 2-Mn+ species increase by increasing the Lewis acidity of redox-inactive metal ions. However, the obtained k2 values for 2-Mn+ species are much lower compared to the k2 value for 2. Such a variation of PCET reactivity between 2 and 2-Mn+ species may be attributed to the interactions between Ni(III) and LAs. Our findings show the significance of the secondary coordination sphere effect on the PCET reactivity of Ni(III) complexes and furnish important insights into the reaction mechanism involving high-valent nickel species, which are frequently invoked as key intermediates in Ni-mediated enzymatic reactions, solar-fuel catalysis, and biomimetic/synthetic transformation reactions.
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Affiliation(s)
- Simarjeet Kaur
- 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
| | - Aakash Santra
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Sandip Munshi
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - George E Sterbinsky
- X-ray Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, United States
| | - Tianpin Wu
- X-ray Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, United States
| | - Dooshaye Moonshiram
- Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Sor Juana Inés de la Cruz, 3, Madrid 28049, Spain
| | - Sayantan Paria
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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14
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Effect of Brшnsted Acid on the Reactivity and Selectivity of the Oxoiron(V) Intermediates in C-H and C=C Oxidation Reactions. Catalysts 2022. [DOI: 10.3390/catal12090949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The effect of HClO4 on the reactivity and selectivity of the catalyst systems 1,2/H2O2/AcOH, based on nonheme iron complexes of the PDP families, [(Me2OMePDP)FeIII(μ-OH)2FeIII(MeOMe2PDP)](OTf)4 (1) and [(NMe2PDP)FeIII(μ-OH)2FeIII(NMe2PDP](OTf)4 (2), toward oxidation of benzylideneacetone (bna), adamantane (ada), and (3aR)-(+)-sclareolide (S) has been studied. Adding HClO4 (2–10 equiv. vs. Fe) has been found to result in the simultaneous improvement of the observed catalytic efficiency (i.e., product yields) and the oxidation regio- or enantioselectivity. At the same time, HClO4 causes a threefold increase of the second-order rate constant for the reaction of the key oxygen-transferring intermediate [(Me2OMePDP)FeV=O(OAc)]2+ (1a), with cyclohexane at −70 °C. The effect of strong Brønsted acid on the catalytic reactivity is discussed in terms of the reversible protonation of the Fe=O moiety of the parent perferryl intermediates.
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15
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Teptarakulkarn P, Lorpaiboon W, Anusanti T, Laowiwatkasem N, Chainok K, Sangtrirutnugul P, Surawatanawong P, Chantarojsiri T. Incorporation of Cation Affects the Redox Reactivity of Fe- NNN Complexes on C-H Oxidation. Inorg Chem 2022; 61:11066-11074. [PMID: 35815773 DOI: 10.1021/acs.inorgchem.2c00762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cations such as Lewis acids have been shown to enhance the catalytic activity of high-valent Fe-oxygen intermediates. Herein, we present a pyridine diamine ethylene glycol macrocycle, which can form Zn(II)- or Fe(III)-complex with the NNN site, while allowing redox-inactive cations to bind to the ethylene glycol moiety. The addition of alkali, alkali earth, and lanthanum ions resulted in positive shifts to the Fe(III/II) redox potential. Calculation of dissociation constants showed the tightest binding with a Ba2+ ion. Density functional theory calculations were used to elucidate the effects of redox inactive cations toward the electronic structures of Fe complexes. Although the Fe-NNN complexes, both in the absence and presence of cations, can catalyze C-H oxidation of 9,10-dihydroanthracene, to give anthracene [hydrogen atom transfer (HAT) product], anthrone, and anthraquinone [oxygen atom transfer (OAT) products], highest overall activity and OAT/HAT product ratios were obtained in the presence of dications, that is, Ba2+ and Mg2+, respectively.
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Affiliation(s)
- Pathorn Teptarakulkarn
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Wanutcha Lorpaiboon
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Thana Anusanti
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Natchapol Laowiwatkasem
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Kittipong Chainok
- Thammasat University Research Unit in Multifunctional Crystalline Materials and Applications (TU-MCMA), Faculty of Science and Technology, Thammasat University, Pathum Thani 12121, Thailand
| | - Preeyanuch Sangtrirutnugul
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Panida Surawatanawong
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Teera Chantarojsiri
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
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16
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Zhang J, Lee YM, Seo MS, Fukuzumi S, Nam W. Acid Catalysis in the Oxidation of Substrates by Mononuclear Manganese(III)-Aqua Complexes. Inorg Chem 2022; 61:6594-6603. [PMID: 35442673 DOI: 10.1021/acs.inorgchem.2c00430] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Acids are known to enhance the reactivities of metal-oxygen intermediates, such as metal-oxo, -hydroperoxo, -peroxo, and -superoxo complexes, in biomimetic oxidation reactions. Although metal-aqua (and metal-hydroxo) complexes have been shown to be potent oxidants in oxidation reactions, acid effects on the reactivities of metal-aqua complexes have never been investigated previously. In this study, a mononuclear manganese(III)-aqua complex, [(dpaq5NO2)MnIII(OH2)]2+ (1; dpaq5NO2 = 2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-ylacetamidate with an NO2 substituent at the 5 position), which is relatively stable in the presence of triflic acid (HOTf), is used in the investigation of acid-catalyzed oxidation reactions by metal-aqua complexes. As a result, we report a remarkable acid catalysis in the six-electron oxidation of anthracene by 1 in the presence of HOTf; anthraquinone is formed as the product. In the HOTf-catalyzed six-electron oxidation of anthracene by 1, the rate constant increases linearly with an increase of the HOTf concentration. Combined with the observed one-electron oxidation product, anthracene (derivative) radical cation, and the substitution effect at the 5 position of the dpaq ligand in 1 on the rate constants of the oxidation of anthracene, it is concluded that the oxidation of anthracene occurs via an acid-promoted electron transfer (APET) from anthracene to 1. The dependence of the rate constants of the APET from electron donors, including anthracene derivatives, to 1 on the driving force of electron transfer is also shown to be well fitted by the Marcus equation of outer-sphere electron transfer. To the best of our knowledge, this is the first example showing acid catalysis in the oxidation of substrates by metal(III)-aqua complexes.
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Affiliation(s)
- Jisheng Zhang
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Korea
| | - Yong-Min Lee
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Korea
| | - Mi Sook Seo
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Korea
| | - Shunichi Fukuzumi
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Korea.,Faculty of Science and Engineering, Meijo University, Nagoya, Aichi 468-8502, Japan
| | - Wonwoo Nam
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Korea.,Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China
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17
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Riesgo-Gonzalez V, Bhattacharjee S, Dong X, Hall DS, Andrei V, Bond AD, Grey CP, Reisner E, Wright DS. Single-Source Deposition of Mixed-Metal Oxide Films Containing Zirconium and 3d Transition Metals for (Photo)electrocatalytic Water Oxidation. Inorg Chem 2022; 61:6223-6233. [PMID: 35412823 PMCID: PMC9098167 DOI: 10.1021/acs.inorgchem.2c00403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The fabrication of mixed-metal oxide films holds promise for the development of practical photoelectrochemical catalyst coatings but currently presents challenges in terms of homogeneity, cost, and scalability. We report a straightforward and versatile approach to produce catalytically active zirconium-based films for electrochemical and photoelectrochemical water oxidation. The mixed-metal oxide catalyst films are derived from novel single-source precursor oxide cage compounds containing Zr with first-row transition metals such as Co, Fe, and Cu. The Zr-based film doped with Co on fluorine-doped tin oxide (FTO)-coated glass exhibits the highest electrocatalytic O2 evolution performance in an alkaline medium and an operational stability above 18 h. The deposition of this film onto a BiVO4 photoanode significantly enhances its photoelectrochemical activity toward solar water oxidation, lowering the onset potential by 0.12-0.21 V vs reversible hydrogen electrode (RHE) and improving the maximum photocurrent density by ∼50% to 2.41 mA cm-2 for the CoZr-coated BiVO4 photoanodes compared to that for bare BiVO4.
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Affiliation(s)
- Victor Riesgo-Gonzalez
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.,The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot OX11 0RA, United Kingdom
| | - Subhajit Bhattacharjee
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Xinsheng Dong
- College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, Jiangsu, China
| | - David S Hall
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.,The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot OX11 0RA, United Kingdom
| | - Virgil Andrei
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Andrew D Bond
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Clare P Grey
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.,The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot OX11 0RA, United Kingdom
| | - Erwin Reisner
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Dominic S Wright
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.,The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot OX11 0RA, United Kingdom
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18
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An H, Hu Y, Song N, Mu T, Bai S, Peng Y, Liu L, Tang Y. Two-dimensional heterostructures built from ultrathin CeO 2 nanosheet surface-coordinated and confined metal-organic frameworks with enhanced stability and catalytic performance. Chem Sci 2022; 13:3035-3044. [PMID: 35382466 PMCID: PMC8905825 DOI: 10.1039/d2sc00308b] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 02/12/2022] [Indexed: 01/11/2023] Open
Abstract
Two-dimensional (2D) metal-organic framework (MOF) based heterostructures will be greatly advantageous to enhance catalytic performance because they increase the contact surface and charge transfer. Herein, a novel 2D heterostructure named CeO2@NiFe-MOFs, in which monolayer NiFe-MOFs is coordinated with ceria (CeO2) to improve catalytic and stability performance, is successfully constructed by the strategy of in situ growth on the surface of ultrathin CeO2 nanosheets being functionalized with monolayer carboxylic acid groups. The 2D heterostructure possesses a sandwich structure, where monolayer NiFe-MOFs are coordinated to both the top and bottom surface of CeO2 nanosheets via joining carboxylic acid groups. In particular, CeO2 with robust coordination plays a significant role in the anchoring of carboxylic acid groups and binding strength of heterostructures. The 2D CeO2@NiFe-MOF heterostructure with a joint effect of metal-ligand coordination not only presents good structural stability but also significantly enhances the oxygen evolution reaction (OER) efficiencies in comparison to bare NiFe-MOFs, achieving a current density of 20 mA cm-2 at a low overpotential of 248 mV as well as durability for at least 40 h. Meanwhile, the electronics, optics, band gap energy and local strains of CeO2 decorated with 2D NiFe-MOFs are different to the properties of bare CeO2. Our study on the construction of an ultrathin CeO2 surface-coordinated and confined MOF layer may pave a new way for novel 2D MOF composites/heterostructures or multi-functional 2D CeO2 materials to be used in energy conversion or other fields.
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Affiliation(s)
- Haiyan An
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University Lanzhou 730000 China
| | - Yang Hu
- Key Laboratory of Magnetism and Magnetic Materials of Ministry of Education, School of Physical Science and Technology, Lanzhou University Lanzhou 730000 China
| | - Nan Song
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University Lanzhou 730000 China
| | - Tingliang Mu
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University Lanzhou 730000 China
| | - Shiqiang Bai
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University Lanzhou 730000 China
| | - Yong Peng
- Key Laboratory of Magnetism and Magnetic Materials of Ministry of Education, School of Physical Science and Technology, Lanzhou University Lanzhou 730000 China
| | - Liangliang Liu
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University Lanzhou 730000 China
| | - Yu Tang
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University Lanzhou 730000 China
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19
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Léonard NG, Chantarojsiri T, Ziller JW, Yang JY. Cationic Effects on the Net Hydrogen Atom Bond Dissociation Free Energy of High-Valent Manganese Imido Complexes. J Am Chem Soc 2022; 144:1503-1508. [PMID: 35041788 PMCID: PMC9118977 DOI: 10.1021/jacs.1c09583] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Local electric fields can alter energy landscapes to impart enhanced reactivity in enzymes and at surfaces. Similar fields can be generated in molecular systems using charged functionalities. Manganese(V) salen nitrido complexes (salen = N,N'-ethylenebis(salicylideneaminato)) appended with a crown ether unit containing Na+ (1-Na), K+, (1-K), Ba2+ (1-Ba), Sr2+ (1-Sr), La3+ (1-La), or Eu3+ (1-Eu) cation were investigated to determine the effect of charge on pKa, E1/2, and the net bond dissociation free energy (BDFE) of N-H bonds. The series, which includes the manganese(V) salen nitrido without an appended crown, spans 4 units of charge. Bounds for the pKa values of the transient imido complexes were used with the Mn(VI/V) reduction potentials to calculate the N-H BDFEs of the imidos in acetonitrile. Despite a span of >700 mV and >9 pKa units across the series, the hydrogen atom BDFE only spans ∼6 kcal/mol (between 73 and 79 kcal/mol). These results suggest that the incorporation of cationic functionalities is an effective strategy for accessing wide ranges of reduction potentials and pKa values while minimally affecting the BDFE, which is essential to modulating electron, proton, or hydrogen atom transfer pathways.
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Affiliation(s)
- Nadia G Léonard
- Department of Chemistry, University of California, Irvine, California 92697, United States
| | - Teera Chantarojsiri
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Joseph W Ziller
- Department of Chemistry, University of California, Irvine, California 92697, United States
| | - Jenny Y Yang
- Department of Chemistry, University of California, Irvine, California 92697, United States
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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20
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Schmidt‐Räntsch T, Verplancke H, Lienert JN, Demeshko S, Otte M, Van Trieste GP, Reid KA, Reibenspies JH, Powers DC, Holthausen MC, Schneider S. Nitrogen Atom Transfer Catalysis by Metallonitrene C−H Insertion: Photocatalytic Amidation of Aldehydes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Till Schmidt‐Räntsch
- Institut für Anorganische Chemie Universität Göttingen Tammannstraße 4 37077 Göttingen Germany
| | - Hendrik Verplancke
- Institut für Anorganische und Analytische Chemie Goethe-Universität Max-von-Laue-Straße 7 60438 Frankfurt am Main Germany
| | - Jonas N. Lienert
- Institut für Anorganische und Analytische Chemie Goethe-Universität Max-von-Laue-Straße 7 60438 Frankfurt am Main Germany
| | - Serhiy Demeshko
- Institut für Anorganische Chemie Universität Göttingen Tammannstraße 4 37077 Göttingen Germany
| | - Matthias Otte
- Institut für Anorganische Chemie Universität Göttingen Tammannstraße 4 37077 Göttingen Germany
| | | | - Kaleb A. Reid
- Department of Chemistry Texas A&M University 3255 TAMU College Station TX 77843 USA
| | | | - David C. Powers
- Department of Chemistry Texas A&M University 3255 TAMU College Station TX 77843 USA
| | - Max C. Holthausen
- Institut für Anorganische und Analytische Chemie Goethe-Universität Max-von-Laue-Straße 7 60438 Frankfurt am Main Germany
| | - Sven Schneider
- Institut für Anorganische Chemie Universität Göttingen Tammannstraße 4 37077 Göttingen Germany
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21
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Shi H, Cheng L, Pan Y, Mak CK, Lau KC, Lau TC. Synergistic effects of CH 3CO 2H and Ca 2+ on C–H bond activation by MnO 4−. Chem Sci 2022; 13:11600-11606. [PMID: 36320399 PMCID: PMC9555569 DOI: 10.1039/d2sc03089f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 09/12/2022] [Indexed: 11/23/2022] Open
Abstract
The activation of metal-oxo species with Lewis acids is of current interest. In this work, the effects of a weak Brønsted acid such as CH3CO2H and a weak Lewis acid such as Ca2+ on C–H bond activation by KMnO4 have been investigated. Although MnO4− is rather non-basic (pKa of MnO3(OH) = −2.25), it can be activated by AcOH or Ca2+ to oxidize cyclohexane at room temperature to give cyclohexanone as the major product. A synergistic effect occurs when both AcOH and Ca2+ are present; the relative rates for the oxidation of cyclohexane by MnO4−/AcOH, MnO4−/Ca2+ and MnO4−/AcOH/Ca2+ are 1 : 73 : 198. DFT calculations show that in the active intermediate of MnO4−/AcOH/Ca2+, MnO4− is H-bonded to 3 AcOH molecules, while Ca2+ is bonded to 3 AcOH molecules as well as to an oxo ligand of MnO4−. Our results also suggest that these synergistic activating effects of a weak Brønsted acid and a weak Lewis acid should be applicable to a variety of metal-oxo species. The activation of metal-oxo species with Lewis acids is of current interest.![]()
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Affiliation(s)
- Huatian Shi
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Lin Cheng
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Yi Pan
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Chi-Keung Mak
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Kai-Chung Lau
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Tai-Chu Lau
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
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22
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Schmidt-Räntsch T, Verplancke H, Lienert JN, Demeschko S, Otte M, Van Trieste GP, Reid KA, Reibenspies JH, Powers DC, Holthausen MC, Schneider S. Nitrogen Atom Transfer Catalysis by Metallonitrene C-H Insertion: Photocatalytic Amidation of Aldehydes. Angew Chem Int Ed Engl 2021; 61:e202115626. [PMID: 34905281 PMCID: PMC9305406 DOI: 10.1002/anie.202115626] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Indexed: 11/18/2022]
Abstract
C−H amination and amidation by catalytic nitrene transfer are well‐established and typically proceed via electrophilic attack of nitrenoid intermediates. In contrast, the insertion of (formal) terminal nitride ligands into C−H bonds is much less developed and catalytic nitrogen atom transfer remains unknown. We here report the synthesis of a formal terminal nitride complex of palladium. Photocrystallographic, magnetic, and computational characterization support the assignment as an authentic metallonitrene (Pd−N) with a diradical nitrogen ligand that is singly bonded to PdII. Despite the subvalent nitrene character, selective C−H insertion with aldehydes follows nucleophilic selectivity. Transamidation of the benzamide product is enabled by reaction with N3SiMe3. Based on these results, a photocatalytic protocol for aldehyde C−H trimethylsilylamidation was developed that exhibits inverted, nucleophilic selectivity as compared to typical nitrene transfer catalysis. This first example of catalytic C−H nitrogen atom transfer offers facile access to primary amides after deprotection.
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Affiliation(s)
- Till Schmidt-Räntsch
- University of Göttingen: Georg-August-Universitat Gottingen, Institut für Anorganische Chemie, GERMANY
| | - Hendrik Verplancke
- Goethe-Universitat Frankfurt am Main, Institut für Anorganische und Analytische Chemie, GERMANY
| | - Jonas N Lienert
- Goethe-Universitat Frankfurt am Main, Institut für Anorganische und Analytische Chemie, GERMANY
| | - Serhiy Demeschko
- University of Göttingen: Georg-August-Universitat Gottingen, Institut für Anorganische Chemie, GERMANY
| | - Matthias Otte
- University of Göttingen: Georg-August-Universitat Gottingen, Institut für Anorganische Chemie, GERMANY
| | | | - Kaleb A Reid
- Texas A&M University, Department of Chemistry, UNITED STATES
| | | | - David C Powers
- Texas A&M University, Department of Chemistry, UNITED STATES
| | - Max C Holthausen
- Goethe-Universitat Frankfurt am Main, Institut für Anorganische und Analytische Chemie, GERMANY
| | - Sven Schneider
- University of Goettingen, Institute for inorganic Chemistry, Tammannstr. 4, 37077, Göttingen, GERMANY
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23
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Panda C, Doyle LM, Gericke R, McDonald AR. Rapid Iron(III)−Fluoride‐Mediated Hydrogen Atom Transfer. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202112683] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Chakadola Panda
- School of Chemistry Trinity College Dublin The University of Dublin, College Green Dublin 2 Ireland
| | - Lorna M. Doyle
- School of Chemistry Trinity College Dublin The University of Dublin, College Green Dublin 2 Ireland
| | - Robert Gericke
- School of Chemistry Trinity College Dublin The University of Dublin, College Green Dublin 2 Ireland
- Current address: Helmholtz-Zentrum Dresden-Rossendorf e. V. Institute of Resource Ecology Bautzner Landstrasse 400 01328 Dresden Germany
| | - Aidan R. McDonald
- School of Chemistry Trinity College Dublin The University of Dublin, College Green Dublin 2 Ireland
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24
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Gupta G, Bera M, Paul S, Paria S. Electrochemical Properties and Reactivity Study of [Mn V(O)(μ-OR-Lewis Acid)] Cores. Inorg Chem 2021; 60:18006-18016. [PMID: 34813300 DOI: 10.1021/acs.inorgchem.1c02601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A mononuclear manganese(V) oxo complex of a bis(amidate)bis(alkoxide) ligand, (NMe4)[MnV(HMPAB)(O)] [2; H4HMPAB = 1,2-bis(2-hydroxy-2-methylpropanamido)benzene], was synthesized and structurally characterized. A Mn-Oterm distance of 1.566(4) Å was observed in the solid-state structure of 2, consistent with the Mn≡O formulation. The reaction of redox-inactive metal ions (Mn+ = Li+, Ca2+, Mg2+, Y3+, and Sc3+) with 2 resulted in the formation of 2-Mn+ species, which were characterized by UV-vis, 1H NMR, cyclic voltammetry, and in situ IR spectroscopy. Theoretical calculations suggested that the alkoxide oxygen atoms of the ligand scaffold are energetically most favorable for coordinating the Mn+ ions in 2. Complex 2 revealed one-electron-reduction potential at -0.01 V versus ferrocenium/ferrocene, which shifted anodically upon coordination of Mn+ ions to 2, and such a shift became more prominent with stronger Lewis acids. The oxygen-atom transfer (OAT) reactivities of 2 and 2-Mn+ species with triphenylphosphine were compared, which exhibited a systematic increase of the reaction rate with increasing Lewis acidity of Mn+ ions, and a plot of log k2 versus Lewis acidity of Mn+ ions (ΔE) followed a linear relationship. It was observed that 2-Sc3+ was ca. 3200 times more reactive toward the OAT reaction compared to 2. Hammett analysis of 2 exhibited a V-shaped plot, indicating a change of the reaction mechanism upon going from electron-rich to electron-deficient Ar3P substrates. In contrast, 2-Ca2+ and 2-Sc3+ showed an electrophilic nature toward the OAT reaction, thus demonstrating the role of the Lewis acid in controlling the OAT mechanism. The hydrogen-atom abstraction reaction of 2 and 2-Mn+ adducts with 1-benzyl-1,4-dihydronicotinamide was investigated, and it was observed that the rate of reaction did not vary considerably with the Lewis acidity of Mn+ ions. On the basis of Eyring analysis of 2 and 2-Mn+ adducts, we hypothesized an entropy-controlled hydrogen-atom-transfer reaction for 2-Sc3+, which is different from the reaction mechanism of 2 and 2-Ca2+.
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Affiliation(s)
- Geetika Gupta
- Department of Chemistry, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016, India
| | - Moumita Bera
- Department of Chemistry, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016, India
| | - Satadal Paul
- Department of Chemistry, Bangabasi Morning College, Kolkata 700009, India
| | - Sayantan Paria
- Department of Chemistry, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110016, India
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25
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Karmalkar DG, Seo MS, Lee YM, Kim Y, Lee E, Sarangi R, Fukuzumi S, Nam W. Deeper Understanding of Mononuclear Manganese(IV)-Oxo Binding Brønsted and Lewis Acids and the Manganese(IV)-Hydroxide Complex. Inorg Chem 2021; 60:16996-17007. [PMID: 34705465 DOI: 10.1021/acs.inorgchem.1c02119] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Binding of Lewis acidic metal ions and Brønsted acid at the metal-oxo group of high-valent metal-oxo complexes enhances their reactivities significantly in oxidation reactions. However, such a binding of Lewis acids and proton at the metal-oxo group has been questioned in several cases and remains to be clarified. Herein, we report the synthesis, characterization, and reactivity studies of a mononuclear manganese(IV)-oxo complex binding triflic acid, {[(dpaq)MnIV(O)]-HOTf}+ (1-HOTf). First, 1-HOTf was synthesized and characterized using various spectroscopic techniques, including resonance Raman (rRaman) and X-ray absorption spectroscopy/extended X-ray absorption fine structure. In particular, in rRaman experiments, we observed a linear correlation between the Mn-O stretching frequencies of 1-HOTf (e.g., νMn-O at ∼793 cm-1) and 1-Mn+ (Mn+ = Ca2+, Zn2+, Lu3+, Al3+, or Sc3+) and the Lewis acidities of H+ and Mn+ ions, suggesting that H+ and Mn+ bind at the metal-oxo moiety of [(dpaq)MnIV(O)]+. Interestingly, a single-crystal structure of 1-HOTf was obtained by X-ray diffraction analysis, but the structure was not an expected Mn(IV)-oxo complex but a Mn(IV)-hydroxide complex, [(dpaq)MnIV(OH)](OTf)2 (4), with a Mn-O bond distance of 1.8043(19) Å and a Mn-O stretch at 660 cm-1. More interestingly, 4 reverted to 1-HOTf upon dissolution, demonstrating that 1-HOTf and 4 are interconvertible depending on the physical states, such as 1-HOTf in solution and 4 in isolated solid. The reactivity of 1-HOTf was investigated in hydrogen atom transfer (HAT) and oxygen atom transfer (OAT) reactions and then compared with those of 1-Mn+ complexes; an interesting correlation between the Mn-O stretching frequencies of 1-HOTf and 1-Mn+ and their reactivities in the OAT and HAT reactions is reported for the first time in this study.
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Affiliation(s)
- Deepika G Karmalkar
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Mi Sook Seo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Youngsuk Kim
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Eunsung Lee
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Ritimukta Sarangi
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
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26
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Guo M, Zhang J, Zhang L, Lee YM, Fukuzumi S, Nam W. Enthalpy-Entropy Compensation Effect in Oxidation Reactions by Manganese(IV)-Oxo Porphyrins and Nonheme Iron(IV)-Oxo Models. J Am Chem Soc 2021; 143:18559-18570. [PMID: 34723505 DOI: 10.1021/jacs.1c08198] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
"Enthalpy-Entropy Compensation Effect" (EECE) is ubiquitous in chemical reactions; however, such an EECE has been rarely explored in biomimetic oxidation reactions. In this study, six manganese(IV)-oxo complexes bearing electron-rich and -deficient porphyrins are synthesized and investigated in various oxidation reactions, such as hydrogen atom transfer (HAT), oxygen atom transfer (OAT), and electron-transfer (ET) reactions. First, all of the six Mn(IV)-oxo porphyrins are highly reactive in the HAT, OAT, and ET reactions. Interestingly, we have observed a reversed reactivity in the HAT and OAT reactions by the electron-rich and -deficient Mn(IV)-oxo porphyrins, depending on reaction temperatures, but not in the ET reactions; the electron-rich Mn(IV)-oxo porphyrins are more reactive than the electron-deficient Mn(IV)-oxo porphyrins at high temperature (e.g., 0 °C), whereas at low temperature (e.g., -60 °C), the electron-deficient Mn(IV)-oxo porphyrins are more reactive than the electron-rich Mn(IV)-oxo porphyrins. Such a reversed reactivity between the electron-rich and -deficient Mn(IV)-oxo porphyrins depending on reaction temperatures is rationalized with EECE; that is, the lower is the activation enthalpy, the more negative is the activation entropy, and vice versa. Interestingly, a unified linear correlation between the activation enthalpies and the activation entropies is observed in the HAT and OAT reactions of the Mn(IV)-oxo porphyrins. Moreover, from the previously reported HAT reactions of nonheme Fe(IV)-oxo complexes, a linear correlation between the activation enthalpies and the activation entropies is also observed. To the best of our knowledge, we report the first detailed mechanistic study of EECE in the oxidation reactions by synthetic high-valent metal-oxo complexes.
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Affiliation(s)
- Mian Guo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.,College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China
| | - Jisheng Zhang
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Lina Zhang
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.,Faculty of Science and Engineering, Meijo University, Nagoya, Aichi 468-8502, Japan
| | - 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, PR China
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27
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Fukuzumi S, Lee Y, Nam W. Deuterium kinetic isotope effects as redox mechanistic criterions. B KOREAN CHEM SOC 2021. [DOI: 10.1002/bkcs.12417] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Shunichi Fukuzumi
- Department of Chemistry and Nano Science Ewha Womans University Seoul Korea
- Faculty of Science and Engineering Meijo University Nagoya Aichi Japan
| | - Yong‐Min Lee
- Department of Chemistry and Nano Science Ewha Womans University Seoul Korea
- Research Institute for Basic Sciences Ewha Womans University Seoul Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science Ewha Womans University Seoul Korea
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28
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Brinkmeier A, Dalle KE, D'Amore L, Schulz RA, Dechert S, Demeshko S, Swart M, Meyer F. Modulation of a μ-1,2-Peroxo Dicopper(II) Intermediate by Strong Interaction with Alkali Metal Ions. J Am Chem Soc 2021; 143:17751-17760. [PMID: 34658244 DOI: 10.1021/jacs.1c08645] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The properties of metal/dioxygen species, which are key intermediates in oxidation catalysis, can be modulated by interaction with redox-inactive Lewis acids, but structural information about these adducts is scarce. Here we demonstrate that even mildly Lewis acidic alkali metal ions, which are typically viewed as innocent "spectators", bind strongly to a reactive cis-peroxo dicopper(II) intermediate. Unprecedented structural insight has now been obtained from X-ray crystallographic characterization of the "bare" CuII2(μ-η1:η1-O2) motif and its Li+, Na+, and K+ complexes. UV-vis, Raman, and electrochemical studies show that the binding persists in MeCN solution, growing stronger in proportion to the cation's Lewis acidity. The affinity for Li+ is surprisingly high (∼70 × 104 M-1), leading to Li+ extraction from its crown ether complex. Computational analysis indicates that the alkali ions influence the entire Cu-OO-Cu core, modulating the degree of charge transfer from copper to dioxygen. This induces significant changes in the electronic, magnetic, and electrochemical signatures of the Cu2O2 species. These findings have far-reaching implications for analyses of transient metal/dioxygen intermediates, which are often studied in situ, and they may be relevant to many (bio)chemical oxidation processes when considering the widespread presence of alkali cations in synthetic and natural environments.
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Affiliation(s)
- Alexander Brinkmeier
- Institute of Inorganic Chemistry, University of Göttingen, Tamannstrasse 4, D-37077 Göttingen, Germany
| | - Kristian E Dalle
- Institute of Inorganic Chemistry, University of Göttingen, Tamannstrasse 4, D-37077 Göttingen, Germany
| | - Lorenzo D'Amore
- Institut de Química Computacional i Catàlisi (IQCC) & Department de Química, Universitat de Girona, 17003 Girona, Spain
| | - Roland A Schulz
- Institute of Inorganic Chemistry, University of Göttingen, Tamannstrasse 4, D-37077 Göttingen, Germany
| | - Sebastian Dechert
- Institute of Inorganic Chemistry, University of Göttingen, Tamannstrasse 4, D-37077 Göttingen, Germany
| | - Serhiy Demeshko
- Institute of Inorganic Chemistry, University of Göttingen, Tamannstrasse 4, D-37077 Göttingen, Germany
| | - Marcel Swart
- Institut de Química Computacional i Catàlisi (IQCC) & Department de Química, Universitat de Girona, 17003 Girona, Spain.,ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Franc Meyer
- Institute of Inorganic Chemistry, University of Göttingen, Tamannstrasse 4, D-37077 Göttingen, Germany.,International Center for Advanced Studies of Energy Conversion (ICASEC), University of Göttingen, D-37077 Göttingen, Germany
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29
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Panda C, Doyle LM, Gericke R, McDonald AR. Rapid Iron(III)-Fluoride-Mediated Hydrogen Atom Transfer. Angew Chem Int Ed Engl 2021; 60:26281-26286. [PMID: 34582619 PMCID: PMC9298026 DOI: 10.1002/anie.202112683] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Indexed: 01/08/2023]
Abstract
We anticipate high-valent metal-fluoride species will be highly effective hydrogen atom transfer (HAT) oxidants because of the magnitude of the H-F bond (in the product) that drives HAT oxidation. We prepared a dimeric FeIII (F)-F-FeIII (F) complex (1) by reacting [FeII (NCCH3 )2 (TPA)](ClO4 )2 (TPA=tris(2-pyridylmethyl)amine) with difluoro(phenyl)-λ3 -iodane (difluoroiodobenzene). 1 was a sluggish oxidant, however, it was readily activated by reaction with Lewis or Brønsted acids to yield a monomeric [FeIII (TPA)(F)(X)]+ complex (2) where X=F/OTf. 1 and 2 were characterized using NMR, EPR, UV/Vis, and FT-IR spectroscopies and mass spectrometry. 2 was a remarkably reactive FeIII reagent for oxidative C-H activation, demonstrating reaction rates for hydrocarbon HAT comparable to the most reactive FeIII and FeIV oxidants.
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Affiliation(s)
- Chakadola Panda
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Lorna M Doyle
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Robert Gericke
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland.,Current address: Helmholtz-Zentrum Dresden-Rossendorf e. V., Institute of Resource Ecology, Bautzner Landstrasse 400, 01328, Dresden, Germany
| | - Aidan R McDonald
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
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30
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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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31
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Kim K, Cho D, Noh H, Ohta T, Baik MH, Cho J. Controlled Regulation of the Nitrile Activation of a Peroxocobalt(III) Complex with Redox-Inactive Lewis Acidic Metals. J Am Chem Soc 2021; 143:11382-11392. [PMID: 34313127 DOI: 10.1021/jacs.1c01674] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Redox-inactive metal ions play vital roles in biological O2 activation and oxidation reactions of various substrates. Recently, we showed a distinct reactivity of a peroxocobalt(III) complex bearing a tetradentate macrocyclic ligand, [CoIII(TBDAP)(O2)]+ (1) (TBDAP = N,N'-di-tert-butyl-2,11-diaza[3.3](2,6)pyridinophane), toward nitriles that afforded a series of hydroximatocobalt(III) complexes, [CoIII(TBDAP)(R-C(═NO)O)]+ (R = Me (3), Et, and Ph). In this study, we report the effects of redox-inactive metal ions on nitrile activation of 1. In the presence of redox-inactive metal ions such as Zn2+, La3+, Lu3+, and Y3+, the reaction does not form the hydroximatocobalt(III) complex but instead gives peroxyimidatocobalt(III) complexes, [CoIII(TBDAP)(R-C(═NH)O2)]2+ (R = Me (2) and Ph (2Ph)). These new intermediates were characterized by various physicochemical methods including X-ray diffraction analysis. The rates of the formation of 2 are found to correlate with the Lewis acidity of the additive metal ions. Moreover, complex 2 was readily converted to 3 by the addition of a base. In the presence of Al3+, Sc3+, or H+, 1 is converted to [CoIII(TBDAP)(O2H)(MeCN)]2+ (4), and further reaction with nitriles did not occur. These results reveal that the reactivity of the peroxocobalt(III) complex 1 in nitrile activation can be regulated by the redox-inactive metal ions and their Lewis acidity. DFT calculations show that the redox-inactive metal ions stabilize the peroxo character of end-on Co-η1-O2 intermediate through the charge reorganization from a CoII-superoxo to a CoIII-peroxo intermediate. A complete mechanistic model explaining the role of the Lewis acid is presented.
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Affiliation(s)
- Kyungmin Kim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.,Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
| | - Dasol Cho
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.,Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Hyeonju Noh
- Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
| | - Takehiro Ohta
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, RSCLP Center, 679-5148 Hyogo, Japan
| | - Mu-Hyun Baik
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.,Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Jaeheung Cho
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.,Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
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32
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Mukherjee G, Satpathy JK, Bagha UK, Mubarak MQE, Sastri CV, de Visser SP. Inspiration from Nature: Influence of Engineered Ligand Scaffolds and Auxiliary Factors on the Reactivity of Biomimetic Oxidants. ACS Catal 2021. [DOI: 10.1021/acscatal.1c01993] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Gourab Mukherjee
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
| | - Jagnyesh K. Satpathy
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
| | - Umesh K. Bagha
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
| | - M. Qadri E. Mubarak
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
- Fakulti Sains dan Teknologi, Universiti Sains Islam Malaysia, Bandar Baru Nilai, 71800 Nilai, Negeri Sembilan Malaysia
| | - Chivukula V. Sastri
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
| | - Sam P. de Visser
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
- Department of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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Tomboc GM, Park Y, Lee K, Jin K. Directing transition metal-based oxygen-functionalization catalysis. Chem Sci 2021; 12:8967-8995. [PMID: 34276926 PMCID: PMC8261717 DOI: 10.1039/d1sc01272j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 06/07/2021] [Indexed: 11/21/2022] Open
Abstract
This review presents the recent progress of oxygen functionalization reactions based on non-electrochemical (conventional organic synthesis) and electrochemical methods. Although both methods have their advantages and limitations, the former approach has been used to synthesize a broader range of organic substances as the latter is limited by several factors, such as poor selectivity and high energy cost. However, because electrochemical methods can replace harmful terminal oxidizers with external voltage, organic electrosynthesis has emerged as greener and more eco-friendly compared to conventional organic synthesis. The progress of electrochemical methods toward oxygen functionalization is presented by an in-depth discussion of different types of electrically driven-chemical organic synthesis, with particular attention to recently developed electrochemical systems and catalyst designs. We hope to direct the attention of readers to the latest breakthroughs of traditional oxygen functionalization reactions and to the potential of electrochemistry for the transformation of organic substrates to useful end products.
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Affiliation(s)
- Gracita M Tomboc
- Department of Chemistry and Research Institute for Natural Sciences, Korea University Seoul 02841 Republic of Korea
| | - Yeji Park
- Department of Chemistry and Research Institute for Natural Sciences, Korea University Seoul 02841 Republic of Korea
| | - Kwangyeol Lee
- Department of Chemistry and Research Institute for Natural Sciences, Korea University Seoul 02841 Republic of Korea
| | - Kyoungsuk Jin
- Department of Chemistry and Research Institute for Natural Sciences, Korea University Seoul 02841 Republic of Korea
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Chandra A, Ansari M, Monte‐Pérez I, Kundu S, Rajaraman G, Ray K. Ligand‐Constraint‐Induced Peroxide Activation for Electrophilic Reactivity. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202100438] [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)
- Anirban Chandra
- Department of Chemistry Humboldt-Universität zu Berlin Brook-Taylor-Strasse 2 12489 Berlin Germany
| | - Mursaleem Ansari
- Department of Chemistry Indian Institute of Technology Bombay, Powai Mumbai Maharashtra 400 076 India
| | - Inés Monte‐Pérez
- Department of Chemistry Humboldt-Universität zu Berlin Brook-Taylor-Strasse 2 12489 Berlin Germany
| | - Subrata Kundu
- Department of Chemistry Humboldt-Universität zu Berlin Brook-Taylor-Strasse 2 12489 Berlin Germany
| | - Gopalan Rajaraman
- Department of Chemistry Indian Institute of Technology Bombay, Powai Mumbai Maharashtra 400 076 India
| | - Kallol Ray
- Department of Chemistry Humboldt-Universität zu Berlin Brook-Taylor-Strasse 2 12489 Berlin Germany
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35
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Chandra A, Ansari M, Monte-Pérez I, Kundu S, Rajaraman G, Ray K. Ligand-Constraint-Induced Peroxide Activation for Electrophilic Reactivity. Angew Chem Int Ed Engl 2021; 60:14954-14959. [PMID: 33843113 PMCID: PMC8252416 DOI: 10.1002/anie.202100438] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/26/2021] [Indexed: 12/16/2022]
Abstract
μ‐1,2‐peroxo‐bridged diiron(III) intermediates P are proposed as reactive intermediates in various biological oxidation reactions. In sMMO, P acts as an electrophile, and performs hydrogen atom and oxygen atom transfers to electron‐rich substrates. In cyanobacterial ADO, however, P is postulated to react by nucleophilic attack on electrophilic carbon atoms. In biomimetic studies, the ability of μ‐1,2‐peroxo‐bridged dimetal complexes of Fe, Co, Ni and Cu to act as nucleophiles that effect deformylation of aldehydes is documented. By performing reactivity and theoretical studies on an end‐on μ‐1,2‐peroxodicobalt(III) complex 1 involving a non‐heme ligand system, L1, supported on a Sn6O6 stannoxane core, we now show that a peroxo‐bridged dimetal complex can also be a reactive electrophile. The observed electrophilic chemistry, which is induced by the constraints provided by the Sn6O6 core, represents a new domain for metal−peroxide reactivity.
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Affiliation(s)
- Anirban Chandra
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
| | - Mursaleem Ansari
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra, 400 076, India
| | - Inés Monte-Pérez
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
| | - Subrata Kundu
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
| | - Gopalan Rajaraman
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra, 400 076, India
| | - Kallol Ray
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany
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36
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Guo M, Lee YM, Fukuzumi S, Nam W. Biomimetic metal-oxidant adducts as active oxidants in oxidation reactions. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2021.213807] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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37
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Sharma N, Zou HB, Lee YM, Fukuzumi S, Nam W. A Mononuclear Non-Heme Manganese(III)-Aqua Complex in Oxygen Atom Transfer Reactions via Electron Transfer. J Am Chem Soc 2021; 143:1521-1528. [PMID: 33439643 DOI: 10.1021/jacs.0c11420] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Metal-oxygen complexes, such as metal-oxo [M(O2-)], -hydroxo [M(OH-)], -peroxo [M(O22-)], -hydroperoxo [M(OOH-)], and -superoxo [M(O2•-)] species, are capable of conducting oxygen atom transfer (OAT) reactions with organic substrates, such as thioanisole (PhSMe) and triphenylphosphine (Ph3P). However, OAT of metal-aqua complexes, [M(OH2)]n+, has yet to be reported. We report herein OAT of a mononuclear non-heme Mn(III)-aqua complex, [(dpaq)MnIII(OH2)]2+ (1, dpaq = 2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-yl-acetamidate), to PhSMe and Ph3P derivatives for the first time; it is noted that no OAT occurs from the corresponding Mn(III)-hydroxo complex, [(dpaq)MnIII(OH)]+ (2), to the substrates. Mechanistic studies reveal that OAT reaction of 1 occurs via electron transfer from 4-methoxythioanisole to 1 to produce the 4-methoxythioanisole radical cation and [(dpaq)MnII(OH2)]+, followed by nucleophilic attack of H2O in [(dpaq)MnII(OH2)]+ to the 4-methoxythioanisole radical cation to produce an OH adduct radical, 2,4-(MeO)2C6H3S•(OH)Me, which disproportionates or undergoes electron transfer to 1 to yield methyl 4-methoxyphenyl sulfoxide. Formation of the thioanisole radical cation derivatives is detected by the stopped-flow transient absorption measurements in OAT from 1 to 2,4-dimethoxythioanisole and 3,4-dimethoxythioanisole, being compared with that in the photoinduced electron transfer oxidation of PhSMe derivatives, which are detected by laser-induced transient absorption measurements. Similarly, OAT from 1 to Ph3P occurs via electron transfer from Ph3P to 1, and the proton effect on the reaction rate has been discussed. The rate constants of electron transfer from electron donors, including PhSMe and Ph3P derivatives, to 1 are fitted well by the electron transfer driving force dependence of the rate constants predicted by the Marcus theory of outer-sphere electron transfer.
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Affiliation(s)
- Namita Sharma
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Huai-Bo Zou
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.,Department of Chemistry and Bioengineering, Key Laboratory of Jiangxi University for Applied Chemistry and Chemical Biology, Yichun University, Yichun 336000, China
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.,Faculty of Science and Engineering, Meijo University, Nagoya, Aichi 468-8502, Japan
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.,Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China
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38
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Devi T, Lee YM, Fukuzumi S, Nam W. Acid-promoted hydride transfer from an NADH analogue to a Cr(iii)-superoxo complex via a proton-coupled hydrogen atom transfer. Dalton Trans 2021; 50:675-680. [PMID: 33331375 DOI: 10.1039/d0dt04004e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The sequential transfer of an electron, a proton and an electron in a hydride transfer from dihydronicotinamide adenine dinucleotide (NADH) and its analogues has never been separated well. In addition, the effect of acids on hydride transfer from an NADH analogue to a metal-superoxo species has yet to be reported. We report herein the first example of an acid-promoted hydride transfer from an NADH analogue, 10-methyl-9,10-dihydroacridine (AcrH2), to a Cr(iii)-superoxo complex, [(TMC)CrIII(O2)]2+, in the presence of HOTf in MeCN at 233 K. The acid-promoted hydride transfer from AcrH2 to [(TMC)CrIII(O2)]2+ occurs via a proton-coupled hydrogen atom transfer from AcrH2 to [(TMC)CrIII(O2)]2+ to produce a radical cation (AcrH2˙+) with an inverse deuterium isotope effect (KIE) of 0.93(5). AcrH2˙+ decayed via a proton transfer from AcrH2˙+ to AcrH2 with a KIE of 2.0(1), followed by the reaction of 10-methylacridinyl radical (AcrH˙) with [(TMC)CrIII(H2O2)]3+ to produce a 10-methylacridinium ion (AcrH+) and [(TMC)CrIII]3+. This work provides valuable insights into the mechanism of hydride transfer of NADH analogues by metal-superoxo intermediates, such as the switchover of the reaction mechanism from a one-step to a separated multi-step pathway in the presence of an acid.
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Affiliation(s)
- Tarali Devi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea. and Faculty of Science and Engineering, Meijo University, Nagoya, Aichi 468-8502, Japan
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea. and Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China
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39
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Yang M, Wang Y, Jian Y, Leng D, Zhang W, Zhang G, Sun H, Gao Z. A sustainable water-tolerant catalyst with enhanced Lewis acidity: Dual activation of Cp2TiCl2 via ligand and solvent. MOLECULAR CATALYSIS 2020. [DOI: 10.1016/j.mcat.2020.111247] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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40
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Zhang L, Lee YM, Guo M, Fukuzumi S, Nam W. Unprecedented Reactivities of Highly Reactive Manganese(III)-Iodosylarene Porphyrins in Oxidation Reactions. J Am Chem Soc 2020; 142:19879-19884. [PMID: 33186008 DOI: 10.1021/jacs.0c10159] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We report that Mn(III)-iodosylarene porphyrins, [MnIII(Porp)(sArIO)]+, are capable of activating the C-H bonds of hydrocarbons, including unactivated alkanes such as cyclohexane, with unprecedented reactivities, such as a low kinetic isotope effect, a saturation behavior of reaction rates, and no electronic effect of porphyrin ligands on the reactivities of [MnIII(Porp)(sArIO)]+. In oxygen atom transfer (OAT) reactions, the sulfoxidation of para-X-substituted thioanisoles by [MnIII(Porp)(sArIO)]+ affords a very unusual behavior in the Hammett plot with the saturation behavior of reaction rates and no electronic effect of porphyrin ligands on reactivities. The reactivities and mechanisms of [MnIII(Porp)(sArIO)]+ are then compared with those of the corresponding MnIV(Porp)(O) complex. The present study reports the first example of highly reactive Mn(III)-iodosylarene porphyrins with unprecedented reactivities in C-H bond activation and OAT reactions.
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Affiliation(s)
- Lina Zhang
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Mian Guo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - 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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41
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Affiliation(s)
- Shunichi Fukuzumi
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 South Korea
- Faculty of Science and Engineering Meijo University Nagoya Aichi 468‐0073 Japan
| | - Yong‐Min Lee
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 South Korea
- Research Institute for Basic Sciences Ewha Womans University Seoul 03760 South Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 South Korea
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42
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Chen G, Ma L, Lo PK, Mak CK, Lau KC, Lau TC. Cooperative activating effects of metal ion and Brønsted acid on a metal oxo species. Chem Sci 2020; 12:632-638. [PMID: 34163794 PMCID: PMC8179018 DOI: 10.1039/d0sc04069j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Metal oxo (M
Created by potrace 1.16, written by Peter Selinger 2001-2019
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O) complexes are common oxidants in chemical and biological systems. The use of Lewis acids to activate metal oxo species has attracted great interest in recent years, especially after the discovery of the CaMn4O5 cluster in the oxygen-evolving centre of photosystem II. Strong Lewis acids such as Sc3+ and BF3, as well as strong Brønsted acids such as H2SO4 and CF3SO3H, are commonly used to activate metal oxo species. In this work, we demonstrate that relatively weak Lewis acids such as Ca2+ and other group 2 metal ions, as well as weak Brønsted acids such as CH3CO2H, can readily activate the stable RuO4− complex towards the oxidation of alkanes. Notably, the use of Ca2+ and CH3CO2H together produces a remarkable cooperative effect on RuO4−, resulting in a much more efficient oxidant. DFT calculations show that Ca2+ and CH3CO2H can bind to two oxo ligands to form a chelate ring. This results in substantial lowering of the barrier for hydrogen atom abstraction from cyclohexane. Combining a weak Lewis acid and weak Brønsted acid produces strong cooperative effects for activating metal oxo species towards alkane oxidation.![]()
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Affiliation(s)
- Gui Chen
- Dongguan Cleaner Production Technology Center, School of Environment and Civil Engineering, Dongguan University of Technology Dongguan Guangdong 523808 China
| | - Li Ma
- Department of Chemistry, Jinan University Guangzhou 510632 China
| | - Po-Kam Lo
- Department of Chemistry, City University of Hong Kong Tat Chee Avenue Kowloon Tong Hong Kong China
| | - Chi-Keung Mak
- Department of Chemistry, City University of Hong Kong Tat Chee Avenue Kowloon Tong Hong Kong China
| | - Kai-Chung Lau
- Department of Chemistry, City University of Hong Kong Tat Chee Avenue Kowloon Tong Hong Kong China
| | - Tai-Chu Lau
- Department of Chemistry, City University of Hong Kong Tat Chee Avenue Kowloon Tong Hong Kong China
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43
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Baeza Cinco MÁ, Hayton TW. Progress toward the Isolation of Late Metal Terminal Sulfides. Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000600] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Miguel Á. Baeza Cinco
- Department of Chemistry and Biochemistry University of California Santa Barbara 93106 Santa Barbara CA USA
| | - Trevor W. Hayton
- Department of Chemistry and Biochemistry University of California Santa Barbara 93106 Santa Barbara CA USA
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44
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Chakraborty B, Kostenko A, Menezes PW, Driess M. A Systems Approach to a One-Pot Electrochemical Wittig Olefination Avoiding the Use of Chemical Reductant or Sacrificial Electrode. Chemistry 2020; 26:11829-11834. [PMID: 32259335 PMCID: PMC7540293 DOI: 10.1002/chem.202001654] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Indexed: 12/17/2022]
Abstract
An unprecedented one‐pot fully electrochemically driven Wittig olefination reaction system without employing a chemical reductant or sacrificial electrode material to regenerate triphenylphosphine (TPP) from triphenylphosphine oxide (TPPO) and base‐free in situ formation of Wittig ylides, is reported. Starting from TPPO, the initial step of the phosphoryl P=O bond activation proceeds through alkylation with RX (R=Me, Et; X=OSO2CF3 (OTf)), affording the corresponding [Ph3POR]+X− salts which undergo efficient electroreduction to TPP in the presence of a substoichiometric amount of the Sc(OTf)3 Lewis acid on a Ag‐electrode. Subsequent alkylation of TPP affords Ph3PR+ which enables a facile and efficient electrochemical in situ formation of the corresponding Wittig ylide under base‐free condition and their direct use for the olefination of various carbonyl compounds. The mechanism and, in particular, the intriguing role of Sc3+ as mediator in the TPPO electroreduction been uncovered by density functional theory calculations.
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Affiliation(s)
- Biswarup Chakraborty
- Department of Chemistry: Metalorganics and Inorganic Materials, Technische Universität Berlin, Straße des 17 Juni 135, Sekr. C2, 10623, Berlin, Germany
| | - Arseni Kostenko
- Department of Chemistry: Metalorganics and Inorganic Materials, Technische Universität Berlin, Straße des 17 Juni 135, Sekr. C2, 10623, Berlin, Germany
| | - Prashanth W Menezes
- Department of Chemistry: Metalorganics and Inorganic Materials, Technische Universität Berlin, Straße des 17 Juni 135, Sekr. C2, 10623, Berlin, Germany
| | - Matthias Driess
- Department of Chemistry: Metalorganics and Inorganic Materials, Technische Universität Berlin, Straße des 17 Juni 135, Sekr. C2, 10623, Berlin, Germany
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45
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Yang J, Seo MS, Kim KH, Lee Y, Fukuzumi S, Shearer J, Nam W. Structure and Unprecedented Reactivity of a Mononuclear Nonheme Cobalt(III) Iodosylbenzene Complex. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202005091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Jindou Yang
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Mi Sook Seo
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Kyung Ha Kim
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Yong‐Min Lee
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Jason Shearer
- Department of Chemistry Trinity University San Antonio TX 78212 USA
| | - Wonwoo Nam
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
- School of Chemistry and Chemical Engineering Shaanxi Normal University Xi'an 710119 China
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46
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Kim B, Kim S, Ohta T, Cho J. Redox-Inactive Metal Ions That Enhance the Nucleophilic Reactivity of an Alkylperoxocopper(II) Complex. Inorg Chem 2020; 59:9938-9943. [PMID: 32614571 DOI: 10.1021/acs.inorgchem.0c01109] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The importance of redox-inactive metal ions in modulating the reactivity of redox-active biological systems is a subject of great current interest. In this work, the effect of redox-inactive metal ions (M3+ = Sc3+, Y3+, Yb3+, La3+) on the nucleophilic reactivity of a mononuclear ligand-based alkylperoxocopper(II) complex, [Cu(iPr2-tren-C(CH3)2O2)]+ (1), was examined. 1 was prepared by the addition of hydrogen peroxide and triethylamine to the solution of [Cu(iPr3-tren)(CH3CN)]+ (iPr3-tren = tris[2-(isopropylamino)ethyl]amine) via the formation of [Cu(iPr3-tren)(O2H)]+ (2) in methanol (CH3OH) at 30 °C. 1 was characterized using density functional theory (DFT) calculations and spectroscopic methods such as UV-vis, resonance Raman (rR), and electron paramagnetic resonance (EPR). DFT calculations support the electronic structure of 1 with an intermediate geometry between the trigonal-bipyramidal and square-pyramidal geometries, which is consistent with the observed EPR signal exhibiting a signal with g⊥ = 2.03 (A⊥ = 16 G) and g|| = 2.19 (A|| = 158 G). The Cu-O bond stretching frequency of 1 was observed at 507 cm-1 for 16O2 species (486 cm-1 for 18O2 species), and its O-O vibrational energy was determined to be 799 cm-1 for 16O2 species (759 cm-1 for 18O2 species) by rR spectroscopy. The reactivity of 1 was investigated in oxidative nucleophilic reactions. The positive slope of the Hammett plot (ρ = 2.3(1)) with para-substituted benzaldehydes and the reactivity order with 1°-, 2°-, and 3°-CHO demonstrate well the nucleophilic character of this copper(II) ligand-based alkylperoxo complex. The Lewis acidity of M3+ improves the oxidizing ability of 1. The modulated reactivity of 1 with M3+ was revealed to be an opposite trend of the Lewis acidity of M3+ in aldehyde deformylation.
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Affiliation(s)
- Bohee Kim
- Department of Emerging Materials Science, DGIST, Daegu 42988, Korea
| | - Seonghan Kim
- Department of Emerging Materials Science, DGIST, Daegu 42988, Korea
| | - Takehiro Ohta
- Picobiology Institute, Graduate School of Life Science, University of Hyogo, RSC-UH LP Center, Hyogo 679-5148, Japan
| | - Jaeheung Cho
- Department of Emerging Materials Science, DGIST, Daegu 42988, Korea
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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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48
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Yang J, Seo MS, Kim KH, Lee Y, Fukuzumi S, Shearer J, Nam W. Structure and Unprecedented Reactivity of a Mononuclear Nonheme Cobalt(III) Iodosylbenzene Complex. Angew Chem Int Ed Engl 2020; 59:13581-13585. [DOI: 10.1002/anie.202005091] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Indexed: 12/21/2022]
Affiliation(s)
- Jindou Yang
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Mi Sook Seo
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Kyung Ha Kim
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Yong‐Min Lee
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Jason Shearer
- Department of Chemistry Trinity University San Antonio TX 78212 USA
| | - Wonwoo Nam
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
- School of Chemistry and Chemical Engineering Shaanxi Normal University Xi'an 710119 China
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Rice DB, Grotemeyer EN, Donovan AM, Jackson TA. Effect of Lewis Acids on the Structure and Reactivity of a Mononuclear Hydroxomanganese(III) Complex. Inorg Chem 2020; 59:2689-2700. [PMID: 32045220 DOI: 10.1021/acs.inorgchem.9b02980] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The addition of Sc(OTf)3 and Al(OTf)3 to the mononuclear MnIII-hydroxo complex [MnIII(OH)(dpaq)]+ (1) gives rise to new intermediates with spectroscopic properties and chemical reactivity distinct from those of [MnIII(OH)(dpaq)]+. The electronic absorption spectra of [MnIII(OH)(dpaq)]+ in the presence of Sc(OTf)3 (1-ScIII) and Al(OTf)3 (1-AlIII) show modest perturbations in electronic transition energies, consistent with moderate changes in the MnIII geometry. A comparison of 1H NMR data for 1 and 1-ScIII confirm this conclusion, as the 1H NMR spectrum of 1-ScIII shows the same number of hyperfine-shifted peaks as the 1H NMR spectrum of 1. These 1H NMR spectra, and that of 1-AlIII, share a similar chemical-shift pattern, providing firm evidence that these Lewis acids do not cause gross distortions to the structure of 1. Mn K-edge X-ray absorption data for 1-ScIII provide evidence of elongation of the axial Mn-OH and Mn-N(amide) bonds relative to those of 1. In contrast to these modest spectroscopic perturbations, 1-ScIII and 1-AlIII show greatly enhanced reactivity toward hydrocarbons. While 1 is unreactive toward 9,10-dihydroanthracene (DHA), 1-ScIII and 1-AlIII react rapidly with DHA (k2 = 0.16(1) and 0.25(2) M-1 s-1 at 50 °C, respectively). The 1-ScIII species is capable of attacking the much stronger C-H bond of ethylbenzene. The basis for these perturbations to the spectroscopic properties and reactivity of 1 in the presence of these Lewis acids was elucidated by comparing properties of 1-ScIII and 1-AlIII with the recently reported MnIII-aqua complex [MnIII(OH2)(dpaq)]2+ ( J. Am. Chem. Soc. 2018, 140, 12695-12699). Because 1-ScIII and 1-AlIII show 1H NMR spectra essentially identical to that of [MnIII(OH2)(dpaq)]2+, the primary effect of these Lewis acids on 1 is protonation of the hydroxo ligand caused by an increase in the Brønsted acidity of the solution.
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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
| | - Elizabeth N Grotemeyer
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, The University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Anna M Donovan
- 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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