1
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Christensen EG, Steele RP. Structural, Thermodynamic, and Spectroscopic Evolution in the Hydration of Copper(II) Ions, Cu 2+(H 2O) 2-8. J Phys Chem A 2023; 127:6660-6676. [PMID: 37552878 DOI: 10.1021/acs.jpca.3c03719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
Gas-phase clusters of the hydrated Cu(II) cation with 2-8 water molecules were investigated using ab initio quantum chemistry. Isomer structures, energies, and vibrational spectra were computed across this size range, yielding a qualitative picture of this ion as an intact Cu2+ hydrate that also partially oxidizes the surrounding water network at equilibrium. At sufficient cluster sizes, these ion hydrates also become thermodynamically preferred over competitive Cu(II) hydroxide hydrates. Competitive coordination environments were found to exist at some cluster sizes, due to both hydrogen-bonding and d-orbital chemical effects, and the dominant coordination number was found in some cases to be temperature-dependent. Clear spectral signatures of the ion's coordination environment were computed to exist at each cluster size, which should make experimental verification of these computational predictions straightforward. Through comparison to recent studies of hydrated CuOH+, the effective charge on the metal center was shown to converge to approximately +1.5 in both cases, despite qualitatively different behavior of their radical spin densities. Therefore, nominally Cu(II) ions exhibit considerable electronic, chemical, and structural flexibility. The electronic origins of this flexibility─including key roles played by the water network itself─are investigated in this work and should provide a conceptual foundation for future studies of copper-based, water-oxidation catalysts.
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Affiliation(s)
- Elizabeth G Christensen
- Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Ryan P Steele
- Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States
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2
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Mehara J, Roithová J. Copper(II)‐TEMPO Interaction. Isr J Chem 2023. [DOI: 10.1002/ijch.202300011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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3
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Płonka D, Kotuniak R, Dąbrowska K, Bal W. Electrospray-Induced Mass Spectrometry Is Not Suitable for Determination of Peptidic Cu(II) Complexes. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:2766-2776. [PMID: 34738801 PMCID: PMC8640992 DOI: 10.1021/jasms.1c00206] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 10/22/2021] [Accepted: 10/25/2021] [Indexed: 06/13/2023]
Abstract
The toolset of mass spectrometry (MS) is still expanding, and the number of metal ion complexes researched this way is growing. The Cu(II) ion forms particularly strong peptide complexes of biological interest which are frequent objects of MS studies, but quantitative aspects of some reported results are at odds with those of experiments performed in solution. Cu(II) complexes are usually characterized by fast ligand exchange rates, despite their high affinity, and we speculated that such kinetic lability could be responsible for the observed discrepancies. In order to resolve this issue, we selected peptides belonging to the ATCUN family characterized with high and thoroughly determined Cu(II) binding constants and re-estimated them using two ESI-MS techniques: standard conditions in combination with serial dilution experiments and very mild conditions for competition experiments. The sample acidification, which accompanies the electrospray formation, was simulated with the pH-jump stopped-flow technique. Our results indicate that ESI-MS should not be used for quantitative studies of Cu(II)-peptide complexes because the electrospray formation process compromises the entropic contribution to the complex stability, yielding underestimations of complex stability constants.
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4
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Kostyukovich AY, Burykina JV, Eremin DB, Ananikov VP. Detection and Structural Investigation of Elusive Palladium Hydride Intermediates Formed from Simple Metal Salts. Inorg Chem 2021; 60:7128-7142. [PMID: 33949864 DOI: 10.1021/acs.inorgchem.1c00173] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Mizoroki-Heck reaction is one of the most known and best studied catalytic transformations and has provided an outstanding driving force for the development of catalysis and synthetic applications. Three out of four classical Mizoroki-Heck catalytic cycle intermediates contain Pd-C bonds and are well known and studied in detail. However, a simple palladium hydride (which is formed after the product-releasing β-H-elimination step) is a kind of elusive intermediate in the Mizoroki-Heck reaction. In the present study, we performed a combined theoretical and mass spectrometry (MS) study of palladium hydride complexes [PdX2H]- (X = Cl, Br, and I), which are reactive intermediates in the Mizoroki-Heck reaction. Static and molecular dynamic calculations revealed that these species have a T-shaped structure with a trans-arrangement of halogen atoms. Other isomers of [PdX2H]- are unstable and easily rearrange into the T-shaped form or decompose. These palladium hydride intermediates were detected by MS in precatalyst activation using NaBH4, Et3N, and a solvent molecule as reducing agents. Online MS monitoring allowed the detection of [PdX2H]- species in the course of the Mizoroki-Heck reaction.
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Affiliation(s)
- Alexander Yu Kostyukovich
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow 119991, Russia
| | - Julia V Burykina
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow 119991, Russia
| | - Dmitry B Eremin
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow 119991, Russia.,The Bridge@USC, University of Southern California, 1002 Childs Way, Los Angeles, California 90089-3502, United States
| | - Valentine P Ananikov
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow 119991, Russia
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5
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Pascher TF, Ončák M, van der Linde C, Beyer MK. Infrared multiple photon dissociation spectroscopy of anionic copper formate clusters. J Chem Phys 2020; 153:184301. [DOI: 10.1063/5.0030034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Tobias F. Pascher
- Institut für Ionen und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Milan Ončák
- Institut für Ionen und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Christian van der Linde
- Institut für Ionen und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Martin K. Beyer
- Institut für Ionen und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
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6
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Das D, Mitra S, Kumar R, Banerjee S, Koti Ainavarapu SR. Copper-induced spectroscopic and structural changes in short peptides derived from azurin. Arch Biochem Biophys 2020; 687:108388. [PMID: 32343975 DOI: 10.1016/j.abb.2020.108388] [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: 02/24/2020] [Revised: 04/07/2020] [Accepted: 04/21/2020] [Indexed: 11/26/2022]
Abstract
The active sites of metalloproteins may be mimicked by designing peptides that bind to their respective metal ions. Studying the binding of protein ligands to metal ions along with the associated structural changes is important in understanding metal uptake, transport and electron transfer functions of proteins. Copper-binding metalloprotein azurin is a 128-residue electron transfer protein with a redox-active copper cofactor. Here, we report the copper-binding associated spectroscopic and structural properties of peptide loops (11 and 13 residues) from the copper-binding site of azurin. These peptides develop a β-turn upon copper-binding with a 1:1 Cu2+:peptide stoichiometry as seen in circular dichroism and exhibit electronic transitions centered at 340 nm and 540 nm. Further addition of copper develops a helical feature along with a shift in the absorption maxima to ~360 nm and ~580 nm at 2:1 Cu2+:peptide stoichiometry, indicating stoichiometric dependence of copper-binding geometry. Mass spectrometry indicates the copper-binding to cysteine, histidine and methionine in the peptide with 1:1 stoichiometry, and interestingly, dimerization through a disulfide linkage at 2:1 stoichiometry, as observed previously for denatured azurin. Fluorescence quenching studies on peptides with tryptophan further confirm the copper-binding induced changes in the two peptides are bi-phasic.
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Affiliation(s)
- Debanjana Das
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai, 400005, India
| | - Soumyajit Mitra
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai, 400005, India
| | - Rohit Kumar
- Department of Chemistry, Indian Institute of Science Education and Research Tirupati, Tirupati, 517507, India
| | - Shibdas Banerjee
- Department of Chemistry, Indian Institute of Science Education and Research Tirupati, Tirupati, 517507, India.
| | - Sri Rama Koti Ainavarapu
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai, 400005, India.
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7
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Larson VA, Battistella B, Ray K, Lehnert N, Nam W. Iron and manganese oxo complexes, oxo wall and beyond. Nat Rev Chem 2020; 4:404-419. [PMID: 37127969 DOI: 10.1038/s41570-020-0197-9] [Citation(s) in RCA: 139] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2020] [Indexed: 11/09/2022]
Abstract
High-valent metal-oxo species with multiply-bonded M-O groups have been proposed as key intermediates in many biological and abiological catalytic oxidation reactions. These intermediates are implicated as active oxidants in alkane hydroxylation, olefin epoxidation and other oxidation reactions. For example, [FeivO(porphyrinato•-)]+ cofactors bearing π-radical porphyrinato•- ligands oxidize organic substrates in cytochrome P450 enzymes, which are common to many life forms. Likewise, high-valent Mn-oxo species are active for H2O oxidation in photosystem II. The chemistry of these native reactive species has inspired chemists to prepare highly oxidized transition-metal complexes as functional mimics. Although many synthetic Fe-O and Mn-O complexes now exist, the analogous oxo complexes of the late transition metals (groups 9-11) are rare. Indeed, late-transition-metal-oxo complexes of tetragonal (fourfold) symmetry should be electronically unstable, a rule commonly referred to as the 'oxo wall'. A few late metal-oxos have been prepared by targeting other symmetries or unusual spin states. These complexes have been studied using spectroscopic and theoretical methods. This Review describes mononuclear non-haem Fe-O and Mn-O species, the nature of the oxo wall and recent advances in the preparation of oxo complexes of Co, Ni and Cu beyond the oxo wall.
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8
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Pascher TF, Ončák M, van der Linde C, Beyer MK. UV/Vis Spectroscopy of Copper Formate Clusters: Insight into Metal-Ligand Photochemistry. Chemistry 2020; 26:8286-8295. [PMID: 32155292 PMCID: PMC7384192 DOI: 10.1002/chem.202000280] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Indexed: 12/13/2022]
Abstract
The electronic structure and photochemistry of copper formate clusters, CuI2(HCO2)3− and CuIIn(HCO2)2n+1−, n≤8, are investigated in the gas phase by using UV/Vis spectroscopy in combination with quantum chemical calculations. A clear difference in the spectra of clusters with CuI and CuII copper ions is observed. For the CuI species, transitions between copper d and s/p orbitals are recorded. For stoichiometric CuII formate clusters, the spectra are dominated by copper d–d transitions and charge‐transfer excitations from formate to the vacant copper d orbital. Calculations reveal the existence of several energetically low‐lying isomers, and the energetic position of the electronic transitions depends strongly on the specific isomer. The oxidation state of the copper centers governs the photochemistry. In CuII(HCO2)3−, fast internal conversion into the electronic ground state is observed, leading to statistical dissociation; for charge‐transfer excitations, specific excited‐state reaction channels are observed in addition, such as formyloxyl radical loss. In CuI2(HCO2)3−, the system relaxes to a local minimum on an excited‐state potential‐energy surface and might undergo fluorescence or reach a conical intersection to the ground state; in both cases, this provides substantial energy for statistical decomposition. Alternatively, a CuII(HCO2)3Cu0− biradical structure is formed in the excited state, which gives rise to the photochemical loss of a neutral copper atom.
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Affiliation(s)
- Tobias F Pascher
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020, Innsbruck, Austria
| | - Milan Ončák
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020, Innsbruck, Austria
| | - Christian van der Linde
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020, Innsbruck, Austria
| | - Martin K Beyer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020, Innsbruck, Austria
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9
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Pascher TF, Ončák M, van der Linde C, Beyer MK. Decomposition of Copper Formate Clusters: Insight into Elementary Steps of Calcination and Carbon Dioxide Activation. ChemistryOpen 2019; 8:1453-1459. [PMID: 31871848 PMCID: PMC6916659 DOI: 10.1002/open.201900282] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 11/13/2019] [Indexed: 11/29/2022] Open
Abstract
The decomposition of copper formate clusters is investigated in the gas phase by infrared multiple photon dissociation of Cu(II) n (HCO2)2n+1 -, n≤8. In combination with quantum chemical calculations and reactivity measurements using oxygen, elementary steps of the decomposition of copper formate are characterized, which play a key role during calcination as well as for the function of copper hydride based catalysts. The decomposition of larger clusters (n >2) takes place exclusively by the sequential loss of neutral copper formate units Cu(II)(HCO2)2 or Cu(II)2(HCO2)4, leading to clusters with n=1 or n=2. Only for these small clusters, redox reactions are observed as discussed in detail previously, including the formation of formic acid or loss of hydrogen atoms, leading to a variety of Cu(I) complexes. The stoichiometric monovalent copper formate clusters Cu(I) m (HCO2) m+1 -, (m=1,2) decompose exclusively by decarboxylation, leading towards copper hydrides in oxidation state +I. Copper oxide centers are obtained via reactions of molecular oxygen with copper hydride centers, species containing carbon dioxide radical anions as ligands or a Cu(0) center. However, stoichiometric copper(I) and copper(II) formate Cu(I)(HCO2)2 - and Cu(II)(HCO2)3 -, respectively, is unreactive towards oxygen.
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Affiliation(s)
- Tobias F. Pascher
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Milan Ončák
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Christian van der Linde
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Martin K. Beyer
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020InnsbruckAustria
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10
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Pascher TF, Ončák M, van der Linde C, Beyer MK. Release of Formic Acid from Copper Formate: Hydride, Proton-Coupled Electron and Hydrogen Atom Transfer All Play their Role. Chemphyschem 2019; 20:1420-1424. [PMID: 30958610 PMCID: PMC6563433 DOI: 10.1002/cphc.201900095] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 03/22/2019] [Indexed: 01/27/2023]
Abstract
Although the mechanism for the transformation of carbon dioxide to formate with copper hydride is well understood, it is not clear how formic acid is ultimately released. Herein, we show how formic acid is formed in the decomposition of the copper formate clusters Cu(II)(HCOO)3- and Cu(II)2 (HCOO)5- . Infrared irradiation resonant with the antisymmetric C-O stretching mode activates the cluster, resulting in the release of formic acid and carbon dioxide. For the binary cluster, electronic structure calculations indicate that CO2 is eliminated first, through hydride transfer from formate to copper. Formic acid is released via proton-coupled electron transfer (PCET) to a second formate ligand, evidenced by close to zero partial charge and spin density at the hydrogen atom in the transition state. Concomitantly, the two copper centers are reduced from Cu(II) to Cu(I). Depending on the detailed situation, either PCET or hydrogen atom transfer (HAT) takes place.
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Affiliation(s)
- Tobias F. Pascher
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Milan Ončák
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Christian van der Linde
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Martin K. Beyer
- Institut für Ionenphysik und Angewandte PhysikUniversität InnsbruckTechnikerstraße 256020InnsbruckAustria
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11
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Cui J, Sun C, Zhao Y, Wang M, Ma J. Hydrogen- and oxygen-atom transfers in the thermal activation of benzene mediated by Cu 2O 2+ cations. Phys Chem Chem Phys 2019; 21:1117-1122. [PMID: 30601529 DOI: 10.1039/c8cp06807k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The mass-selected copper oxide cluster cations Cu2O2+ are successfully prepared by laser ablation and reacted with benzene in a linear ion trap reactor. The cluster reaction is characterized by reflectron mass spectrometry in conjunction with density functional theory calculations. Four types of reaction channels are observed: (1) Cu2OH+ + C6H5O˙, (2) Cu2C6H6+ + O2, (3) Cu(C6H6)2+ + Cu and (4) Cu2O2C6H6+, in which the first one is the major product. Observation of the products Cu2OH+ indicates that oxygen atom transfer (OAT) accompanying hydrogen atom transfer (HAT) occurs, and the oxygen-centered radical (O-˙) in Cu2O2+ is crucial to the cleavages of C-H and Cu-O bonds. It is interesting that HAT and OAT occur in a single reaction channel to form C6H5O˙, which has not been reported in the reactions of gas-phase ions with benzene. The calculated results are in agreement with the experimental observations, and no two-state reactivity scenario is present in the potential energy surface of channel 1. This work can provide useful insights into the nature of active sites over copper oxides and reaction mechanisms in the corresponding heterogeneous reactions.
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Affiliation(s)
- Jiatong Cui
- Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, 100081, Beijing, People's Republic of China.
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12
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Zhou S, Sun X, Yue L, Schlangen M, Schwarz H. Selective C-O Coupling Hidden in the Thermal Reaction of [Al 2 CuO 5 ] + with Methane. Chemistry 2018; 24:14649-14653. [PMID: 30091489 DOI: 10.1002/chem.201804059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Indexed: 01/09/2023]
Abstract
The thermal gas-phase reaction of [Al2 CuO5 ]+ with methane has been explored by using FT-ICR mass spectrometry complemented by high-level quantum chemical calculations. The generation of atomic [Cu]+ from the [Al2 CuO5 ]+ /CH4 couple corresponds to the only reaction channel. Labeling experiments and computational studies strongly suggest that methane activation is indeed involved in the production of [Cu]+ , and generation of CH2 O prevails. Mechanistic aspects and the associated doping effects are discussed.
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Affiliation(s)
- Shaodong Zhou
- Zhejiang Provincial Key Laboratory of, Advanced Chemical Engineering Manufacture Technology, College of Chemical and Biological Engineering, Zhejiang University, 310027, Hangzhou, P.R. China.,Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Xiaoyan Sun
- Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Lei Yue
- Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Maria Schlangen
- Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Helmut Schwarz
- Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, 10623, Berlin, Germany
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13
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Cui XY, Ge Y, Tan SM, Jiang H, Tan D, Lu Y, Lee R, Tan CH. (Guanidine)copper Complex-Catalyzed Enantioselective Dynamic Kinetic Allylic Alkynylation under Biphasic Condition. J Am Chem Soc 2018; 140:8448-8455. [DOI: 10.1021/jacs.7b12806] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Xi-Yang Cui
- Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Yicen Ge
- Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Siu Min Tan
- Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372
| | - Huan Jiang
- Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Davin Tan
- Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
- Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372
| | - Yunpeng Lu
- Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Richmond Lee
- Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372
| | - Choon-Hong Tan
- Division of Chemistry and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
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14
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Dang A, Shaffer CJ, Bím D, Lawler J, Lesslie M, Ryzhov V, Tureček F. Near-UV Water Splitting by Cu, Ni, and Co Complexes in the Gas Phase. J Phys Chem A 2018; 122:2069-2078. [DOI: 10.1021/acs.jpca.7b12445] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andy Dang
- Department
of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Christopher J. Shaffer
- Department
of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Daniel Bím
- Institute
of Organic Chemistry and Biochemistry, Czech Academy of Sciences, 117
20 Prague 1, Czech Republic
| | - John Lawler
- Department
of Chemistry, Northern Illinois University, DeKalb, Illinois 60115-2828, United States
| | - Michael Lesslie
- Department
of Chemistry, Northern Illinois University, DeKalb, Illinois 60115-2828, United States
| | - Victor Ryzhov
- Department
of Chemistry, Northern Illinois University, DeKalb, Illinois 60115-2828, United States
| | - František Tureček
- Department
of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
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15
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Chen H, Cai C, Li S, Ma Y, Luozhong S, Zhu Z. Intermediates Stabilized by Tris(triazolylmethyl)amines in the CuAAC Reaction. Chemistry 2017; 23:4730-4735. [DOI: 10.1002/chem.201700555] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Indexed: 01/09/2023]
Affiliation(s)
- Haoqing Chen
- Department of Chemistry University of Houston 3585 Cullen Blvd. Houston Texas 77204-5003 USA
| | - Chengzhi Cai
- Department of Chemistry University of Houston 3585 Cullen Blvd. Houston Texas 77204-5003 USA
| | - Siheng Li
- Department of Chemistry University of Houston 3585 Cullen Blvd. Houston Texas 77204-5003 USA
| | - Yong Ma
- Department of Pharmacological and Pharmaceutical Sciences University of Houston 1441 Moursund St. Houston Texas 77030 USA
| | - Sijin Luozhong
- Department of Chemical Engineering Tsinghua University Beijing 100084 P. R. China
| | - Zhiling Zhu
- Department of Chemistry University of Houston 3585 Cullen Blvd. Houston Texas 77204-5003 USA
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16
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Iacobucci C, Lebon A, De Angelis F, Memboeuf A. CuAAC Click Reactions in the Gas Phase: Unveiling the Reactivity of Bis-Copper Intermediates. Chemistry 2016; 22:18690-18694. [PMID: 27558289 DOI: 10.1002/chem.201603518] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Indexed: 11/09/2022]
Abstract
Copper-catalysed azide alkyne cycloaddition (CuAAC) has been considered a breakthrough transformation over the last 15 years. Its debated mechanism arouses continuously growing interest. By means of a mass spectrometer modified ad hoc, the entire catalytic cycle of CuAAC reaction has been investigated in the gas phase. Ion-molecule reactions were performed inside the mass spectrometer to reproduce step-by-step, at a molecular level, the complete catalytic cycle of the click reaction. We successfully challenged the reactivity of elusive mono- and bis-copper intermediates by ion-molecule reactions leading to the production of mass-characterized triazole products, paving the way for detailed energetic studies to be performed in the gas phase. The structures of the relevant species, calculated at a DFT level, helped rationalise our experimental results.
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Affiliation(s)
- Claudio Iacobucci
- UMR CNRS 6521, CEMCA, Université de Bretagne Occidentale, 6 Av. Le Gorgeu, CS 93837, 29238, Cedex 3, France
| | - Alexandre Lebon
- UMR CNRS 6521, CEMCA, Université de Bretagne Occidentale, 6 Av. Le Gorgeu, CS 93837, 29238, Cedex 3, France
| | - Francesco De Angelis
- Department Physical and Chemical Sciences, University of L'Aquila, Via Vetoio, 67100, L'Aquila, Italy
| | - Antony Memboeuf
- UMR CNRS 6521, CEMCA, Université de Bretagne Occidentale, 6 Av. Le Gorgeu, CS 93837, 29238, Cedex 3, France
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Pericas À, Jiménez R, Granados A, Shafir A, Vallribera A, Roglans A, Molins E. Lanthanides-pybox: An Excellent Combination for Highly Enantioselective Electrophilic α-Amination of Acyclic β-Keto Esters. Isolation of Ternary Pybox/Ln/β-Keto Ester Complexes. ChemistrySelect 2016. [DOI: 10.1002/slct.201600820] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Àlex Pericas
- Department of Chemistry and Centro de Innovación en Química Avanzada (ORFEO-CINQA); Universitat Autònoma de Barcelona, Campus de la UAB; 08193-Cerdanyola del Vallès Barcelona Spain
| | - Rubén Jiménez
- Department of Chemistry and Centro de Innovación en Química Avanzada (ORFEO-CINQA); Universitat Autònoma de Barcelona, Campus de la UAB; 08193-Cerdanyola del Vallès Barcelona Spain
| | - Albert Granados
- Department of Chemistry and Centro de Innovación en Química Avanzada (ORFEO-CINQA); Universitat Autònoma de Barcelona, Campus de la UAB; 08193-Cerdanyola del Vallès Barcelona Spain
| | - Alexandr Shafir
- Department of Chemistry and Centro de Innovación en Química Avanzada (ORFEO-CINQA); Universitat Autònoma de Barcelona, Campus de la UAB; 08193-Cerdanyola del Vallès Barcelona Spain
- Institut of Chemical Research of Catalonia (ICIQ); Barcelona Institute of Science and Technology; Avda. Països Catalans 16 43007 Tarragona Spain
| | - Adelina Vallribera
- Department of Chemistry and Centro de Innovación en Química Avanzada (ORFEO-CINQA); Universitat Autònoma de Barcelona, Campus de la UAB; 08193-Cerdanyola del Vallès Barcelona Spain
| | - Anna Roglans
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química; Universitat de Girona, Campus de Montilivi; 17071- Girona Spain
| | - Elies Molins
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB; 08193-Cerdanyola del Vallès Barcelona Spain
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Putau A, Brand H, Koszinowski K. Intermediates Formed in the Reactions of Organocuprates with α,β-Unsaturated Nitriles. Chemistry 2016; 22:12868-76. [PMID: 27461093 DOI: 10.1002/chem.201602451] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Indexed: 11/10/2022]
Abstract
Conjugate additions of organocuprates are of outstanding importance for organic synthesis. To improve our mechanistic understanding of these reactions, we have used electrospray ionization mass spectrometry for the identification of the ionic intermediates formed upon the treatment of LiCuR2 ⋅LiCN (R=Me, Bu, Ph) with a series of α,β-unsaturated nitriles. Acrylonitrile, the weakest Michael acceptor included, did not afford any detectable intermediates. Fumaronitrile (FN) yielded adducts of the type Lin-1 Cun R2n (FN)n (-) , n=1-3. When subjected to fragmentation in the gas phase, these adducts were not converted into the conjugate addition products, but re-dissociated into the reactants. In contrast, the reaction with 1,1-dicyanoethylene furnished the products of the conjugate addition without any observable intermediates. Tri- and tetracyanoethylene proved to be quite reactive as well. The presence of several cyano groups in these substrates opened up reaction pathways different from simple conjugate additions, however, and led to dimerization and substitution reactions. Moreover, the gas-phase fragmentation behavior of the species formed from these substrates indicated the occurrence of single-electron transfer processes. Additional quantum-chemical calculations provided insight into the structures and stabilities of the observed intermediates and their consecutive reactions.
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Affiliation(s)
- Aliaksei Putau
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany
| | - Harald Brand
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany
| | - Konrad Koszinowski
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany.
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Weske S, Schoop R, Koszinowski K. The Role of Ate Complexes in the Copper-Mediated Trifluoromethylation of Alkynes. Chemistry 2016; 22:11310-6. [PMID: 27385188 DOI: 10.1002/chem.201601261] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Indexed: 01/30/2023]
Abstract
Trifluoromethylation reactions have recently received increased attention because of the beneficial effect of the trifluoromethyl group on the pharmacological properties of numerous substances. A common method to introduce the trifluoromethyl group employs the Ruppert-Prakash reagent, that is, Si(CH3 )3 CF3 , together with a copper(I) halide. We have applied this method to the trifluoromethylation of aromatic alkynes and used electrospray-ionization mass spectrometry to investigate the mechanism of these reactions in tetrahydrofuran, dichloromethane, and acetonitrile as well as with and without added 1,10-phenanthroline. In the absence of the alkyne component, the homoleptic ate complexes [Cu(CF3 )2 ](-) and [Cu(CF3 )4 ](-) were observed. In the presence of the alkynes RH, the heteroleptic complexes [Cu(CF3 )3 R](-) were detected as well. Upon gas-phase fragmentation, these key intermediates released the cross-coupling products R-CF3 with perfect selectivity. Apparently, the [Cu(CF3 )3 R](-) complexes did not originate from homoleptic cuprate anions, but from unobservable neutral precursors. The present results moreover point to the involvement of oxygen as the oxidizing agent.
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Affiliation(s)
- Sebastian Weske
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammanstraße 2, 37077, Göttingen, Germany
| | - Ramona Schoop
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammanstraße 2, 37077, Göttingen, Germany
| | - Konrad Koszinowski
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammanstraße 2, 37077, Göttingen, Germany.
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Rijs NJ, González-Navarrete P, Schlangen M, Schwarz H. Penetrating the Elusive Mechanism of Copper-Mediated Fluoromethylation in the Presence of Oxygen through the Gas-Phase Reactivity of Well-Defined [LCuO](+) Complexes with Fluoromethanes (CH(4-n)Fn, n = 1-3). J Am Chem Soc 2016; 138:3125-35. [PMID: 26859159 DOI: 10.1021/jacs.5b12972] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Traveling wave ion mobility spectrometry (TWIMS) isomer separation was exploited to react the particularly well-defined ionic species [LCuO](+) (L = 1,10-phenanthroline) with the neutral fluoromethane substrates CH(4-n)Fn (n = 1-3) in the gas phase. Experimentally, the monofluoromethane substrate (n = 1) undergoes both hydrogen-atom transfer, forming the copper hydroxide complex [LCuOH](•+) and concomitantly a CH2F(•) radical, and oxygen-atom transfer, yielding the observable ionic product [LCu](+) plus the neutral oxidized substrate [C,H3,O,F]. DFT calculations reveal that the mechanism for both product channels relies on the initial C-H bond activation of the substrate. Compared to nonfluorinated methane, the addition of fluorine to the substrate assists the reactivity through a lowering of the C-H bond energy and reaction preorganization (through noncovalent interaction in the encounter complex). A two-state reactivity scenario is mandatory for the oxidation, which competitively results in the unusual fluoromethanol product, CH2FOH, or the decomposed products, CH2O and HF, with the latter channel being kinetically disfavored. Difluoromethane (n = 2) is predicted to undergo the analogous reactions at room temperature, although the reactions are less favored than those of monofluoromethane. The reaction of trifluoromethane (n = 3, fluoroform) through C-H activation is kinetically hindered under ambient conditions but might be expected to occur in the condensed phase upon heating or with further lowering of reaction barriers through templation with counterions, such as potassium. Overall, formation of CH(3-n)Fn(•) and CH(3-n)FnOH occurs under relatively gentle energetic conditions, which sheds light on their potential as reactive intermediates in fluoromethylation reactions mediated by copper in the presence of oxygen.
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Affiliation(s)
- Nicole J Rijs
- Institute of Nanotechnology, Karlsruhe Institute of Technology , Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | | | - Maria Schlangen
- Institut für Chemie, Technische Universität Berlin , Straße des 17. Juni 115, 10623 Berlin, Germany
| | - Helmut Schwarz
- Institut für Chemie, Technische Universität Berlin , Straße des 17. Juni 115, 10623 Berlin, Germany
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