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Li Y, Ji GC, Chao C, Bi S, Jiang YY. Computation Study on Copper-Catalyzed Aerobic Intramolecular Aminooxyge native C═C Bond Cleavage to Imides: Different Roles of Mononuclear and Dinuclear Copper Complexes. ACS Catal 2023. [DOI: 10.1021/acscatal.2c06040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Affiliation(s)
- Yu Li
- School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, People′s Republic of China
| | - Guo-Cui Ji
- School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, People′s Republic of China
| | - Chen Chao
- School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, People′s Republic of China
| | - Siwei Bi
- School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, People′s Republic of China
| | - Yuan-Ye Jiang
- School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, People′s Republic of China
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2
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Kisgeropoulos EC, Gan YJ, Greer SM, Hazel JM, Shafaat HS. Pulsed Multifrequency Electron Paramagnetic Resonance Spectroscopy Reveals Key Branch Points for One- vs Two-Electron Reactivity in Mn/Fe Proteins. J Am Chem Soc 2022; 144:11991-12006. [PMID: 35786920 DOI: 10.1021/jacs.1c13738] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Traditionally, the ferritin-like superfamily of proteins was thought to exclusively use a diiron active site in catalyzing a diverse array of oxygen-dependent reactions. In recent years, novel redox-active cofactors featuring heterobimetallic Mn/Fe active sites have been discovered in both the radical-generating R2 subunit of class Ic (R2c) ribonucleotide reductases (RNRs) and the related R2-like ligand-binding oxidases (R2lox). However, the protein-specific factors that differentiate the radical reactivity of R2c from the C-H activation reactions of R2lox remain unknown. In this work, multifrequency pulsed electron paramagnetic resonance (EPR) spectroscopy and ligand hyperfine techniques in conjunction with broken-symmetry density functional theory calculations are used to characterize the molecular and electronic structures of two EPR-active intermediates trapped during aerobic assembly of the R2lox Mn/Fe cofactor. A MnIII(μ-O)(μ-OH)FeIII species is identified as the first EPR-active species and represents a common state between the two classes of redox-active Mn/Fe proteins. The species downstream from the MnIII(μ-O)(μ-OH)FeIII state exhibits unique EPR properties, including unprecedented spectral breadth and isotope-dependent g-tensors, which are attributed to a weakly coupled, hydrogen-bonded MnIII(μ-OH)FeIII species. This final intermediate precedes formation of the MnIII/FeIII resting state and is suggested to be relevant to understanding the endogenous reactivity of R2lox.
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Affiliation(s)
- Effie C Kisgeropoulos
- The Ohio State Biochemistry Program, The Ohio State University, 100 W 18th Avenue, Columbus, Ohio 43210, United States
| | - Yunqiao J Gan
- Department of Chemistry and Biochemistry, The Ohio State University, 100 W 18th Avenue, Columbus, Ohio 43210, United States
| | - Samuel M Greer
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States.,Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Joseph M Hazel
- Department of Chemistry and Biochemistry, The Ohio State University, 100 W 18th Avenue, Columbus, Ohio 43210, United States
| | - Hannah S Shafaat
- The Ohio State Biochemistry Program, The Ohio State University, 100 W 18th Avenue, Columbus, Ohio 43210, United States.,Department of Chemistry and Biochemistry, The Ohio State University, 100 W 18th Avenue, Columbus, Ohio 43210, United States
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3
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Eedugurala N, Wang Z, Kanbur U, Ellern A, Pruski M, Sadow AD. Synthesis and Characterization of Tris(oxazolinyl)borato Copper(II) and Copper(I) Complexes. Helv Chim Acta 2021. [DOI: 10.1002/hlca.202000209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Naresh Eedugurala
- Department of Chemistry Iowa State University 1605 Gilman Hall Ames IA 50011 United States
- U.S. Department of Energy Ames Laboratory 2416 Pammel Drive Iowa State University Ames IA 50011 United States
| | - Zhuoran Wang
- Department of Chemistry Iowa State University 1605 Gilman Hall Ames IA 50011 United States
- U.S. Department of Energy Ames Laboratory 2416 Pammel Drive Iowa State University Ames IA 50011 United States
| | - Uddhav Kanbur
- Department of Chemistry Iowa State University 1605 Gilman Hall Ames IA 50011 United States
- U.S. Department of Energy Ames Laboratory 2416 Pammel Drive Iowa State University Ames IA 50011 United States
| | - Arkady Ellern
- Department of Chemistry Iowa State University 1605 Gilman Hall Ames IA 50011 United States
| | - Marek Pruski
- Department of Chemistry Iowa State University 1605 Gilman Hall Ames IA 50011 United States
- U.S. Department of Energy Ames Laboratory 2416 Pammel Drive Iowa State University Ames IA 50011 United States
| | - Aaron D. Sadow
- Department of Chemistry Iowa State University 1605 Gilman Hall Ames IA 50011 United States
- U.S. Department of Energy Ames Laboratory 2416 Pammel Drive Iowa State University Ames IA 50011 United States
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4
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Kisgeropoulos EC, Manesis AC, Shafaat HS. Ligand Field Inversion as a Mechanism to Gate Bioorganometallic Reactivity: Investigating a Biochemical Model of Acetyl CoA Synthase Using Spectroscopy and Computation. J Am Chem Soc 2021; 143:849-867. [PMID: 33415980 DOI: 10.1021/jacs.0c10135] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The biological global carbon cycle is largely regulated through microbial nickel enzymes, including carbon monoxide dehydrogenase (CODH), acetyl coenzyme A synthase (ACS), and methyl coenzyme M reductase (MCR). These systems are suggested to utilize organometallic intermediates during catalysis, though characterization of these species has remained challenging. We have established a mutant of nickel-substituted azurin as a scaffold upon which to develop protein-based models of enzymatic intermediates, including the organometallic states of ACS. In this work, we report the comprehensive investigation of the S = 1/2 Ni-CO and Ni-CH3 states using pulsed EPR spectroscopy and computational techniques. While the Ni-CO state shows conventional metal-ligand interactions and a classical ligand field, the Ni-CH3 hyperfine interactions between the methyl protons and the nickel indicate a closer distance than would be expected for an anionic methyl ligand. Structural analysis instead suggests a near-planar methyl ligand that can be best described as cationic. Consistent with this conclusion, the frontier molecular orbitals of the Ni-CH3 species indicate a ligand-centered LUMO, with a d9 population on the metal center, rather than the d7 population expected for a typical metal-alkyl species generated by oxidative addition. Collectively, these data support the presence of an inverted ligand field configuration for the Ni-CH3 Az species, in which the lowest unoccupied orbital is centered on the ligands rather than the more electropositive metal. These analyses provide the first evidence for an inverted ligand field within a biological system. The functional relevance of the electronic structures of both the Ni-CO and Ni-CH3 species are discussed in the context of native ACS, and an inverted ligand field is proposed as a mechanism by which to gate reactivity both within ACS and in other thiolate-containing metalloenzymes.
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Affiliation(s)
- Effie C Kisgeropoulos
- Department of Chemistry and Biochemistry and Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
| | - Anastasia C Manesis
- Department of Chemistry and Biochemistry and Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
| | - Hannah S Shafaat
- Department of Chemistry and Biochemistry and Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
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5
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Bocian A, Gorczyński A, Marcinkowski D, Witomska S, Kubicki M, Mech P, Bogunia M, Brzeski J, Makowski M, Pawluć P, Patroniak V. New benzothiazole based copper(II) hydrazone Schiff base complexes for selective and environmentally friendly oxidation of benzylic alcohols: The importance of the bimetallic species tuned by the choice of the counterion. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.112590] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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6
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Marti-Muñoz J, Xuriguera E, Layton JW, Planell JA, Rankin SE, Engel E, Castaño O. Feasible and pure P 2O 5-CaO nanoglasses: An in-depth NMR study of synthesis for the modulation of the bioactive ion release. Acta Biomater 2019; 94:574-584. [PMID: 31141734 DOI: 10.1016/j.actbio.2019.05.065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 05/19/2019] [Accepted: 05/24/2019] [Indexed: 12/12/2022]
Abstract
The use of bioactive glasses (e.g. silicates, phosphates, borates) has demonstrated to be an effective therapy for the restoration of bone fractures, wound healing and vascularization. Their partial dissolution towards the surrounding tissue has shown to trigger positive bioactive responses, without the necessity of using growth factors or cell therapy, which reduces money-costs, side effects and increases their translation to the clinics. However, bioactive glasses often need from stabilizers (e.g. SiO44-, Ti4+, Co2+, etc.) that are not highly abundant in the body and which metabolization is not fully understood. In this study, we were focused on synthesizing pure calcium phosphate glasses without the presence of such stabilizers. We combined a mixture of ethylphosphate and calcium 2-methoxyethoxide to synthesize nanoparticles with different compositions and degradability. Synthesis was followed by an in-depth nuclear magnetic resonance characterization, complemented with other techniques that helped us to correlate the chemical structure of the glasses with their physiochemical properties and reaction mechanism. After synthesis, the organically modified xerogel (i.e. calcium monoethylphosphate) was treated at 200 or 350 °C and its solubility was maintained and controlled due to the elimination of organics, increase of phosphate-calcium interactions and phosphate polycondensation. To the best of our knowledge, we are reporting the first sol-gel synthesis of binary (P2O5-CaO) calcium phosphate glass nanoparticles in terms of continuous polycondensated phosphate chains structure without the addition of extra ions. The main goal is to straightforward the synthesis, to get a safer metabolization and to modulate the bioactive ion release. Additionally, we shed light on the chemical structure, reaction mechanism and properties of calcium phosphate glasses with high calcium contents, which nowadays are poorly understood. STATEMENT OF SIGNIFICANCE: The use of bioactive inorganic materials (i.e. bioactive ceramics, glass-ceramics and glasses) for biomedical applications is attractive due to their good integration with the host tissue without the necessity of adding exogenous cells or growth factors. In particular, degradable calcium phosphate glasses are completely resorbable, avoiding the retention in the body of the highly stable silica network of silicate glasses, and inducing a more controllable degradability than bioactive ceramics. However, most calcium phosphate glasses include the presence of stabilizers (e.g. Ti4+, Na+, Co2+), which metabolization is not fully understood and complicates their synthesis. The development of binary calcium phosphate glasses with controlled degradability reduces these limitations, offering a simple and completely metabolizable material with higher transfer to the clinics.
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Affiliation(s)
- Joan Marti-Muñoz
- Biomaterials for Regenerative Therapies, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain; CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid, Spain
| | - Elena Xuriguera
- Materials Science and Physical Chemistry Department, University of Barcelona (UB), 08028 Barcelona, Spain
| | - John W Layton
- Department of Chemistry, University of Kentucky (UKY), Lexington, KY 40506-0053, USA
| | - Josep A Planell
- Biomaterials for Regenerative Therapies, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain; CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid, Spain
| | - Stephen E Rankin
- Chemical and Materials Engineering Department, University of Kentucky (UKY), Lexington, KY 40506-0053, USA
| | - Elisabeth Engel
- Biomaterials for Regenerative Therapies, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain; CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid, Spain; Materials Science and Metallurgy Department (EEBE), Technical University of Catalonia (UPC), 08019 Barcelona, Spain.
| | - Oscar Castaño
- Serra Hunter Fellow, Electronics and Biomedical Engineering Department, University of Barcelona (UB), 08028 Barcelona, Spain; Biomaterials for Regenerative Therapies, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain; CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid, Spain; Institute of Nanoscience and Nanotechnology Department, University of Barcelona (UB), 08028 Barcelona, Spain.
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7
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Han Q, Li W, Wang S, He J, Du W, Li M. Asymmetric Cascade Catalysis with Chiral Polyoxometalate-Based Frameworks: Sequential Direct Aldol and Epoxidation Reactions. ChemCatChem 2017. [DOI: 10.1002/cctc.201700160] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Qiuxia Han
- Henan Key Laboratory of Polyoxometalate Chemistry; Institute of Molecular and Crystal Engineering; School of Chemistry and Chemical Engineering; Henan University; Kaifeng 475004 P. R. China
| | - Wenwen Li
- Henan Key Laboratory of Polyoxometalate Chemistry; Institute of Molecular and Crystal Engineering; School of Chemistry and Chemical Engineering; Henan University; Kaifeng 475004 P. R. China
| | - Shugai Wang
- Henan Key Laboratory of Polyoxometalate Chemistry; Institute of Molecular and Crystal Engineering; School of Chemistry and Chemical Engineering; Henan University; Kaifeng 475004 P. R. China
| | - Jiachen He
- Henan Key Laboratory of Polyoxometalate Chemistry; Institute of Molecular and Crystal Engineering; School of Chemistry and Chemical Engineering; Henan University; Kaifeng 475004 P. R. China
| | - Wei Du
- Henan Key Laboratory of Polyoxometalate Chemistry; Institute of Molecular and Crystal Engineering; School of Chemistry and Chemical Engineering; Henan University; Kaifeng 475004 P. R. China
| | - Mingxue Li
- Henan Key Laboratory of Polyoxometalate Chemistry; Institute of Molecular and Crystal Engineering; School of Chemistry and Chemical Engineering; Henan University; Kaifeng 475004 P. R. China
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8
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Porter TR, Hayes EC, Kaminsky W, Mayer JM. Sterically directed nitronate complexes of 2,6-di-tert-butyl-4-nitrophenoxide with Cu( ii) and Zn( ii) and their H-atom transfer reactivity. Dalton Trans 2017; 46:2551-2558. [DOI: 10.1039/c6dt04427a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The bulky 2,6-di-tert-butyl-4-nitrophenolate ligand forms complexes with [TptBuCuII]+ and [TptBuZnII]+ binding via the nitro group in an unusual nitronato-quinone resonance form (TptBu = hydro-tris(3-tert-butyl-pyrazol-1-yl)borate).
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Affiliation(s)
- Thomas R. Porter
- Department of Chemistry
- University of Washington
- Seattle
- USA
- Laboratoire d'Electrochimie Moléculaire
| | - Ellen C. Hayes
- Department of Chemistry
- University of Washington
- Seattle
- USA
| | | | - James M. Mayer
- Department of Chemistry
- University of Washington
- Seattle
- USA
- Department of Chemistry
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9
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Porter TR, Capitao D, Kaminsky W, Qian Z, Mayer JM. Synthesis, Radical Reactivity, and Thermochemistry of Monomeric Cu(II) Alkoxide Complexes Relevant to Cu/Radical Alcohol Oxidation Catalysis. Inorg Chem 2016; 55:5467-75. [PMID: 27171230 DOI: 10.1021/acs.inorgchem.6b00491] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Two new monomeric Cu(II) alkoxide complexes were prepared and fully characterized as models for intermediates in copper/radical mediated alcohol oxidation catalysis: Tp(tBuR)Cu(II)OCH2CF3 with Tp(tBu) = hydro-tris(3-tert-butyl-pyrazol-1-yl)borate 1 or Tp(tBuMe) = hydro-tris(3-tert-butyl-5-methyl-pyrazol-1-yl)borate 2. These complexes were made as models for potential intermediates in enzymatic and synthetic catalytic cycles for alcohol oxidation. However, the alkoxide ligands are not readily oxidized by loss of H; instead, these complexes were found to be hydrogen atom acceptors. They oxidize the hydroxylamine TEMPOH, 2,4,6-tri-t-butylphenol, and 1,4-cyclohexadiene to the nitroxyl radical, phenoxyl radical, and benzene, with formation of HOCH2CF3 (TFE) and the Cu(I) complexes Tp(tBuR)Cu(I)-MeCN in dichloromethane/1% MeCN or 1/2 [Tp(tBuR)Cu(I)]2 in toluene. On the basis of thermodynamics and kinetics arguments, these reactions likely proceed through concerted proton-electron transfer mechanisms. Thermochemical analyses give lower limits for the "effective bond dissociation free energies (BDFE)" of the O-H bonds in 1/2[Tp(tBuR)Cu(I)]2 + TFE and upper limits for the free energies associated with alkoxide oxidations via hydrogen atom transfer (effective alkoxide α-C-H BDFEs). These values are summations of the free energies of multiple chemical steps, which include the energetically favorable formation of 1/2[Tp(tBuR)Cu(I)]2. The effective alkoxide α-C-H bonds are very weak, BDFE ≤ 38 ± 4 kcal mol(-1) for 1 and ≤44 ± 5 kcal mol(-1) for 2 (gas-phase estimates), because C-H homolysis is thermodynamically coupled to one electron transfer to Cu(II) as well as the favorable formation of the 1/2[Tp(tBuR)Cu(I)]2 dimer. Treating 1 with the H atom acceptor (t)Bu3ArO(•) did not result in the expected alkoxide oxidation to an aldehyde, but rather net 2,2,2-trifluoroethoxyl radical transfer occurred to generate an unusual 2-substituted dienone-ether product. Treating 2 with (t)Bu3ArO(•) gives no reaction, despite evidence that overall ligand oxidation and formation of 1/2[Tp(tBuMe)Cu(I)]2 is significantly exoergic. The origin of this lack of reactivity may be due to insufficient weakening of the alcohol α-C-H bond upon complexation to copper.
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Affiliation(s)
- Thomas R Porter
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195, United States
| | - Dany Capitao
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195, United States
| | - Werner Kaminsky
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195, United States
| | - Zhaoshen Qian
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195, United States
| | - James M Mayer
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195, United States
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10
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Ziegler MS, Levine DS, Lakshmi KV, Tilley TD. Aryl Group Transfer from Tetraarylborato Anions to an Electrophilic Dicopper(I) Center and Mixed-Valence μ-Aryl Dicopper(I,II) Complexes. J Am Chem Soc 2016; 138:6484-91. [PMID: 27176131 DOI: 10.1021/jacs.6b00802] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis of discrete, cationic binuclear μ-aryl dicopper complexes [Cu2(μ-η(1):η(1)-Ar)DPFN]X (Ar = C6H5, 3,5-(CF3)2C6H3, and C6F5; DPFN = 2,7-bis(fluoro-di(2-pyridyl)methyl)-1,8-naphthyridine; X = BAr4(-) and NTf2(-); Tf = SO2CF3) was achieved by treatment of a dicopper complex [Cu2(μ-η(1):η(1)-NCCH3)DPFN]X2 (X = PF6(-) and NTf2(-)) with tetraarylborates. Structural characterization revealed symmetrically bridging aryl groups, and (1)H NMR spectroscopy evidenced the same structure in solution at 24 °C. Electrochemical investigation of the resulting arylcopper complexes uncovered reversible redox events that led to the synthesis and isolation of a rare mixed-valence organocopper complex [Cu2(μ-η(1):η(1)-Ph)DPFN](NTf2)2 in high yield. The solid-state structure of the mixed-valence μ-phenyl complex exhibits inequivalent copper centers, despite a short Cu···Cu distance. Electronic and variable-temperature electron paramagnetic resonance spectroscopy of the mixed-valence μ-phenyl complex suggest that the degree of spin localization is temperature-dependent, with a high degree of spin localization observed at lower temperatures. Electronic structure calculations agree with the experimental results and suggest that the spin is localized almost entirely on one metal center.
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Affiliation(s)
- Micah S Ziegler
- Department of Chemistry, University of California , Berkeley, California 94720-1460, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Daniel S Levine
- Department of Chemistry, University of California , Berkeley, California 94720-1460, United States
| | - K V Lakshmi
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - T Don Tilley
- Department of Chemistry, University of California , Berkeley, California 94720-1460, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
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