1
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Lohmeyer L, Werr M, Kaifer E, Himmel H. Interplay and Competition Between Two Different Types of Redox-Active Ligands in Cobalt Complexes: How to Allocate the Electrons? Chemistry 2022; 28:e202201789. [PMID: 35894809 PMCID: PMC9804828 DOI: 10.1002/chem.202201789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Indexed: 01/09/2023]
Abstract
The field of molecular transition metal complexes with redox-active ligands is dominated by compounds with one or two units of the same redox-active ligand; complexes in which different redox-active ligands are bound to the same metal are uncommon. This work reports the first molecular coordination compounds in which redox-active bisguanidine or urea azine (biguanidine) ligands as well as oxolene ligands are bound to the same cobalt atom. The combination of two different redox-active ligands leads to mono- as well as unprecedented dinuclear cobalt complexes, being multiple (four or six) center redox systems with intriguing electronic structures, all exhibiting radical ligands. By changing the redox potential of the ligands through derivatisation, the electronic structure of the complexes could be altered in a rational way.
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Affiliation(s)
- Lukas Lohmeyer
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Marco Werr
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Elisabeth Kaifer
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
| | - Hans‐Jörg Himmel
- Anorganisch-Chemisches InstitutRuprecht-Karls-Universität HeidelbergIm Neuenheimer Feld 27069120HeidelbergGermany
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2
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Agarwal RG, Coste SC, Groff BD, Heuer AM, Noh H, Parada GA, Wise CF, Nichols EM, Warren JJ, Mayer JM. Free Energies of Proton-Coupled Electron Transfer Reagents and Their Applications. Chem Rev 2021; 122:1-49. [PMID: 34928136 DOI: 10.1021/acs.chemrev.1c00521] [Citation(s) in RCA: 145] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We present an update and revision to our 2010 review on the topic of proton-coupled electron transfer (PCET) reagent thermochemistry. Over the past decade, the data and thermochemical formalisms presented in that review have been of value to multiple fields. Concurrently, there have been advances in the thermochemical cycles and experimental methods used to measure these values. This Review (i) summarizes those advancements, (ii) corrects systematic errors in our prior review that shifted many of the absolute values in the tabulated data, (iii) provides updated tables of thermochemical values, and (iv) discusses new conclusions and opportunities from the assembled data and associated techniques. We advocate for updated thermochemical cycles that provide greater clarity and reduce experimental barriers to the calculation and measurement of Gibbs free energies for the conversion of X to XHn in PCET reactions. In particular, we demonstrate the utility and generality of reporting potentials of hydrogenation, E°(V vs H2), in almost any solvent and how these values are connected to more widely reported bond dissociation free energies (BDFEs). The tabulated data demonstrate that E°(V vs H2) and BDFEs are generally insensitive to the nature of the solvent and, in some cases, even to the phase (gas versus solution). This Review also presents introductions to several emerging fields in PCET thermochemistry to give readers windows into the diversity of research being performed. Some of the next frontiers in this rapidly growing field are coordination-induced bond weakening, PCET in novel solvent environments, and reactions at material interfaces.
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Affiliation(s)
- Rishi G Agarwal
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Scott C Coste
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Benjamin D Groff
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Abigail M Heuer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Hyunho Noh
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Giovanny A Parada
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States.,Department of Chemistry, The College of New Jersey, Ewing, New Jersey 08628, United States
| | - Catherine F Wise
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Eva M Nichols
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - James M Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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3
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Guo X, Li YY, Wang SH, Zhang FM, Li BS, Tu YQ, Zhang XM. Construction of the tetracyclic core of the Lycopodium alkaloid annotinolide C. Org Chem Front 2021. [DOI: 10.1039/d1qo00087j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A concise approach to the tetracyclic core of annotinolide C has been developed which contains two key reactions epoxidation/1,2-migration to construct an aza [6.5] spiro ring (A and B) and semireduction/cyclization to construct lactone ring D.
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Affiliation(s)
- Xiang Guo
- State Key Laboratory of Applied Organic Chemistry & College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou 730000
- China
| | - Yong-Yao Li
- State Key Laboratory of Applied Organic Chemistry & College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou 730000
- China
| | - Shuang-Hu Wang
- State Key Laboratory of Applied Organic Chemistry & College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou 730000
- China
| | - Fu-Min Zhang
- State Key Laboratory of Applied Organic Chemistry & College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou 730000
- China
| | - Bao-Sheng Li
- School of Chemistry and Chemical Engineering
- Chongqing University
- Chongqing 400044
- China
| | - Yong-Qiang Tu
- State Key Laboratory of Applied Organic Chemistry & College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou 730000
- China
- School of Chemistry & Chemical Engineering
| | - Xiao-Ming Zhang
- State Key Laboratory of Applied Organic Chemistry & College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou 730000
- China
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4
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Dong K, Jin XL, Chen S, Wu LZ, Liu Q. Controllable synthesis of 2- and 3-aryl-benzomorpholines from 2-aminophenols and 4-vinylphenols. Chem Commun (Camb) 2020; 56:7941-7944. [PMID: 32531007 DOI: 10.1039/d0cc02662j] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present herein a method for the controllable synthesis of 3-aryl-benzomorpholine and 2-aryl-benzomorpholine cycloadducts via cross-coupling/annulation between electron-rich 2-aminophenols and 4-vinylphenols. Molecular oxygen was successfully used in the reaction as the terminal oxidant and the complete inversion of chemoselectivity was achieved by the adjustment of the solvents and bases at room temperature.
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Affiliation(s)
- Kui Dong
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 222 South Tianshui Road, Lanzhou 730000, P. R. China.
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5
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Gianino J, Brown SN. Highly covalent metal-ligand π bonding in chelated bis- and tris(iminoxolene) complexes of osmium and ruthenium. Dalton Trans 2020; 49:7015-7027. [PMID: 32367103 DOI: 10.1039/d0dt01287d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The bis(aminophenol) 2,2'-biphenylbis(3,5-di-tert-butyl-2-hydroxyphenylamine) (ClipH4) forms trans-(Clip)Os(py)2 upon aerobic reaction of the ligand with {(p-cymene)OsCl2}2 in the presence of pyridine and triethylamine. A more oxidized species, cis-β-(Clip)Os(OCH2CH2O), is formed from reaction of the ligand with the osmium(vi) complex OsO(OCH2CH2O)2, and reacts with Me3SiCl to give the chloro complex cis-β-(Clip)OsCl2. Octahedral osmium and ruthenium tris-iminoxolene complexes are formed from the chelating ligand tris(2-(3',5'-di-tert-butyl-2'-hydroxyphenyl)amino-4-methylphenyl)amine (MeClampH6) on aerobic reaction with divalent metal precursors. The complexes' structural and electronic features are well described using a simple bonding model that emphasizes the covalency of the π bonding between the metal and iminoxolene ligands rather than attempting to dissect the parts into discrete oxidation states. Emphasizing the continuity of bonding between disparate complexes, the structural data from a variety of Os and Ru complexes show good correlations to π bond order, and the response of the intraligand bond distances to the bond order can be analyzed to illuminate the polarity of the bonding between metal and the redox-active orbital on the iminoxolenes. The osmium compounds'π bonding orbitals are about 40% metal-centered and 60% ligand-centered, with the ruthenium compounds' orbitals about 65% metal-centered and 35% ligand-centered.
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Affiliation(s)
- Jacqueline Gianino
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556-5670, USA.
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6
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Baryshnikova SV, Poddel'sky AI, Bellan EV, Smolyaninov IV, Cherkasov AV, Fukin GK, Berberova NT, Cherkasov VK, Abakumov GA. Ferrocene-Containing Tin(IV) Complexes Based on o-Benzoquinone and o-Iminobenzoquinone Ligands. Synthesis, Molecular Structure, and Electrochemical Properties. Inorg Chem 2020; 59:6774-6784. [PMID: 32338505 DOI: 10.1021/acs.inorgchem.9b03757] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The addition of different substituted o-benzoquinones and o-iminobenzoquinones to tin(II) bis(o-iminophenolates) of the types (Fc-IP)2SnII and (Fc-4,6-IP)2SnII (where Fc-IP is anion 2-(ferrocenylmethyleneamino)phenolate [Fc-C(H)═N(C6H4)O-] and Fc-4,6-IP is anion 2-(ferrocenylmethyleneamino)-4,6-di-tert-butylphenolate [Fc-C(H)═N(4,6-tBu-C6H2)O-]) in tetrahydrofuran leads to the oxidation of Sn(II) to Sn(IV) with formation of the corresponding tin(IV) catecholates (Fc-4,6-IP)2SnIV(3,6-Cat) (1), (Fc-IP)2SnIV(3,6-Cat) (2), (Fc-4,6-IP)2SnIV(4-Cl-3,6-Cat) (3), (Fc-IP)2SnIV(4-Cl-3,6-Cat) (4), (Fc-4,6-IP)2SnIV(4,5-Cl2-3,6-Cat) (5), and (Fc-IP)2SnIV(4,5-Cl2-3,6-Cat) (6) or the o-amidophenolates (Fc-4,6-IP)2SnIV(AP-Me) (7), (Fc-IP)2SnIV(AP-iPr) (8), and (Fc-4,6-IP)2SnIV(AP-iPr) (9). Here ligands 3,6-Cat, 4-Cl-3,6-Cat, and 4,5-Cl2-3,6-Cat are dianions 3,6-di-tert-butyl-, 4-chloro-3,6-di-tert-butyl-, and 4,5-dichloro-3,6-di-tert-butylcatecholates, respectively, and AP-Me and AP-iPr are dianions 4,6-di-tert-butyl-N-(2,6-dimethylphenyl)-o-amidophenolate and 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-amidophenolate, respectively. Complexes 1-9 have been characterized in detail by IR spectroscopy, cyclic voltammetry, and 1H, 13C, and 119Sn NMR spectroscopy. The molecular structures of tin(IV) complexes 5, 7, and 9 in the crystalline state were determined by single-crystal X-ray diffraction analysis. Complexes demonstrate a series of successive oxidations involving alternately catecholato/o-amidophenolato centers and ferrocenyl moieties. The relative oxidation potentials of these redox centers depend on the acceptor properties of the redox-active chelating O,O' or O,N ligand. An increase in the acceptor properties of redox-active o-quinonato-type ligands leads to an increase in the oxidation potentials of redox ligands as well as the following oxidation of ferrocenyl group(s). In two series of complexes, (Fc-4,6-L)2SnL' and (Fc-L)2SnL', where L' is AP-iPr, AP-Me, 3,6-Cat, 4-Cl-3,6-Cat, and 4,5-Cl2-3,6-Cat, a more pronounced convergence of the oxidation potentials of the redox-active o-quinonato ligand and ferrocenyl group occurs in the series (Fc-L)2SnL'.
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Affiliation(s)
- Svetlana V Baryshnikova
- G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina strasse 49, Nizhny Novgorod 603137, Russia
| | - Andrey I Poddel'sky
- G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina strasse 49, Nizhny Novgorod 603137, Russia
| | - Ekaterina V Bellan
- G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina strasse 49, Nizhny Novgorod 603137, Russia
| | - Ivan V Smolyaninov
- Federal State Budgetary Institution of Science "Federal Research Centre the Southern Scientific Centre of the Russian Academy of Sciences", Chehova avenue 41, Rostov-on-Don 344006, Russia.,Astrakhan State Technical University, Tatisheva strasse 16, Astrakhan 414025, Russia
| | - Anton V Cherkasov
- G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina strasse 49, Nizhny Novgorod 603137, Russia
| | - Georgy K Fukin
- G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina strasse 49, Nizhny Novgorod 603137, Russia
| | - Nadezhda T Berberova
- Astrakhan State Technical University, Tatisheva strasse 16, Astrakhan 414025, Russia
| | - Vladimir K Cherkasov
- G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina strasse 49, Nizhny Novgorod 603137, Russia
| | - Gleb A Abakumov
- G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina strasse 49, Nizhny Novgorod 603137, Russia
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7
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Samanta D, Saha P, Ghosh P. Proton-Coupled Oxidation of Aldimines and Stabilization of H-Bonded Phenoxyl Radical-Phenol Skeletons. Inorg Chem 2019; 58:15060-15077. [DOI: 10.1021/acs.inorgchem.9b01568] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Debasish Samanta
- Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata 700103, India
| | - Pinaki Saha
- Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata 700103, India
| | - Prasanta Ghosh
- Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata 700103, India
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8
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Coughlin EJ, Qiao Y, Lapsheva E, Zeller M, Schelter EJ, Bart SC. Uranyl Functionalization Mediated by Redox-Active Ligands: Generation of O-C Bonds via Acylation. J Am Chem Soc 2019; 141:1016-1026. [PMID: 30532952 DOI: 10.1021/jacs.8b11302] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A series of uranyl compounds with the redox-active iminoquinone ligand have been synthesized, and their electronic structures elucidated using multinuclear NMR, EPR, electronic absorption spectroscopies, SQUID magnetometry, and X-ray crystallography. Characterization and analysis of the iminoquinone (iq0) complex, (dippiq)UO2(OTf)2THF (1-iq), the iminosemiquinone (isq1-) complex, (dippisq)2UO2THF (2-isq), and the amidophenolate (ap2-) complex, [(dippap)2UO2THF][K(18-crown-6)(THF)2]2(3-ap crown) show that reduction events are ligand-based, with the uranium center remaining in the hexavalent state. Reactivity of 2-isq with B-chlorocatecholborane or pivaloyl chloride leads to U-Ouranyl bond scission and reduction of U(VI) to U(IV) concomitant with ligand oxidation along with organic byproducts. 18O isotopic labeling experiments along with IR spectroscopy, mass spectrometry, and multinuclear NMR spectroscopy confirm that the organic byproducts contain oxygen atoms which originate from U-Ouranyl bond activation.
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Affiliation(s)
- Ezra J Coughlin
- H.C. Brown Laboratory, Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Yusen Qiao
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
| | - Ekaterina Lapsheva
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
| | - Matthias Zeller
- H.C. Brown Laboratory, Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Eric J Schelter
- P. Roy and Diana T. Vagelos Laboratories, Department of Chemistry , University of Pennsylvania , 231 South 34th Street , Philadelphia , Pennsylvania 19104 , United States
| | - Suzanne C Bart
- H.C. Brown Laboratory, Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
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9
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Safaei E, Balaghi SE, Chiang L, Clarke RM, Martelino D, Webb MI, Wong EWY, Savard D, Walsby CJ, Storr T. Stabilization of different redox levels of a tridentate benzoxazole amidophenoxide ligand when bound to Co(iii) or V(v). Dalton Trans 2019; 48:13326-13336. [DOI: 10.1039/c9dt02865j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The electronic structure of Co and V complexes of a tridentate benzoxazole-containing aminophenol ligand NNOH2 were characterized by both experimental and theoretical methods.
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Affiliation(s)
- Elham Safaei
- Department of Chemistry
- College of Science
- Shiraz University
- Shiraz
- Iran
| | | | - Linus Chiang
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Ryan M. Clarke
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Diego Martelino
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Michael I. Webb
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Edwin W. Y. Wong
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Didier Savard
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Charles J. Walsby
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
| | - Tim Storr
- Department of Chemistry
- Simon Fraser University
- 8888 University Drive
- Burnaby
- Canada
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10
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Conner KM, Arostegui AC, Swanson DD, Brown SN. When Do Strongly Coupled Diradicals Show Strongly Coupled Reactivity? Thermodynamics and Kinetics of Hydrogen Atom Transfer Reactions of Palladium and Platinum Bis(iminosemiquinone) Complexes. Inorg Chem 2018. [PMID: 29517233 DOI: 10.1021/acs.inorgchem.8b00068] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The 2,2'-biphenylene-bridged bis(iminosemiquinone) complexes ( tBuClip)M [ tBuClipH4 = 4,4'-di- tert-butyl- N, N'-bis(3,5-di- tert-butyl-2-hydroxyphenyl)-2,2'-diaminobiphenyl; M = Pd, Pt] can be reduced to the bis(aminophenoxide) complexes ( tBuClipH2)M by reaction with hydrazobenzene (M = Pd) or by catalytic hydrogenation (M = Pt). The palladium complex with one aminophenoxide ligand and one iminosemiquinone ligand, ( tBuClipH)Pd, is generated by comproportionation of ( tBuClip)Pd with ( tBuClipH2)Pd in a process that is both slow (0.06 M-1 s-1 in toluene at 23 °C) and only modestly favorable ( Kcom = 1.9 in CDCl3), indicating that both N-H bonds have essentially the same bond strength. The mono(iminoquinone) complex ( tBuClipH)Pt has not been observed, indicating that the platinum analogue shows no tendency to comproportionate ( Kcom < 0.1). The average bond dissociation free energies (BDFE) of the complexes have been established by equilibration with suitably substituted hydrazobenzenes, and the palladium bis(iminosemiquinone) is markedly more oxidizing than the platinum compound, with hydrogen transfer from ( tBuClipH2)Pt to ( tBuClip)Pd occurring with Δ G° = -8.9 kcal mol-1. The palladium complex ( tBuClipH2)Pd reacts with nitroxyl radicals in two observable steps, with the first hydrogen transfer taking place slightly faster than the second. In the platinum analogue, the first hydrogen transfer is much slower than the second, presumably because the N-H bond in the monoradical complex ( tBuClipH)Pt is unusually weak. Using driving force-rate correlations, it is estimated that this bond has a BDFE of 55.1 kcal mol-1, which is 7.1 kcal mol-1 weaker than that of the first N-H bond in ( tBuClipH2)Pt. The two radical centers in the platinum, but not the palladium, complex thus act in concert with each other and display a strong thermodynamic bias toward two-electron reactivity. The greater thermodynamic and kinetic coupling in the platinum complex is attributed to the stronger metal-ligand π interactions in this compound.
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Affiliation(s)
- Kyle M Conner
- Department of Chemistry and Biochemistry , University of Notre Dame , 251 Nieuwland Science Hall , Notre Dame , Indiana 46556-5670 , United States
| | - AnnaMaria C Arostegui
- Department of Chemistry and Biochemistry , University of Notre Dame , 251 Nieuwland Science Hall , Notre Dame , Indiana 46556-5670 , United States
| | - Daniel D Swanson
- Department of Chemistry and Biochemistry , University of Notre Dame , 251 Nieuwland Science Hall , Notre Dame , Indiana 46556-5670 , United States
| | - Seth N Brown
- Department of Chemistry and Biochemistry , University of Notre Dame , 251 Nieuwland Science Hall , Notre Dame , Indiana 46556-5670 , United States
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11
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Conner KM, Perugini AL, Malabute M, Brown SN. Group 10 Bis(iminosemiquinone) Complexes: Measurement of Singlet–Triplet Gaps and Analysis of the Effects of Metal and Geometry on Electronic Structure. Inorg Chem 2018; 57:3272-3286. [DOI: 10.1021/acs.inorgchem.8b00062] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Kyle M. Conner
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
| | - Amanda L. Perugini
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
| | - Miko Malabute
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
| | - Seth N. Brown
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
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12
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Bamford KL, Longobardi LE, Liu L, Grimme S, Stephan DW. FLP reduction and hydroboration of phenanthrene o-iminoquinones and α-diimines. Dalton Trans 2018; 46:5308-5319. [PMID: 28382362 DOI: 10.1039/c7dt01024a] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Redox active, or non-innocent, ligands containing O or N heteroatoms are frequently used in transition metal complexes, imparting unique catalytic properties, but have seen comparatively limited use in the chemistry of group 13 elements. In this article we report the frustrated Lewis pair (FLP) hydrogenation and hydroboration of an N-aryl-phenanthrene-o-iminoquinone and two N,N'-diaryl-phenanthrene α-diimines. These reactions exploit B(C6F5)3/H2, HB(C6F5)2 and H2BC6F5·SMe2 to give a series of derivatives including 1,3,2-oxaza- and diazaboroles and borocyclic radicals. The reaction pathways leading to these products are outlined and supported by DFT-calculations and experimental insight. The modular and unusual synthetic strategies described herein give access to new boroles as well as air-stable boron-containing radicals, thus extending the chemistry of redox active ligands in main group systems.
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Affiliation(s)
- Karlee L Bamford
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, Ontario M5S 3H6, Canada.
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13
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Mondal D, Majee MC, Kundu S, Mörtel M, Abbas G, Endo A, Khusniyarov MM, Chaudhury M. Dinuclear Iron(III) and Cobalt(III) Complexes Featuring a Biradical Bridge: Their Molecular Structures and Magnetic, Spectroscopic, and Redox Properties. Inorg Chem 2018; 57:1004-1016. [DOI: 10.1021/acs.inorgchem.7b02340] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dhrubajyoti Mondal
- Department of Inorganic
Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
| | - Mithun Chandra Majee
- Department of Inorganic
Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
| | - Sanchita Kundu
- Department of Inorganic
Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
| | - Max Mörtel
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstrasse
1, 91058 Erlangen, Germany
| | - Ghulam Abbas
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstrasse
1, 91058 Erlangen, Germany
| | - Akira Endo
- Department
of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1
Kioi-cho, Chiyoda-ku, Tokyo 102-8554, Japan
| | - Marat M. Khusniyarov
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstrasse
1, 91058 Erlangen, Germany
| | - Muktimoy Chaudhury
- Department of Inorganic
Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
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14
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Abstract
Strong π bonding in molybdenum(vi) tris(amidophenoxides) drives a preference for the fac geometry and quenches the metal's Lewis acidity.
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Affiliation(s)
- Alexander N. Erickson
- Department of Chemistry and Biochemistry
- 251 Nieuwland Science Hall
- University of Notre Dame
- Notre Dame
- USA
| | - Seth N. Brown
- Department of Chemistry and Biochemistry
- 251 Nieuwland Science Hall
- University of Notre Dame
- Notre Dame
- USA
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15
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Coughlin EJ, Zeller M, Bart SC. Neodymium(III) Complexes Capable of Multi-Electron Redox Chemistry. Angew Chem Int Ed Engl 2017; 56:12142-12145. [PMID: 28763142 DOI: 10.1002/anie.201705423] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Indexed: 11/09/2022]
Abstract
A family of neodymium complexes featuring a redox-active ligand in three different oxidation states has been synthesized, including the iminoquinone (L0 ) derivative, (dipp iq)2 NdI3 (1-iq), the iminosemiquinone (L1- ) compound, (dipp isq)2 NdI(THF) (1-isq), and the amidophenolate (L2- ) [K(THF)2 ][(dipp ap)2 Nd(THF)2 ] (1-ap) and [K(18-crown-6)][(dipp ap)2 Nd(THF)2 ] (1-ap crown) species. Full spectroscopic and structural characterization of each derivative established the +3 neodymium oxidation state with redox chemistry occurring at the ligand rather than the neodymium center. Oxidation with elemental chalcogens showed the reversible nature of the ligand-mediated reduction process, forming the iminosemiquinone metallocycles, [K(18-crown-6)][(dipp isq)2 Nd(S5 )] (2-isq crown) and [K(18-crown-6)(THF)][(dipp isq)2 Nd(Se5 )] (3-isq crown), which are characterized to contain a 6-membered twist-boat ring.
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Affiliation(s)
- Ezra J Coughlin
- H.C. Brown Laboratory, Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - Matthias Zeller
- H.C. Brown Laboratory, Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - Suzanne C Bart
- H.C. Brown Laboratory, Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA
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16
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Coughlin EJ, Zeller M, Bart SC. Neodymium(III) Complexes Capable of Multi‐Electron Redox Chemistry. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201705423] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Ezra J. Coughlin
- H.C. Brown Laboratory Department of Chemistry Purdue University West Lafayette IN 47907 USA
| | - Matthias Zeller
- H.C. Brown Laboratory Department of Chemistry Purdue University West Lafayette IN 47907 USA
| | - Suzanne C. Bart
- H.C. Brown Laboratory Department of Chemistry Purdue University West Lafayette IN 47907 USA
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17
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Mondal S, Maity S, Ghosh P. A Redox-Active Cascade Precursor: Isolation of a Zwitterionic Triphenylphosphonio-Hydrazyl Radical and an Indazolo-Indazole Derivative. Inorg Chem 2017; 56:8878-8888. [PMID: 28696110 DOI: 10.1021/acs.inorgchem.7b00818] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A redox-active [ML] unit (M = CoII and MnII; LH2 = N'-(1,4-dioxo-1,4-dihydronaphthalen-2-yl)benzohydrazide) defined as a cascade precursor that undergoes a multicomponent redox reaction comprising of a C-N bond formation, tautomerization, oxidation, C-C coupling, demetalation, and affording 6,14-dibenzoylbenzo[f]benzo[5,6]indazolo[3a,3-c]indazole-5,8,13,16-tetraone (IndL2) is reported. Conversion of LH2 → IndL2 in air is overall a (6H++6e) oxidation reaction, and it opens a route for the syntheses of bioactive diarylindazolo[3a,3-c]indazole derivatives. The reaction occurs via a radical coupling reaction, and the radical intermediate was isolated as a triphenylphosphonio adduct. In presence of PPh3 the [ML] unit promotes a reaction that involves a C-P bond formation, tautomerization, and oxidation to yield a stable zwitterionic triphenylphosphonio-hydrazyl radical (PPh3L±•). Conversion of LH2 → PPh3L±• is a (3H++3e) oxidation reaction. To authenticate the [ML] unit, in addition to the IndL2, a zinc(II) complex, [(L3)ZnII(H2O)Cl]·2MeOH (1·2MeOH), was successfully isolated (L3H = a pyridazine derivative of 1,4 naphthoquinone) from a reaction of LH2 with hydrated ZnCl2. Conversion of 3LH2 → 1 is also a multicomponent (6H++6e) oxidation reaction promoted by zinc(II) ion via a radical intermediate. Facile oxidation of [L2-] to [L•-] that was considered as an intermediate of these conversions was confirmed by isolating a 1,4 naphthoquinone-benzhydrazyl radical (LH•) complex, [(LH•)ZnII(H2O)Cl2] (2H•). The intermediates of LH2 → IndL2, LH2 → PPh3L±•, and 3LH2 → 1 conversions were analyzed by electrospray ionization mass spectroscopy. The molecular and electronic structures of PPh3L±•, IndL2, 1·2MeOH, and 2H• were confirmed by single-crystal X-ray crystallography, electron paramagnetic resonance spectroscopy, and density functional theory calculations.
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Affiliation(s)
- Sandip Mondal
- Department of Chemistry, R. K. Mission Residential College, Narendrapur , Kolkata 103, West Bengal, India
| | - Suvendu Maity
- Department of Chemistry, R. K. Mission Residential College, Narendrapur , Kolkata 103, West Bengal, India
| | - Prasanta Ghosh
- Department of Chemistry, R. K. Mission Residential College, Narendrapur , Kolkata 103, West Bengal, India
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Duan L, Jia Y, Li X, Li Y, Hu H, Li J, Cui C. Synthesis, Characterization, and Reversible Multielectron Redox Properties of a Biradical Yttrium Complex Containing Bis(2‐isopropylaminophenyl)amide. Eur J Inorg Chem 2017. [DOI: 10.1002/ejic.201601457] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Lili Duan
- State Key Laboratory of Medicinal Chemical Biology College of Pharmacy and Tianjin Key Laboratory of Molecular Drug Research Institution Nankai University 300071 Tianjin China
| | - Yi‐Bo Jia
- State Key Laboratory of Medicinal Chemical Biology College of Pharmacy and Tianjin Key Laboratory of Molecular Drug Research Institution Nankai University 300071 Tianjin China
| | - Xiao‐Gen Li
- State Key Laboratory of Medicinal Chemical Biology College of Pharmacy and Tianjin Key Laboratory of Molecular Drug Research Institution Nankai University 300071 Tianjin China
| | - Yue‐Ming Li
- State Key Laboratory of Medicinal Chemical Biology College of Pharmacy and Tianjin Key Laboratory of Molecular Drug Research Institution Nankai University 300071 Tianjin China
| | - Hongfan Hu
- State Key Laboratory of Elemento‐Organic Chemistry Collaborative Innovation Center of Chemical Science and Engineering Nankai University 300071 Tianjin China
| | - Jianfeng Li
- State Key Laboratory of Elemento‐Organic Chemistry Collaborative Innovation Center of Chemical Science and Engineering Nankai University 300071 Tianjin China
| | - Chunming Cui
- State Key Laboratory of Elemento‐Organic Chemistry Collaborative Innovation Center of Chemical Science and Engineering Nankai University 300071 Tianjin China
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19
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Swanson DD, Conner KM, Brown SN. A chelating bis(aminophenol) ligand bridged by a 1,1′-ferrocene-bis(para-phenylene) linker. Dalton Trans 2017; 46:9049-9057. [DOI: 10.1039/c7dt01945a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The 1,1′-ferrocene-bis(p-phenylene) group serves as a structural linker connecting two iminosemiquinones to palladium without significant electronic interactions between the ferrocene and the palladium complex.
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Affiliation(s)
- Daniel D. Swanson
- Department of Chemistry and Biochemistry
- University of Notre Dame
- Notre Dame
- USA
| | - Kyle M. Conner
- Department of Chemistry and Biochemistry
- University of Notre Dame
- Notre Dame
- USA
| | - Seth N. Brown
- Department of Chemistry and Biochemistry
- University of Notre Dame
- Notre Dame
- USA
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20
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Chakraborty B, Bhunya S, Paul A, Paine TK. Reactivity of Biomimetic Iron(II)-2-aminophenolate Complexes toward Dioxygen: Mechanistic Investigations on the Oxidative C–C Bond Cleavage of Substituted 2-Aminophenols. Inorg Chem 2014; 53:4899-912. [DOI: 10.1021/ic403043e] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Biswarup Chakraborty
- Department of Inorganic Chemistry, ‡Raman Center for Atomic, Molecular and Optical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Sourav Bhunya
- Department of Inorganic Chemistry, ‡Raman Center for Atomic, Molecular and Optical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Ankan Paul
- Department of Inorganic Chemistry, ‡Raman Center for Atomic, Molecular and Optical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
| | - Tapan Kanti Paine
- Department of Inorganic Chemistry, ‡Raman Center for Atomic, Molecular and Optical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India
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21
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Matson EM, Franke SM, Anderson NH, Cook TD, Fanwick PE, Bart SC. Radical Reductive Elimination from Tetrabenzyluranium Mediated by an Iminoquinone Ligand. Organometallics 2014. [DOI: 10.1021/om4012104] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ellen M. Matson
- H. C. Brown Laboratory, Department
of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Sebastian M. Franke
- Department of Chemistry and Pharmacy, Inorganic
Chemistry, Friedrich Alexander University, Egerlandstraße 1, 91058 Erlangen, Germany
| | - Nickolas H. Anderson
- H. C. Brown Laboratory, Department
of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Timothy D. Cook
- H. C. Brown Laboratory, Department
of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Phillip E. Fanwick
- H. C. Brown Laboratory, Department
of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Suzanne C. Bart
- H. C. Brown Laboratory, Department
of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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22
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Metzinger R, Demeshko S, Limberg C. A Novel Pentadentate Redox-Active Ligand and Its Iron(III) Complexes: Electronic Structures and O2Reactivity. Chemistry 2014; 20:4721-35. [DOI: 10.1002/chem.201304535] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 01/15/2014] [Indexed: 11/11/2022]
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23
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Bittner MM, Kraus D, Lindeman SV, Popescu CV, Fiedler AT. Synthetic, spectroscopic, and DFT studies of iron complexes with iminobenzo(semi)quinone ligands: implications for o-aminophenol dioxygenases. Chemistry 2013; 19:9686-98. [PMID: 23744733 PMCID: PMC3965334 DOI: 10.1002/chem.201300520] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 04/17/2013] [Indexed: 11/10/2022]
Abstract
The oxidative C-C bond cleavage of o-aminophenols by nonheme Fe dioxygenases is a critical step in both human metabolism (the kynurenine pathway) and the microbial degradation of nitroaromatic pollutants. The catalytic cycle of o-aminophenol dioxygenases (APDOs) has been proposed to involve formation of an Fe(II)/O2/iminobenzosemiquinone complex, although the presence of a substrate radical has been called into question by studies of related ring-cleaving dioxygenases. Recently, we reported the first synthesis of an iron(II) complex coordinated to an iminobenzosemiquinone (ISQ) ligand, namely, [Fe((Ph2)Tp)((tBu)ISQ)] (2a; where (Ph2)Tp=hydrotris(3,5-diphenylpyrazol-1-yl)borate and (tBu)ISQ is the radical anion derived from 2-amino-4,6-di-tert-butylphenol). In the current manuscript, density functional theory (DFT) calculations and a wide variety of spectroscopic methods (electronic absorption, Mössbauer, magnetic circular dichroism, and resonance Raman) were employed to obtain detailed electronic-structure descriptions of 2a and its one-electron oxidized derivative [3a](+). In addition, we describe the synthesis and characterization of a parallel series of complexes featuring the neutral supporting ligand tris(4,5-diphenyl-1-methylimidazol-2-yl)phosphine ((Ph2)TIP). The isomer shifts of about 0.97 mm s(-1) obtained through Mössbauer experiments confirm that 2a (and its (Ph2)TIP-based analogue [2b](+)) contain Fe(II) centers, and the presence of an ISQ radical was verified by analysis of the absorption spectra in light of time-dependent DFT calculations. The collective spectroscopic data indicate that one-electron oxidation of the Fe(II)-ISQ complexes yields complexes ([3a](+) and [3b](2+)) with electronic configurations between the Fe(III)-ISQ and Fe(II)-IBQ limits (IBQ=iminobenzoquinone), highlighting the ability of o-amidophenolates to access multiple oxidation states. The implications of these results for the mechanism of APDOs and other ring-cleaving dioxygenases are discussed.
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Affiliation(s)
- Michael M. Bittner
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States
| | - David Kraus
- Department of Chemistry, Ursinus College, Collegeville, Pennsylvania 19426, United States
| | - Sergey V. Lindeman
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States
| | - Codrina V. Popescu
- Department of Chemistry, Ursinus College, Collegeville, Pennsylvania 19426, United States
| | - Adam T. Fiedler
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States
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24
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Wang M, England J, Weyhermüller T, Kokatam SL, Pollock CJ, DeBeer S, Shen J, Yap GPA, Theopold KH, Wieghardt K. New Complexes of Chromium(III) Containing Organic π-Radical Ligands: An Experimental and Density Functional Theory Study. Inorg Chem 2013; 52:4472-87. [PMID: 23531224 DOI: 10.1021/ic302743s] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Mei Wang
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
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25
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Siengalewicz P, Mulzer J, Rinner U. Lycopodium alkaloids--synthetic highlights and recent developments. THE ALKALOIDS. CHEMISTRY AND BIOLOGY 2013; 72:1-151. [PMID: 24712098 DOI: 10.1016/b978-0-12-407774-4.00001-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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26
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Williams VA, Hulley EB, Wolczanski PT, Lancaster KM, Lobkovsky EB. Exploring the limits of redox non-innocence: pseudo square planar [{κ4-Me2C(CH2NCHpy)2}Ni]n (n = 2+, 1+, 0, −1, −2) favor Ni(ii). Chem Sci 2013. [DOI: 10.1039/c3sc50743b] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Electrochemistry and bioactivity relationship of 6-substituted-4H-pyrido[4,3,2-kl]acridin-4-one antitumor drug candidates. Bioelectrochemistry 2012; 88:103-9. [PMID: 22885855 DOI: 10.1016/j.bioelechem.2012.07.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 07/05/2012] [Accepted: 07/09/2012] [Indexed: 11/23/2022]
Abstract
We report here the electrochemical characterization of eight synthetic DNA intercalators based on the 4H-pyrido[4,3,2-kl]acridin-4-one structure. We found that the electrochemical behavior of these redox active drugs is strongly influenced by the nature of the solvent. A single two-electron reduction is observed in an aqueous phosphate buffer (PB) whereas two successive one-electron reductions are observed in aprotic solution (acetonitrile). The influence of the molecular structure on the potential values is addressed along with a comparison between the DNA binding constant (K(DNA)) and the cytotoxic activity against HT29 cells (IC(50)). For typical DNA intercalators, one could expect that toxicity will be roughly proportional to the DNA binding constant. Yet, a structure/activity comparison solely based on the DNA affinity was not conclusive. In contrast, a direct relationship was evidenced for the first time between the decimal logarithm of the in vitro bioactivity and the reduction potential of pyridoacridones recorded in PB at pH 7.0. Moreover, most of the bio/electrochemical relationships previously described for quinone-based drugs were reported with electrochemical characterization in aprotic solvents (typically acetonitrile, dimethylformamide or dimethylsulfoxide). But aqueous solution electrochemistry is definitely the most bio-relevant because the redox mechanism of quinone or iminoquinone reduction directly depends on the protic nature of the solvent.
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28
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Kopec JA, Shekar S, Brown SN. Molybdenum(VI) Complexes of a 2,2′-Biphenyl-bridged Bis(amidophenoxide): Competition between Metal–Ligand and Metal–Amidophenoxide π Bonding. Inorg Chem 2012; 51:1239-50. [DOI: 10.1021/ic201736h] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Jason A. Kopec
- Department of Chemistry and Biochemistry, 251 Nieuwland
Science Hall, University of Notre Dame,
Notre Dame, Indiana 46556-5670, United States
| | - Sukesh Shekar
- Department of Chemistry and Biochemistry, 251 Nieuwland
Science Hall, University of Notre Dame,
Notre Dame, Indiana 46556-5670, United States
| | - Seth N. Brown
- Department of Chemistry and Biochemistry, 251 Nieuwland
Science Hall, University of Notre Dame,
Notre Dame, Indiana 46556-5670, United States
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29
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Hatzipanayioti D, Kontotheodorou K. The chemistry and preparation of tantalum complexes with 2,3-dihydroxy benzoic acid: experimental and theoretical investigation. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2011; 78:949-960. [PMID: 21216659 DOI: 10.1016/j.saa.2010.11.049] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 11/01/2010] [Accepted: 11/30/2010] [Indexed: 05/30/2023]
Abstract
The effect of 2,3-dihydroxybenzoic acid (2,3DHBA, pyrocatechuic acid) on the chloro-alkoxo-species [TaCl(5-x)(OMe)(x)], formed by dissolving TaCl(5) in MeOH, has been studied. The coordination of 2,3DHBA-H(2)(-) on Ta (V) replacing MeO-terminal groups was monitored via NMR spectroscopy. The yellow solid 1 was isolated from the mixture of TaCl(5), with neutral 2,3-DHBA, in MeOH. From this solid the elemental (C, H and Ta), the thermogravimetric analyses, the IR, NMR, ESR and electronic spectra support the formula Ta(2)(2,3DHBA)(2)(O)(2)Cl(4)(MeO)(4). The ESR spectrum of solid 1, at 4.2 K, shows a half-field signal apart from a multiline signal around g=2, supporting evidence for semiquinone and Ta (IV) presence. The occurrence of superoxide radical, in the low temperature of ESR spectrum recording, cannot be ruled out. By heating the solid 1 at 500°C, an oxide phase showing porous character (SEM) and retaining CO(2) (IR), is evident. Solid 1 heated at 900°C, leads to the formation of β-Ta(2)O(5) orthorhombic phase, as the XRD pattern indicates. The hydrolytic process of solid 1, in aqueous solutions, has been studied; the presence of paramagnetic species generated in situ upon addition of base and the consequent degradative process of 2,3-DHBA, under aerobic conditions is obvious. In order to gain information for the structure of solid 1, DFT calculations have been performed for some theoretical models, based on the empirical formula of solid 1. The calculated structural and spectroscopic parameters have been correlated to experimental results. The energy optimized structures may give an idea about the way of MeCl and MeOMe formation as well some possible intermediates of the hydrolytic mechanism.
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31
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Nguyen AI, Blackmore KJ, Carter SM, Zarkesh RA, Heyduk AF. One- and two-electron reactivity of a tantalum(V) complex with a redox-active tris(amido) ligand. J Am Chem Soc 2010; 131:3307-16. [PMID: 19219982 DOI: 10.1021/ja808542j] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A new redox-active, tris(amido) ligand platform, bis(2-isopropylamino-4-methoxyphenylamine [NNN(cat)](3-), has been prepared and used in the preparation of tantalum(V) complexes. The ligand was prepared in its protonated form by a three-step procedure from commercially available 4-methoxy-2-nitroaniline and 1-iodo-4-methoxy-2-nitrobenzene. Direct reaction of [NNN(cat)]H(3) with TaCl(2)Me(3) afforded five-coordinate [NNN(cat)]TaCl(2) (1), which accepted the strong sigma-donor ligand (t)BuNC to form the six-coordinate adduct [NNN(cat)]TaCl(2)(CN(t)Bu) (2). Complex 1 is formally a d(0), Ta(V) complex; however, one- and two-electron reactivity is enabled at the metal center by the redox-activity of the ligand platform. Complex 1 was oxidized by one electron to afford the radical species [NNN(sq*)]TaCl(3) (3), which was characterized by solution EPR spectroscopy. Cyclic voltammetry studies of complex 3 showed clean one-electron oxidation and reduction processes at 0.148 and -0.324 V vs [Cp(2)Fe](+/0), indicating the accessibility of three oxidation states, [NNN(cat)](3-), [NNN(sq*)](2-), and [NNN(q)](-), for the metallated ligand. Complex 1 also can undergo two-electron reactions, as evidenced by the reaction with nitrene transfer reagents to form tantalum imido species. Thus 1 reacted with organic azides, RN(3) (R = Ph, p-C(6)H(4)Me, p-C(6)H(4)(t)Bu), to form [NNN(q)]TaCl(2)(NR) (4). Similarly, the tantalum diphenylmethylidenehydrazido complex, [NNN(q)]TaCl(2)(NNCPh(2)) (5), was formed by reaction of 1 with the diazoalkane, N(2)CPh(2).
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Affiliation(s)
- Andy I Nguyen
- Department of Chemistry, University of California, Irvine, California 92697, USA
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32
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Barry N, Furrer J, Therrien B. In- and Out-of-Cavity Interactions by Modulating the Size of Ruthenium Metallarectangles. Helv Chim Acta 2010. [DOI: 10.1002/hlca.200900422] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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33
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Ilango S, Vidjayacoumar B, Gambarotta S. Samarium complexes of a sigma-/pi-pyrrolide/arene based macrocyclic ligand. Dalton Trans 2010; 39:6853-7. [PMID: 20495730 DOI: 10.1039/c002514n] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A bis-pyrrolide macrocyclic ligand [L = trans-calix[2]benzene[2]pyrrole(H)] containing two aromatic phenyl rings in the macrocycle backbone was reacted with SmCl(3)(THF)(3) to afford the corresponding [LSm(III)Cl] (1) complex. Its crystal structure showed the ligand adopting the sigma-bonding mode with the pyrrolide moieties and the pi-bonding with the two aromatic rings. Reaction of 1 with MeLi in THF gave a mixture of two compounds. The major was a C-H activated complex [LSm(III)(THF)] (2a) where the bonding mode of the pyrrolide rings was switched from sigma- to pi- as a result of the deprotonation and metallation of one of the two aromatic rings. The minor component was an unusual [(L)Sm(III)(HL')] (2b) complex containing both a regular ligand and an "N-confused" macrocyclic ligand. The two ligands wrapped the Sm center with the regular ligand adopting a bonding mode similar to 1. The second ligand instead acted as a simple sigma-bonded monodentate ligand, only using one nitrogen atom of one pyrrolide ring. However, this particular pyrrolide moiety has been isomerized by shifting the ring attachment to the macrocycle (N-confused system). In addition, the second pyrrolide ring has been protonated at the nitrogen atom. Complex 2b was obtained as major compound and in analytically pure form by reacting 1 with NaH.
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Affiliation(s)
- Sougandi Ilango
- Department of Chemistry, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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34
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Boyer JL, Rochford J, Tsai MK, Muckerman JT, Fujita E. Ruthenium complexes with non-innocent ligands: Electron distribution and implications for catalysis. Coord Chem Rev 2010. [DOI: 10.1016/j.ccr.2009.09.006] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Korobkov I, Vidjayacoumar B, Gorelsky SI, Billone P, Gambarotta S. Attempting to Reduce the Irreducible: Preparation of a Rare Paramagnetic Thorium Species. Organometallics 2010. [DOI: 10.1021/om900996n] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Ilia Korobkov
- Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Balamurugan Vidjayacoumar
- Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Serge I. Gorelsky
- Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Paul Billone
- Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Sandro Gambarotta
- Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
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Seyedsayamdost MR, Argirević T, Minnihan EC, Stubbe J, Bennati M. Structural examination of the transient 3-aminotyrosyl radical on the PCET pathway of E. coli ribonucleotide reductase by multifrequency EPR spectroscopy. J Am Chem Soc 2009; 131:15729-38. [PMID: 19821570 PMCID: PMC4703294 DOI: 10.1021/ja903879w] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Indexed: 11/28/2022]
Abstract
E. coli ribonucleotide reductase (RNR) catalyzes the conversion of nucleotides to deoxynucleotides, a process that requires long-range radical transfer over 35 A from a tyrosyl radical (Y(122)*) within the beta2 subunit to a cysteine residue (C(439)) within the alpha2 subunit. The radical transfer step is proposed to occur by proton-coupled electron transfer via a specific pathway consisting of Y(122) --> W(48) --> Y(356) in beta2, across the subunit interface to Y(731) --> Y(730) --> C(439) in alpha2. Using the suppressor tRNA/aminoacyl-tRNA synthetase (RS) methodology, 3-aminotyrosine has been incorporated into position 730 in alpha2. Incubation of this mutant with beta2, substrate, and allosteric effector resulted in loss of the Y(122)* and formation of a new radical, previously proposed to be a 3-aminotyrosyl radical (NH(2)Y*). In the current study [(15)N]- and [(14)N]-NH(2)Y(730)* have been generated in H(2)O and D(2)O and characterized by continuous wave 9 GHz EPR and pulsed EPR spectroscopies at 9, 94, and 180 GHz. The data give insight into the electronic and molecular structure of NH(2)Y(730)*. The g tensor (g(x) = 2.0052, g(y) = 2.0042, g(z) = 2.0022), the orientation of the beta-protons, the hybridization of the amine nitrogen, and the orientation of the amino protons relative to the plane of the aromatic ring were determined. The hyperfine coupling constants and geometry of the NH(2) moiety are consistent with an intramolecular hydrogen bond within NH(2)Y(730)*. This analysis is an essential first step in using the detailed structure of NH(2)Y(730)* to formulate a model for a PCET mechanism within alpha2 and for use of NH(2)Y in other systems where transient Y*s participate in catalysis.
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Affiliation(s)
- Mohammad R Seyedsayamdost
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA
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Tamboura FB, Cazin CSJ, Pattacini R, Braunstein P. Reactions of Amines with Zwitterionic Quinoneimines: Synthesis of New Anionic and Zwitterionic Quinonoids. European J Org Chem 2009. [DOI: 10.1002/ejoc.200900154] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ismail FMD, Drew MGB, Navaratnam S, Bisby RH. A pulse radiolysis study of free radicals formed by one-electron oxidation of the antimalarial drug pyronaridine. RESEARCH ON CHEMICAL INTERMEDIATES 2009. [DOI: 10.1007/s11164-009-0051-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Das A, Sarkar B, Duboc C, Strobel S, Fiedler J, Záliš S, Lahiri G, Kaim W. Das ungeradzahlig elektronenkonfigurierte Komplexion [Ruk(NOm)(Qn)(terpy)]2+mit zwei idealtypischen “nicht-unschuldigen” Liganden. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200900767] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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40
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Das A, Sarkar B, Duboc C, Strobel S, Fiedler J, Záliš S, Lahiri G, Kaim W. An Odd-Electron Complex [Ruk(NOm)(Qn)(terpy)]2+with Two Prototypical Non-Innocent Ligands. Angew Chem Int Ed Engl 2009; 48:4242-5. [DOI: 10.1002/anie.200900767] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Yi C, Blum C, Liu SX, Keene TD, Frei G, Neels A, Decurtins S. Isolable Zwitterionic Pyridinio-semiquinone π-Radicals. Mild and Efficient Single-Step Access to Stable Radicals. Org Lett 2009; 11:2261-4. [PMID: 19402676 DOI: 10.1021/ol900559p] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chenyi Yi
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland, and XRD Application LAB, CSEM Centre Suisse d’Electronique et de Microtechnique SA, Jaquet-Droz 1, Case postale, CH-2002 Neuchâtel, Switzerland
| | - Carmen Blum
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland, and XRD Application LAB, CSEM Centre Suisse d’Electronique et de Microtechnique SA, Jaquet-Droz 1, Case postale, CH-2002 Neuchâtel, Switzerland
| | - Shi-Xia Liu
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland, and XRD Application LAB, CSEM Centre Suisse d’Electronique et de Microtechnique SA, Jaquet-Droz 1, Case postale, CH-2002 Neuchâtel, Switzerland
| | - Tony D. Keene
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland, and XRD Application LAB, CSEM Centre Suisse d’Electronique et de Microtechnique SA, Jaquet-Droz 1, Case postale, CH-2002 Neuchâtel, Switzerland
| | - Gabriela Frei
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland, and XRD Application LAB, CSEM Centre Suisse d’Electronique et de Microtechnique SA, Jaquet-Droz 1, Case postale, CH-2002 Neuchâtel, Switzerland
| | - Antonia Neels
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland, and XRD Application LAB, CSEM Centre Suisse d’Electronique et de Microtechnique SA, Jaquet-Droz 1, Case postale, CH-2002 Neuchâtel, Switzerland
| | - Silvio Decurtins
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland, and XRD Application LAB, CSEM Centre Suisse d’Electronique et de Microtechnique SA, Jaquet-Droz 1, Case postale, CH-2002 Neuchâtel, Switzerland
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