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Li K, Zakharov LN, Pluth MD. Synthesis, Characterization, and Reactivity of a Synthetic End-On Cobalt(II) Alkyl Persulfide Complex as a Model Platform for Thiolate Persulfidation. J Am Chem Soc 2024; 146:21999-22007. [PMID: 39044627 DOI: 10.1021/jacs.4c07276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
Persulfides (RSS-) are ubiquitous source of sulfides (S2-) in biology, and interactions between RSS- and bioinorganic metal centers play critical roles in biological hydrogen sulfide (H2S) biogenesis, signaling, and catabolism. Here, we report the use of contact-ion stabilized [Na(15-crown-5)][tBuSS] (1) as a simple synthon to access rare metal alkyl persulfide complexes and to investigate the reactivity of RSS- with transition metal centers to provide insights into metal thiolate persulfidation, including the fundamental difference between alkyl persulfides and alkyl thiolates. Reaction of 1 with [CoII(TPA)(OTf)]+ afforded the η1-alkyl persulfide complex [CoII(TPA)(SStBu)]+ (2), which was characterized by X-ray crystallography, UV-vis spectroscopy, and Raman spectroscopy. RSS- coordination to the Lewis acidic Co2+ center provided additional stability to the S-S bond, as evidenced by a significant increase in the Raman stretching frequency for 2 (vS-S = 522 cm-1, ΔvS-S = 66 cm-1). The effect of persulfidation on metal center redox potentials was further elucidated using cyclic voltammetry, in which the Co2+ → Co3+ oxidation potential of 2 (Ep,a = +89 mV vs SCE) is lowered by nearly 700 mV when compared to the corresponding thiolate complex [CoII(TPA)(StBu)]+ (3) (Ep,a = +818 mV vs SCE), despite persulfidation being generally seen as an oxidative post-translational modification. The reactivity of 2 toward reducing agents including PPh3, BH4-, and biologically relevant thiol reductant DTT led to different S2- output pathways, including formation of a dinuclear 2Co-2SH complex [CoII2(TPA)2(μ2-SH)2]2+(4).
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Affiliation(s)
- Keyan Li
- Department of Chemistry and Biochemistry, Materials Science Institute, Knight Campus for Accelerating Scientific Impact, and Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1253, United States
| | - Lev N Zakharov
- Department of Chemistry and Biochemistry, Materials Science Institute, Knight Campus for Accelerating Scientific Impact, and Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1253, United States
| | - Michael D Pluth
- Department of Chemistry and Biochemistry, Materials Science Institute, Knight Campus for Accelerating Scientific Impact, and Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1253, United States
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2
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Yoshinari N, Kuwamura N, Kojima T, Konno T. Development of coordination chemistry with thiol-containing amino acids. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214857] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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3
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Naskar T, Jana M, Majumdar A. Binuclear manganese(II)-thiolate complexes: Synthesis, characterization and nitrite induced structural changes. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.133041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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4
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Hunsicker-Wang LM, Vogt MJ, Hoogstraten CG, Cosper NJ, Davenport AM, Hendon CH, Scott RA, Britt RD, DeRose VJ. Spectroscopic characterization of Mn2+ and Cd2+ coordination to phosphorothioates in the conserved A9 metal site of the hammerhead ribozyme. J Inorg Biochem 2022; 230:111754. [DOI: 10.1016/j.jinorgbio.2022.111754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 01/28/2022] [Accepted: 02/04/2022] [Indexed: 11/25/2022]
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5
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Yang P, Xie XB, Shi QS. Crystal structure of bis-{2-hy-droxy- N'-[1-(pyrazin-2-yl)ethyl-idene]benzohydrazidato}cadmium(II). Acta Crystallogr E Crystallogr Commun 2021; 77:153-157. [PMID: 33614145 PMCID: PMC7869545 DOI: 10.1107/s2056989021000657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 01/19/2021] [Indexed: 11/15/2022]
Abstract
In the title complex mol-ecule, [Cd(C13H11N4O2)2], the Cd atom is coordinated in a distorted octa-hedral geometry by two tridentate ligands synthesized from 2-hy-droxy-benzohydrazide and 1-(pyrazin-2-yl)ethan-1-one. The mol-ecule has twofold crystallographic symmetry and is isomorphous to its Mn, Co, Ni, Cu and Zn counterparts.
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Affiliation(s)
- Ping Yang
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, People’s Republic of China
| | - Xiao-Bao Xie
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, People’s Republic of China
| | - Qing-Shan Shi
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, People’s Republic of China
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6
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Inoue S, Yan YN, Yamanishi K, Kataoka Y, Kawamoto T. Photocatalytic and electrocatalytic hydrogen production using nickel complexes supported by hemilabile and non-innocent ligands. Chem Commun (Camb) 2020; 56:2829-2832. [PMID: 32073053 DOI: 10.1039/c9cc09568c] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nickel complexes with non-innocent ligands generated by one-electron reduction of octahedral Schiff base nickel(ii) complexes with hemilabile ligands exhibited excellent catalytic activities of over 5000 TONs through a metal-ligand cooperation mechanism for hydrogen evolution from water under visible light irradiation.
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Affiliation(s)
- Satoshi Inoue
- Department of Chemistry, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, 259-1293, Japan.
| | - Yin-Nan Yan
- Department of Chemistry, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, 259-1293, Japan.
| | - Katsunori Yamanishi
- Department of Chemistry, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, 259-1293, Japan.
| | - Yusuke Kataoka
- Department of Chemistry, Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, 690-8504, Japan
| | - Tatsuya Kawamoto
- Department of Chemistry, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, 259-1293, Japan.
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7
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González Nieves K, Piñero Cruz DM. Crystal structure of a nickel compound comprising two nickel(II) complexes with different ligand environments: [Ni(tren)(H 2O) 2][Ni(H 2O) 6](SO 4) 2. Acta Crystallogr E Crystallogr Commun 2020; 76:314-317. [PMID: 32148867 PMCID: PMC7057385 DOI: 10.1107/s2056989020001358] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 01/30/2020] [Indexed: 11/11/2022]
Abstract
The title compound, di-aqua-[tris-(2-amino-eth-yl)amine]-nickel(II) hexa-aqua-nickel(II) bis-(sulfate), [Ni(C6H18N4)(H2O)2][Ni(H2O)6](SO4)2 or [Ni(tren)(H2O)2][Ni(H2O)6](SO4)2, consists of two octa-hedral nickel complexes within the same unit cell. These metal complexes are formed from the reaction of [Ni(H2O)6](SO4) and the ligand tris-(2-amino-eth-yl)amine (tren). The crystals of the title compound are purple, different from those of the starting complex [Ni(H2O)6](SO4), which are turquoise. The reaction was performed both in a 1:1 and 1:2 metal-ligand molar ratio, always yielding the co-precipitation of the two types of crystals. The asymmetric unit of the title compound, which crystallizes in the space group Pnma, consists of two half NiII complexes and a sulfate counter-anion. The mononuclear cationic complex [Ni(tren)(H2O)2]2+ comprises an Ni ion, the tren ligand and two water mol-ecules, while the mononuclear complex [Ni(H2O)6]2+ consists of another Ni ion surrounded by six coordinated water mol-ecules. The [Ni(tren)(H2O)2] and [Ni(H2O)6] subunits are connected to the SO4 2- counter-anions through hydrogen bonding, thus consolidating the crystal structure.
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Affiliation(s)
- Karilys González Nieves
- Department of Natural Sciences, University of Puerto Rico, Carolina Campus, 2100 Avenida Sur, Carolina, PR 00987, Puerto Rico
| | - Dalice M. Piñero Cruz
- Department of Chemistry, University of Puerto Rico, Rio Piedras Campus, Ponce de Leon Avenue, San Juan, PR 00931, Puerto Rico
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8
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Dedushko MA, Schweitzer D, Blakely MN, Swartz RD, Kaminsky W, Kovacs JA. Geometric and electronic structure of a crystallographically characterized thiolate-ligated binuclear peroxo-bridged cobalt(III) complex. J Biol Inorg Chem 2019; 24:919-926. [PMID: 31342141 PMCID: PMC6948190 DOI: 10.1007/s00775-019-01686-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 07/11/2019] [Indexed: 10/26/2022]
Abstract
In order to shed light on metal-dependent mechanisms for O-O bond cleavage, and its microscopic reverse, we compare herein the electronic and geometric structures of O2-derived binuclear Co(III)- and Mn(III)-peroxo compounds. Binuclear metal peroxo complexes are proposed to form as intermediates during Mn-promoted photosynthetic H2O oxidation, and a Co-containing artificial leaf inspired by nature's photosynthetic H2O oxidation catalyst. Crystallographic characterization of an extremely activated peroxo is made possible by working with substitution-inert, low-spin Co(III). Density functional theory (DFT) calculations show that the frontier orbitals of the Co(III)-peroxo compound differ noticeably from the analogous Mn(III)-peroxo compound. The highest occupied molecular orbital (HOMO) associated with the Co(III)-peroxo is more localized on the peroxo in an antibonding π*(O-O) orbital, whereas the HOMO of the structurally analogous Mn(III)-peroxo is delocalized over both the metal d-orbitals and peroxo π*(O-O) orbital. With low-spin d6 Co(III), filled t2g orbitals prevent π-back-donation from the doubly occupied antibonding π*(O-O) orbital onto the metal ion. This is not the case with high-spin d4 Mn(III), since these orbitals are half-filled. This weakens the peroxo O-O bond of the former relative to the latter.
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Affiliation(s)
- Maksym A Dedushko
- The Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - Dirk Schweitzer
- The Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - Maike N Blakely
- The Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - Rodney D Swartz
- The Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - Werner Kaminsky
- The Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA
| | - Julie A Kovacs
- The Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195-1700, USA.
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9
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Recent developments in penta-, hexa- and heptadentate Schiff base ligands and their metal complexes. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2019.03.010] [Citation(s) in RCA: 189] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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10
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Wang L, Gennari M, Cantú Reinhard FG, Gutiérrez J, Morozan A, Philouze C, Demeshko S, Artero V, Meyer F, de Visser SP, Duboc C. A Non-Heme Diiron Complex for (Electro)catalytic Reduction of Dioxygen: Tuning the Selectivity through Electron Delivery. J Am Chem Soc 2019; 141:8244-8253. [DOI: 10.1021/jacs.9b02011] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Lianke Wang
- Université Grenoble Alpes, CNRS UMR 5250, DCM, F-38000 Grenoble, France
| | - Marcello Gennari
- Université Grenoble Alpes, CNRS UMR 5250, DCM, F-38000 Grenoble, France
| | - Fabián G. Cantú Reinhard
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Javier Gutiérrez
- Université Grenoble Alpes, CNRS UMR 5250, DCM, F-38000 Grenoble, France
| | - Adina Morozan
- Université Grenoble Alpes, CNRS, CEA, Laboratoire de Chimie et
Biologie des Métaux, F-38000 Grenoble, France
| | | | - Serhiy Demeshko
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Vincent Artero
- Université Grenoble Alpes, CNRS, CEA, Laboratoire de Chimie et
Biologie des Métaux, F-38000 Grenoble, France
| | - Franc Meyer
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Sam P. de Visser
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Carole Duboc
- Université Grenoble Alpes, CNRS UMR 5250, DCM, F-38000 Grenoble, France
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11
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Gordon JB, Vilbert AC, Siegler MA, Lancaster KM, Moënne-Loccoz P, Goldberg DP. A Nonheme Thiolate-Ligated Cobalt Superoxo Complex: Synthesis and Spectroscopic Characterization, Computational Studies, and Hydrogen Atom Abstraction Reactivity. J Am Chem Soc 2019; 141:3641-3653. [PMID: 30776222 DOI: 10.1021/jacs.8b13134] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The synthesis and characterization of a Co(II) dithiolato complex Co(Me3TACN)(S2SiMe2) (1) are reported. Reaction of 1 with O2 generates a rare thiolate-ligated cobalt-superoxo species Co(O2)(Me3TACN)(S2SiMe2) (2) that was characterized spectroscopically and structurally by resonance Raman, EPR, and X-ray absorption spectroscopies as well as density functional theory. Metal-superoxo species are proposed to S-oxygenate metal-bound thiolate donors in nonheme thiol dioxygenases, but 2 does not lead to S-oxygenation of the intramolecular thiolate donors and does not react with exogenous sulfur donors. However, complex 2 is capable of oxidizing the O-H bonds of 2,2,6,6-tetramethylpiperidin-1-ol derivatives via H atom abstraction. Complementary proton-coupled electron-transfer reactivity is seen for 2 with separated proton/reductant pairs. The reactivity studies indicate that 2 can abstract H atoms from weak X-H bonds with bond dissociation free energy (BDFE) ≤ 70 kcal mol-1. DFT calculations predict that the putative Co(OOH) product has an O-H BDFE = 67 kcal mol-1, which matches the observed pattern of reactivity seen for 2. These data provide new information regarding the selectivity of S-oxygenation versus H atom abstraction in thiolate-ligated nonheme metalloenzymes that react with O2.
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Affiliation(s)
- Jesse B Gordon
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
| | - Avery C Vilbert
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
| | - Maxime A Siegler
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
| | - Pierre Moënne-Loccoz
- Department of Biochemistry & Molecular Biology , Oregon Health & Science University , Portland , Oregon 97239-3098 , United States
| | - David P Goldberg
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
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12
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Kumar P, Lymperopoulou S, Loukopoulos E, Matsuda W, Kourkoumelis N, Seki S, Kostakis GE. Catalytic and conductivity studies in two dimensional coordination polymers built with a thiazole based ligand. Polyhedron 2018. [DOI: 10.1016/j.poly.2018.04.040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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13
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Leipzig BK, Rees JA, Kowalska JK, Theisen RM, Kavčič M, Poon PCY, Kaminsky W, DeBeer S, Bill E, Kovacs JA. How Do Ring Size and π-Donating Thiolate Ligands Affect Redox-Active, α-Imino-N-heterocycle Ligand Activation? Inorg Chem 2018; 57:1935-1949. [PMID: 29411979 PMCID: PMC8312276 DOI: 10.1021/acs.inorgchem.7b02748] [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: 11/29/2022]
Abstract
Considerable effort has been devoted to the development of first-row transition-metal catalysts containing redox-active imino-pyridine ligands that are capable of storing multiple reducing equivalents. This property allows abundant and inexpensive first-row transition metals, which favor sequential one-electron redox processes, to function as competent catalysts in the concerted two-electron reduction of substrates. Herein we report the syntheses and characterization of a series of iron complexes that contain both π-donating thiolate and π-accepting (α-imino)-N-heterocycle redox-active ligands, with progressively larger N-heterocycle rings (imidazole, pyridine, and quinoline). A cooperative interaction between these complementary redox-active ligands is shown to dictate the properties of these complexes. Unusually intense charge-transfer (CT) bands, and intraligand metrical parameters, reminiscent of a reduced (α-imino)-N-heterocycle ligand (L•-), initially suggested that the electron-donating thiolate had reduced the N-heterocycle. Sulfur K-edge X-ray absorption spectroscopic (XAS) data, however, provides evidence for direct communication, via backbonding, between the thiolate sulfur and the formally orthogonal (α-imino)-N-heterocycle ligand π*-orbitals. DFT calculations provide evidence for extensive delocalization of bonds over the sulfur, iron, and (α-imino)-N-heterocycle, and TD-DFT shows that the intense optical CT bands involve transitions between a mixed Fe/S donor, and (α-imino)-N-heterocycle π*-acceptor orbital. The energies and intensities of the optical and S K-edge pre-edge XAS transitions are shown to correlate with N-heterocycle ring size, as do the redox potentials. When the thiolate is replaced with a thioether, or when the low-spin S = 0 Fe(II) is replaced with a high-spin S = 3/2 Co(II), the N-heterocycle ligand metrical parameters and electronic structure do not change relative to the neutral L0 ligand. With respect to the development of future catalysts containing redox-active ligands, the energy cost of storing reducing equivalents is shown to be lowest when a quinoline, as opposed to imidazole or pyridine, is incorporated into the ligand backbone of the corresponding Fe complex.
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Affiliation(s)
- Benjamin K. Leipzig
- The Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
| | - Julian A. Rees
- The Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
| | - Joanna K. Kowalska
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34–36, D–45470 Mülheim an der Ruhr, Germany
| | - Roslyn M. Theisen
- The Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
| | | | | | - Werner Kaminsky
- The Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34–36, D–45470 Mülheim an der Ruhr, Germany
| | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34–36, D–45470 Mülheim an der Ruhr, Germany
| | - Julie A. Kovacs
- The Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
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14
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Truong PT, Gale EM, Dzul SP, Stemmler TL, Harrop TC. Steric Enforcement about One Thiolate Donor Leads to New Oxidation Chemistry in a NiSOD Model Complex. Inorg Chem 2017; 56:7761-7780. [PMID: 28459242 DOI: 10.1021/acs.inorgchem.7b00485] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ni-containing superoxide dismutase (NiSOD) represents an unusual member of the SOD family due to the presence of oxygen-sensitive Ni-SCys bonds at its active site. Reported in this account is the synthesis and properties of the NiII complex of the N3S2 ligand [N3S2Me2]3- ([N3S2Me2]3- = deprotonated form of 2-((2-mercapto-2-methylpropyl)(pyridin-2-ylmethyl)amino)-N-(2-mercaptoethyl)acetamide), namely Na[Ni(N3S2Me2)] (2), as a NiSOD model that features sterically robust gem-(CH3)2 groups on the thiolate α-C positioned trans to the carboxamide. The crystal structure of 2, coupled with spectroscopic measurements from 1H NMR, X-ray absorption, IR, UV-vis, and mass spectrometry (MS), reveal a planar NiII (S = 0) ion coordinated by only the N2S2 basal donors of the N3S2 ligand. While the structure and spectroscopic properties of 2 resemble those of NiSODred and other models, the asymmetric S ligands open up new reaction paths upon chemical oxidation. One unusual oxidation product is the planar NiII-N3S complex [Ni(Lox)] (5; Lox = 2-(5,5-dimethyl-2-(pyridin-2-yl)thiazolidin-3-yl)-N-(2-mercaptoethyl)acetamide), where two-electron oxidation takes place at the substituted thiolate and py-CH2 carbon to generate a thiazolidine heterocycle. Electrochemical measurements of 2 reveal irreversible events wholly consistent with thiolate redox, which were identified by comparison to the ZnII complex Na[Zn(N3S2Me2)] (3). Although no reaction is observed between 2 and azide, reaction of 2 with superoxide produces multiple products on the basis of UV-vis and MS data, one of which is 5. Density functional theory (DFT) computations suggest that the HOMO in 2 is π* with primary contributions from Ni-dπ/S-pπ orbitals. These contributions can be modulated and biased toward Ni when electron-withdrawing groups are placed on the thiolate α-C. Analysis of the oxidized five-coordinate species 2ox* by DFT reveal a singly occupied spin-up (α) MO that is largely thiolate based, which supports the proposed NiIII-thiolate/NiII-thiyl radical intermediates that ultimately yield 5 and other products.
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Affiliation(s)
- Phan T Truong
- Department of Chemistry and Center for Metalloenzyme Studies, The University of Georgia , 140 Cedar Street, Athens, Georgia 30602, United States
| | - Eric M Gale
- Department of Chemistry and Center for Metalloenzyme Studies, The University of Georgia , 140 Cedar Street, Athens, Georgia 30602, United States
| | - Stephen P Dzul
- Departments of Pharmaceutical Sciences, Biochemistry and Molecular Biology, Wayne State University , Detroit, Michigan 48201, United States
| | - Timothy L Stemmler
- Departments of Pharmaceutical Sciences, Biochemistry and Molecular Biology, Wayne State University , Detroit, Michigan 48201, United States
| | - Todd C Harrop
- Department of Chemistry and Center for Metalloenzyme Studies, The University of Georgia , 140 Cedar Street, Athens, Georgia 30602, United States
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15
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Pogány L, Moncol J, Gál M, Šalitroš I, Boča R. Four cobalt(III) Schiff base complexes – Structural, spectroscopic and electrochemical studies. Inorganica Chim Acta 2017. [DOI: 10.1016/j.ica.2017.03.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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16
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Villar-Acevedo G, Lugo-Mas P, Blakely MN, Rees JA, Ganas AS, Hanada EM, Kaminsky W, Kovacs JA. Metal-Assisted Oxo Atom Addition to an Fe(III) Thiolate. J Am Chem Soc 2016; 139:119-129. [PMID: 28033001 DOI: 10.1021/jacs.6b03512] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cysteinate oxygenation is intimately tied to the function of both cysteine dioxygenases (CDOs) and nitrile hydratases (NHases), and yet the mechanisms by which sulfurs are oxidized by these enzymes are unknown, in part because intermediates have yet to be observed. Herein, we report a five-coordinate bis-thiolate ligated Fe(III) complex, [FeIII(S2Me2N3(Pr,Pr))]+ (2), that reacts with oxo atom donors (PhIO, IBX-ester, and H2O2) to afford a rare example of a singly oxygenated sulfenate, [FeIII(η2-SMe2O)(SMe2)N3(Pr,Pr)]+ (5), resembling both a proposed intermediate in the CDO catalytic cycle and the essential NHase Fe-S(O)Cys114 proposed to be intimately involved in nitrile hydrolysis. Comparison of the reactivity of 2 with that of a more electron-rich, crystallographically characterized derivative, [FeIIIS2Me2NMeN2amide(Pr,Pr)]- (8), shows that oxo atom donor reactivity correlates with the metal ion's ability to bind exogenous ligands. Density functional theory calculations suggest that the mechanism of S-oxygenation does not proceed via direct attack at the thiolate sulfurs; the average spin-density on the thiolate sulfurs is approximately the same for 2 and 8, and Mulliken charges on the sulfurs of 8 are roughly twice those of 2, implying that 8 should be more susceptible to sulfur oxidation. Carboxamide-ligated 8 is shown to be unreactive towards oxo atom donors, in contrast to imine-ligated 2. Azide (N3-) is shown to inhibit sulfur oxidation with 2, and a green intermediate is observed, which then slowly converts to sulfenate-ligated 5. This suggests that the mechanism of sulfur oxidation involves initial coordination of the oxo atom donor to the metal ion. Whether the green intermediate is an oxo atom donor adduct, Fe-O═I-Ph, or an Fe(V)═O remains to be determined.
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Affiliation(s)
- Gloria Villar-Acevedo
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Priscilla Lugo-Mas
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Maike N Blakely
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Julian A Rees
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Abbie S Ganas
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Erin M Hanada
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Werner Kaminsky
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Julie A Kovacs
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
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Hilbert J, Näther C, Weihrich R, Bensch W. Room-Temperature Synthesis of Thiostannates from {[Ni(tren)]2[Sn2S6]}n. Inorg Chem 2016; 55:7859-65. [PMID: 27479453 DOI: 10.1021/acs.inorgchem.6b00625] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The compound {[Ni(tren)]2[Sn2S6]}n (1) (tren = tris(2-aminoethyl)amine, C6H18N4) was successfully applied as source for the room-temperature synthesis of the new thiostannates [Ni(tren)(ma)(H2O)]2[Sn2S6]·4H2O (2) (ma = methylamine, CH5N) and [Ni(tren)(1,2-dap)]2[Sn2S6]·2H2O (3) (1,2-dap = 1,2-diaminopropane, C3H10N2). The Ni-S bonds in the Ni2S2N8 bioctahedron in the structure of 1 are analyzed with density functional theory calculations demonstrating significantly differing Ni-S bond strengths. Because of this asymmetry they are easily broken in the presence of an excess of ma or 1,2-dap immediately followed by Ni-N bond formation to N donor atoms of the amine ligands thus generating [Ni(tren)(amine)](2+) complexes. The chemical reactions are fast, and compounds 2 and 3 are formed within 1 h. The synthesis concept presented here opens hitherto unknown possibilities for preparation of new thiostannates.
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Affiliation(s)
- Jessica Hilbert
- Institute of Inorganic Chemistry, Christian-Albrechts-University of Kiel , Max-Eyth-Str. 2, 24118 Kiel, Germany
| | - Christian Näther
- Institute of Inorganic Chemistry, Christian-Albrechts-University of Kiel , Max-Eyth-Str. 2, 24118 Kiel, Germany
| | - Richard Weihrich
- Institute of Inorganic Chemistry, University of Regensburg , Universitätsstraße 31, 93040 Regensburg, Germany
| | - Wolfgang Bensch
- Institute of Inorganic Chemistry, Christian-Albrechts-University of Kiel , Max-Eyth-Str. 2, 24118 Kiel, Germany
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18
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Mondragón A, Martínez-Alanis PR, Aullón G, Hernández-Ortega S, Robles-Marín E, Flores-Alamo M, Ugalde-Saldívar VM, Castillo I. Redox flexibility of iron complexes supported by sulfur-based tris(o-methylenethiophenolato)amine relative to its tripodal oxygen-based congener. Dalton Trans 2016; 45:9996-10006. [DOI: 10.1039/c6dt00814c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Tripodal ligands designed to generate a local C3 symmetry have resulted in novel types of metal complexes that feature unusual bonding and electronic properties.
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Affiliation(s)
| | - Paulina R. Martínez-Alanis
- Departament de Química Inorgànica and Institut de Química Teòrica i Computacional
- Universitat de Barcelona
- 08028 Barcelona
- Spain
| | - Gabriel Aullón
- Departament de Química Inorgànica and Institut de Química Teòrica i Computacional
- Universitat de Barcelona
- 08028 Barcelona
- Spain
| | | | - Elvis Robles-Marín
- Instituto de Química
- Universidad Nacional Autónoma de México
- México DF
- México
| | - Marcos Flores-Alamo
- Facultad de Química
- División de Estudios de Posgrado
- Universidad Nacional Autónoma de México
- México DF
- México
| | - Víctor M. Ugalde-Saldívar
- Facultad de Química
- División de Estudios de Posgrado
- Universidad Nacional Autónoma de México
- México DF
- México
| | - Ivan Castillo
- Instituto de Química
- Universidad Nacional Autónoma de México
- México DF
- México
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19
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Gennari M, Brazzolotto D, Pécaut J, Cherrier MV, Pollock CJ, DeBeer S, Retegan M, Pantazis DA, Neese F, Rouzières M, Clérac R, Duboc C. Dioxygen Activation and Catalytic Reduction to Hydrogen Peroxide by a Thiolate-Bridged Dimanganese(II) Complex with a Pendant Thiol. J Am Chem Soc 2015; 137:8644-53. [DOI: 10.1021/jacs.5b04917] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Marcello Gennari
- CNRS
UMR 5250, DCM, Université Grenoble Alpes, F-38000 Grenoble, France
| | | | - Jacques Pécaut
- INAC-SCIB, Université Grenoble Alpes, F-38000 Grenoble, France
- Reconnaissance Ionique et Chimie de Coordination, CEA, INAC-SCIB, F-38000 Grenoble, France
| | - Mickael V. Cherrier
- Metalloproteins
Unit, Institut de Biologie Structurale Jean-Pierre Ebel, CEA, CNRS
UMR 5075, Université Grenoble Alpes, 41 rue Horowitz, 38027 Grenoble Cedex 1, France
- Université de Lyon, F-69622 Lyon, France
- Université Claude Bernard Lyon 1, F-69622 Villeurbanne, France
- CNRS,
UMR 5086 Bases Moléculaires et Structurales de Systèmes
Infectieux, Institut de Biologie et Chimie des Protéines, 7 Passage du Vercors, F-69367 Lyon, France
| | - Christopher J. Pollock
- Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Serena DeBeer
- Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
- Department
of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Marius Retegan
- Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Dimitrios A. Pantazis
- Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Mathieu Rouzières
- CNRS, CRPP, UPR 8641, F-33600 Pessac, France
- CRPP,
UPR 8641, Université Bordeaux, F-33600 Pessac, France
| | - Rodolphe Clérac
- CNRS, CRPP, UPR 8641, F-33600 Pessac, France
- CRPP,
UPR 8641, Université Bordeaux, F-33600 Pessac, France
| | - Carole Duboc
- CNRS
UMR 5250, DCM, Université Grenoble Alpes, F-38000 Grenoble, France
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20
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Adly OM, Taha A, Fahmy SA. Spectroscopic, thermal, antimicrobial and molecular modeling studies of mononuclear pentafunctional Schiff base metal chelates derived from 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione. J Mol Struct 2015. [DOI: 10.1016/j.molstruc.2014.10.052] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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21
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Brines LM, Coggins MK, Poon PCY, Toledo S, Kaminsky W, Kirk ML, Kovacs JA. Water-soluble Fe(II)-H2O complex with a weak O-H bond transfers a hydrogen atom via an observable monomeric Fe(III)-OH. J Am Chem Soc 2015; 137:2253-64. [PMID: 25611075 DOI: 10.1021/ja5068405] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Understanding the metal ion properties that favor O-H bond formation versus cleavage should facilitate the development of catalysts tailored to promote a specific reaction, e.g., C-H activation or H2O oxidation. The first step in H2O oxidation involves the endothermic cleavage of a strong O-H bond (BDFE = 122.7 kcal/mol), promoted by binding the H2O to a metal ion, and by coupling electron transfer to proton transfer (PCET). This study focuses on details regarding how a metal ion's electronic structure and ligand environment can tune the energetics of M(HO-H) bond cleavage. The synthesis and characterization of an Fe(II)-H2O complex, 1, that undergoes PCET in H2O to afford a rare example of a monomeric Fe(III)-OH, 7, is described. High-spin 7 is also reproducibly generated via the addition of H2O to {[Fe(III)(O(Me2)N4(tren))]2-(μ-O)}(2+) (8). The O-H bond BDFE of Fe(II)-H2O (1) (68.6 kcal/mol) is calculated using linear fits to its Pourbaix diagram and shown to be 54.1 kcal/mol less than that of H2O and 10.9 kcal/mol less than that of [Fe(II)(H2O)6](2+). The O-H bond of 1 is noticeably weaker than the majority of reported M(n+)(HxO-H) (M = Mn, Fe; n+ = 2+, 3+; x = 0, 1) complexes. Consistent with their relative BDFEs, Fe(II)-H2O (1) is found to donate a H atom to TEMPO(•), whereas the majority of previously reported M(n+)-O(H) complexes, including [Mn(III)(S(Me2)N4(tren))(OH)](+) (2), have been shown to abstract H atoms from TEMPOH. Factors responsible for the weaker O-H bond of 1, such as differences in the electron-donating properties of the ligand, metal ion Lewis acidity, and electronic structure, are discussed.
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Affiliation(s)
- Lisa M Brines
- Department of Chemistry, University of Washington , Campus Box 351700, Seattle, Washington 98195-1700, United States
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22
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Metal-binding and redox properties of substituted linear and cyclic ATCUN motifs. J Inorg Biochem 2014; 139:65-76. [PMID: 24980953 DOI: 10.1016/j.jinorgbio.2014.06.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 05/29/2014] [Accepted: 06/02/2014] [Indexed: 01/13/2023]
Abstract
The amino-terminal copper and nickel binding (ATCUN) motif is a short peptide sequence found in human serum albumin and other proteins. Synthetic ATCUN-metal complexes have been used to oxidatively cleave proteins and DNA, cross-link proteins, and damage cancer cells. The ATCUN motif consists of a tripeptide that coordinates Cu(II) and Ni(II) ions in a square planar geometry, anchored by chelation sites at the N-terminal amine, histidine imidazole and two backbone amides. Many studies have shown that the histidine is required for tight binding and square planar geometry. Previously, we showed that macrocyclization of the ATCUN motif can lead to high-affinity binding with altered metal ion selectivity and enhanced Cu(II)/Cu(III) redox cycling (Inorg. Chem. 2013, 52, 2729-2735). In this work, we synthesize and characterize several linear and cyclic ATCUN variants to explore how substitutions at the histidine alter the metal-binding and catalytic properties. UV-visible spectroscopy, EPR spectroscopy and mass spectrometry indicate that cyclization can promote the formation of ATCUN-like complexes even in the absence of imidazole. We also report several novel ATCUN-like complexes and quantify their redox properties. These findings further demonstrate the effects of conformational constraints on short, metal-binding peptides, and also provide novel redox-active metallopeptides suitable for testing as catalysts for stereoselective or regioselective oxidation reactions.
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23
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Lincoln KM, Offutt ME, Hayden TD, Saunders RE, Green KN. Structural, Spectral, and Electrochemical Properties of Nickel(II), Copper(II), and Zinc(II) Complexes Containing 12-Membered Pyridine- and Pyridol-Based Tetra-aza Macrocycles. Inorg Chem 2014; 53:1406-16. [DOI: 10.1021/ic402119s] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Kimberly M. Lincoln
- Department
of Chemistry, Texas Christian University, Fort Worth, Texas 76109, United States
| | - Michael E. Offutt
- Department
of Chemistry, Texas Christian University, Fort Worth, Texas 76109, United States
| | - Travis D. Hayden
- Department
of Chemistry, Texas Christian University, Fort Worth, Texas 76109, United States
| | - Ryker E. Saunders
- Department
of Chemistry, Texas Christian University, Fort Worth, Texas 76109, United States
| | - Kayla N. Green
- Department
of Chemistry, Texas Christian University, Fort Worth, Texas 76109, United States
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24
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Fadaee F, Amirnasr M, Schenk-Joß K. Synthesis, characterization and X-ray crystal structures of two polymorphs of a cobalt(III) complex with a N3O2 pentadentate Schiff base ligand, and benzylamine: spectral and electrochemical studies. JOURNAL OF THE IRANIAN CHEMICAL SOCIETY 2013. [DOI: 10.1007/s13738-013-0246-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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25
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Coggins MK, Brines LM, Kovacs JA. Synthesis and structural characterization of a series of Mn(III)OR complexes, including a water-soluble Mn(III)OH that promotes aerobic hydrogen-atom transfer. Inorg Chem 2013; 52:12383-93. [PMID: 24156315 DOI: 10.1021/ic401234t] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Hydrogen-atom-transfer (HAT) reactions are a class of proton-coupled electron-transfer (PCET) reactions used in biology to promote substrate oxidation. The driving force for such reactions depends on both the oxidation potential of the catalyst and the pKa value of the proton-acceptor site. Both high-valent transition-metal oxo M(IV)═O (M = Fe, Mn) and lower-valent transition-metal hydroxo compounds M(III)OH (M = Fe, Mn) have been shown to promote these reactions. Herein we describe the synthesis, structure, and reactivity properties of a series of Mn(III)OR compounds [R = (p)NO2Ph (5), Ph (6), Me (7), H (8)], some of which abstract H atoms. The Mn(III)OH complex 8 is water-soluble and represents a rare example of a stable mononuclear Mn(III)OH. In water, the redox potential of 8 was found to be pH-dependent and the Pourbaix (E(p,c) vs pH) diagram has a slope (52 mV pH(-1)) that is indicative of the transfer a single proton with each electron (i.e., PCET). The two compounds with the lowest oxidation potential, hydroxide- and methoxide-bound 7 and 8, are found to oxidize 2,2',6,6'-tetramethylpiperidin-1-ol (TEMPOH), whereas the compounds with the highest oxidation potential, phenol-ligated 5 and 6, are shown to be unreactive. Hydroxide-bound 8 reacts with TEMPOH an order of magnitude faster than methoxide-bound 7. Kinetic data [kH/kD = 3.1 (8); kH/kD = 2.1 (7)] are consistent with concerted H-atom abstraction. The reactive species 8 can be aerobically regenerated in H2O, and at least 10 turnovers can be achieved without significant degradation of the "catalyst". The linear correlation between the redox potential and pH, obtained from the Pourbaix diagram, was used to calculate the bond dissociation free energy (BDFE) = 74.0 ± 0.5 kcal mol(-1) for Mn(II)OH2 in water, and in MeCN, its BDFE was estimated to be 70.1 kcal mol(-1). The reduced protonated derivative of 8, [Mn(II)(S(Me2)N4(tren))(H2O)](+) (9), was estimated to have a pKa of 21.2 in MeCN. The ability (7) and inability (5 and 6) of the other members of the series to abstract a H atom from TEMPOH was used to estimate either an upper or lower limit to the Mn(II)O(H)R pKa based on their experimentally determined redox potentials. The trend in pKa [21.2 (R = H) > 16.2 (R = Me) > 13.5 (R = Ph) > 12.2 (R = (p)NO2Ph)] is shown to oppose that of the oxidation potential E(p,c) [-220 (R = (p)NO2Ph) > -300 (R = Ph) > -410 (R = Me) > -600 (R = H) mV vs Fc(+/0)] for this particular series.
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Affiliation(s)
- Michael K Coggins
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
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26
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Knight JC, Wuest M, Saad FA, Wang M, Chapman DW, Jans HS, Lapi SE, Kariuki BM, Amoroso AJ, Wuest F. Synthesis, characterisation and evaluation of a novel copper-64 complex with selective uptake in EMT-6 cells under hypoxic conditions. Dalton Trans 2013; 42:12005-14. [DOI: 10.1039/c3dt50960e] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Li Z, Zhang H, GE X, Liang Y, An X, Yang C, Fang B, Xie H, Wei J. A nanocomposite of copper(ii) functionalized graphene and application for sensing sulfurated organophosphorus pesticides. NEW J CHEM 2013. [DOI: 10.1039/c3nj00528c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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28
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Coggins MK, Toledo S, Shaffer E, Kaminsky W, Shearer J, Kovacs JA. Characterization and dioxygen reactivity of a new series of coordinatively unsaturated thiolate-ligated manganese(II) complexes. Inorg Chem 2012; 51:6633-44. [PMID: 22642272 DOI: 10.1021/ic300192q] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis, structural, and spectroscopic characterization of four new coordinatively unsaturated mononuclear thiolate-ligated manganese(II) complexes ([Mn(II)(S(Me2)N(4)(6-Me-DPEN))](BF(4)) (1), [Mn(II)(S(Me2)N(4)(6-Me-DPPN))](BPh(4))·MeCN (3), [Mn(II)(S(Me2)N(4)(2-QuinoPN))](PF(6))·MeCN·Et(2)O (4), and [Mn(II)(S(Me2)N(4)(6-H-DPEN)(MeOH)](BPh(4)) (5)) is described, along with their magnetic, redox, and reactivity properties. These complexes are structurally related to recently reported [Mn(II)(S(Me2)N(4)(2-QuinoEN))](PF(6)) (2) (Coggins, M. K.; Kovacs, J. A. J. Am. Chem. Soc.2011, 133, 12470). Dioxygen addition to complexes 1-5 is shown to result in the formation of five new rare examples of Mn(III) dimers containing a single, unsupported oxo bridge: [Mn(III)(S(Me2)N(4)(6-Me-DPEN)](2)-(μ-O)(BF(4))(2)·2MeOH (6), [Mn(III)(S(Me2)N(4)(QuinoEN)](2)-(μ-O)(PF(6))(2)·Et(2)O (7), [Mn(III)(S(Me2)N(4)(6-Me-DPPN)](2)-(μ-O)(BPh(4))(2) (8), [Mn(III)(S(Me2)N(4)(QuinoPN)](2)-(μ-O)(BPh(4))(2) (9), and [Mn(III)(S(Me2)N(4)(6-H-DPEN)](2)-(μ-O)(PF(6))(2)·2MeCN (10). Labeling studies show that the oxo atom is derived from (18)O(2). Ligand modifications, involving either the insertion of a methylene into the backbone or the placement of an ortho substituent on the N-heterocyclic amine, are shown to noticeably modulate the magnetic and reactivity properties. Fits to solid-state magnetic susceptibility data show that the Mn(III) ions of μ-oxo dimers 6-10 are moderately antiferromagnetically coupled, with coupling constants (2J) that fall within the expected range. Metastable intermediates, which ultimately convert to μ-oxo bridged 6 and 7, are observed in low-temperature reactions between 1 and 2 and dioxygen. Complexes 3-5, on the other hand, do not form observable intermediates, thus illustrating the effect that relatively minor ligand modifications have upon the stability of metastable dioxygen-derived species.
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Affiliation(s)
- Michael K Coggins
- The Department of Chemistry, University of Washington, Campus Box 351700, Seattle, Washington 98195-1700, USA
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29
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Bruyneel F, Letondor C, Bastürk B, Gualandi A, Pordea A, Stoeckli-Evans H, Neier R. Catalytic Epoxidation of Alkenes by the Manganese Complex of a Reduced Porphyrinogen Macrocycle. Adv Synth Catal 2012. [DOI: 10.1002/adsc.201100433] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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30
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Gennari M, Gerey B, Hall N, Pécaut J, Vezin H, Collomb MN, Orio M, Duboc C. Structural, spectroscopic and redox properties of a mononuclear CoII thiolate complex – the reactivity toward S-alkylation: an experimental and theoretical study. Dalton Trans 2012; 41:12586-94. [DOI: 10.1039/c2dt31222k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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31
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Vázquez-Lima H, Guadarrama P, Martínez-Anaya C. Geometric distortions on a three-coordinated T1 Cu site model as a potential strategy to modulate redox potential. A theoretical study. J Mol Model 2011; 18:455-66. [DOI: 10.1007/s00894-011-1063-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Accepted: 03/22/2011] [Indexed: 10/18/2022]
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32
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Amirnasr M, Fadaee F, Mereiter K. Synthesis, and characterization of cobalt(III) complexes with Schiff bases derived from 2-hydroxynaphthaldehyde, (naph)2dien and (naph)2dpt, and monodentate amine ligands: Crystal structure, spectral and redox properties. Inorganica Chim Acta 2011. [DOI: 10.1016/j.ica.2011.02.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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33
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Swartz RD, Coggins MK, Kaminsky W, Kovacs JA. Nitrile hydration by thiolate- and alkoxide-ligated Co-NHase analogues. Isolation of Co(III)-amidate and Co(III)-iminol intermediates. J Am Chem Soc 2011; 133:3954-63. [PMID: 21351789 DOI: 10.1021/ja108749f] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitrile hydratases (NHases) are thiolate-ligated Fe(III)- or Co(III)-containing enzymes, which convert nitriles to the corresponding amide under mild conditions. Proposed NHase mechanisms involve M(III)-NCR, M(III)-OH, M(III)-iminol, and M(III)-amide intermediates. There have been no reported crystallographically characterized examples of these key intermediates. Spectroscopic and kinetic data support the involvement of a M(III)-NCR intermediate. A H-bonding network facilitates this enzymatic reaction. Herein we describe two biomimetic Co(III)-NHase analogues that hydrate MeCN, and four crystallographically characterized NHase intermediate analogues, [Co(III)(S(Me2)N(4)(tren))(MeCN)](2+) (1), [Co(III)(S(Me2)N(4)(tren))(OH)](+) (3), [Co(III)(S(Me2)N(4)(tren))(NHC(O)CH(3))](+) (2), and [Co(III)(O(Me2)N(4)(tren))(NHC(OH)CH(3))](2+) (5). Iminol-bound 5 represents the first example of a Co(III)-iminol compound in any ligand environment. Kinetic parameters (k(1)(298 K) = 2.98(5) M(-1) s(-1), ΔH(‡) = 12.65(3) kcal/mol, ΔS(‡) = -14(7) e.u.) for nitrile hydration by 1 are reported, and the activation energy E(a) = 13.2 kcal/mol is compared with that (E(a) = 5.5 kcal/mol) of the NHase enzyme. A mechanism involving initial exchange of the bound MeCN for OH- is ruled out by the fact that nitrile exchange from 1 (k(ex)(300 K) = 7.3(1) × 10(-3) s(-1)) is 2 orders of magnitude slower than nitrile hydration, and that hydroxide bound 3 does not promote nitrile hydration. Reactivity of an analogue that incorporates an alkoxide as a mimic of the highly conserved NHase serine residue shows that this moiety facilitates nitrile hydration under milder conditions. Hydrogen-bonding to the alkoxide stabilizes a Co(III)-iminol intermediate. Comparison of the thiolate versus alkoxide intermediate structures shows that C≡N bond activation and C═O bond formation proceed further along the reaction coordinate when a thiolate is incorporated into the coordination sphere.
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Affiliation(s)
- Rodney D Swartz
- The Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
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34
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Masitas CA, Mashuta MS, Grapperhaus CA. Asymmetric Oxygenation of a Ruthenium Dithiolate Mimics the Mixed Sulfenato/Sulfinato Donor Sets of Nitrile Hydratase and Thiocyanate Hydrolase. Inorg Chem 2010; 49:5344-6. [DOI: 10.1021/ic100414c] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- César A. Masitas
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292
| | - Mark S. Mashuta
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292
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35
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Zhang C, Matsumoto T, Samoc M, Petrie S, Meng S, Christopher Corkery T, Stranger R, Zhang J, Humphrey M, Tatsumi K. Dodecanuclear-Ellipse and Decanuclear-Wheel Nickel(II) Thiolato Clusters with Efficient Femtosecond Nonlinear Absorption. Angew Chem Int Ed Engl 2010; 49:4209-12. [DOI: 10.1002/anie.200907074] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Zhang C, Matsumoto T, Samoc M, Petrie S, Meng S, Christopher Corkery T, Stranger R, Zhang J, Humphrey M, Tatsumi K. Dodecanuclear-Ellipse and Decanuclear-Wheel Nickel(II) Thiolato Clusters with Efficient Femtosecond Nonlinear Absorption. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.200907074] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Quan YP, Yin P, Han NN, Yang AH, Gao HL, Cui JZ, Shi W, Cheng P. Novel hetero-polynuclear metal complexes (CuL)3[Mn(NCS)5]2 and (NiL)3[Mn(NCS)5]2 containing trigonal bipyramidal geometric [Mn(NCS)5]3− as bridging ligand. INORG CHEM COMMUN 2009. [DOI: 10.1016/j.inoche.2009.03.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Lugo-Mas P, Taylor W, Schweitzer D, Theisen RM, Xu L, Shearer J, Swartz RD, Gleaves MC, Dipasquale A, Kaminsky W, Kovacs JA. Properties of square-pyramidal alkyl-thiolate Fe(III) complexes, including an analogue of the unmodified form of nitrile hydratase. Inorg Chem 2008; 47:11228-36. [PMID: 18989922 PMCID: PMC2659597 DOI: 10.1021/ic801704n] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The syntheses and structures of three new coordinatively unsaturated, monomeric, square-pyramidal thiolate-ligated Fe(III) complexes are described, [Fe(III)((tame-N(3))S(2)(Me2))](+) (1), [Fe(III)(Et-N(2)S(2)(Me2))(py)](1-) (3), and [Fe(III)((tame-N(2)S)S(2)(Me2))](2-) (15). The anionic bis-carboxamide, tris-thiolate N(2)S(3) coordination sphere of 15 is potentially similar to that of the yet-to-be characterized unmodified form of NHase. Comparison of the magnetic and reactivity properties of these reveals how anionic charge build up (from cationic 1 to anionic 3 and dianionic 15) and spin-state influence apical ligand affinity. For all of the ligand-field combinations examined, an intermediate S = 3/2 spin state was shown to be favored by a strong N(2)S(2) basal plane ligand field, and this was found to reduce the affinity for apical ligands, even when they are built in. This is in contrast to the post-translationally modified NHase active site, which is low spin and displays a higher affinity for apical ligands. Cationic 1 and its reduced Fe(II) precursor are shown to bind NO and CO, respectively, to afford [Fe(III)((tame-N(3))S(2)(Me))(NO)](+) (18, nu(NuO) = 1865 cm(-1)), an analogue of NO-inactivated NHase, and [Fe(II)((tame-N(3))S(2)(Me))(CO)] (16; nu(CO) stretch (1895 cm(-1)). Anions (N(3)(-), CN(-)) are shown to be unreactive toward 1, 3, and 15 and neutral ligands unreactive toward 3 and 15, even when present in 100-fold excess and at low temperatures. The curtailed reactivity of 15, an analogue of the unmodified form of NHase, and its apical-oxygenated S = 3/2 derivative [Fe(III)((tame-N(2)SO(2))S(2)(Me2))](2-) (20) suggests that regioselective post-translational oxygenation of the basal plane NHase cysteinate sulfurs plays an important role in promoting substrate binding. This is supported by previously reported theoretical (DFT) calculations.
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Affiliation(s)
- Priscilla Lugo-Mas
- The Department of Chemistry, University of Washington, Box 351700 Seattle, Washington 98195-1700, USA
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Brines LM, Villar-Acevedo G, Kitagawa T, Swartz RD, Lugo-Mas P, Kaminsky W, Benedict JB, Kovacs JA. Comparison of Structurally-Related Alkoxide, Amine, and Thiolate-Ligated M (M= Fe, Co) Complexes: the Influence of Thiolates on the Properties of Biologically Relevant Metal Complexes. Inorganica Chim Acta 2008; 361:1070-1078. [PMID: 21731109 DOI: 10.1016/j.ica.2007.07.038] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Mechanistic pathways of metalloenzymes are controlled by the metal ion's electronic and magnetic properties, which are tuned by the coordinated ligands. The functional advantage gained by incorporating cysteinates into the active site of non-heme iron enzymes such as superoxide reductase (SOR) is not entirely understood. Herein we compare the structural and redox properties of a series of structurally-related thiolate, alkoxide, and amine-ligated Fe(II) complexes in order to determine how the thiolate influences properties critical to function. Thiolates are shown to reduce metal ion Lewis acidity relative to alkoxides and amines, and have a strong trans influence thereby helping to maintain an open coordination site. Comparison of the redox potentials of the structurally analogous compounds described herein indicates that alkoxide ligands favor the higher-valent Fe(3+) oxidation state, amine ligands favor the reduced Fe(2+) oxidation state, and thiolates fall somewhere in between. These properties provide a functional advantange for substrate reducing enzymes in that they provide a site at the metal ion for substrate to bind, and a moderate potential that facilitates both substrate reduction, and regeneration of the catalytically active reduced state. Redox potentials for structurally-related Co(II) complexes are shown to be cathodically-shifted relative to their Fe(II) analogues, making them ineffective reducing agents for substrates such as superoxide.
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Affiliation(s)
- Lisa M Brines
- The Department of Chemistry, University of Washington: Box 351700 Seattle, WA 98195-1700
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