1
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Malik DD, Ryu W, Kim Y, Singh G, Kim JH, Sankaralingam M, Lee YM, Seo MS, Sundararajan M, Ocampo D, Roemelt M, Park K, Kim SH, Baik MH, Shearer J, Ray K, Fukuzumi S, Nam W. Identification, Characterization, and Electronic Structures of Interconvertible Cobalt-Oxygen TAML Intermediates. J Am Chem Soc 2024; 146:13817-13835. [PMID: 38716885 PMCID: PMC11216523 DOI: 10.1021/jacs.3c14346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2024]
Abstract
The reaction of Li[(TAML)CoIII]·3H2O (TAML = tetraamido macrocyclic tetraanionic ligand) with iodosylbenzene at 253 K in acetone in the presence of redox-innocent metal ions (Sc(OTf)3 and Y(OTf)3) or triflic acid affords a blue species 1, which is converted reversibly to a green species 2 upon cooling to 193 K. The electronic structures of 1 and 2 have been determined by combining advanced spectroscopic techniques (X-band electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR), X-ray absorption spectroscopy/extended X-ray absorption fine structure (XAS/EXAFS), and magnetic circular dichroism (MCD)) with ab initio theoretical studies. Complex 1 is best represented as an S = 1/2 [(Sol)(TAML•+)CoIII---OH(LA)]- species (LA = Lewis/Brønsted acid and Sol = solvent), where an S = 1 Co(III) center is antiferromagnetically coupled to S = 1/2 TAML•+, which represents a one-electron oxidized TAML ligand. In contrast, complex 2, also with an S = 1/2 ground state, is found to be multiconfigurational with contributions of both the resonance forms [(H-TAML)CoIV═O(LA)]- and [(H-TAML•+)CoIII═O(LA)]-; H-TAML and H-TAML•+ represent the protonated forms of TAML and TAML•+ ligands, respectively. Thus, the interconversion of 1 and 2 is associated with a LA-associated tautomerization event, whereby H+ shifts from the terminal -OH group to TAML•+ with the concomitant formation of a terminal cobalt-oxo species possessing both singlet (SCo = 0) Co(III) and doublet (SCo = 1/2) Co(IV) characters. The reactivities of 1 and 2 at different temperatures have been investigated in oxygen atom transfer (OAT) and hydrogen atom transfer (HAT) reactions to compare the activation enthalpies and entropies of 1 and 2.
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Affiliation(s)
- Deesha D Malik
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Wooyeol Ryu
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Yujeong Kim
- Western Seoul Center, Korea Basic Science Institute, Seoul 03759, Korea
| | - Gurjot Singh
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Jun-Hyeong Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science, Daejeon 34141, Korea
| | | | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Mi Sook Seo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Mahesh Sundararajan
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science, Daejeon 34141, Korea
- Theoretical Chemistry Section, Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Daniel Ocampo
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
| | - Michael Roemelt
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Kiyoung Park
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Sun Hee Kim
- Western Seoul Center, Korea Basic Science Institute, Seoul 03759, Korea
- Department of Chemistry, Chung-Ang University, Seoul 06974, Korea
| | - Mu-Hyun Baik
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science, Daejeon 34141, Korea
| | - Jason Shearer
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
| | - Kallol Ray
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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2
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Heim P, Biswas S, Lopez H, Gericke R, Twamley B, McDonald AR. A Co II-Hydroxide Complex That Converts Directly to a Co II-Acetamide during Catalytic Nitrile Hydration. Inorg Chem 2024; 63:7896-7902. [PMID: 38607349 PMCID: PMC11061833 DOI: 10.1021/acs.inorgchem.4c00754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 03/25/2024] [Accepted: 04/01/2024] [Indexed: 04/13/2024]
Abstract
In exploring structural and functional mimics of nitrile hydratases, we report the synthesis of the pseudo-trigonal bipyramidal CoII complexes (K)[CoII(DMF)(LPh)] (1(DMF)), (NMe4)2[CoII(OAc)(LPh)] (1(OAc)), and (NMe4)2[CoII(OH)(LPh)] (1(OH)) (LPh = 2,2',2''-nitrilo-tris-(N-phenylacetamide; DMF = N,N-dimethylformamide; -OAc = acetate)). The complexes were characterized using NMR, FT-IR, ESI-MS, electronic absorption spectroscopy, and X-ray crystallography, showing the LPh ligand to bind in a tetradentate tripodal fashion alongside the respective ancillary donor. One of the complexes, 1(OH), is an unusual structural and functional mimic of the Co active site in Co nitrile hydratases. 1(OH) reacted with acetonitrile to yield the CoII-acetamide complex (NMe4)2[CoII(NHC(O)CH3)(LPh)], 2, which was also thoroughly characterized. In the presence of excess hydroxide, 1(OH) was found to catalyze quantitative conversion of the added hydroxide into acetamide. Despite the differences in Co oxidation state in nitrile hydratases and 1(OH) (CoIII versus CoII, respectively), 1(OH) was nonetheless an effective nitrile hydration catalyst, selectively producing acetamide over multiple turnovers.
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Affiliation(s)
- Philipp Heim
- School
of Chemistry, Trinity College Dublin, The
University of Dublin, College Green, Dublin 2, Ireland
| | - Sachidulal Biswas
- School
of Chemistry, Trinity College Dublin, The
University of Dublin, College Green, Dublin 2, Ireland
| | - Hugo Lopez
- School
of Chemistry, Trinity College Dublin, The
University of Dublin, College Green, Dublin 2, Ireland
| | - Robert Gericke
- School
of Chemistry, Trinity College Dublin, The
University of Dublin, College Green, Dublin 2, Ireland
- Helmholtz-Zentrum
Dresden-Rossendorf e.V., Institute of Resource
Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Brendan Twamley
- School
of Chemistry, Trinity College Dublin, The
University of Dublin, College Green, Dublin 2, Ireland
| | - Aidan R. McDonald
- School
of Chemistry, Trinity College Dublin, The
University of Dublin, College Green, Dublin 2, Ireland
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3
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Lionetti D, Suseno S, Shiau AA, de Ruiter G, Agapie T. Redox Processes Involving Oxygen: The Surprising Influence of Redox-Inactive Lewis Acids. JACS AU 2024; 4:344-368. [PMID: 38425928 PMCID: PMC10900226 DOI: 10.1021/jacsau.3c00675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 03/02/2024]
Abstract
Metalloenzymes with heteromultimetallic active sites perform chemical reactions that control several biogeochemical cycles. Transformations catalyzed by such enzymes include dioxygen generation and reduction, dinitrogen reduction, and carbon dioxide reduction-instrumental transformations for progress in the context of artificial photosynthesis and sustainable fertilizer production. While the roles of the respective metals are of interest in all these enzymatic transformations, they share a common factor in the transfer of one or multiple redox equivalents. In light of this feature, it is surprising to find that incorporation of redox-inactive metals into the active site of such an enzyme is critical to its function. To illustrate, the presence of a redox-inactive Ca2+ center is crucial in the Oxygen Evolving Complex, and yet particularly intriguing given that the transformation catalyzed by this cluster is a redox process involving four electrons. Therefore, the effects of redox inactive metals on redox processes-electron transfer, oxygen- and hydrogen-atom transfer, and O-O bond cleavage and formation reactions-mediated by transition metals have been studied extensively. Significant effects of redox inactive metals have been observed on these redox transformations; linear free energy correlations between Lewis acidity and the redox properties of synthetic model complexes are observed for several reactions. In this Perspective, these effects and their relevance to multielectron processes will be discussed.
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Affiliation(s)
| | - Sandy Suseno
- Division of Chemistry and
Chemical Engineering, California Institute
of Technology, 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
| | - Angela A. Shiau
- Division of Chemistry and
Chemical Engineering, California Institute
of Technology, 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
| | - Graham de Ruiter
- Division of Chemistry and
Chemical Engineering, California Institute
of Technology, 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
| | - Theodor Agapie
- Division of Chemistry and
Chemical Engineering, California Institute
of Technology, 1200 East California Boulevard, MC 127-72, Pasadena, California 91125, United States
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4
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Yang J, Tripodi GL, Derks MTGM, Seo MS, Lee YM, Southwell KW, Shearer J, Roithová J, Nam W. Generation, Spectroscopic Characterization, and Computational Analysis of a Six-Coordinate Cobalt(III)-Imidyl Complex with an Unusual S = 3/2 Ground State that Promotes N-Group and Hydrogen Atom-Transfer Reactions with Exogenous Substrates. J Am Chem Soc 2023; 145:26106-26121. [PMID: 37997643 PMCID: PMC11175169 DOI: 10.1021/jacs.3c08117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
We report the synthesis and characterization of a mononuclear nonheme cobalt(III)-imidyl complex, [Co(NTs)(TQA)(OTf)]+ (1), with an S = 3/2 spin state that is capable of facilitating exogenous substrate modifications. Complex 1 was generated from the reaction of CoII(TQA)(OTf)2 with PhINTs at -20 °C. A flow setup with ESI-MS detection was used to explore the kinetics of the formation, stability, and degradation pathway of 1 in solution by treating the Co(II) precursor with PhINTs. Co K-edge XAS data revealed a distinct shift in the Co K-edge compared to the Co(II) precursor, in agreement with the formation of a Co(III) intermediate. The unusual S = 3/2 spin state was proposed based on EPR, DFT, and CASSCF calculations and Co Kβ XES results. Co K-edge XAS and IR photodissociation (IRPD) spectroscopies demonstrate that 1 is a six-coordinate species, and IRPD and resonance Raman spectroscopies are consistent with 1 being exclusively the isomer with the NT ligand occupying the vacant site trans to the TQA aliphatic amine nitrogen atom. Electronic structure calculations (broken symmetry DFT and CASSCF/NEVPT2) demonstrate an S = 3/2 oxidation state resulting from the strong antiferromagnetic coupling of an •NTs spin to the high-spin S = 2 Co(III) center. Reactivity studies of 1 with PPh3 derivatives revealed its electrophilic characteristic in the nitrene-transfer reaction. While the activation of C-H bonds by 1 was proved to be kinetically challenging, 1 could oxidize weak O-H and N-H bonds. Complex 1 is, therefore, a rare example of a Co(III)-imidyl complex capable of exogenous substrate transformations.
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Affiliation(s)
- Jindou Yang
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Guilherme L. Tripodi
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Max T. G. M. Derks
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Mi Sook Seo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Kendal W. Southwell
- Department of Chemistry, Trinity University, San Antonio, Texas 78212, United States
| | - Jason Shearer
- Department of Chemistry, Trinity University, San Antonio, Texas 78212, United States
| | - Jana Roithová
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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5
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Monika, Kumar M, Somi, Sarkar A, Gupta MK, Ansari A. Theoretical study of the formation of metal-oxo species of the first transition series with the ligand 14-TMC: driving factors of the "Oxo Wall". Dalton Trans 2023; 52:14160-14169. [PMID: 37750348 DOI: 10.1039/d3dt02109b] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
Terminal metal-oxo species of the early transition metal series are well known, whereas those for the late transition series are rare, and this is related to the "Oxo Wall". Here, we have undertaken a theoretical study on the formation of metal-oxo species from the metal hydroperoxo species of the 3d series (Cr, Mn, Fe, Co, Ni, and Cu) with the ligand 14-TMC (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) via O⋯O bond cleavage. DFT calculations reveal that the barrier for O⋯O bond cleavage is higher with the late transition metals (Co, Ni, and Cu) than the early transition metals (Cr, Mn, and Fe), and the formed late metal-oxo species are also thermodynamically less stable. The higher barrier may be due to electronic repulsion because of the pairing of d electrons. In the late transition metal series, the electron goes into an antibonding orbital, which decreases the bond order and hence decreases the possibility of metal-oxo formation. Computed structural parameters and spin densities suggest that valence tautomerism occurs in the late transition metal-oxo species which remain as a metal-oxyl. Our findings support the concept of the "Oxo Wall".
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Affiliation(s)
- Monika
- Department of Chemistry, Central University of Haryana, Mahendergarh-123031, Haryana, India.
| | - Manjeet Kumar
- Department of Chemistry, Central University of Haryana, Mahendergarh-123031, Haryana, India.
| | - Somi
- Department of Chemistry, Central University of Haryana, Mahendergarh-123031, Haryana, India.
| | - Arup Sarkar
- Department of Chemistry, The University of Chicago 5735 South Ellis Avenue, Chicago, IL 60637, USA
| | - Manoj Kumar Gupta
- Department of Chemistry, Central University of Haryana, Mahendergarh-123031, Haryana, India.
| | - Azaj Ansari
- Department of Chemistry, Central University of Haryana, Mahendergarh-123031, Haryana, India.
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6
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Hastings CD, Huffman LSX, Tiwari CK, Betancourth JG, Brennessel WW, Barnett BR. Coordinatively Unsaturated Metallates of Cobalt(II), Nickel(II), and Zinc(II) Guarded by a Rigid and Narrow Void. Inorg Chem 2023; 62:11920-11931. [PMID: 37462947 PMCID: PMC10394664 DOI: 10.1021/acs.inorgchem.3c01335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
Both natural enzymatic systems and synthetic porous material catalysts utilize well-defined and uniform channels to dictate reaction selectivities on the basis of size or shape. Mimicry of this design element in homogeneous systems is generally difficult owing to the flexibility inherent in most small molecular species. Herein, we report the synthesis of a tripodal ligand scaffold that orients a narrow and rigid cavity atop accessible metal coordination space. The permanent void is formed through a macrocyclization reaction whereby the 3,5-dihydroxyphenyl arms are covalently linked through methylene bridges. Deprotonative metallation leads to anionic and coordinatively unsaturated complexes of divalent cobalt, nickel, and zinc. An analogous series of trigonal monopyramidal complexes bearing a nonmacrocyclized variant of the tripodal ligand are also reported. Physical characterization of the coordination complexes has been carried out using multiple spectroscopic techniques (NMR, EPR, and UV-vis), cyclic voltammetry, and X-ray diffraction. Complexes of the macrocyclized [LOCH2O]3- ligand retain a rigid cavity upon metallation, with this cavity guarding the entrance to the open axial coordination site. Through a combination of spectroscopic and computational studies, it is shown that acetonitrile entry into the void is sterically precluded, disrupting anticipated coordination at the intracavity site.
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Affiliation(s)
- Christopher D Hastings
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Lucy S X Huffman
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Chandan Kumar Tiwari
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | | | - William W Brennessel
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Brandon R Barnett
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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7
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Golwankar RR, Kumar A, Day VW, Blakemore JD. Revealing the Influence of Diverse Secondary Metal Cations on Redox‐Active Palladium Complexes. Chemistry 2022; 28:e202200344. [DOI: 10.1002/chem.202200344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Riddhi R. Golwankar
- Department of Chemistry University of Kansas 1567 Irving Hill Road Lawrence Kansas 66045 USA
| | - Amit Kumar
- Department of Chemistry University of Kansas 1567 Irving Hill Road Lawrence Kansas 66045 USA
- Current address: Department of Chemistry University of Pennsylvania Philadelphia Pennsylvania 19104 USA
| | - Victor W. Day
- Department of Chemistry University of Kansas 1567 Irving Hill Road Lawrence Kansas 66045 USA
| | - James D. Blakemore
- Department of Chemistry University of Kansas 1567 Irving Hill Road Lawrence Kansas 66045 USA
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8
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Ghosh I, Chakraborty B, Bera A, Paul S, Paine TK. Selective oxygenation of C-H and CC bonds with H 2O 2 by high-spin cobalt(II)-carboxylate complexes. Dalton Trans 2022; 51:2480-2492. [PMID: 35050271 DOI: 10.1039/d1dt02235k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Four cobalt(II)-carboxylate complexes [(6-Me3-TPA)CoII(benzoate)](BPh4) (1), [(6-Me3-TPA)CoII(benzilate)](ClO4) (2), [(6-Me3-TPA)CoII(mandelate)](BPh4) (3), and [(6-Me3-TPA)CoII(MPA)](BPh4) (4) (HMPA = 2-methoxy-2-phenylacetic acid) of the 6-Me3-TPA (tris((6-methylpyridin-2-yl)methyl)amine) ligand were isolated to investigate their ability in H2O2-dependent selective oxygenation of C-H and CC bonds. All six-coordinate complexes contain a high-spin cobalt(II) center. While the cobalt(II) complexes are inert toward dioxygen, each of these complexes reacts readily with hydrogen peroxide to form a diamagnetic cobalt(III) species, which decays with time leading to the oxidation of the methyl groups on the pyridine rings of the supporting ligand. Intramolecular ligand oxidation by the cobalt-based oxidant is partially inhibited in the presence of external substrates, and the substrates are converted to their corresponding oxidized products. Kinetic studies and labelling experiments indicate the involvement of a metal-based oxidant in affecting the chemo- and stereo-selective catalytic oxygenation of aliphatic C-H bonds and epoxidation of alkenes. An electrophilic cobalt-oxygen species that exhibits a kinetic isotope effect (KIE) value of 5.3 in toluene oxidation by 1 is proposed as the active oxidant. Among the complexes, the cobalt(II)-benzoate (1) and cobalt(II)-MPA (4) complexes display better catalytic activity compared to their α-hydroxy analogues (2 and 3). Catalytic studies with the cobalt(II)-acetonitrile complex [(6-Me3-TPA)CoII(CH3CN)2](ClO4)2 (5) in the presence and absence of externally added benzoate support the role of the carboxylate co-ligand in oxidation reactions. The proposed catalytic reaction involves a carboxylate-bridged dicobalt complex in the activation of H2O2 followed by the oxidation of substrates by a metal-based oxidant.
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Affiliation(s)
- Ivy Ghosh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, India.
| | - Biswarup Chakraborty
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, India.
| | - Abhijit Bera
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, India.
| | - Satadal Paul
- Department of Chemistry, Bangabasi Morning College, 19, Rajkumar Chakraborty Sarani, Kolkata - 700 009, India
| | - Tapan Kanti Paine
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, India.
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9
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Yang J, Dong HT, Seo MS, Larson VA, Lee YM, Shearer J, Lehnert N, Nam W. The Oxo-Wall Remains Intact: A Tetrahedrally Distorted Co(IV)-Oxo Complex. J Am Chem Soc 2021; 143:16943-16959. [PMID: 34609879 DOI: 10.1021/jacs.1c04919] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In this paper, we report the preparation, spectroscopic and theoretical characterization, and reactivity studies of a Co(IV)-oxo complex bearing an N4-macrocyclic coligand, 12-TBC (12-TBC = 1,4,7,10-tetrabenzyl-1,4,7,10-tetraazacyclododecane). On the basis of the ligand and the structure of the Co(II) precursor, [CoII(12-TBC)(CF3SO3)2], one would assume that this species corresponds to a tetragonal Co(IV)-oxo complex, but the spectroscopic data do not support this notion. Co K-edge XAS data show that the treatment of the Co(II) precursor with iodosylbenzene (PhIO) as an oxidant at -40 °C in the presence of a proton source leads to a distinct shift in the Co K-edge, in agreement with the formation of a Co(IV) intermediate. The presence of the oxo group is further demonstrated by resonance Raman (rRaman) spectroscopy. Interestingly, the EPR data of this complex show a high degree of rhombicity, indicating structural distortion. This is further supported by the EXAFS data. Using DFT calculations, a structural model is developed for this complex with a ligand-protonated structure that features a Co═O···HN hydrogen bond and a four-coordinate Co center in a seesaw-shaped coordination geometry. Magnetic circular dichroism (MCD) spectroscopy further supports this finding. The hydrogen bond leads to an interesting polarization of the Co-oxo π-bonds, where one O(p) lone-pair is stabilized and leads to a regular Co(d) interaction, whereas the other π-bond shows an inverted ligand field. The reactivity of this complex in hydrogen atom and oxygen atom transfer reactions is discussed as well.
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Affiliation(s)
- Jindou Yang
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Hai T Dong
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Mi Sook Seo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Virginia A Larson
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Jason Shearer
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
| | - Nicolai Lehnert
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.,School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, China
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10
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Malik DD, Chandra A, Seo MS, Lee YM, Farquhar ER, Mebs S, Dau H, Ray K, Nam W. Formation of cobalt-oxygen intermediates by dioxygen activation at a mononuclear nonheme cobalt(ii) center. Dalton Trans 2021; 50:11889-11898. [PMID: 34373886 PMCID: PMC8499697 DOI: 10.1039/d1dt01996a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A mononuclear nonheme cobalt(ii) complex, [(TMG3tren)CoII(OTf)](OTf) (1), activates dioxygen in the presence of hydrogen atom donor substrates, such as tetrahydrofuran and cyclohexene, resulting in the generation of a cobalt(ii)-alkylperoxide intermediate (2), which then converts to the previously reported cobalt(iv)-oxo complex, [(TMG3tren)CoIV(O)]2+-(Sc(OTf)3)n (3), in >90% yield upon addition of a redox-inactive metal ion, Sc(OTf)3. Intermediates 2 and 3 represent the cobalt analogues of the proposed iron(ii)-alkylperoxide precursor that converts to an iron(iv)-oxo intermediate via O-O bond heterolysis in pterin-dependent nonheme iron oxygenases. In reactivity studies, 2 shows an amphoteric reactivity in electrophilic and nucleophilic reactions, whereas 3 is an electrophilic oxidant. To the best of our knowledge, the present study reports the first example showing the generation of cobalt-oxygen intermediates by activating dioxygen at a cobalt(ii) center and the reactivities of the cobalt-oxygen intermediates in oxidation reaction.
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Affiliation(s)
- Deesha D Malik
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.
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11
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Kelsey SR, Kumar A, Oliver AG, Day VW, Blakemore JD. Promotion and Tuning of the Electrochemical Reduction of Hetero‐ and Homobimetallic Zinc Complexes**. ChemElectroChem 2021. [DOI: 10.1002/celc.202100358] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Shaun R. Kelsey
- Department of Chemistry University of Kansas 1567 Irving Hill Rd Lawrence KS 66045
| | - Amit Kumar
- Department of Chemistry University of Kansas 1567 Irving Hill Rd Lawrence KS 66045
| | - Allen G. Oliver
- Department of Chemistry and Biochemistry University of Notre Dame 149 Stepan Chemistry Notre Dame IN 46556 USA
| | - Victor W. Day
- Department of Chemistry University of Kansas 1567 Irving Hill Rd Lawrence KS 66045
| | - James D. Blakemore
- Department of Chemistry University of Kansas 1567 Irving Hill Rd Lawrence KS 66045
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12
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Coordination environment variations in multinuclear trigonal bipyramid Co(II) complexes bearing tetradentate sulfonamide N-donors and phenoxazinone synthase activities. Inorganica Chim Acta 2020. [DOI: 10.1016/j.ica.2020.119664] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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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: 136] [Impact Index Per Article: 34.0] [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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14
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Oswald VF, Lee JL, Biswas S, Weitz AC, Mittra K, Fan R, Li J, Zhao J, Hu MY, Alp EE, Bominaar EL, Guo Y, Green MT, Hendrich MP, Borovik AS. Effects of Noncovalent Interactions on High-Spin Fe(IV)-Oxido Complexes. J Am Chem Soc 2020; 142:11804-11817. [PMID: 32489096 DOI: 10.1021/jacs.0c03085] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
High-valent nonheme FeIV-oxido species are key intermediates in biological oxidation, and their properties are proposed to be influenced by the unique microenvironments present in protein active sites. Microenvironments are regulated by noncovalent interactions, such as hydrogen bonds (H-bonds) and electrostatic interactions; however, there is little quantitative information about how these interactions affect crucial properties of high valent metal-oxido complexes. To address this knowledge gap, we introduced a series of FeIV-oxido complexes that have the same S = 2 spin ground state as those found in nature and then systematically probed the effects of noncovalent interactions on their electronic, structural, and vibrational properties. The key design feature that provides access to these complexes is the new tripodal ligand [poat]3-, which contains phosphinic amido groups. An important structural aspect of [FeIVpoat(O)]- is the inclusion of an auxiliary site capable of binding a Lewis acid (LAII); we used this unique feature to further modulate the electrostatic environment around the Fe-oxido unit. Experimentally, studies confirmed that H-bonds and LAII s can interact directly with the oxido ligand in FeIV-oxido complexes, which weakens the Fe═O bond and has an impact on the electronic structure. We found that relatively large vibrational changes in the Fe-oxido unit correlate with small structural changes that could be difficult to measure, especially within a protein active site. Our work demonstrates the important role of noncovalent interactions on the properties of metal complexes, and that these interactions need to be considered when developing effective oxidants.
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Affiliation(s)
- Victoria F Oswald
- Department of Chemistry, 1102 Natural Sciences II, University of California at Irvine, Irvine, California 92697, United States
| | - Justin L Lee
- Department of Chemistry, 1102 Natural Sciences II, University of California at Irvine, Irvine, California 92697, United States
| | - Saborni Biswas
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Andrew C Weitz
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Kaustuv Mittra
- Department of Molecular Biosciences and Biochemistry, University of California at Irvine, Irvine, California 92697, United States
| | - Ruixi Fan
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Jikun Li
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Jiyong Zhao
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Michael Y Hu
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Esen E Alp
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Emile L Bominaar
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Michael T Green
- Department of Chemistry, 1102 Natural Sciences II, University of California at Irvine, Irvine, California 92697, United States.,Department of Molecular Biosciences and Biochemistry, University of California at Irvine, Irvine, California 92697, United States
| | - Michael P Hendrich
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - A S Borovik
- Department of Chemistry, 1102 Natural Sciences II, University of California at Irvine, Irvine, California 92697, United States
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15
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Comba P, Löhr A, Pfaff F, Ray K. Redox Potentials of High‐Valent Iron‐, Cobalt‐, and Nickel‐Oxido Complexes: Evidence for Exchange Enhanced Reactivity. Isr J Chem 2020. [DOI: 10.1002/ijch.202000038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Peter Comba
- Universität Heidelberg Anorganisch-Chemisches Institut, INF 270 D-69120 Heidelberg Germany
- Universität Heidelberg Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR) D-69120 Heidelberg Germany
| | - Anna‐Maria Löhr
- Universität Heidelberg Anorganisch-Chemisches Institut, INF 270 D-69120 Heidelberg Germany
| | - Florian Pfaff
- Department of Chemistry Humboldt-Universität zu Berlin Brook-Taylor-Strasse 2 Berlin Germany 12489
| | - Kallol Ray
- Department of Chemistry Humboldt-Universität zu Berlin Brook-Taylor-Strasse 2 Berlin Germany 12489
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16
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Wind ML, Hoof S, Braun-Cula B, Herwig C, Limberg C. Routes to Heterotrinuclear Metal Siloxide Complexes for Cooperative Activation of O2. Inorg Chem 2020; 59:6866-6875. [DOI: 10.1021/acs.inorgchem.0c00279] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Marie-Louise Wind
- Chemistry Department, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
| | - Santina Hoof
- Chemistry Department, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
| | - Beatrice Braun-Cula
- Chemistry Department, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
| | - Christian Herwig
- Chemistry Department, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
| | - Christian Limberg
- Chemistry Department, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
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17
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Kumar A, Lionetti D, Day VW, Blakemore JD. Redox-Inactive Metal Cations Modulate the Reduction Potential of the Uranyl Ion in Macrocyclic Complexes. J Am Chem Soc 2020; 142:3032-3041. [DOI: 10.1021/jacs.9b11903] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Amit Kumar
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Davide Lionetti
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Victor W. Day
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - James D. Blakemore
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
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18
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Oloyede HO, Woods JAO, Görls H, Plass W, Eseola AO. New cobalt( ii) coordination designs and the influence of varying chelate characters, ligand charges and incorporated group I metal ions on enzyme-like oxidative coupling activity. NEW J CHEM 2020. [DOI: 10.1039/d0nj02347g] [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
In transition-metal-mediated catalysis, design of new, well defined coordination architectures and subjecting them to catalysis testing under the same reaction conditions is a necessity tool for improved understanding of desirable active site geometries and characteristics.
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Affiliation(s)
| | | | - Helmar Görls
- Institut für Anorganische und Analytische Chemie
- Friedrich-Schiller-Universität Jena
- 07743 Jena
- Germany
| | - Winfried Plass
- Institut für Anorganische und Analytische Chemie
- Friedrich-Schiller-Universität Jena
- 07743 Jena
- Germany
| | - Abiodun Omokehinde Eseola
- Institut für Anorganische und Analytische Chemie
- Friedrich-Schiller-Universität Jena
- 07743 Jena
- Germany
- Materials Chemistry Group
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19
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Taylor JW, Harman WH. CO scission and reductive coupling of organic carbonyls by a redox-active diboraanthracene. Chem Commun (Camb) 2020; 56:4480-4483. [PMID: 32201869 DOI: 10.1039/d0cc01142h] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A gold-stabilized diboraanthracene mediates reductive transformations of carbonyls, including C–O and C–C bond formation, and deoxygenation of acetone to propene and hydroxide.
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Affiliation(s)
| | - W. Hill Harman
- Department of Chemistry
- University of California
- Riverside
- USA
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20
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Liu Y, Lau TC. Activation of Metal Oxo and Nitrido Complexes by Lewis Acids. J Am Chem Soc 2019; 141:3755-3766. [DOI: 10.1021/jacs.8b13100] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Yingying Liu
- Department of Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong 999077, China
| | - Tai-Chu Lau
- Department of Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong 999077, China
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21
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Schulte KA, Vignesh KR, Dunbar KR. Effects of coordination sphere on unusually large zero field splitting and slow magnetic relaxation in trigonally symmetric molecules. Chem Sci 2018; 9:9018-9026. [PMID: 30647894 PMCID: PMC6301199 DOI: 10.1039/c8sc02820f] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 09/15/2018] [Indexed: 01/29/2023] Open
Abstract
Geometric control in mononuclear complexes has come to the forefront in the field of molecular magnets due to its profound effects on relaxation pathways and blocking temperature in single molecule magnets (SMMs). Herein we report the synthesis and magnetic characterization of six trigonally symmetric, divalent Fe, Co, and Ni molecules, with the rigid geometry enforced via the use of the tris-anionic, tetradentate ligand MST (N,N',N''-[2,2',2''-nitrilotris-(ethane-2,1-diyl)]tris(2,4,6-trimethylbenzenesulfonamide)). A systematic study on the effect of converting between trigonal monopyramidal complexes, (Me4N)[M(MST)], and trigonal bipyramidal complexes, (Me4N)[M(MST)(OH2)] was conducted experimentally and computationally. It was found that (Me4N)[Ni(MST)] exhibits a very large, near record zero-field splitting parameter (D) value of -434 cm-1, owing to an extremely low lying first excited state. The trigonal monopyramidal cobalt and iron complexes exhibit slow magnetic relaxation under applied fields, resulting in barriers of 45 K and 63.9 K respectively. Coordination of a single water molecule in the open axial site of the trigonal monopyramidal complexes exerts drastic dampening effects on the D value as well as slow relaxation. Computations reveal that coordination of water rotates the D zz axis away from the C 3 axis of symmetry resulting in a smaller D value. The aquo species (Me4N)[Co(MST)(OH2)] also exhibits magnetic relaxation under an applied field, but the barrier is reduced to 9.9 K. Water coordination totally quenches the magnetic behavior in the iron complex, and reduces the D value for nickel to -185 cm-1. These results showcase the drastic effect that a small change in the coordination environment can have on magnetic behavior, as well as that trigonal monopyramidal geometry can lead to near record D values.
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Affiliation(s)
- Kelsey A Schulte
- Department of Chemistry , Texas A&M University , College Station , Texas 77843 , USA .
| | - Kuduva R Vignesh
- Department of Chemistry , Texas A&M University , College Station , Texas 77843 , USA .
| | - Kim R Dunbar
- Department of Chemistry , Texas A&M University , College Station , Texas 77843 , USA .
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22
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Oswald VF, Weitz AC, Biswas S, Ziller JW, Hendrich MP, Borovik AS. Manganese-Hydroxido Complexes Supported by a Urea/Phosphinic Amide Tripodal Ligand. Inorg Chem 2018; 57:13341-13350. [PMID: 30299920 DOI: 10.1021/acs.inorgchem.8b01886] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hydrogen bonds (H-bonds) within the secondary coordination sphere are often invoked as essential noncovalent interactions that lead to productive chemistry in metalloproteins. Incorporating these types of effects within synthetic systems has proven a challenge in molecular design that often requires the use of rigid organic scaffolds to support H-bond donors or acceptors. We describe the preparation and characterization of a new hybrid tripodal ligand ([H2pout]3-) that contains two monodeprotonated urea groups and one phosphinic amide. The urea groups serve as H-bond donors, while the phosphinic amide group serves as a single H-bond acceptor. The [H2pout]3- ligand was utilized to stabilize a series of Mn-hydroxido complexes in which the oxidation state of the metal center ranges from 2+ to 4+. The molecular structure of the MnIII-OH complex demonstrates that three intramolecular H-bonds involving the hydroxido ligand are formed. Additional evidence for the formation of intramolecular H-bonds was provided by vibrational spectroscopy in which the energy of the O-H vibration supports its assignment as an H-bond donor. The stepwise oxidation of [MnIIH2pout(OH)]2- to its higher oxidized analogs was further substantiated by electrochemical measurements and results from electronic absorbance and electron paramagnetic resonance spectroscopies. Our findings illustrate the utility of controlling both the primary and secondary coordination spheres to achieve structurally similar Mn-OH complexes with varying oxidation states.
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Affiliation(s)
- Victoria F Oswald
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , United States
| | - Andrew C Weitz
- Department of Chemistry , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Saborni Biswas
- Department of Chemistry , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Joseph W Ziller
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , United States
| | - Michael P Hendrich
- Department of Chemistry , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - A S Borovik
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , United States
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23
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A spin-crossover Co(II) complex catalyzes the activation of sp3 C–H bonds by two-electron oxidants. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2018.06.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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24
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Lau N, Sano Y, Ziller JW, Borovik AS. Modular bimetallic complexes with a sulfonamido-based ligand. Dalton Trans 2018; 47:12362-12372. [PMID: 30118133 PMCID: PMC6165629 DOI: 10.1039/c8dt02455c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of bimetallic complexes prepared with the ligands N,N,N',N'-tetramethylethane-1,2-diamine (TMEDA) and N,N',N''-[2,2',2''-nitrilotris(ethane-2,1-diyl)]tris(2,4,6-trimethylbenzenesulfonamido) ([MST]3-) is described. Four diiron compounds of the formulation (TMEDA)FeII(X)-(μ-OH)-FeIIIMST were prepared, in which the X- ligands are the anions OTf-, Br-, SCN-, or N3-. Additionally, two heterobimetallic compounds of the formulation (TMEDA)MII(OTf)-(μ-OH)-FeIIIMST (MII = CoII or NiII) were synthesized. All these compounds have similar spectroscopic and structural properties. The diiron compounds exhibit perpendicular-mode electron paramagnetic resonance spectra consistent with S = 1/2 spin ground states, which is expected for high-spin FeII and FeIII centres that are antiferromagnetically coupled. The heterobimetallic (TMEDA)NiII(OTf)-(μ-OH)-FeIIIMST complex had a spin state of S = 3/2 that also resulted from antiferromagnetic coupling between the high-spin NiII and FeIII centres. The modularity of this system is further demonstrated by the substitution of the TMEDA ligand with ethylenediamine (en); for this species two equivalents of en coordinate to the FeII centre to form [(en)2FeII-(μ-OH)-FeIIIMST]OTf. These results demonstrate that a modular bimetallic system has been developed in which the key components can be modified.
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Affiliation(s)
- Nathanael Lau
- Department of Chemistry, University of California - Irvine, 1102 Natural Sciences II, Irvine, CA 92697-2025, USA.
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25
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Cook SA, Bogart JA, Levi N, Weitz AC, Moore C, Rheingold AL, Ziller JW, Hendrich MP, Borovik AS. Mononuclear complexes of a tridentate redox-active ligand with sulfonamido groups: structure, properties, and reactivity. Chem Sci 2018; 9:6540-6547. [PMID: 30310585 PMCID: PMC6115676 DOI: 10.1039/c7sc05445a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 06/30/2018] [Indexed: 12/16/2022] Open
Abstract
The design of molecular complexes of earth-abundant first-row transition metals that can catalyze multi-electron C-H bond activation processes is of interest for achieving efficient, low-cost syntheses of target molecules. To overcome the propensity of these metals to perform single-electron processes, redox-active ligands have been utilized to provide additional electron equivalents. Herein, we report the synthesis of a novel redox active ligand, [ibaps]3-, which binds to transition metals such as FeII and CoII in a meridional fashion through the three anionic nitrogen atoms and provides additional coordination sites for other ligands. In this study, the neutral bidentate ligand 2,2'-bipyridine (bpy) was used to complete the coordination spheres of the metal ions and form NEt4[MII(ibaps)bpy] (M = Fe (1) or Co (1-Co)) salts. The FeII salt exhibited rich electrochemical properties and could be chemically oxidized by 1 and 2 equiv. of ferrocenium to form singly and doubly oxidized species, respectively. The reactivity of 1 towards intramolecular C-H bond amination of aryl azides at benzylic and aliphatic carbon centers was explored, and moderate to good yields of the resulting indoline products were obtained.
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Affiliation(s)
- Sarah A Cook
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , USA .
| | - Justin A Bogart
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , USA .
| | - Noam Levi
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , USA .
| | - Andrew C Weitz
- Department of Chemistry , Carnegie Melon University , Pittsburgh , Pennsylvania 15213 , USA
| | - Curtis Moore
- Department of Chemistry and Biochemistry , University of California-San Diego , San Diego , California 92093 , USA
| | - Arnold L Rheingold
- Department of Chemistry and Biochemistry , University of California-San Diego , San Diego , California 92093 , USA
| | - Joseph W Ziller
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , USA .
| | - Michael P Hendrich
- Department of Chemistry , Carnegie Melon University , Pittsburgh , Pennsylvania 15213 , USA
| | - A S Borovik
- Department of Chemistry , University of California-Irvine , 1102 Natural Sciences II , Irvine , California 92697 , USA .
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26
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Hill EA, Kelty ML, Filatov AS, Anderson JS. Isolable iodosylarene and iodoxyarene adducts of Co and their O-atom transfer and C-H activation reactivity. Chem Sci 2018; 9:4493-4499. [PMID: 29896391 PMCID: PMC5958341 DOI: 10.1039/c8sc01167b] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 04/19/2018] [Indexed: 01/04/2023] Open
Abstract
We report an unusual series of discrete iodosyl- and iodoxyarene adducts of Co(ii) including detailed studies of their O-transfer reactivity and mechanism.
We report an unusual series of discrete iodosyl- and iodoxyarene adducts of Co. The formation of these adducts was confirmed by a suite of techniques including single crystal X-ray diffraction. The reactivity of these adducts with O-atom acceptors and an H-atom donor has been investigated with particular focus on elucidating mechanistic details. Detailed kinetic analysis allows for discrimination between proposed oxo and adduct mediated mechanisms. In particular, these reactions have been interrogated by competition experiments with isotopically labelled mixtures which shows that all of the studied adducts display a large KIE. These studies suggest different mechanisms may be relevant depending on subtle substituent changes in the adduct complexes. Reactivity data are consistent with the involvement of a transient oxo complex in one case, while the two other systems appear to react with substrates directly as iodosyl- or iodoxyarene adducts. These results support that reactivity typically ascribed to metal-oxo complexes, such as O-atom transfer and C–H activation, can also be mediated by discrete transition metal iodosyl- or iodoxyarene adducts that are frequent intermediates in the generation of oxo complexes. The influence of additional Lewis acids such as Sc3+ on the reactivity of these systems has also been investigated.
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Affiliation(s)
- Ethan A Hill
- Department of Chemistry , The University of Chicago , 5735 S. Ellis Ave , Chicago , IL 60637 , USA .
| | - Margaret L Kelty
- Department of Chemistry , The University of Chicago , 5735 S. Ellis Ave , Chicago , IL 60637 , USA .
| | - Alexander S Filatov
- Department of Chemistry , The University of Chicago , 5735 S. Ellis Ave , Chicago , IL 60637 , USA .
| | - John S Anderson
- Department of Chemistry , The University of Chicago , 5735 S. Ellis Ave , Chicago , IL 60637 , USA .
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27
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Kinauer M, Diefenbach M, Bamberger H, Demeshko S, Reijerse EJ, Volkmann C, Würtele C, van Slageren J, de Bruin B, Holthausen MC, Schneider S. An iridium(iii/iv/v) redox series featuring a terminal imido complex with triplet ground state. Chem Sci 2018; 9:4325-4332. [PMID: 29780564 PMCID: PMC5944377 DOI: 10.1039/c8sc01113c] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 04/13/2018] [Indexed: 01/11/2023] Open
Abstract
An iridium(iii–v) imido series has been isolated that features an iridium complex with an unprecedented triplet ground state.
The iridium(iii/iv/v) imido redox series [Ir(NtBu){N(CHCHPtBu2)2}]0/+/2+ was synthesized and examined spectroscopically, magnetically, crystallographically and computationally. The monocationic iridium(iv) imide exhibits an electronic doublet ground state with considerable ‘imidyl’ character as a result of covalent Ir–NtBu bonding. Reduction gives the neutral imide [Ir(NtBu){N(CHCHPtBu2)2}] as the first example of an iridium complex with a triplet ground state. Its reactivity with respect to nitrene transfer to selected electrophiles (CO2) and nucleophiles (PMe3), respectively, is reported.
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Affiliation(s)
- Markus Kinauer
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstr. 4 , 37077 Göttingen , Germany .
| | - Martin Diefenbach
- Institut für Anorganische und Analytische Chemie , Goethe-Universität , Max-von-Laue-Str. 7 , 60438 Frankfurt am Main , Germany
| | - Heiko Bamberger
- Institut für Physikalische Chemie , Universität Stuttgart , Pfaffenwaldring 55 , D-70569 Stuttgart , Germany
| | - Serhiy Demeshko
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstr. 4 , 37077 Göttingen , Germany .
| | - Edward J Reijerse
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstr. 34-36 , 45470 Mülheim an der Ruhr , Germany
| | - Christian Volkmann
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstr. 4 , 37077 Göttingen , Germany .
| | - Christian Würtele
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstr. 4 , 37077 Göttingen , Germany .
| | - Joris van Slageren
- Institut für Physikalische Chemie , Universität Stuttgart , Pfaffenwaldring 55 , D-70569 Stuttgart , Germany
| | - Bas de Bruin
- van 't Hoff Institute for Molecular Sciences (HIMS) , University of Amsterdam , The Netherlands .
| | - Max C Holthausen
- Institut für Anorganische und Analytische Chemie , Goethe-Universität , Max-von-Laue-Str. 7 , 60438 Frankfurt am Main , Germany
| | - Sven Schneider
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstr. 4 , 37077 Göttingen , Germany .
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28
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Non-redox metal ions accelerated oxygen atom transfer by Mn-Me3tacn complex with H2O2 as oxygen resource. MOLECULAR CATALYSIS 2018. [DOI: 10.1016/j.mcat.2018.01.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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29
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Khosrowabadi Kotyk JF, Hanna CM, Combs RL, Ziller JW, Yang JY. Intramolecular hydrogen-bonding in a cobalt aqua complex and electrochemical water oxidation activity. Chem Sci 2018; 9:2750-2755. [PMID: 29732059 PMCID: PMC5912104 DOI: 10.1039/c7sc04960a] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Accepted: 02/05/2018] [Indexed: 11/30/2022] Open
Abstract
Water oxidation is catalysed in Nature by a redox cofactor embedded in a hydrogen-bonded network designed to orchestrate proton transfer throughout the challenging 4 electron reaction.
Water oxidation is catalysed in Nature by a redox cofactor embedded in a hydrogen-bonded network designed to orchestrate proton transfer throughout the challenging 4 electron reaction. In order to mimic aspects of this microenvironment, [CoLDMA(CH3CN)2][BF4]2 (2) was synthesized, where LDMA is a dipyridyldiamine ligand with two dimethylamine bases in the secondary coordination sphere. Structural characterization of the corresponding aqua complexes establish hydrogen bonding between the bound water and pendant base(s). Cyclic voltammetry of [CoLDMA(CH3CN)2][BF4]2 (2) reveals enhanced oxidative current upon titration with water and controlled potential electrolysis confirms evolution of O2. The related complex [CoLH(CH3CN)2][BF4]2 (1), which has the same primary coordination environment as 2 but lacks pendant bases, is inactive. The structural and electrochemical studies illustrate the role positioned proton relays can play in promoting redox reactivity.
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Affiliation(s)
| | - Caitlin M Hanna
- Department of Chemistry , University of California , Irvine , USA .
| | - Rebecca L Combs
- Department of Chemistry , University of California , Irvine , USA .
| | - Joseph W Ziller
- Department of Chemistry , University of California , Irvine , USA .
| | - Jenny Y Yang
- Department of Chemistry , University of California , Irvine , USA .
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30
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Affiliation(s)
- Paolo Pirovano
- School of Chemistry and CRANN/AMBER Nanoscience Institute; Trinity College Dublin; The University of Dublin; College Green 2 Dublin Ireland
| | - Aidan R. McDonald
- School of Chemistry and CRANN/AMBER Nanoscience Institute; Trinity College Dublin; The University of Dublin; College Green 2 Dublin Ireland
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31
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Sano Y, Lau N, Weitz AC, Ziller JW, Hendrich MP, Borovik A. Models for Unsymmetrical Active Sites in Metalloproteins: Structural, Redox, and Magnetic Properties of Bimetallic Complexes with M II-(μ-OH)-Fe III Cores. Inorg Chem 2017; 56:14118-14128. [PMID: 29112385 PMCID: PMC5696092 DOI: 10.1021/acs.inorgchem.7b02230] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Bimetallic complexes are important sites in metalloproteins but are often difficult to prepare synthetically. We have previously introduced an approach to form discrete bimetallic complexes with MII-(μ-OH)-FeIII (MII = Mn, Fe) cores using the tripodal ligand N,N',N″-[2,2',2″-nitrilotris(ethane-2,1-diyl)]tris(2,4,6-trimethylbenzenesulfonamido) ([MST]3-). This series is extended to include the rest of the late 3d transition metal ions (MII = Co, Ni, Cu, Zn). All of the bimetallic complexes have similar spectroscopic and structural properties that reflect little change despite varying the MII centers. Magnetic studies performed on the complexes in solution using electron paramagnetic resonance spectroscopy showed that the observed spin states varied incrementally from S = 0 through S = 5/2; these results are consistent with antiferromagnetic coupling between the high-spin MII and FeIII centers. However, the difference in the MII ion occupancy yielded only slight changes in the magnetic exchange coupling strength, and all complexes had J values ranging from +26(4) to +35(3) cm-1.
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Affiliation(s)
- Yohei Sano
- Department of Chemistry, University of California – Irvine, 1102 Natural Sciences II, Irvine, CA 92697-2025, United States
| | - Nathanael Lau
- Department of Chemistry, University of California – Irvine, 1102 Natural Sciences II, Irvine, CA 92697-2025, United States
| | - Andrew C. Weitz
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, United States
| | - Joseph W. Ziller
- Department of Chemistry, University of California – Irvine, 1102 Natural Sciences II, Irvine, CA 92697-2025, United States
| | - Michael P. Hendrich
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, United States
| | - A.S. Borovik
- Department of Chemistry, University of California – Irvine, 1102 Natural Sciences II, Irvine, CA 92697-2025, United States
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Lv Z, Chen Z, Hu Y, Zheng W, Wang H, Mo W, Yin G. A General Strategy for Open-Flask Alkene Isomerization by Ruthenium Hydride Complexes with Non-Redox Metal Salts. ChemCatChem 2017. [DOI: 10.1002/cctc.201700687] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Zhanao Lv
- School of Chemistry and Chemical Engineering; Key laboratory of Material Chemistry for Energy Conversion and Storage; Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure; Huazhong University of Science and Technology; Wuhan 430074 P.R. China
| | - Zhuqi Chen
- School of Chemistry and Chemical Engineering; Key laboratory of Material Chemistry for Energy Conversion and Storage; Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure; Huazhong University of Science and Technology; Wuhan 430074 P.R. China
| | - Yue Hu
- School of Chemistry and Chemical Engineering; Key laboratory of Material Chemistry for Energy Conversion and Storage; Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure; Huazhong University of Science and Technology; Wuhan 430074 P.R. China
| | - Wenrui Zheng
- School of Chemistry and Chemical Engineering; Key laboratory of Material Chemistry for Energy Conversion and Storage; Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure; Huazhong University of Science and Technology; Wuhan 430074 P.R. China
| | - Haibin Wang
- School of Chemistry and Chemical Engineering; Key laboratory of Material Chemistry for Energy Conversion and Storage; Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure; Huazhong University of Science and Technology; Wuhan 430074 P.R. China
| | - Wanling Mo
- School of Chemistry and Chemical Engineering; Key laboratory of Material Chemistry for Energy Conversion and Storage; Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure; Huazhong University of Science and Technology; Wuhan 430074 P.R. China
| | - Guochuan Yin
- School of Chemistry and Chemical Engineering; Key laboratory of Material Chemistry for Energy Conversion and Storage; Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure; Huazhong University of Science and Technology; Wuhan 430074 P.R. China
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33
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Stauber JM, Alliger GE, Nocera DG, Cummins CC. Second-Coordination-Sphere Assisted Selective Colorimetric Turn-on Fluoride Sensing by a Mono-Metallic Co(II) Hexacarboxamide Cryptand Complex. Inorg Chem 2017; 56:7615-7619. [DOI: 10.1021/acs.inorgchem.7b01335] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Julia M. Stauber
- Department
of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts
Ave, Cambridge, Massachusetts 02139, United States
| | - Glen E. Alliger
- Department
of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts
Ave, Cambridge, Massachusetts 02139, United States
| | - Daniel G. Nocera
- Department
of Chemistry and Chemical Biology, Harvard University, 12 Oxford
Street, Cambridge, Massachusetts 02138, United States
| | - Christopher C. Cummins
- Department
of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts
Ave, Cambridge, Massachusetts 02139, United States
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Lau N, Sano Y, Ziller JW, Borovik AS. Terminal Ni II-OH/-OH 2 complexes in trigonal bipyramidal geometries derived from H 2O. Polyhedron 2017; 125:179-185. [PMID: 29170577 PMCID: PMC5695699 DOI: 10.1016/j.poly.2016.11.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The preparation and characterization of two NiII complexes are described, a terminal NiII-OH complex with the tripodal ligand tris[(N)-tertbutylureaylato)-N-ethyl)]aminato ([H3buea]3-) and a terminal Ni II-OH2 complex with the tripodal ligand N,N',N″-[2,2',2″-nitrilotris(ethane-2,1-diyl)]tris(2,4,6-trimethylbenzenesulfonamido) ([MST]3-). For both complexes, the source of the -OH and -OH2 ligand is water. The salts K2[NiIIH3buea(OH)] and NMe4[NiIIMST(OH2)] were characterized using perpendicular-mode X-band electronic paramagnetic resonance, Fourier transform infrared, UV-visible spectroscopies, and its electrochemical properties were evaluated using cyclic voltammetry. The solid state structures of these complexes determined by X-ray diffraction methods reveal that they adopt a distorted trigonal bipyramidal geometry, an unusual structure for 5-coordinate NiII complexes. Moreover, the NiII-OH and NiII-OH2 units form intramolecular hydrogen bonding networks with the [H3buea]3- and [MST]3- ligands. The oxidation chemistry of these complexes was explored by treating the high-spin NiII compounds with one-electron oxidants. Species were formed with S = 1/2 spin ground states that are consistent with formation of monomeric NiIII species. While the formation of NiIII-OH complexes cannot be ruled out, the lack of observable O-H vibrations from the putative Ni-OH units suggest the possibility that other high valent Ni species are formed.
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Affiliation(s)
- Nathanael Lau
- Department of Chemistry, University of California - Irvine, 1102 Natural Sciences II, Irvine, CA 92697-2025, United States
| | - Yohei Sano
- Department of Chemistry, University of California - Irvine, 1102 Natural Sciences II, Irvine, CA 92697-2025, United States
| | - Joseph W Ziller
- Department of Chemistry, University of California - Irvine, 1102 Natural Sciences II, Irvine, CA 92697-2025, United States
| | - A S Borovik
- Department of Chemistry, University of California - Irvine, 1102 Natural Sciences II, Irvine, CA 92697-2025, United States
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Synthesis and reactivity of a mononuclear non-haem cobalt(IV)-oxo complex. Nat Commun 2017; 8:14839. [PMID: 28337985 PMCID: PMC5376677 DOI: 10.1038/ncomms14839] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 02/03/2017] [Indexed: 12/21/2022] Open
Abstract
Terminal cobalt(IV)-oxo (CoIV-O) species have been implicated as key intermediates in various cobalt-mediated oxidation reactions. Herein we report the photocatalytic generation of a mononuclear non-haem [(13-TMC)CoIV(O)]2+ (2) by irradiating [CoII(13-TMC)(CF3SO3)]+ (1) in the presence of [RuII(bpy)3]2+, Na2S2O8, and water as an oxygen source. The intermediate 2 was also obtained by reacting 1 with an artificial oxidant (that is, iodosylbenzene) and characterized by various spectroscopic techniques. In particular, the resonance Raman spectrum of 2 reveals a diatomic Co-O vibration band at 770 cm-1, which provides the conclusive evidence for the presence of a terminal Co-O bond. In reactivity studies, 2 was shown to be a competent oxidant in an intermetal oxygen atom transfer, C-H bond activation and olefin epoxidation reactions. The present results lend strong credence to the intermediacy of CoIV-O species in cobalt-catalysed oxidation of organic substrates as well as in the catalytic oxidation of water that evolves molecular oxygen.
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36
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Xue XS, Ji P, Zhou B, Cheng JP. The Essential Role of Bond Energetics in C-H Activation/Functionalization. Chem Rev 2017; 117:8622-8648. [PMID: 28281752 DOI: 10.1021/acs.chemrev.6b00664] [Citation(s) in RCA: 304] [Impact Index Per Article: 43.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The most fundamental concepts in chemistry are structure, energetics, reactivity and their inter-relationships, which are indispensable for promoting chemistry into a rational science. In this regard, bond energy, the intrinsic determinant directly related to structure and reactivity, should be most essential in serving as a quantitative basis for the design and understanding of organic transformations. Although C-H activation/functionalization have drawn tremendous research attention and flourished during the past decades, understanding the governing rules of bond energetics in these processes is still fragmentary and seems applicable only to limited cases, such as metal-oxo-mediated hydrogen atom abstraction. Despite the complexity of C-H activation/functionalization and the difficulties in measuring bond energies both for the substrates and intermediates, this is definitely a very important issue that should be more generally contemplated. To this end, this review is rooted in the energetic aspects of C-H activation/functionalization, which were previously rarely discussed in detail. Starting with a concise but necessary introduction of various classical methods for measuring heterolytic and homolytic energies for C-H bonds, the present review provides examples that applied the concept and values of C-H bond energy in rationalizing the observations associated with reactivity and/or selectivity in C-H activation/functionalization.
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Affiliation(s)
- Xiao-Song Xue
- State Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University , Tianjin, 300071, China
| | - Pengju Ji
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University , Beijing, 100084, China
| | - Biying Zhou
- State Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University , Tianjin, 300071, China
| | - Jin-Pei Cheng
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University , Beijing, 100084, China.,State Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University , Tianjin, 300071, China
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37
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Jones JR, Ziller JW, Borovik AS. Modulating the Primary and Secondary Coordination Spheres within a Series of Co II-OH Complexes. Inorg Chem 2017; 56:1112-1120. [PMID: 28094522 DOI: 10.1021/acs.inorgchem.6b01956] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The interplay between the primary and secondary coordination spheres is crucial to determining the properties of transition metal complexes. To examine these effects, a series of trigonal bipyramidal Co-OH complexes have been prepared with tripodal ligands that control both coordination spheres. The ligands contain a combination of either urea or sulfonamide groups that control the primary coordination sphere through anionic donors in the trigonal plane and the secondary coordination sphere through intramolecular hydrogen bonds. Variations in the anion donor strengths were evaluated using electronic absorbance spectroscopy and a qualitative ligand field analysis to find that deprotonated urea donors are stronger field ligands than deprotonated sulfonamides. Structural variations were found in the CoII-O bond lengths that range from 1.953(4) to 2.051(3) Å; this range in bond lengths were attributed to the differences in the intramolecular hydrogen bonds that surround the hydroxido ligand. A similar trend was observed between the hydrogen bonding networks and the vibrations of the O-H bonds. Attempts to isolate the corresponding CoIII-OH complexes were hampered by their instability at room temperature.
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Affiliation(s)
- Jason R Jones
- Department of Chemistry, University of California-Irvine , 1102 Natural Sciences II, Irvine, California 92697-2025, United States
| | - Joseph W Ziller
- Department of Chemistry, University of California-Irvine , 1102 Natural Sciences II, Irvine, California 92697-2025, United States
| | - A S Borovik
- Department of Chemistry, University of California-Irvine , 1102 Natural Sciences II, Irvine, California 92697-2025, United States
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38
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Zhang Q, Bell-Taylor A, Bronston FM, Gorden JD, Goldsmith CR. Aldehyde Deformylation and Catalytic C–H Activation Resulting from a Shared Cobalt(II) Precursor. Inorg Chem 2016; 56:773-782. [DOI: 10.1021/acs.inorgchem.6b02127] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Qiao Zhang
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Angela Bell-Taylor
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Fraser M. Bronston
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - John D. Gorden
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Christian R. Goldsmith
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
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39
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Narute S, Parnes R, Toste FD, Pappo D. Enantioselective Oxidative Homocoupling and Cross-Coupling of 2-Naphthols Catalyzed by Chiral Iron Phosphate Complexes. J Am Chem Soc 2016; 138:16553-16560. [PMID: 27959518 DOI: 10.1021/jacs.6b11198] [Citation(s) in RCA: 176] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Novel chiral iron phosphate complexes were prepared as catalysts for asymmetric oxidative coupling reactions. These catalysts were applied for the synthesis of enantio-enriched C1- and C2-symmetric BINOLs, in which the 3 and 3' positions are available for chemical modifications. It was proposed that the reaction takes place via an oxidative radical-anion coupling mechanism. A destructive BINOL racemization that competes with the enantioselective oxidative coupling of 2-naphthols was revealed, thereby offering new insights into this highly important reaction.
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Affiliation(s)
- Sachin Narute
- Department of Chemistry, Ben-Gurion University of the Negev , Beer-Sheva 84105, Israel
| | - Regev Parnes
- Department of Chemistry, Ben-Gurion University of the Negev , Beer-Sheva 84105, Israel
| | - F Dean Toste
- Department of Chemistry, University of California , Berkeley, California 94720, United States
| | - Doron Pappo
- Department of Chemistry, Ben-Gurion University of the Negev , Beer-Sheva 84105, Israel
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40
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Oxygen activation by mononuclear Mn, Co, and Ni centers in biology and synthetic complexes. J Biol Inorg Chem 2016; 22:407-424. [PMID: 27853875 DOI: 10.1007/s00775-016-1402-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 10/21/2016] [Indexed: 10/20/2022]
Abstract
The active sites of metalloenzymes that catalyze O2-dependent reactions generally contain iron or copper ions. However, several enzymes are capable of activating O2 at manganese or nickel centers instead, and a handful of dioxygenases exhibit activity when substituted with cobalt. This minireview summarizes the catalytic properties of oxygenases and oxidases with mononuclear Mn, Co, or Ni active sites, including oxalate-degrading oxidases, catechol dioxygenases, and quercetin dioxygenase. In addition, recent developments in the O2 reactivity of synthetic Mn, Co, or Ni complexes are described, with an emphasis on the nature of reactive intermediates featuring superoxo-, peroxo-, or oxo-ligands. Collectively, the biochemical and synthetic studies discussed herein reveal the possibilities and limitations of O2 activation at these three "overlooked" metals.
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41
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Corona T, Draksharapu A, Padamati SK, Gamba I, Martin-Diaconescu V, Acuña-Parés F, Browne WR, Company A. Rapid Hydrogen and Oxygen Atom Transfer by a High-Valent Nickel-Oxygen Species. J Am Chem Soc 2016; 138:12987-12996. [PMID: 27598293 DOI: 10.1021/jacs.6b07544] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Terminal high-valent metal-oxygen species are key reaction intermediates in the catalytic cycle of both enzymes (e.g., oxygenases) and synthetic oxidation catalysts. While tremendous efforts have been directed toward the characterization of the biologically relevant terminal manganese-oxygen and iron-oxygen species, the corresponding analogues based on late-transition metals such as cobalt, nickel or copper are relatively scarce. This scarcity is in part related to the "Oxo Wall" concept, which predicts that late transition metals cannot support a terminal oxido ligand in a tetragonal environment. Here, the nickel(II) complex (1) of the tetradentate macrocyclic ligand bearing a 2,6-pyridinedicarboxamidate unit is shown to be an effective catalyst in the chlorination and oxidation of C-H bonds with sodium hypochlorite as terminal oxidant in the presence of acetic acid (AcOH). Insight into the active species responsible for the observed reactivity was gained through the study of the reaction of 1 with ClO- at low temperature by UV-vis absorption, resonance Raman, EPR, ESI-MS, and XAS analyses. DFT calculations aided the assignment of the trapped chromophoric species (3) as a nickel-hypochlorite species. Despite the fact that the formal oxidation state of the nickel in 3 is +4, experimental and computational analysis indicate that 3 is best formulated as a NiIII complex with one unpaired electron delocalized in the ligands surrounding the metal center. Most remarkably, 3 reacts rapidly with a range of substrates including those with strong aliphatic C-H bonds, indicating the direct involvement of 3 in the oxidation/chlorination reactions observed in the 1/ClO-/AcOH catalytic system.
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Affiliation(s)
- Teresa Corona
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 69 , E17003 Girona, Catalonia, Spain
| | - Apparao Draksharapu
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Sandeep K Padamati
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Ilaria Gamba
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 69 , E17003 Girona, Catalonia, Spain
| | - Vlad Martin-Diaconescu
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 69 , E17003 Girona, Catalonia, Spain
| | - Ferran Acuña-Parés
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 69 , E17003 Girona, Catalonia, Spain
| | - Wesley R Browne
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Mathematics and Natural Sciences, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Anna Company
- Grup de Química Bioinspirada, Supramolecular i Catàlisi (QBIS-CAT), Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Facultat de Ciències, Universitat de Girona, C/ Maria Aurèlia Capmany 69 , E17003 Girona, Catalonia, Spain
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42
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Hydrogen Peroxide Coordination to Cobalt(II) Facilitated by Second‐Sphere Hydrogen Bonding. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201606561] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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43
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MacLeod KC, Menges FS, McWilliams SF, Craig SM, Mercado BQ, Johnson MA, Holland PL. Alkali-Controlled C-H Cleavage or N-C Bond Formation by N2-Derived Iron Nitrides and Imides. J Am Chem Soc 2016; 138:11185-91. [PMID: 27571271 PMCID: PMC5266523 DOI: 10.1021/jacs.6b04984] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Formation of N-H and N-C bonds from functionalization of N2 is a potential route to utilization of this abundant resource. One of the key challenges is to make the products of N2 activation reactive enough to undergo further reactions under mild conditions. This paper explores the strategy of "alkali control," where the presence of an alkali metal cation enables the reduction of N2 under mild conditions, and then chelation of the alkali metal cation uncovers a highly reactive species that can break benzylic C-H bonds to give new N-H and Fe-C bonds. The ability to "turn on" this C-H activation pathway with 18-crown-6 is demonstrated with three different N2 reduction products of N2 cleavage in an iron-potassium system. The alkali control strategy can also turn on an intermolecular reaction of an N2-derived nitride with methyl tosylate that gives a new N-C bond. Since the transient K(+)-free intermediate reacts with this electrophile but not with the weak C-H bonds in 1,4-cyclohexadiene, it is proposed that the C-H cleavage occurs by a deprotonation mechanism. The combined results demonstrate that a K(+) ion can mask the latent nucleophilicity of N2-derived nitride and imide ligands within a trimetallic iron system and points a way toward control over N2 functionalization.
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Affiliation(s)
- K. Cory MacLeod
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Fabian S. Menges
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Sean F. McWilliams
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Stephanie M. Craig
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Brandon Q. Mercado
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Mark A. Johnson
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Patrick L. Holland
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
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44
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Kim KR, Lee KS, Ahn CY, Yu SH, Sung YE. Discharging a Li-S battery with ultra-high sulphur content cathode using a redox mediator. Sci Rep 2016; 6:32433. [PMID: 27573528 PMCID: PMC5004098 DOI: 10.1038/srep32433] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 08/09/2016] [Indexed: 11/21/2022] Open
Abstract
Lithium-sulphur batteries are under intense research due to the high specific capacity and low cost. However, several problems limit their commercialization. One of them is the insulating nature of sulphur, which necessitates a large amount of conductive agent and binder in the cathode, reducing the effective sulphur load as well as the energy density. Here we introduce a redox mediator, cobaltocene, which acts as an electron transfer agent between the conductive surface and the polysulphides in the electrolyte. We confirmed that cobaltocene could effectively convert polysulphides to Li2S using scanning electron microscope, X-ray absorption near-edge structure and in-situ X-ray diffraction studies. This redox mediator enabled excellent electrochemical performance in a cathode with ultra-high sulphur content (80 wt%). It delivered 400 mAh g−1cathode capacity after 50 cycles, which is equivalent to 800 mAh g−1S in a typical cathode with 50 wt% sulphur. Furthermore, the volumetric capacity was also dramatically improved.
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Affiliation(s)
- Kwi Ryong Kim
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, South Korea.,School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, South Korea
| | - Kug-Seung Lee
- Beamline Department, Pohang Accelerator Laboratory (PAL), Pohang 790-784, South Korea
| | - Chi-Yeong Ahn
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, South Korea.,School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, South Korea
| | - Seung-Ho Yu
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, South Korea.,School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, South Korea
| | - Yung-Eun Sung
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, South Korea.,School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, South Korea
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45
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Wallen CM, Palatinus L, Bacsa J, Scarborough CC. Hydrogen Peroxide Coordination to Cobalt(II) Facilitated by Second-Sphere Hydrogen Bonding. Angew Chem Int Ed Engl 2016; 55:11902-6. [PMID: 27560462 DOI: 10.1002/anie.201606561] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Indexed: 11/11/2022]
Abstract
M(H2 O2 ) adducts have been postulated as intermediates in biological and industrial processes; however, only one observable M(H2 O2 ) adduct has been reported, where M is redox-inactive zinc. Herein, direct solution-phase detection of an M(H2 O2 ) adduct with a redox-active metal, cobalt(II), is described. This Co(II) (H2 O2 ) compound is made observable by incorporating second-sphere hydrogen-bonding interactions between bound H2 O2 and the supporting ligand, a trianionic trisulfonamido ligand. Thermodynamics of H2 O2 binding and decay kinetics of the Co(II) (H2 O2 ) species are described, as well as the reaction of this Co(II) (H2 O2 ) species with Group 2 cations.
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Affiliation(s)
- Christian M Wallen
- Department of Chemistry, Emory University, 1515 Dickey Dr., Atlanta, GA, 30322, USA
| | - Lukáš Palatinus
- Department of Structure Analysis, Institute of Physics of the AS CR, Prague, Czechia
| | - John Bacsa
- Department of Chemistry, Emory University, 1515 Dickey Dr., Atlanta, GA, 30322, USA
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46
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Lv Z, Zheng W, Chen Z, Tang Z, Mo W, Yin G. Synergistic oxygen atom transfer by ruthenium complexes with non-redox metal ions. Dalton Trans 2016; 45:11369-83. [PMID: 27333442 DOI: 10.1039/c6dt01077f] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Non-redox metal ions can affect the reactivity of active redox metal ions in versatile biological and heterogeneous oxidation processes; however, the intrinsic roles of these non-redox ions still remain elusive. This work demonstrates the first example of the use of non-redox metal ions as Lewis acids to sharply improve the catalytic oxygen atom transfer efficiency of a ruthenium complex bearing the classic 2,2'-bipyridine ligand. In the absence of Lewis acid, the oxidation of ruthenium(ii) complex by PhI(OAc)2 generates the Ru(iv)[double bond, length as m-dash]O species, which is very sluggish for olefin epoxidation. When Ru(bpy)2Cl2 was tested as a catalyst alone, only 21.2% of cyclooctene was converted, and the yield of 1,2-epoxycyclooctane was only 6.7%. As evidenced by electronic absorption spectra and EPR studies, both the oxidation of Ru(ii) by PhI(OAc)2 and the reduction of Ru(iv)[double bond, length as m-dash]O by olefin are kinetically slow. However, adding non-redox metal ions such as Al(iii) can sharply improve the oxygen transfer efficiency of the catalyst to 100% conversion with 89.9% yield of epoxide under identical conditions. Through various spectroscopic characterizations, an adduct of Ru(iv)[double bond, length as m-dash]O with Al(iii), Ru(iv)[double bond, length as m-dash]O/Al(iii), was proposed to serve as the active species for epoxidation, which in turn generated a Ru(iii)-O-Ru(iii) dimer as the reduced form. In particular, both the oxygen transfer from Ru(iv)[double bond, length as m-dash]O/Al(iii) to olefin and the oxidation of Ru(iii)-O-Ru(iii) back to the active Ru(iv)[double bond, length as m-dash]O/Al(iii) species in the catalytic cycle can be remarkably accelerated by adding a non-redox metal, such as Al(iii). These results have important implications for the role played by non-redox metal ions in catalytic oxidation at redox metal centers as well as for the understanding of the redox mechanism of ruthenium catalysts in the oxygen atom transfer reaction.
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Affiliation(s)
- Zhanao Lv
- Key laboratory of Material Chemistry for Energy Conversion and Storage (Huazhong University of Science and Technology), Ministry of Education, Key laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China.
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47
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Ouerghui A, Elamari H, Dardouri M, Ncib S, Meganem F, Girard C. Chemical modifications of poly(vinyl chloride) to poly(vinyl azide) and “clicked” triazole bearing groups for application in metal cation extraction. REACT FUNCT POLYM 2016. [DOI: 10.1016/j.reactfunctpolym.2016.01.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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48
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Wallen CM, Wielizcko M, Bacsa J, Scarborough CC. Heterotrimetallic sandwich complexes supported by sulfonamido ligands. Inorg Chem Front 2016. [DOI: 10.1039/c5qi00233h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
CoII complexes bearing sulfonamido ligands derived from tris(2-aminoethyl)amine (H6tren) assemble into complex architectures in the presence of Group II ions through interactions between the Group II ion and the sulfonyl oxygens.
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Affiliation(s)
| | | | - John Bacsa
- Department of Chemistry
- Emory University
- Atlanta
- USA
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49
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Stauber JM, Bloch ED, Vogiatzis KD, Zheng SL, Hadt RG, Hayes D, Chen LX, Gagliardi L, Nocera DG, Cummins CC. Pushing Single-Oxygen-Atom-Bridged Bimetallic Systems to the Right: A Cryptand-Encapsulated Co–O–Co Unit. J Am Chem Soc 2015; 137:15354-7. [DOI: 10.1021/jacs.5b09827] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Julia M. Stauber
- Department
of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Eric D. Bloch
- Department
of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department
of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Konstantinos D. Vogiatzis
- Department
of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Shao-Liang Zheng
- Department
of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Ryan G. Hadt
- Chemical
Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Dugan Hayes
- Chemical
Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Lin X. Chen
- Chemical
Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Laura Gagliardi
- Department
of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Daniel G. Nocera
- Department
of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Christopher C. Cummins
- Department
of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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50
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Abstract
Metal(H2O2) complexes have been implicated in kinetic and computational studies but have never been observed. Accordingly, H2O2 has been described as a very weak ligand. We report the first metal(H2O2) adduct, which is made possible by incorporating intramolecular hydrogen-bonding interactions with bound H2O2. This Zn(II)(H2O2) complex decays in solution by a second-order process that is slow enough to enable characterization of this species by X-ray crystallography. This report speaks to the intermediacy of metal(H2O2) adducts in chemistry and biology and opens the door to exploration of these species in oxidation catalysis.
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Affiliation(s)
- Christian M Wallen
- Department of Chemistry, Emory University , 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - John Bacsa
- Department of Chemistry, Emory University , 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - Christopher C Scarborough
- Department of Chemistry, Emory University , 1515 Dickey Drive, Atlanta, Georgia 30322, United States
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