1
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Yang L, Ito R, Sugimoto H, Morimoto Y, Itoh S. Oxidation mechanism of phenols by copper(II)-halide complexes. Chem Commun (Camb) 2024; 60:7586-7589. [PMID: 38949670 DOI: 10.1039/d4cc02483d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
The mechanism of oxidation of phenols by tetrahedral copper(II)-halide complexes was investigated to demonstrate that phenols with an electron-withdrawing substituent are oxidized via a proton-transfer/electron-transfer (PTET) mechanism, whereas phenols with an electron-donating substituent involve a concerted proton/electron transfer (CPET) mechanism. The importance of the tetrahedral geometry of the metal centre as well as the effects of the halide ligands of the substrates were explored.
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Affiliation(s)
- Lan Yang
- Department of Molecular Chemistry, Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
| | - Rin Ito
- Department of Molecular Chemistry, Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
| | - Hideki Sugimoto
- Department of Molecular Chemistry, Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
| | - Yuma Morimoto
- Department of Molecular Chemistry, Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
| | - Shinobu Itoh
- Department of Molecular Chemistry, Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
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2
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Kayne M, Murphy PS, Kwon YM, Lee Y, Jackson TA, Wang D. Generation, Characterization and Reactivity of a High-Valent Mononuclear Cobalt(IV)-Diazide Complex. Chemistry 2024; 30:e202401218. [PMID: 38644346 DOI: 10.1002/chem.202401218] [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: 04/17/2024] [Accepted: 04/20/2024] [Indexed: 04/23/2024]
Abstract
High-valent Fe(IV)=O intermediates of metalloenzymes have inspired numerous efforts to generate synthetic analogs to mimic and understand their substrate oxidation reactivities. However, high-valent M(IV) complexes of late transition metals are rare. We have recently reported a novel Co(IV)-dinitrate complex (1-NO3) that activates sp3 C-H bonds up to 87 kcal/mol. In this work, we have shown that the nitrate ligands in 1-NO3 can be replaced by azide, a more basic coordinating base, resulting in the formation of a more potent Co(IV)-diazide species (1-N3) that reacts with substrates (hydrocarbons and phenols) at faster rate constants and activates stronger C-H bonds than the parent complex 1-NO3. We have characterized 1-N3 employing a combination of spectroscopic and computational approaches. Our results clearly show that the coordination of azide leads to the modulation of the Co(IV) electronic structure and the Co(IV/III) redox potential. Together with the higher basicity of azide, these thermodynamic parameters contribute to the higher driving forces of 1-N3 than 1-NO3 for C-H bond activation. Our discoveries are thus insightful for designing more reactive bio-inspired high-valent late transition metal complexes for activating inert aliphatic hydrocarbons.
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Affiliation(s)
- Michael Kayne
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana, 59812, United States
| | - Patrick S Murphy
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas, 66045, United States
| | - Yubin M Kwon
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana, 59812, United States
| | - Yuri Lee
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas, 66045, United States
| | - Timothy A Jackson
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas, 66045, United States
| | - Dong Wang
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana, 59812, United States
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3
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Jeong D, Lee Y, Lee Y, Kim K, Cho J. Synthesis, Characterization, and Reactivity of a Highly Oxidative Mononuclear Manganese(IV)-Bis(Fluoro) Complex. J Am Chem Soc 2024; 146:4172-4177. [PMID: 38311844 DOI: 10.1021/jacs.3c13324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2024]
Abstract
Recently, transition-metal terminal nonoxo complexes have shown a remarkable ability to activate and functionalize C-H bonds via proton-coupled electron transfer (PCET). Here we report the first example of a mononuclear manganese(IV) bis(fluoro) complex bearing a tetradentate pyridinophane ligand, [MnIV(TBDAP)(F)2]2+ (3), with an X-ray single crystal structure and physicochemical characterization. The manganese(IV) bis(fluoro) complex has a very high reduction potential of 1.61 V vs SCE, thereby enabling the four-electron oxidation of mesitylene to 3,5-dimethylbenzaldehyde. Kinetic studies, including the kinetic isotope effect and employment of other toluene derivatives, reveal the electron transfer (ET)-driven PCET in the C-H bond activation of mesitylene by 3. This novel metal halide intermediate would be prominently valuable for expanding transition-metal halide chemistry.
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Affiliation(s)
- Donghyun Jeong
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Yujeong Lee
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Yuri Lee
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Kyungmin Kim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Jaeheung Cho
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
- Graduate School of Carbon Neutrality, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
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4
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Awasthi A, Mallojjala SC, Kumar R, Eerlapally R, Hirschi JS, Draksharapu A. Altering the Localization of an Unpaired Spin in a Formal Ni(V) Species. Chemistry 2024; 30:e202302824. [PMID: 37903027 PMCID: PMC10841873 DOI: 10.1002/chem.202302824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 10/28/2023] [Accepted: 10/30/2023] [Indexed: 11/01/2023]
Abstract
The participation of both ligand and the metal center in the redox events has been recognized as one of the ways to attain the formal high valent complexes for the late 3d metals, such as Ni and Cu. Such an approach has been employed successfully to stabilize a Ni(III) bisphenoxyl diradical species in which there exist an equilibrium between the ligand and the Ni localized resultant spin. The present work, however, broadens the scope of the previously reported three oxidized equivalent species by conveying the approaches that tend to affect the reported equilibrium in CH3 CN at 233 K. Various spectroscopic characterization revealed that employing exogenous N-donor ligands like 1-methyl imidazole and pyridine favors the formation of the Ni centered localized spin though axial binding. In contrast, due to its steric hinderance, quinoline favors an exclusive ligand localized radical species. DFT studies shed light on the novel intermediates' complex electronic structure. Further, the three oxidized equivalent species with the Ni centered spin was examined for its hydrogen atom abstraction ability stressing their key role in alike reactions.
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Affiliation(s)
- Ayushi Awasthi
- Southern Laboratories-208 A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | | | - Rakesh Kumar
- Southern Laboratories-208 A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Raju Eerlapally
- Southern Laboratories-208 A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Jennifer S Hirschi
- Department of Chemistry, Binghamton University, Binghamton, New York, 13902, USA
| | - Apparao Draksharapu
- Southern Laboratories-208 A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
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5
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Li Y, Abelson C, Que L, Wang D. 10 6-fold faster C-H bond hydroxylation by a Co III,IV2(µ-O) 2 complex [via a Co III2(µ-O)(µ-OH) intermediate] versus its Fe IIIFe IV analog. Proc Natl Acad Sci U S A 2023; 120:e2307950120. [PMID: 38085777 PMCID: PMC10743362 DOI: 10.1073/pnas.2307950120] [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: 05/11/2023] [Accepted: 11/04/2023] [Indexed: 12/24/2023] Open
Abstract
The hydroxylation of C-H bonds can be carried out by the high-valent CoIII,IV2(µ-O)2 complex 2a supported by the tetradentate tris(2-pyridylmethyl)amine ligand via a CoIII2(µ-O)(µ-OH) intermediate (3a). Complex 3a can be independently generated either by H-atom transfer (HAT) in the reaction of 2a with phenols as the H-atom donor or protonation of its conjugate base, the CoIII2(µ-O)2 complex 1a. Resonance Raman spectra of these three complexes reveal oxygen-isotope-sensitive vibrations at 560 to 590 cm-1 associated with the symmetric Co-O-Co stretching mode of the Co2O2 diamond core. Together with a Co•••Co distance of 2.78(2) Å previously identified for 1a and 2a by Extended X-ray Absorption Fine Structure (EXAFS) analysis, these results provide solid evidence for their "diamond core" structural assignments. The independent generation of 3a allows us to investigate HAT reactions of 2a with phenols in detail, measure the redox potential and pKa of the system, and calculate the O-H bond strength (DO-H) of 3a to shed light on the C-H bond activation reactivity of 2a. Complex 3a is found to be able to transfer its hydroxyl ligand onto the trityl radical to form the hydroxylated product, representing a direct experimental observation of such a reaction by a dinuclear cobalt complex. Surprisingly, reactivity comparisons reveal 2a to be 106-fold more reactive in oxidizing hydrocarbon C-H bonds than corresponding FeIII,IV2(µ-O)2 and MnIII,IV2(µ-O)2 analogs, an unexpected outcome that raises the prospects for using CoIII,IV2(µ-O)2 species to oxidize alkane C-H bonds.
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Affiliation(s)
- Yan Li
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT59812
| | - Chase Abelson
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN55455
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN55455
| | - Dong Wang
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT59812
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6
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Sarkar A, Das S, Mondal P, Maiti B, Sen Gupta S. Synthesis, Characterization, and Reactivity of High-Valent Carbene Dicarboxamide-Based Nickel Pincer Complexes. Inorg Chem 2023. [PMID: 38001041 DOI: 10.1021/acs.inorgchem.3c03465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2023]
Abstract
High-valent metal-fluoride complexes are currently being explored for concerted proton-electron transfer (CPET) reactions, the driving force being the high bond dissociation energy of H-F (BDEH-F = 135 kcal/mol) that is formed after the reaction. Ni(III)-fluoride-based complexes on the pyridine dicarboxamide pincer ligand framework have been utilized for CPET reactions toward phenols and hydrocarbons. We have replaced the central pyridine ligand with an N-heterocyclic carbene carbene to probe its effect in both stabilizing the high-valent Ni(III) state and its ability to initiate CPET reactions. We report a monomeric carbene-diamide-based Ni(II)-fluoride pincer complex that was characterized through 1H/19F NMR, mass spectrometry, UV-vis, and X-ray crystallography analysis. Although carbenes and deprotonated carboxamides in the Ni(II)-fluoride complex are expected to stabilize the Ni(III) state upon oxidation, the Ni(III)/Ni(II) redox process occurred at very high potential (0.87 V vs Fc+/Fc, dichloromethane) and was irreversible. Structural studies indicate significant distortion in the imidazolium "NCN" carbene plane of Ni(II)-fluoride caused by the formation of six-membered metallacycles. The high-valent NiIII-fluoride analogue was synthesized by the addition of 1.0 equiv CTAN (ceric tetrabutylammonium nitrate) in dichloromethane at -20 °C which was characterized by UV-vis, mass spectrometry, and EPR spectroscopy. Density functional theory studies indicate that the Ni-carbene bond elongated, while the Ni-F bond shortened upon oxidation to the Ni(III) species. The high-valent Ni(III)-fluoride was found to react with the substituted phenols. Analysis of the KIE and linear free energy relationship correlates well with the CPET nature of the reaction. Preliminary analysis indicates that the CPET is asynchronous and is primarily driven by the E0' of the Ni(III)-fluoride complex.
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Affiliation(s)
- Aniruddha Sarkar
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur 741246, India
| | - Soumadip Das
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur 741246, India
| | - Prasenjit Mondal
- Department of Chemistry, Indian Institute of Technology Tirupati (IIT Tirupati), Tirupati, AP 517619, India
| | - Biswajit Maiti
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Sayam Sen Gupta
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur 741246, India
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7
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Nguyen BX, VandeVen W, MacNeil GA, Zhou W, Paterson AR, Walsby CJ, Chiang L. High-Valent Ni and Cu Complexes of a Tetraanionic Bis(amidateanilido) Ligand. Inorg Chem 2023; 62:15180-15194. [PMID: 37676794 DOI: 10.1021/acs.inorgchem.3c02358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
High-valent metal species are often invoked as intermediates during enzymatic and synthetic catalytic cycles. Anionic donors are often required to stabilize such high-valent states by forming strong bonds with the Lewis acidic metal centers while decreasing their oxidation potentials. In this report, we discuss the synthesis of two high-valent metal complexes [ML]+ in which the NiIII and CuIII centers are ligated by a new tetradentate, tetraanionic bis(amidateanilido) ligand. [ML]+, obtained via chemical oxidation of ML, exhibits UV-vis-NIR, EPR, and XANES spectra characteristic of square planar, high-valent MIII species, suggesting the locus of oxidation for both [ML]+ is predominantly metal-based. This is supported by theoretical analyses, which also support the observed visible transitions as ligand-to-metal charge transfer transitions characteristic of square planar, high-valent MIII species. Notably, [ML]+ can also be obtained via O2 oxidation of ML due to its remarkably negative oxidation potentials (CuL/[CuL]+: -1.16 V, NiL/[NiL]+: -1.01 V vs Fc/Fc+ in MeCN). This demonstrates the exceptionally strong donating nature of the tetraanionic bis(amidateanilido) ligation and its ability to stabilize high-valent metal centers..
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Affiliation(s)
- Bach X Nguyen
- Department of Chemistry, University of the Fraser Valley, Abbotsford, British Columbia V2S 7M8, Canada
- Department of Chemistry, Simon Fraser University, Burnaby, British Columba V5A 1S6, Canada
| | - Warren VandeVen
- Department of Chemistry, Simon Fraser University, Burnaby, British Columba V5A 1S6, Canada
| | - Gregory A MacNeil
- Department of Chemistry, Simon Fraser University, Burnaby, British Columba V5A 1S6, Canada
| | - Wen Zhou
- Department of Chemistry, Simon Fraser University, Burnaby, British Columba V5A 1S6, Canada
| | - Alisa R Paterson
- Canadian Light Source, 44 Innovation Boulevard, Saskatoon, Saskatchewan S7N 2 V3, Canada
| | - Charles J Walsby
- Department of Chemistry, Simon Fraser University, Burnaby, British Columba V5A 1S6, Canada
| | - Linus Chiang
- Department of Chemistry, University of the Fraser Valley, Abbotsford, British Columbia V2S 7M8, Canada
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8
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Titova YY. Dynamic EPR Studies of the Formation of Catalytically Active Centres in Multicomponent Hydrogenation Systems. Catalysts 2023. [DOI: 10.3390/catal13040653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
Abstract
The formation of catalytically active nano-sized cobalt-containing structures in multicomponent hydrogenation systems based on Co(acac)2 complex and various cocatalysts, namely, AlEt3, AlEt2(OEt), Li-n-Bu, and (PhCH2)MgCl, has been studied for the first time in detail using dynamic EPR spectroscopy. It is shown that after mixing the initial components, paramagnetic structures are formed, which include a fragment containing Co(0) with the electronic configuration 3d9, as well as a fragment bearing an aluminium, lithium, or magnesium atom, depending on the nature of the used cocatalyst. Such bimetallic paramagnetic sites are stabilized by acetylacetonate ligands. In addition, the paramagnetic complex contains the arene molecule(s), and the cobalt atom is bonded with the atom of the corresponding non-transition through the alkyl group of the co-catalyst, in particular through the carbon atom in the α-position with respect to the atom of the non-transition element. Due to the high reactivity of the described intermediates, they, under the conditions of hydrogenation catalysis, are transformed into nano-sized cobalt-containing structures that act as carriers of the catalytically active sites. Furthermore, because of the high reactivity and paramagnetism, such intermediates can be detected only by the EPR technique. The paper describes the whole experimental way of interpreting the EPR signals corresponding to the intermediates, precursors of catalytically active structures. In addition, a possible mathematical model based on the obtained experimental EPR data is presented.
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9
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Panda C, Anny-Nzekwue O, Doyle LM, Gericke R, McDonald AR. Evidence for a High-Valent Iron-Fluoride That Mediates Oxidative C(sp 3)-H Fluorination. JACS AU 2023; 3:919-928. [PMID: 37006763 PMCID: PMC10052241 DOI: 10.1021/jacsau.3c00021] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 02/14/2023] [Accepted: 02/15/2023] [Indexed: 06/19/2023]
Abstract
[FeII(NCCH3)(NTB)](OTf)2 (NTB = tris(2-benzimidazoylmethyl)amine, OTf = trifluoromethanesulfonate) was reacted with difluoro(phenyl)-λ3-iodane (PhIF2) in the presence of a variety of saturated hydrocarbons, resulting in the oxidative fluorination of the hydrocarbons in moderate-to-good yields. Kinetic and product analysis point towards a hydrogen atom transfer oxidation prior to fluorine radical rebound to form the fluorinated product. The combined evidence supports the formation of a formally FeIV(F)2 oxidant that performs hydrogen atom transfer followed by the formation of a dimeric μ-F-(FeIII)2 product that is a plausible fluorine atom transfer rebound reagent. This approach mimics the heme paradigm for hydrocarbon hydroxylation, opening up avenues for oxidative hydrocarbon halogenation.
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10
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Zhou A, Li XX, Sun D, Cao X, Wu Z, Chen H, Zhao Y, Nam W, Wang Y. Theoretical investigation on the elusive structure-activity relationship of bioinspired high-valence nickel-halogen complexes in oxidative fluorination reactions. Dalton Trans 2023; 52:1977-1988. [PMID: 36691931 DOI: 10.1039/d2dt03212k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Very recently, bioinspired high-valence metal-halogen complexes have been proven to be competent oxidants in the C-H bond activation and heteroatom dihalogenation reactions. However, the structure-activity relationship of such active species and the reaction mechanisms of oxidations mediated by these oxidants are still elusive. In this study, density functional theory (DFT) calculations were performed to systematically study the oxidizing ability of the high-valence NiIII-X (X = F and Cl) complexes Et4N[NiIII(Cl/F)(L)], (1Cl/F, Et = ethyl, L = N,N'-(2,6-dimethylphenyl)-2,6-pyridinedicarboxamide), such as the reaction mechanism of fluorination of 1,4-cyclohexadiene (CHD) by 1F in the presence of AgF and the reaction mechanism of difluorination of triphenyl phosphine (PPh3) by 1F. All calculated results fit well with the experiments and present new mechanistic findings. The C-H bond activation by the high-valence nickel(III)-halogen complexes was found to proceed via a hydrogen-atom transfer (HAT) mechanism by analysis of the molecular orbitals of the transition states. C-H bond activation by 1F takes a Ni-F-H angle of ca. 180°, whereas that by 1Cl takes an angle of ca. 120° on the transition states. These results indicate that the exchange-enhanced reactivity is responsible for the dramatic oxidative difference between these two oxidants. The role of AgF in C-H fluorination of CHD by 1F is proposed to act as a Lewis acid adduct, AgF-binding Ni(III)-fluorine complex 1F-Ag-F, which acts both as an oxidant in C-H bond activation and as a fluorine donor in the fluorination step. A cooperative oxidation mechanism involving two 1F oxidants was proposed for the difluorination of PPh3 by 1F. These theoretical findings will enrich the knowledge of high-valence metal-halogen chemistry and play a positive role in the rational design of new catalysts.
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Affiliation(s)
- Anran Zhou
- Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China. .,Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo 315211, China
| | - Xiao-Xi Li
- Institute of Molecular Science and Engineering, Institute of Frontier and Interdisciplinary Sciences, Shandong University, Qingdao 266237, China
| | - Dongru Sun
- Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China. .,Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo 315211, China
| | - Xuanyu Cao
- Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo 315211, China
| | - Zhimin Wu
- Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China. .,Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo 315211, China
| | - Huanhuan Chen
- Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China. .,Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo 315211, China
| | - Yufen Zhao
- Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China. .,Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo 315211, China
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.
| | - Yong Wang
- Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China. .,Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo 315211, China
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11
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Bower JK, Reese MS, Mazin IM, Zarnitsa LM, Cypcar AD, Moore CE, Sokolov AY, Zhang S. C(sp 3)-H cyanation by a formal copper(iii) cyanide complex. Chem Sci 2023; 14:1301-1307. [PMID: 36756315 PMCID: PMC9891353 DOI: 10.1039/d2sc06573h] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 01/05/2023] [Indexed: 01/18/2023] Open
Abstract
High-valent metal oxo complexes are prototypical intermediates for the activation and hydroxylation of alkyl C-H bonds. Substituting the oxo ligand with other functional groups offers the opportunity for additional C-H functionalization beyond C-O bond formation. However, few species aside from metal oxo complexes have been reported to both activate and functionalize alkyl C-H bonds. We herein report the first example of an isolated copper(iii) cyanide complex (LCuIIICN) and its C-H cyanation reactivity. We found that the redox potential (E ox) of substrates, instead of C-H bond dissociation energy, is a key determinant of the rate of PCET, suggesting an oxidative asynchronous CPET or ETPT mechanism. Among substrates with the same BDEs, those with low redox potentials transfer H atoms up to a million-fold faster. Capitalizing on this mechanistic insight, we found that LCuIIICN is highly selective for cyanation of amines, which is predisposed to oxidative asynchronous or stepwise transfer of H+/e-. Our study demonstrates that the asynchronous effect of PCET is an appealing tool for controlling the selectivity of C-H functionalization.
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Affiliation(s)
- Jamey K. Bower
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Maxwell S. Reese
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Ilia M. Mazin
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Lina M. Zarnitsa
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Andrew D. Cypcar
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Curtis E. Moore
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Alexander Yu. Sokolov
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Shiyu Zhang
- Department of Chemistry and Biochemistry, The Ohio State University 100 W. 18th Ave Columbus OH 43210 USA
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12
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Peng X, Rahim A, Peng W, Jiang F, Gu Z, Wen S. Recent Progress in Cyclic Aryliodonium Chemistry: Syntheses and Applications. Chem Rev 2023; 123:1364-1416. [PMID: 36649301 PMCID: PMC9951228 DOI: 10.1021/acs.chemrev.2c00591] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Indexed: 01/18/2023]
Abstract
Hypervalent aryliodoumiums are intensively investigated as arylating agents. They are excellent surrogates to aryl halides, and moreover they exhibit better reactivity, which allows the corresponding arylation reactions to be performed under mild conditions. In the past decades, acyclic aryliodoniums are widely explored as arylation agents. However, the unmet need for acyclic aryliodoniums is the improvement of their notoriously low reaction economy because the coproduced aryl iodides during the arylation are often wasted. Cyclic aryliodoniums have their intrinsic advantage in terms of reaction economy, and they have started to receive considerable attention due to their valuable synthetic applications to initiate cascade reactions, which can enable the construction of complex structures, including polycycles with potential pharmaceutical and functional properties. Here, we are summarizing the recent advances made in the research field of cyclic aryliodoniums, including the nascent design of aryliodonium species and their synthetic applications. First, the general preparation of typical diphenyl iodoniums is described, followed by the construction of heterocyclic iodoniums and monoaryl iodoniums. Then, the initiated arylations coupled with subsequent domino reactions are summarized to construct polycycles. Meanwhile, the advances in cyclic aryliodoniums for building biaryls including axial atropisomers are discussed in a systematic manner. Finally, a very recent advance of cyclic aryliodoniums employed as halogen-bonding organocatalysts is described.
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Affiliation(s)
- Xiaopeng Peng
- College
of Pharmacy, Key Laboratory of Prevention and Treatment of Cardiovascular
and Cerebrovascular Diseases, Ministry of Education, Jiangxi Province
Key Laboratory of Biomaterials and Biofabrication for Tissue Engineering, Gannan Medical University, Ganzhou341000, P.R. China
- State
Key Laboratory of Oncology in South China, Collaborative Innovation
Center for Cancer Medicine, Sun Yat-sen
University Cancer Center, 651 Dongfeng East Road, Guangzhou510060, P. R. China
| | - Abdur Rahim
- Department
of Chemistry, University of Science and
Technology of China, 96 Jinzhai Road, Hefei230026, P. R. China
| | - Weijie Peng
- College
of Pharmacy, Key Laboratory of Prevention and Treatment of Cardiovascular
and Cerebrovascular Diseases, Ministry of Education, Jiangxi Province
Key Laboratory of Biomaterials and Biofabrication for Tissue Engineering, Gannan Medical University, Ganzhou341000, P.R. China
| | - Feng Jiang
- College
of Pharmacy, Key Laboratory of Prevention and Treatment of Cardiovascular
and Cerebrovascular Diseases, Ministry of Education, Jiangxi Province
Key Laboratory of Biomaterials and Biofabrication for Tissue Engineering, Gannan Medical University, Ganzhou341000, P.R. China
| | - Zhenhua Gu
- Department
of Chemistry, University of Science and
Technology of China, 96 Jinzhai Road, Hefei230026, P. R. China
| | - Shijun Wen
- State
Key Laboratory of Oncology in South China, Collaborative Innovation
Center for Cancer Medicine, Sun Yat-sen
University Cancer Center, 651 Dongfeng East Road, Guangzhou510060, P. R. China
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13
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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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14
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Ionic Liquid Mediated Triple Catalysis for Alkylation and Methylation of Acyl Chlorides with Mechanistic Insight. J Catal 2022. [DOI: 10.1016/j.jcat.2022.10.013] [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]
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15
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Yadav V, Wen L, Rodriguez RJ, Siegler MA, Goldberg DP. Nonheme Iron(III) Azide and Iron(III) Isothiocyanate Complexes: Radical Rebound Reactivity, Selectivity, and Catalysis. J Am Chem Soc 2022; 144:20641-20652. [PMID: 36382466 PMCID: PMC10226418 DOI: 10.1021/jacs.2c07224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The new nonheme iron complexes FeII(BNPAPh2O)(N3) (1), FeIII(BNPAPh2O)(OH)(N3) (2), FeII(BNPAPh2O)(OH) (3), FeIII(BNPAPh2O)(OH)(NCS) (4), FeII(BNPAPh2O)(NCS) (5), FeIII(BNPAPh2O)(NCS)2 (6), and FeIII(BNPAPh2O)(N3)2 (7) (BNPAPh2O = 2-(bis((6-(neopentylamino)pyridin-2-yl) methyl)amino)-1,1-diphenylethanolate) were synthesized and characterized by single crystal X-ray diffraction (XRD), as well as by 1H NMR, 57Fe Mössbauer, and ATR-IR spectroscopies. Complex 2 was reacted with a series of carbon radicals, ArX3C· (ArX = p-X-C6H4), analogous to the proposed radical rebound step for nonheme iron hydroxylases and halogenases. The results show that for ArX3C· (X = Cl, H, tBu), only OH· transfer occurs to give ArX3COH. However, when X = OMe, a mixture of alcohol (ArX3COH) (30%) and azide (ArX3CN3) (40%) products was obtained. These data indicate that the rebound selectivity is influenced by the electron-rich nature of the carbon radicals for the azide complex. Reaction of 2 with Ph3C· in the presence of Sc3+ or H+ reverses the selectivity, giving only the azide product. In contrast to the mixed selectivity seen for 2, the reactivity of cis-FeIII(OH)(NCS) with the X = OMe radical derivative leads only to hydroxylation. Catalytic azidation was achieved with 1 as catalyst, λ3-azidoiodane as oxidant and azide source, and Ph3CH as test substrate, giving Ph3CN3 in 84% (TON = 8). These studies show that hydroxylation is favored over azidation for nonheme iron(III) complexes, but the nature of the carbon radical can alter this selectivity. If an OH· transfer pathway can be avoided, the FeIII(N3) complexes are capable of mediating both stoichiometric and catalytic azidation.
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Affiliation(s)
- Vishal Yadav
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
| | - Lyupeng Wen
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
| | - Rodolfo J. Rodriguez
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
| | - Maxime A. Siegler
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
| | - David P. Goldberg
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
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16
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Awasthi A, Leach IF, Engbers S, Kumar R, Eerlapally R, Gupta S, Klein JEMN, Draksharapu A. Formation and Reactivity of a Fleeting Ni III Bisphenoxyl Diradical Species. Angew Chem Int Ed Engl 2022; 61:e202211345. [PMID: 35978531 PMCID: PMC9826141 DOI: 10.1002/anie.202211345] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Indexed: 01/11/2023]
Abstract
Cytochrome P450s and Galactose Oxidases exploit redox active ligands to form reactive high valent intermediates for oxidation reactions. This strategy works well for the late 3d metals where accessing high valent states is rather challenging. Herein, we report the oxidation of NiII (salen) (salen=N,N'-bis(3,5-di-tert-butyl-salicylidene)-1,2-cyclohexane-(1R,2R)-diamine) with mCPBA (meta-chloroperoxybenzoic acid) to form a fleeting NiIII bisphenoxyl diradical species, in CH3 CN and CH2 Cl2 at -40 °C. Electrochemical and spectroscopic analyses using UV/Vis, EPR, and resonance Raman spectroscopies revealed oxidation events both on the ligand and the metal centre to yield a NiIII bisphenoxyl diradical species. DFT calculations found the electronic structure of the ligand and the d-configuration of the metal center to be consistent with a NiIII bisphenoxyl diradical species. This three electron oxidized species can perform hydrogen atom abstraction and oxygen atom transfer reactions.
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Affiliation(s)
- Ayushi Awasthi
- Southern Laboratories-208 ADepartment of ChemistryIndian Institute of Technology KanpurKanpur208016India
| | - Isaac F. Leach
- Molecular Inorganic ChemistryStratingh Institute for ChemistryUniversity of Groningen9747 AGGroningenThe Netherlands
| | - Silène Engbers
- Molecular Inorganic ChemistryStratingh Institute for ChemistryUniversity of Groningen9747 AGGroningenThe Netherlands
| | - Rakesh Kumar
- Southern Laboratories-208 ADepartment of ChemistryIndian Institute of Technology KanpurKanpur208016India
| | - Raju Eerlapally
- Southern Laboratories-208 ADepartment of ChemistryIndian Institute of Technology KanpurKanpur208016India
| | - Sikha Gupta
- Southern Laboratories-208 ADepartment of ChemistryIndian Institute of Technology KanpurKanpur208016India
| | - Johannes E. M. N. Klein
- Molecular Inorganic ChemistryStratingh Institute for ChemistryUniversity of Groningen9747 AGGroningenThe Netherlands
| | - Apparao Draksharapu
- Southern Laboratories-208 ADepartment of ChemistryIndian Institute of Technology KanpurKanpur208016India
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17
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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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18
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Awasthi A, Leach IF, Engbers S, Kumar R, Eerlapally R, Gupta S, Klein JEMN, Draksharapu A. Formation and Reactivity of a Fleeting Ni(III) Bisphenoxyl Diradical Species. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202211345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - Isaac F. Leach
- University of Groningen Zernike Institute for Advanced Materials: Rijksuniversiteit Groningen Zernike Institute for Advanced Materials Stratingh Institute for Chemistry NETHERLANDS
| | - Silène Engbers
- University of Groningen Zernike Institute for Advanced Materials: Rijksuniversiteit Groningen Zernike Institute for Advanced Materials Stratingh Institute for Chemistry NETHERLANDS
| | - Rakesh Kumar
- Indian Institute of Technology Kanpur Chemistry INDIA
| | | | - Sikha Gupta
- Indian Institute of Technology Kanpur Chemistry INDIA
| | - Johannes E. M. N. Klein
- University of Groningen Zernike Institute for Advanced Materials: Rijksuniversiteit Groningen Zernike Institute for Advanced Materials Stratingh Institute for Chemistry NETHERLANDS
| | - Apparao Draksharapu
- IITK: Indian Institute of Technology Kanpur Chemistry SL-208A 208016 Kanpur INDIA
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19
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Kwon YM, Lee Y, Schmautz AK, Jackson TA, Wang D. C-H Bond Activation by a Mononuclear Nickel(IV)-Nitrate Complex. J Am Chem Soc 2022; 144:12072-12080. [PMID: 35767834 DOI: 10.1021/jacs.2c02454] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The recent focus on developing high-valent non-oxo-metal complexes for late transition metals has proven to be an effective strategy to study the rich chemistry of these high-valent species while bypassing the synthetic challenges of obtaining the oxo-metal counterparts. In our continuing work of exploring late transition metal complexes of unusually high oxidation states, we have obtained in the present study a formal mononuclear Ni(IV)-nitrate complex (2) upon 1-e- oxidation of its Ni(III) derivatives (1-OH and 1-NO3). Characterization of these Ni complexes by combined spectroscopic and computational approaches enables deep understanding of their geometric and electronic structures, bonding interactions, and spectroscopic properties, showing that all of them are square planar complexes and exhibit strong π-covalency with the amido N-donors of the N3 ligand. Furthermore, results obtained from X-ray absorption spectroscopy and density functional theory calculations provide strong support for the assignment of the Ni(IV) oxidation state of complex 2, albeit with strong ligand-to-metal charge donation. Notably, 2 is able to oxidize hydrocarbons with C-H bond strength in the range of 76-92 kcal/mol, representing a rare example of high-valent late transition metal complexes capable of activating strong sp3 C-H bonds.
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Affiliation(s)
- Yubin M Kwon
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana 59812, United States
| | - Yuri Lee
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Anna K Schmautz
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana 59812, United States
| | - Timothy A Jackson
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Dong Wang
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana 59812, United States
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20
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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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21
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Park Y, Kim S, Kim K, Shin B, Jang Y, Cho KB, Cho J. Structure and Reactivity of Nonporphyrinic Terminal Manganese(IV)-Hydroxide Complexes in the Oxidative Electrophilic Reaction. Inorg Chem 2022; 61:4292-4301. [PMID: 35226491 DOI: 10.1021/acs.inorgchem.1c03104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
High-valent transition metal-hydroxide complexes have been proposed as essential intermediates in biological and synthetic catalytic reactions. In this work, we report the single-crystal X-ray structure and spectroscopic characteristics of a mononuclear nonporphyrinic MnIV-(OH) complex, [MnIV(Me3-TPADP)(OH)(OCH2CH3)]2+ (2), using various physicochemical methods. Likewise, [MnIV(Me3-TPADP)(OH)(OCH2CF3)]2+ (3), which is thermally stable at room temperature, was also synthesized and characterized spectroscopically. The MnIV-(OH) adducts are capable of performing oxidation reactions with external organic substrates such as C-H bond activation, sulfoxidation, and epoxidation. Kinetic studies, involving the Hammett correlation and kinetic isotope effect, and product analyses indicate that 2 and 3 exhibit electrophilic oxidative reactivity toward hydrocarbons. Density functional theory calculations support the assigned electronic structure and show that direct C-H bond activation of the MnIV-(OH) species is indeed possible.
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Affiliation(s)
- Younwoo Park
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea.,Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Seonghan Kim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea.,Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Kyungmin Kim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea.,Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Bongki Shin
- Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Youngchae Jang
- Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Kyung-Bin Cho
- Department of Chemistry, Jeonbuk National University, Jeonju 54896, Korea
| | - Jaeheung Cho
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea
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22
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Lee JL, Biswas S, Sun C, Ziller JW, Hendrich MP, Borovik AS. Bioinspired Di-Fe Complexes: Correlating Structure and Proton Transfer over Four Oxidation States. J Am Chem Soc 2022; 144:4559-4571. [PMID: 35192354 DOI: 10.1021/jacs.1c12888] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Metalloproteins with active sites containing di-Fe cores exhibit diverse chemical reactivity that is linked to the precise transfer of protons and electrons which directly involve the di-Fe units. The redox conversions are commonly corroborated by spectroscopic methods, but the associated structural changes are often difficult to assess, particularly those related to proton movements. This report describes the development of di-Fe complexes in which the movements of protons and electrons are pinpointed during the stepwise oxidation of a di-FeII species to one with an FeIIIFeIV core. Complex formation was promoted using the phosphinic amido tripodal ligand [poat]3- (N,N',N″-[nitrilotris(ethane-2,1-diyl)]tris(P,P-diphenylphosphinic amido)) that provided dynamic coordination spheres that assisted in regulating both electron and proton transfer processes. Oxidation of an [FeII-(μ-OH)-FeIII] complex led to the corresponding di-FeIII species containing a hydroxido bridge that was not stable at room temperature and converted to a species containing an oxido bridging ligand and protonation of one phosphinic amido group to form [Hpoat]2-. Deprotonation led to a new species with an [FeIII-(μ-O)-FeIII] core that could be further oxidized to its FeIIIFeIV analogue. Reactions with phenols suggest homolytic cleavage of the O-H bond to give products that are consistent with the initial formation of a phenoxyl radical─spectroscopic studies indicated that the electron is transferred to the FeIV center, and the proton is initially transferred to the more sterically hindered oxido ligand but then relocates to [poat]3-. These findings offer new mechanistic insights related to the stability of and the reactions performed by di-Fe enzymes.
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Affiliation(s)
- Justin L Lee
- Department of Chemistry, University of California,1102 Natural Sciences II, Irvine, California 92697, United States
| | - Saborni Biswas
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Chen Sun
- Department of Chemistry, University of California,1102 Natural Sciences II, Irvine, California 92697, United States
| | - Joseph W Ziller
- Department of Chemistry, University of California,1102 Natural Sciences II, Irvine, California 92697, United States
| | - Michael P Hendrich
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - A S Borovik
- Department of Chemistry, University of California,1102 Natural Sciences II, Irvine, California 92697, United States
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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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Spedalotto G, Lovisari M, McDonald AR. Reactivity Properties of Mixed- and High-Valent Bis(μ-Hydroxide)-Dinickel Complexes. ACS OMEGA 2021; 6:28162-28170. [PMID: 34723014 PMCID: PMC8554787 DOI: 10.1021/acsomega.1c04225] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/22/2021] [Indexed: 06/13/2023]
Abstract
Despite their potential role in enzymatic systems, there is a dearth of hydroxide-bridged high-valent oxidants. We recently reported the synthesis and characterization of NiIINiIII(μ-OH)2 (2) and Ni2 III(μ-OH)2 (3) species supported by a dicarboxamidate ligand (N,N'-bis(2,6-dimethyl-phenyl)-2,2-dimethylmalonamide). Herein, we explore the oxidative reactivity of these species using a series of para-substituted 2,6-di-tert-butyl-phenols (4-X-2,6-DTBP, X = -OCH3, -CH2CH3, -CH3, -C(CH3)3, -H, -Br, -CN, and -NO2) as a mechanistic probe. Interestingly, upon reaction of 3 with the substrates, the formation of a new transient species, 2', was observed. 2' is postulated to be a protic congener of 2. All three species were demonstrated to react with the substituted phenols through a hydrogen atom transfer reaction mechanism, which was elucidated further by analysis of the postreaction mixtures. Critically, 3 was demonstrated to react at far superior rates to 2 and 2', and oxidized substrates more efficiently than any bis-μ-oxo-Ni2 III reported to date. The kinetic superiority of 3 with respect to 2 and 2' was attributed to a stronger bond in the product of oxidation by 3 when compared to those calculated for 2 and 2'.
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25
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Lovisari M, Gericke R, Twamley B, McDonald AR. Comparing Metal-Halide and -Oxygen Adducts in Oxidative C/O-H Activation: Au III-Cl versus Au III-OH. Inorg Chem 2021; 60:15610-15616. [PMID: 34582177 PMCID: PMC8527453 DOI: 10.1021/acs.inorgchem.1c02222] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
![]()
High-valent metal–halides
have come to prominence as highly
effective oxidants. A direct comparison of their efficacy against
that of traditional metal–oxygen adducts is needed. [AuIII(Cl)(terpy)](ClO4)2 (1; terpy = 2,2′:6′,2-terpyridine) readily oxidized substrates bearing O–H and C–H bonds
via a hydrogen atom transfer mechanism. A direct comparison with [AuIII(OH)(terpy)](ClO4)2 (2) showed that 1 was a kinetically superior oxidant with
respect to 2 for all substrates tested. We ascribe this
to the greater thermodynamic driving force imbued by the Cl ligand
versus the OH ligand. We report a
direct comparison of the efficacy of metal−halide
oxidants to those of traditional metal−oxygen adducts. AuIII−Cl and AuIII−OH oxidants, supported
by the same ancillary ligand, readily oxidized substrates via a hydrogen
atom transfer mechanism. The AuIII−Cl oxidant was
kinetically superior for all substrates. We ascribed this to the greater
thermodynamic driving force imbued by the Cl ligand versus the OH
ligand.
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Affiliation(s)
- Marta Lovisari
- 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
| | - Brendan Twamley
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Aidan R McDonald
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
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26
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Chi H, Wan J, Zhou X, Sun J, Yan B. Fe@C activated peroxymonosulfate system for effectively degrading emerging contaminants: Analysis of the formation and activation mechanism of Fe coordinately unsaturated metal sites. JOURNAL OF HAZARDOUS MATERIALS 2021; 419:126535. [PMID: 34218190 DOI: 10.1016/j.jhazmat.2021.126535] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 06/22/2021] [Accepted: 06/26/2021] [Indexed: 06/13/2023]
Abstract
Carbon-encapsulated Fe nanocomposites (Fe@C), obtained by pyrolysis of metal-organic frameworks (MOFs), can activate peroxymonosulfate (PMS) to remove emerging contaminants (ECs). Unfortunately, the current MOFs-derived catalysts always inevitably produce more iron-oxide compounds that unfavorable for PMS activation. In this work, according to the thermogravimetric curve of Fe(II)-MOF-74, to discuss the role of pyrolysis temperature on the structural characteristics of Fe@C. The results demonstrated that Fe@C-4 could obtain abundant coordinately unsaturated metal sites and exhibited the best activation performance. Radical-quenching experiments and EPR measurements confirm that the generated sulfate radical (SO4-˙) and singlet oxygen (1O2) only degraded approximately 35% of TBBPA. Meanwhile, negatively charged complex intermediates formed by the weak interaction between Fe@C-4 and PMS was proposed as the dominant reactive species, and approximately 65% of TBBPA was degraded. This work optimizes the synthesis strategy and mechanism of Fe@C and provides a methodological reference for the design of Fe-based catalysts.
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Affiliation(s)
- Haiyuan Chi
- Institute of Environmental Research at Greater Bay Area, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006, China.
| | - Jinquan Wan
- College of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Xiaoxia Zhou
- Institute of Environmental Research at Greater Bay Area, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006, China.
| | - Jian Sun
- College of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Bing Yan
- Institute of Environmental Research at Greater Bay Area, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006, China
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27
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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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28
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Na H, Watson MB, Tang F, Rath NP, Mirica LM. Photoreductive chlorine elimination from a Ni(iii)Cl 2 complex supported by a tetradentate pyridinophane ligand. Chem Commun (Camb) 2021; 57:7264-7267. [PMID: 34195702 DOI: 10.1039/d1cc02114a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein we report the isolation, characterization, and photoreactivity of a stable NiIII dichloride complex supported by a tetradentate pyridinophane N-donor ligand. Upon irradiation, this complex undergoes an efficient photoreductive chlorine elimination reaction, both in solution and the solid-state. Subsequently, the NiIIICl2 species can be regenerated via a reaction with PhICl2.
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Affiliation(s)
- Hanah Na
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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29
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Kariofillis SK, Doyle AG. Synthetic and Mechanistic Implications of Chlorine Photoelimination in Nickel/Photoredox C(sp 3)-H Cross-Coupling. Acc Chem Res 2021; 54:988-1000. [PMID: 33511841 DOI: 10.1021/acs.accounts.0c00694] [Citation(s) in RCA: 105] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In recent years, the development of light-driven reactions has contributed numerous advances in synthetic organic chemistry. A particularly active research area combines photoredox catalysis with nickel catalysis to accomplish otherwise inaccessible cross-coupling reactions. In these reactions, the photoredox catalyst absorbs light to generate an electronically excited charge-transfer state that can engage in electron or energy transfer with a substrate and the nickel catalyst. Our group questioned whether photoinduced activation of the nickel catalyst itself could also contribute new approaches to cross-coupling. Over the past 5 years, we have sought to advance this hypothesis for the development of a suite of mild and site-selective C(sp3)-H cross-coupling reactions with chloride-containing coupling partners via photoelimination of a Ni-Cl bond.On the basis of a report from the Nocera laboratory, we reasoned that photolysis of a Ni(III) aryl chloride species, generated by single-electron oxidation of a typical Ni(II) intermediate in cross-coupling, might allow for the catalytic generation of chlorine atoms. Combining this with the ability of Ni(II) to accept alkyl radicals, we hypothesized that photocatalytically generated chlorine atoms could mediate hydrogen atom transfer (HAT) with C(sp3)-H bonds to generate a substrate-derived alkyl radical that is captured by the Ni center in cross-coupling. A photoredox catalyst was envisioned to promote the necessary single-electron oxidation and reduction of the Ni catalyst to facilitate an overall redox-neutral process. Overall, this strategy would offer a visible-light-driven mechanism for chlorine radical formation enabled by the sequential capture of two photons.As an initial demonstration, we developed a Ni/photoredox-catalyzed α-oxy C(sp3)-H arylation of cyclic and acyclic ethers. This method was extended to a mild formylation of abundant and complex aryl chlorides through selective 2-functionalization of 1,3-dioxolane. Seeking to develop a suite of reactions that introduce carbon at all different oxidation states, we explored C(sp3)-H cross-coupling with trimethyl orthoformate, a common laboratory solvent. We found that trimethyl orthoformate serves as a source of methyl radical for a methylation reaction via β-scission from a tertiary radical generated upon chlorine-mediated HAT. Since chlorine radical is capable of abstracting unactivated C(sp3)-H bonds, our efforts have also been directed at cross-coupling with a range of feedstock chemicals, such as alkanes and toluenes, along with late-stage intermediates, using chloroformates as coupling partners. Overall, this platform enables access to valuable synthetic transformations with (hetero)aryl chlorides, which despite being the most ubiquitous and inexpensive aryl halide coupling partners, are rarely reactive in Ni/photoredox catalysis.Little is known about the photophysics and photochemistry of organometallic Ni complexes relevant to cross-coupling. We have conducted mechanistic investigations, including computational, spectroscopic, emission quenching, and stoichiometric oxidation studies, of Ni(II) aryl halide complexes common to Ni/photoredox reactions. These studies indicate that chlorine radical generation from excited Ni(III) is operative in the described C(sp3)-H functionalization methods. More generally, the studies illustrate that the photochemistry of cross-coupling catalysts cannot be ignored in metallaphotoredox reactions. We anticipate that further mechanistic understanding should facilitate new catalyst design and lead to the development of new synthetic methods.
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Affiliation(s)
- Stavros K. Kariofillis
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Abigail G. Doyle
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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30
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Zhao N, Filatov AS, Xie J, Hill EA, Rogachev AY, Anderson JS. Generation and Reactivity of a Ni III2(μ-1,2-peroxo) Complex. J Am Chem Soc 2020; 142:21634-21639. [PMID: 33320644 DOI: 10.1021/jacs.0c10958] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
High-valent transition metal-oxo, -peroxo, and -superoxo complexes are crucial intermediates in both biological and synthetic oxidation of organic substrates, water oxidation, and oxygen reduction. While high-valent oxygenated complexes of Mn, Fe, Co, and Cu are increasingly well-known, high-valent oxygenated Ni complexes are comparatively rarer. Herein we report the isolation of such an unusual high-valent species in a thermally unstable NiIII2(μ-1,2-peroxo) complex, which has been characterized using single-crystal X-ray diffraction and X-ray absorption, NMR, and UV-vis spectroscopies. Reactivity studies show that this complex is stable toward dissociation of oxygen but reacts with simple nucleophiles and electrophiles.
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Affiliation(s)
- Norman Zhao
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Alexander S Filatov
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Jiaze Xie
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Ethan A Hill
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - Andrey Yu Rogachev
- Department of Chemistry, Illinois Institute of Technology, Chicago, Illinois 60616, United States
| | - John S Anderson
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
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31
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Song P, Zhu S. Nickel-Catalyzed Hydrofluorination of Unactivated Alkenes through a HAT Pathway. ACS Catal 2020. [DOI: 10.1021/acscatal.0c03884] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Peihong Song
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, People’s Republic of China
| | - Shaolin Zhu
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, People’s Republic of China
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32
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Gericke R, Doyle LM, Farquhar ER, McDonald AR. Oxo-Free Hydrocarbon Oxidation by an Iron(III)-Isoporphyrin Complex. Inorg Chem 2020; 59:13952-13961. [PMID: 32955871 DOI: 10.1021/acs.inorgchem.0c01618] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Metal-halides that perform proton coupled electron-transfer (PCET) oxidation are an important new class of high-valent oxidant. In investigating metal-dihalides, we reacted [FeIII(Cl)(T(OMe)PP)] (1, T(OMe)PP = meso-tetra(4-methoxyphenyl)porphyrinyl) with (dichloroiodo)benzene. An FeIII-meso-chloro-isoporphyrin complex [FeIII(Cl)2(T(OMe)PP-Cl)] (2) was obtained. 2 was characterized by electronic absorption, 1H NMR, EPR, and X-ray absorption spectroscopies and mass spectrometry with support from computational analyses. 2 was reacted with a series of hydrocarbon substrates. The measured kinetic data exhibited a nonlinear behavior, whereby the oxidation followed a hydrogen-atom-transfer (HAT) PCET mechanism. The meso-chlorine atom was identified as the HAT agent. In one case, a halogenated product was identified by mass spectrometry. Our findings demonstrate that oxo-free hydrocarbon oxidation with heme systems is possible and show the potential for iron-dihalides in oxidative hydrocarbon halogenation.
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Affiliation(s)
- Robert Gericke
- School of Chemistry, College Green, Trinity College Dublin, The University of Dublin, Dublin 2 D02 PN40, Ireland
| | - Lorna M Doyle
- School of Chemistry, College Green, Trinity College Dublin, The University of Dublin, Dublin 2 D02 PN40, Ireland
| | - Erik R Farquhar
- National Synchrotron Light Source II, Brookhaven National Laboratory, Case Western Reserve University Center for Synchrotron Biosciences, Upton, New York 11973, United States
| | - Aidan R McDonald
- School of Chemistry, College Green, Trinity College Dublin, The University of Dublin, Dublin 2 D02 PN40, Ireland
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33
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Lee GS, Won J, Choi S, Baik M, Hong SH. Synergistic Activation of Amides and Hydrocarbons for Direct C(sp
3
)–H Acylation Enabled by Metallaphotoredox Catalysis. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202004441] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Geun Seok Lee
- Department of Chemistry Korean Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Department of Chemistry College of Natural Sciences Seoul National University Seoul 08826 Republic of Korea
| | - Joonghee Won
- Department of Chemistry Korean 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
| | - Seulhui Choi
- Department of Chemistry Korean 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
| | - Mu‐Hyun Baik
- Department of Chemistry Korean 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
| | - Soon Hyeok Hong
- Department of Chemistry Korean Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
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34
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Mondal P, McDonald AR. Phenol Oxidation by a Nickel(III)-Fluoride Complex: Exploring the Influence of the Proton Accepting Ligand in PCET Oxidation. Chemistry 2020; 26:10083-10089. [PMID: 32567726 DOI: 10.1002/chem.202002135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/15/2020] [Indexed: 11/05/2022]
Abstract
In order to gain insight into the influence of the H+ -accepting terminal ligand in high-valent oxidant mediated proton coupled electron transfer (PCET) reactions, the reactivity of a high valent nickel-fluoride complex [NiIII (F)(L)] (2, L=N,N'-(2,6-dimethylphenyl)-2,6-pyridinecarboxamidate) with substituted phenols was explored. Analysis of kinetic data from these reactions (Evans-Polanyi, Hammett, and Marcus plots, and KIE measurements) and the formed products show that 2 reacted with electron rich phenols through a hydrogen atom transfer (HAT, or concerted PCET) mechanism and with electron poor phenols through a stepwise proton transfer/electron transfer (PT/ET) reaction mechanism. The analogous complexes [NiIII (Z)(L)] (Z=Cl, OCO2 H, O2 CCH3 , ONO2 ) reacted with all phenols through a HAT mechanism. We explore the reason for a change in mechanism with the highly basic fluoride ligand in 2. Complex 2 was also found to react one to two orders of magnitude faster than the corresponding analogous [NiIII (Z)(L)] complexes. This was ascribed to a high bond dissociation free energy value associated with H-F (135 kcal mol-1 ), which is postulated to be the product formed from PCET oxidation by 2 and is believed to be the driving force for the reaction. Our findings show that high-valent metal-fluoride complexes represent a class of highly reactive PCET oxidants.
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Affiliation(s)
- Prasenjit Mondal
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin, 2, Ireland
| | - Aidan R McDonald
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin, 2, Ireland
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35
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Kwon YM, Lee Y, Evenson GE, Jackson TA, Wang D. Crystal Structure and C-H Bond-Cleaving Reactivity of a Mononuclear Co IV-Dinitrate Complex. J Am Chem Soc 2020; 142:13435-13441. [PMID: 32639730 PMCID: PMC7429286 DOI: 10.1021/jacs.0c04368] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
High-valent FeIV═O intermediates with a terminal metal-oxo moiety are key oxidants in many enzymatic and synthetic C-H bond oxidation reactions. While generating stable metal-oxo species for late transition metals remains synthetically challenging, notably, a number of high-valent non-oxo-metal species of late transition metals have been recently described as strong oxidants that activate C-H bonds. In this work, we obtained an unprecedented mononuclear CoIV-dinitrate complex (2) upon one-electron oxidation of its Co(III) precursor supported by a tridentate dianionic N3 ligand. 2 was structurally characterized by X-ray crystallography, showing a square pyramidal geometry with two coordinated nitrate anions. Furthermore, characterization of 2 using combined spectroscopic and computational methods revealed that 2 is a low-spin (S = 1/2) Co(IV) species with the unpaired electron located on the cobalt dz2 orbital, which is well positioned for substrate oxidations. Indeed, while having a high thermal stability, 2 is able to cleave sp3 C-H bonds up to 87 kcal/mol to afford rate constants and kinetic isotope effects (KIEs) of 2-6 that are comparable to other high-valent metal oxidants. The ability to oxidize strong C-H bonds has yet to be observed for CoIV-O and CoIII═O species previously reported. Therefore, 2 represents the first high-valent Co(IV) species that is both structurally characterized by X-ray crystallography and capable of activating strong C-H bonds.
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Affiliation(s)
- Yubin M. Kwon
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana 59803, United States
| | - Yuri Lee
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, The University of Kansas, Kansas 66045, United States
| | - Garrett E. Evenson
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana 59803, United States
| | - Timothy A. Jackson
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, The University of Kansas, Kansas 66045, United States
| | - Dong Wang
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana 59803, United States
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36
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Panda C, Sarkar A, Sen Gupta S. Coordination chemistry of carboxamide ‘Nx’ ligands to metal ions for bio-inspired catalysis. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213314] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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37
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Lee GS, Won J, Choi S, Baik M, Hong SH. Synergistic Activation of Amides and Hydrocarbons for Direct C(sp
3
)–H Acylation Enabled by Metallaphotoredox Catalysis. Angew Chem Int Ed Engl 2020; 59:16933-16942. [DOI: 10.1002/anie.202004441] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 05/26/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Geun Seok Lee
- Department of Chemistry Korean Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Department of Chemistry College of Natural Sciences Seoul National University Seoul 08826 Republic of Korea
| | - Joonghee Won
- Department of Chemistry Korean 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
| | - Seulhui Choi
- Department of Chemistry Korean 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
| | - Mu‐Hyun Baik
- Department of Chemistry Korean 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
| | - Soon Hyeok Hong
- Department of Chemistry Korean Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
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38
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Mondal P, Lovisari M, Twamley B, McDonald AR. Fast Hydrocarbon Oxidation by a High‐Valent Nickel–Fluoride Complex. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202004639] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Prasenjit Mondal
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
| | - Marta Lovisari
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
| | - Brendan Twamley
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
| | - Aidan R. McDonald
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
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39
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Mondal P, Lovisari M, Twamley B, McDonald AR. Fast Hydrocarbon Oxidation by a High‐Valent Nickel–Fluoride Complex. Angew Chem Int Ed Engl 2020; 59:13044-13050. [DOI: 10.1002/anie.202004639] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Indexed: 11/11/2022]
Affiliation(s)
- Prasenjit Mondal
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
| | - Marta Lovisari
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
| | - Brendan Twamley
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
| | - Aidan R. McDonald
- School of Chemistry Trinity College Dublin The University of Dublin College Green Dublin 2 Ireland
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40
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Bower JK, Cypcar AD, Henriquez B, Stieber SCE, Zhang S. C(sp 3)-H Fluorination with a Copper(II)/(III) Redox Couple. J Am Chem Soc 2020; 142:8514-8521. [PMID: 32275410 DOI: 10.1021/jacs.0c02583] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Despite the growing interest in the synthesis of fluorinated organic compounds, few reactions are able to incorporate fluoride ions directly into alkyl C-H bonds. Here, we report the C(sp3)-H fluorination reactivity of a formally copper(III) fluoride complex. The C-H fluorination intermediate, LCuF, along with its chloride and bromide analogues, LCuCl and LCuBr, were prepared directly from halide sources with a chemical oxidant and fully characterized with single-crystal X-ray diffraction, X-ray absorption spectroscopy, UV-vis spectroscopy, and 1H nuclear magnetic resonance spectroscopy. Quantum chemical calculations reveal significant halide radical character for all complexes, suggesting their ability to initiate and terminate a C(sp3)-H halogenation sequence by sequential hydrogen atom abstraction (HAA) and radical capture. The capability of HAA by the formally copper(III) halide complexes was explored with 9,10-dihydroanthracene, revealing that LCuF exhibits rates 2 orders of magnitude higher than LCuCl and LCuBr. In contrast, all three complexes efficiently capture carbon radicals to afford C(sp3)-halogen bonds. Mechanistic investigation of radical capture with a triphenylmethyl radical revealed that LCuF proceeds through a concerted mechanism, while LCuCl and LCuBr follow a stepwise electron transfer-halide transfer pathway. The capability of LCuF to perform both hydrogen atom abstraction and radical capture was leveraged to enable fluorination of allylic and benzylic C-H bonds and α-C-H bonds of ethers at room temperature.
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Affiliation(s)
- Jamey K Bower
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Andrew D Cypcar
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Brenda Henriquez
- Department of Chemistry & Biochemistry, California State Polytechnic University, Pomona, 3801 West Temple Avenue, Pomona, California 91768, United States
| | - S Chantal E Stieber
- Department of Chemistry & Biochemistry, California State Polytechnic University, Pomona, 3801 West Temple Avenue, Pomona, California 91768, United States
| | - Shiyu Zhang
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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41
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Fisher KJ, Feuer ML, Lant HMC, Mercado BQ, Crabtree RH, Brudvig GW. Concerted proton-electron transfer oxidation of phenols and hydrocarbons by a high-valent nickel complex. Chem Sci 2020; 11:1683-1690. [PMID: 32206289 PMCID: PMC7069233 DOI: 10.1039/c9sc05565g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 12/29/2019] [Indexed: 12/21/2022] Open
Abstract
The high-valent nickel(iii) complex Ni(pyalk)2 + (2) was prepared by oxidation of a nickel(ii) complex, Ni(pyalk)2 (1) (pyalk = 2-pyridyl-2-propanoate). 2 and derivatives were fully characterized by mass spectrometry and X-ray crystallography. Electron paramagnetic resonance spectroscopy and X-ray photoelectron spectroscopy confirm that the oxidation is metal-centered. 2 was found to react with a variety of phenolic and hydrocarbon substrates. A linear correlation between the measured rate constant and the substrate bond dissociation enthalpy (BDE) was found for both phenolic and hydrocarbon substrates. Large H/D kinetic isotope effects were also observed for both sets of substrates. These results suggest that 2 reacts through concerted proton-electron transfer (CPET). Analysis of measured thermodynamic parameters allows us to calculate a bond dissociation free energy (BDFE) of ∼91 kcal mol-1 for the O-H bond of the bound pyalk ligand. These findings may shed light onto CPET steps in oxidative catalysis and have implications for ligand design in catalytic systems.
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Affiliation(s)
- Katherine J Fisher
- Department of Chemistry , Yale University , New Haven , CT 06520 , USA . ;
| | - Margalit L Feuer
- Department of Chemistry , Yale University , New Haven , CT 06520 , USA . ;
| | - Hannah M C Lant
- Department of Chemistry , Yale University , New Haven , CT 06520 , USA . ;
| | - Brandon Q Mercado
- Department of Chemistry , Yale University , New Haven , CT 06520 , USA . ;
| | - Robert H Crabtree
- Department of Chemistry , Yale University , New Haven , CT 06520 , USA . ;
| | - Gary W Brudvig
- Department of Chemistry , Yale University , New Haven , CT 06520 , USA . ;
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42
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Unjaroen D, Gericke R, Lovisari M, Nelis D, Mondal P, Pirovano P, Twamley B, Farquhar ER, McDonald AR. High-Valent d 7 Ni III versus d 8 Cu III Oxidants in PCET. Inorg Chem 2019; 58:16838-16848. [PMID: 31804808 DOI: 10.1021/acs.inorgchem.9b03101] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Oxygenases have been postulated to utilize d4 FeIV and d8 CuIII oxidants in proton-coupled electron transfer (PCET) hydrocarbon oxidation. In order to explore the influence the metal ion and d-electron count can hold over the PCET reactivity, two metastable high-valent metal-oxygen adducts, [NiIII(OAc)(L)] (1b) and [CuIII(OAc)(L)] (2b), L = N,N'-(2,6-diisopropylphenyl)-2,6-pyridinedicarboxamidate, were prepared from their low-valent precursors [NiII(OAc)(L)]- (1a) and [CuII(OAc)(L)]- (2a). The complexes 1a/b-2a/b were characterized using nuclear magnetic resonance, Fourier transform infrared, electron paramagnetic resonance, X-ray diffraction, and absorption spectroscopies and mass spectrometry. Both complexes were capable of activating substrates through a concerted PCET mechanism (hydrogen atom transfer, HAT, or concerted proton and electron transfer, CPET). The reactivity of 1b and 2b toward a series of para-substituted 2,6-di-tert-butylphenols (p-X-2,6-DTBP; X = OCH3, C(CH3)3, CH3, H, Br, CN, NO2) was studied, showing similar rates of reaction for both complexes. In the oxidation of xanthene, the d8 CuIII oxidant displayed a small increase in the rate constant compared to that of the d7 NiIII oxidant. The d8 CuIII oxidant was capable of oxidizing a large family of hydrocarbon substrates with bond dissociation enthalpy (BDEC-H) values up to 90 kcal/mol. It was previously observed that exchanging the ancillary anionic donor ligand in such complexes resulted in a 20-fold enhancement in the rate constant, an observation that is further enforced by comparison of 1b and 2b to the literature precedents. In contrast, we observed only minor differences in the rate constants upon comparing 1b to 2b. It was thus concluded that in this case the metal ion has a minor impact, while the ancillary donor ligand yields more kinetic control over HAT/CPET oxidation.
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Affiliation(s)
- Duenpen Unjaroen
- 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
| | - Marta Lovisari
- School of Chemistry, Trinity College Dublin , The University of Dublin , College Green , Dublin 2 , Ireland
| | - Daniel Nelis
- School of Chemistry, Trinity College Dublin , The University of Dublin , College Green , Dublin 2 , Ireland
| | - Prasenjit Mondal
- School of Chemistry, Trinity College Dublin , The University of Dublin , College Green , Dublin 2 , Ireland
| | - Paolo Pirovano
- School of Chemistry, Trinity College Dublin , The University of Dublin , College Green , Dublin 2 , Ireland
| | - Brendan Twamley
- School of Chemistry, Trinity College Dublin , The University of Dublin , College Green , Dublin 2 , Ireland
| | - Erik R Farquhar
- Case Western Reserve University Center for Synchrotron Biosciences, National Synchrotron Light Source II , Brookhaven National Laboratory II , Upton , New York 11973 , United States
| | - Aidan R McDonald
- School of Chemistry, Trinity College Dublin , The University of Dublin , College Green , Dublin 2 , Ireland
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43
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Spedalotto G, Gericke R, Lovisari M, Farquhar ER, Twamley B, McDonald AR. Preparation and Characterisation of a Bis-μ-Hydroxo-Ni III 2 Complex. Chemistry 2019; 25:11983-11990. [PMID: 31237966 DOI: 10.1002/chem.201902812] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Indexed: 12/20/2022]
Abstract
Hydroxide-bridged high-valent oxidants have been implicated as the active oxidants in methane monooxygenases and other oxidases that employ bimetallic clusters in their active site. To understand the properties of such species, bis-μ-hydroxo-NiII 2 complex (1) supported by a new dicarboxamidate ligand (N,N'-bis(2,6-dimethyl-phenyl)-2,2-dimethylmalonamide) was prepared. Complex 1 contained a diamond core made up of two NiII ions and two bridging hydroxide ligands. Titration of the 1 e- oxidant (NH4 )2 [CeIV (NO3 )6 ] with 1 at -45 °C showed the formation of the high-valent species 2 and 3, containing NiII NiIII and NiIII 2 diamond cores, respectively, maintaining the bis-μ-hydroxide core. Both complexes were characterised using electron paramagnetic resonance, X-ray absorption, and electronic absorption spectroscopies. Density functional theory computations supported the spectroscopic assignments. Oxidation reactivity studies showed that bis-μ-hydroxide-NiIII 2 3 was capable of oxidizing substrates at -45 °C at rates greater than that of the most reactive bis-μ-oxo-NiIII complexes reported to date.
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Affiliation(s)
- Giuseppe Spedalotto
- 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
| | - Marta Lovisari
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Erik R Farquhar
- Center for Synchrotron Biosciences, National Synchrotron Light Source II, Brookhaven, National Laboratory, Case Western Reserve University, Upton, NY, 11973, USA
| | - Brendan Twamley
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Aidan R McDonald
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
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44
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McManus C, Mondal P, Lovisari M, Twamley B, McDonald AR. Carboxamidate Ligand Noninnocence in Proton Coupled Electron Transfer. Inorg Chem 2019; 58:4515-4523. [PMID: 30864788 DOI: 10.1021/acs.inorgchem.9b00055] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Caitilín McManus
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Prasenjit Mondal
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Marta Lovisari
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Brendan Twamley
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
| | - Aidan R. McDonald
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
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45
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Ackerman LKG, Martinez Alvarado JI, Doyle AG. Direct C-C Bond Formation from Alkanes Using Ni-Photoredox Catalysis. J Am Chem Soc 2018; 140:14059-14063. [PMID: 30351143 PMCID: PMC6411045 DOI: 10.1021/jacs.8b09191] [Citation(s) in RCA: 142] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A method for direct cross coupling between unactivated C(sp3)-H bonds and chloroformates has been accomplished via nickel and photoredox catalysis. A diverse range of feedstock chemicals, such as (a)cyclic alkanes and toluenes, along with late-stage intermediates, undergo intermolecular C-C bond formation to afford esters under mild conditions using only 3 equiv of the C-H partner. Site selectivity is predictable according to bond strength and polarity trends that are consistent with the intermediacy of a chlorine radical as the hydrogen atom-abstracting species.
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Affiliation(s)
| | | | - Abigail G. Doyle
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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46
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Shen Y, Gu Y, Martin R. sp 3 C-H Arylation and Alkylation Enabled by the Synergy of Triplet Excited Ketones and Nickel Catalysts. J Am Chem Soc 2018; 140:12200-12209. [PMID: 30184423 DOI: 10.1021/jacs.8b07405] [Citation(s) in RCA: 229] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Triplet ketone sensitizers are of central importance within the realm of photochemical transformations. Although the radical-type character of triplet excited states of diaryl ketones suggests the viability for triggering hydrogen-atom transfer (HAT) and single-electron transfer (SET) processes, among others, their use as multifaceted catalysts in C-C bond-formation via sp3 C-H functionalization of alkane feedstocks still remains rather unexplored. Herein, we unlock a modular photochemical platform for forging C( sp3)-C( sp2) and C( sp3)-C( sp3) linkages from abundant alkane sp3 C-H bonds as functional handles using the synergy between nickel catalysts and simple, cheap and modular diaryl ketones. This method is distinguished by its wide scope that is obtained from cheap catalysts and starting precursors, thus complementing existing inner-sphere C-H functionalization protocols or recent photoredox scenarios based on iridium polypyridyl complexes. Additionally, such a platform provides a new strategy for streamlining the synthesis of complex molecules with high levels of predictable site-selectivity and preparative utility. Mechanistic experiments suggest that sp3 C-H abstraction occurs via HAT from the ketone triplet excited state. We believe this study will contribute to a more systematic utilization of triplet excited ketones as catalysts in metallaphotoredox scenarios.
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Affiliation(s)
- Yangyang Shen
- Institute of Chemical Research of Catalonia (ICIQ) , The Barcelona Institute of Science and Technology , Av. Països Catalans 16 , 43007 Tarragona , Spain.,Departament de Química Analítica i Química Orgànica , Universitat Rovira i Virgili , c/Marcel·lí Domingo 1 , 43007 Tarragona , Spain
| | - Yiting Gu
- Institute of Chemical Research of Catalonia (ICIQ) , The Barcelona Institute of Science and Technology , Av. Països Catalans 16 , 43007 Tarragona , Spain.,Departament de Química Analítica i Química Orgànica , Universitat Rovira i Virgili , c/Marcel·lí Domingo 1 , 43007 Tarragona , Spain
| | - Ruben Martin
- Institute of Chemical Research of Catalonia (ICIQ) , The Barcelona Institute of Science and Technology , Av. Països Catalans 16 , 43007 Tarragona , Spain.,ICREA , Passeig Lluïs Companys 23 , 08010 Barcelona , Spain
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47
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Krishnan VM, Davis I, Baker TM, Curran DJ, Arman HD, Neidig ML, Liu A, Tonzetich ZJ. Backbone Dehydrogenation in Pyrrole-Based Pincer Ligands. Inorg Chem 2018; 57:9544-9553. [PMID: 30040391 DOI: 10.1021/acs.inorgchem.8b01643] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Treatment of both [CoCl( tBuPNP)] and [NiCl( tBuPNP)] ( tBuPNP = anion of 2,5-bis((di- tert-butylphosphino)methyl)pyrrole) with one equivalent of benzoquinone affords the corresponding chloride complexes containing a dehydrogenated PNP ligand, tBudPNP ( tBudPNP = anion of 2,5-bis((di- tert-butylphosphino)methylene)-2,5-dihydropyrrole). Dehydrogenation of PNP to dPNP results in minimal change to steric profile of the ligand but has important consequences for the resulting redox potentials of the metal complexes, resulting in the ability to isolate both [CoH( tBudPNP)] and [CoEt( tBudPNP)], which are more challenging (hydride) or not possible (ethyl) to prepare with the parent PNP ligand. Electrochemical measurements with both the Co and Ni dPNP species demonstrate a substantial shift in redox potentials for both the M(II/III) and M(II/I) couples. In the case of the former, oxidation to trivalent Co was found to be reversible, and subsequent reaction with AgSbF6 afforded a rare example of a square-planar Co(III) species. Corresponding reduction of [CoCl( tBudPNP)] with KC8 produced the diamagnetic Co(I) species, [Co(N2)( tBudPNP)]. Further reduction of the Co(I) complex was found to generate a pincer-based π-radical anion that demonstrated well-resolved EPR features to the four hydrogen atoms and lone nitrogen atom of the ligand with minor contributions from cobalt and coordinated N2. Changes in the electronic character of the PNP ligand upon dehydrogenation are proposed to result from loss of aromaticity in the pyrrole ligand, resulting in a more reducing central amido donor. DFT calculations on the Co(II) complexes were performed to shed further insight into the electronic structure of the pincer complexes.
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Affiliation(s)
- V Mahesh Krishnan
- Department of Chemistry , University of Texas at San Antonio (UTSA) , San Antonio , Texas 78249 , United States
| | - Ian Davis
- Department of Chemistry , University of Texas at San Antonio (UTSA) , San Antonio , Texas 78249 , United States
| | - Tessa M Baker
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , United States
| | - Daniel J Curran
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , United States
| | - Hadi D Arman
- Department of Chemistry , University of Texas at San Antonio (UTSA) , San Antonio , Texas 78249 , United States
| | - Michael L Neidig
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , United States
| | - Aimin Liu
- Department of Chemistry , University of Texas at San Antonio (UTSA) , San Antonio , Texas 78249 , United States
| | - Zachary J Tonzetich
- Department of Chemistry , University of Texas at San Antonio (UTSA) , San Antonio , Texas 78249 , United States
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48
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Rosenkoetter KE, Wojnar MK, Charette BJ, Ziller JW, Heyduk AF. Hydrogen-Atom Noninnocence of a Tridentate [SNS] Pincer Ligand. Inorg Chem 2018; 57:9728-9737. [DOI: 10.1021/acs.inorgchem.8b00618] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Kyle E. Rosenkoetter
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Michael K. Wojnar
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Bronte J. Charette
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Joseph W. Ziller
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Alan F. Heyduk
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
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