1
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Phearman AS, Ardon Y, Goldberg KI. Insertion of Molecular Oxygen into a Gold(III)-Hydride Bond. J Am Chem Soc 2024; 146:4045-4059. [PMID: 38290523 DOI: 10.1021/jacs.3c12285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
The use of molecular oxygen as an oxidant in chemical synthesis has significant environmental and economic benefits, and it is widely used as such in large-scale industrial processes. However, its adoption in highly selective homogeneous catalytic transformations, particularly to produce oxygenated organics, has been hindered by our limited understanding of the mechanisms by which O2 reacts with transition metals. Of particular relevance are the mechanisms of the reactions of oxygen with late transition metal hydrides as these metal centers are better poised to release oxygenated products. Homogeneous catalysis with gold complexes has markedly increased, and herein we report the synthesis and full characterization of a rare AuIII-H, supported by a diphosphine pincer ligand (tBuPCP = 2,6-bis(di-tert-butylphosphinomethyl)benzene). [(tBuPCP)AuIII-H]+ was found to cleanly react with molecular oxygen to yield a stable AuIII-OOH complex that was also fully characterized. Extensive kinetic studies on the reaction via variable temperature NMR spectroscopy have been completed, and the results are consistent with an autoaccelerating radical chain mechanism. The observed kinetic behavior exhibits similarities to that of previously reported PdII-H and PtIV-H reactions with O2 but is not fully consistent with any known O2 insertion mechanism. As such, this study contributes to the nascent fundamental understanding of the mechanisms of aerobic oxidation of late metal hydrides.
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Affiliation(s)
- Alexander S Phearman
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Yotam Ardon
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Karen I Goldberg
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
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2
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Agarwal RG, Coste SC, Groff BD, Heuer AM, Noh H, Parada GA, Wise CF, Nichols EM, Warren JJ, Mayer JM. Free Energies of Proton-Coupled Electron Transfer Reagents and Their Applications. Chem Rev 2021; 122:1-49. [PMID: 34928136 DOI: 10.1021/acs.chemrev.1c00521] [Citation(s) in RCA: 134] [Impact Index Per Article: 44.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We present an update and revision to our 2010 review on the topic of proton-coupled electron transfer (PCET) reagent thermochemistry. Over the past decade, the data and thermochemical formalisms presented in that review have been of value to multiple fields. Concurrently, there have been advances in the thermochemical cycles and experimental methods used to measure these values. This Review (i) summarizes those advancements, (ii) corrects systematic errors in our prior review that shifted many of the absolute values in the tabulated data, (iii) provides updated tables of thermochemical values, and (iv) discusses new conclusions and opportunities from the assembled data and associated techniques. We advocate for updated thermochemical cycles that provide greater clarity and reduce experimental barriers to the calculation and measurement of Gibbs free energies for the conversion of X to XHn in PCET reactions. In particular, we demonstrate the utility and generality of reporting potentials of hydrogenation, E°(V vs H2), in almost any solvent and how these values are connected to more widely reported bond dissociation free energies (BDFEs). The tabulated data demonstrate that E°(V vs H2) and BDFEs are generally insensitive to the nature of the solvent and, in some cases, even to the phase (gas versus solution). This Review also presents introductions to several emerging fields in PCET thermochemistry to give readers windows into the diversity of research being performed. Some of the next frontiers in this rapidly growing field are coordination-induced bond weakening, PCET in novel solvent environments, and reactions at material interfaces.
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Affiliation(s)
- Rishi G Agarwal
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Scott C Coste
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Benjamin D Groff
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Abigail M Heuer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Hyunho Noh
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Giovanny A Parada
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States.,Department of Chemistry, The College of New Jersey, Ewing, New Jersey 08628, United States
| | - Catherine F Wise
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Eva M Nichols
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - James M Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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3
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Shimoyama Y, Ohgomori Y, Kon Y, Hong D. Hydrogen peroxide production from oxygen and formic acid by homogeneous Ir-Ni catalyst. Dalton Trans 2021; 50:9410-9416. [PMID: 34096959 DOI: 10.1039/d1dt01431e] [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
Hydrogen peroxide was directly produced from oxygen and formic acid, catalysed by a hetero-dinuclear Ir-Ni complex with two adjacent sites, at ambient temperature. Synergistic catalysis derived from the hetero-dinuclear Ir and Ni centres was demonstrated by comparing its activity to those of the component mononuclear Ir and Ni complexes. A reaction intermediate of Ir-hydrido was detected by UV-vis, ESI-TOF-MS, and 1H NMR spectroscopies. It was revealed that the Ir moiety serves as an active species of Ir-hydrido, reacting with oxygen to afford an Ir-hydroperoxide species through O2 insertion, which is the rate-determining step for H2O2 production. Meanwhile, the Ni moiety promotes H2O2 formation by activating solvents as proton sources. We also found that H2O2 production is strongly affected by the solvent dielectric constants (DE); the highest H2O2 concentration was obtained in ethylene glycol with a moderate DE. The catalytic mechanism of H2O2 production by the Ir-Ni complex was discussed, based on kinetic analysis, isotope labelling experiments, and theoretical DFT calculations.
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Affiliation(s)
- Yoshihiro Shimoyama
- Interdisciplinary Research Centre for Catalytic Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
| | - Yuji Ohgomori
- Interdisciplinary Research Centre for Catalytic Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
| | - Yoshihiro Kon
- Interdisciplinary Research Centre for Catalytic Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
| | - Dachao Hong
- Interdisciplinary Research Centre for Catalytic Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
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4
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Arisawa M, Fukumoto K, Yamaguchi M. Rhodium-Catalyzed Oxidation of Unprotected Peptide Thiols to Disulfides with Oxygen in Water. ACS Catal 2020. [DOI: 10.1021/acscatal.0c04799] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Mieko Arisawa
- Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan
| | - Kohei Fukumoto
- Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan
| | - Masahiko Yamaguchi
- Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan
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5
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Affiliation(s)
- Weihao Zhu
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - T. Brent Gunnoe
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
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6
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Konnick MM, Knapp SM, Stahl SS. Mechanism of the reaction of an NHC-coordinated palladium(II)-hydride with O2 in acetonitrile. Polyhedron 2020. [DOI: 10.1016/j.poly.2020.114501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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7
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Wright AM, Pahls DR, Gary JB, Warner T, Williams JZ, M Knapp SM, Allen KE, Landis CR, Cundari TR, Goldberg KI. Experimental and Computational Investigation of the Aerobic Oxidation of a Late Transition Metal-Hydride. J Am Chem Soc 2019; 141:10830-10843. [PMID: 31259542 DOI: 10.1021/jacs.9b04706] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The rational development of homogeneous catalytic systems for selective aerobic oxidations of organics has been hampered by the limited available knowledge of how oxygen reacts with important organometallic intermediates. Recently, several mechanisms for oxygen insertion into late transition metal-hydride bonds have been described. Contributing to this nascent understanding of how oxygen reacts with metal-hydrides, a detailed mechanistic study of the reaction of oxygen with the IrIII hydride complex (dmPhebox)Ir(OAc)(H) (1) in the presence of acetic acid, which proceeds to form the IrIII complex (dmPhebox)Ir(OAc)2(OH2) (2), is described. The evidence supports a multifaceted mechanism wherein a small amount of an initially formed metal hydroperoxide proceeds to generate a metal-oxyl species that then initiates a radical chain reaction to rapidly convert the remaining IrIII-H. Insight into the initiation step was gained through kinetic and mechanistic studies of the radical chain inhibition by BHT (butylated hydroxytoluene). Computational studies were employed to contribute to a further understanding of initiation and propagation in this system.
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Affiliation(s)
- Ashley M Wright
- Department of Chemistry , University of Washington , Box 351700, Seattle , Washington 98195-1700 , United States
| | - Dale R Pahls
- Department of Chemistry and Center for Advanced Scientific Computing and Modeling (CASCaM) , University of North Texas , 1155 Union Circle, #305070 , Denton , Texas 76203-5017 , United States
| | - J Brannon Gary
- Department of Chemistry and Center for Advanced Scientific Computing and Modeling (CASCaM) , University of North Texas , 1155 Union Circle, #305070 , Denton , Texas 76203-5017 , United States.,Department of Chemistry and Biochemistry , Stephen F. Austin State University , P.O. Box 13006, SFA Station , Nacogdoches , Texas 75962-3006 , United States
| | - Theresa Warner
- Department of Chemistry and Center for Advanced Scientific Computing and Modeling (CASCaM) , University of North Texas , 1155 Union Circle, #305070 , Denton , Texas 76203-5017 , United States
| | - Jacob Z Williams
- Department of Chemistry and Center for Advanced Scientific Computing and Modeling (CASCaM) , University of North Texas , 1155 Union Circle, #305070 , Denton , Texas 76203-5017 , United States
| | - Spring Melody M Knapp
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53719 , United States
| | - Kate E Allen
- Department of Chemistry , University of Washington , Box 351700, Seattle , Washington 98195-1700 , United States
| | - Clark R Landis
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53719 , United States
| | - Thomas R Cundari
- Department of Chemistry and Center for Advanced Scientific Computing and Modeling (CASCaM) , University of North Texas , 1155 Union Circle, #305070 , Denton , Texas 76203-5017 , United States
| | - Karen I Goldberg
- Department of Chemistry , University of Washington , Box 351700, Seattle , Washington 98195-1700 , United States.,Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
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9
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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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10
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Gain S, Das RS, Banerjee R, Mukhopadhyay S. Kinetics and mechanism of oxidation of thiourea by a bridging superoxide in the presence of Ellman’s reagent. J COORD CHEM 2016. [DOI: 10.1080/00958972.2016.1206198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Sekhar Gain
- Department of Chemistry, Ramakrishna Mission Vidyamandira, Howrah, India
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11
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Takashita K, Matsumoto T, Yatabe T, Nakai H, Suzuki M, Ogo S. A Water-soluble Ni Dihydrido Complex That Reduces O2 to H2O in Water. CHEM LETT 2016. [DOI: 10.1246/cl.150935] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Keisuke Takashita
- Center for Small Molecule Energy, Kyushu University
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University
| | - Takahiro Matsumoto
- Center for Small Molecule Energy, Kyushu University
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University
| | - Takeshi Yatabe
- Center for Small Molecule Energy, Kyushu University
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University
| | - Hidetaka Nakai
- Center for Small Molecule Energy, Kyushu University
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University
| | - Masatatsu Suzuki
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University
| | - Seiji Ogo
- Center for Small Molecule Energy, Kyushu University
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University
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12
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Keith JM, Ye Y, Wei H, Buck MR. Mechanistic examination of aerobic Pt oxidation: insertion of molecular oxygen into Pt–H bonds through a radical chain mechanism. Dalton Trans 2016; 45:11650-6. [DOI: 10.1039/c6dt00419a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
DFT calculations were performed in an effort to evaluate the mechanism of O2 insertion into the Pt–H bond of TpMe2PtIVMe2H catalyzed by AIBN or light.
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Affiliation(s)
| | - Yixin Ye
- Department of Chemistry
- Colgate University
- Hamilton
- USA
| | - Haochuan Wei
- Department of Chemistry
- Colgate University
- Hamilton
- USA
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13
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Schiwek C, Meiners J, Förster M, Würtele C, Diefenbach M, Holthausen MC, Schneider S. Oxygen Reduction with a Bifunctional Iridium Dihydride Complex. Angew Chem Int Ed Engl 2015; 54:15271-5. [PMID: 26511744 DOI: 10.1002/anie.201504369] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 09/07/2015] [Indexed: 11/06/2022]
Abstract
The iridium dihydride [Ir(H)2 (HPNP)](+) (PNP=N(CH2 CH2 PtBu2 )2 ) reacts with O2 to give the unusual, square-planar iridium(III) hydroxide [Ir(OH)(PNP)](+) and water. Regeneration of the dihydride with H2 closes a quasi-catalytic synthetic oxygen-reduction reaction (ORR) cycle that can be run several times. Experimental and computational examinations are in agreement with an oxygenation mechanism via rate-limiting O2 coordination followed by H-transfer at a single metal site, facilitated by the cooperating pincer ligand. Hence, the four electrons required for the ORR are stored within the two covalent MH bonds of a mononuclear metal complex.
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Affiliation(s)
- Christoph Schiwek
- Institut für Anorganische Chemie, Georg-August-Universität, Tammannstr. 4, 37077 Göttingen (Germany)
| | - Jenni Meiners
- Institut für Anorganische Chemie, Georg-August-Universität, Tammannstr. 4, 37077 Göttingen (Germany)
| | - Moritz Förster
- Insitut für Anorganische und Analytische Chemie, Goethe-Universität, Max-von-Laue-Str. 7, 60438 Frankfurt am Main (Germany)
| | - Christian Würtele
- Institut für Anorganische Chemie, Georg-August-Universität, Tammannstr. 4, 37077 Göttingen (Germany)
| | - Martin Diefenbach
- Insitut für Anorganische und Analytische Chemie, Goethe-Universität, Max-von-Laue-Str. 7, 60438 Frankfurt am Main (Germany)
| | - Max C Holthausen
- Insitut für Anorganische und Analytische Chemie, Goethe-Universität, Max-von-Laue-Str. 7, 60438 Frankfurt am Main (Germany).
| | - Sven Schneider
- Institut für Anorganische Chemie, Georg-August-Universität, Tammannstr. 4, 37077 Göttingen (Germany).
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14
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Schiwek C, Meiners J, Förster M, Würtele C, Diefenbach M, Holthausen MC, Schneider S. Oxygen Reduction with a Bifunctional Iridium Dihydride Complex. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201504369] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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Goo YR, Maity AC, Cho KB, Lee YM, Seo MS, Park YJ, Cho J, Nam W. Tuning the Reactivity of Chromium(III)-Superoxo Species by Coordinating Axial Ligands. Inorg Chem 2015; 54:10513-20. [PMID: 26486819 DOI: 10.1021/acs.inorgchem.5b02068] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Metal-superoxo species have attracted much attention recently as key intermediates in enzymatic and biomimetic oxidation reactions. The effect(s) of axial ligands on the chemical properties of metal-superoxo complexes has never been explored previously. In this study, we synthesized and characterized chromium(III)-superoxo complexes bearing TMC derivatives with pendant pyridine and imidazole donors, such as [Cr(III)(O2)(TMC-Py)](2+) (1, TMC-Py = 4,8,11-trimethyl-1-(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane) and [Cr(III)(O2)(TMC-Im)](2+) (2, TMC-Im = 4,8,11-trimethyl-1-(2-methylimidazolmethyl)-1,4,8,11-tetraazacyclotetradecane). The reactivity of chromium(III)-superoxo complexes binding different axial ligands, such as 1, 2, and [Cr(III)(O2)(TMC)(Cl)](+) (3, TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), was then investigated in C-H bond activation and oxygen atom transfer reactions. Kinetic studies revealed that the reactivity of the Cr(III)-superoxo complexes depends on the axial ligands, showing the reactivity order of 1 > 2 > 3 in those electrophilic oxidation reactions. It was also shown that there is a good correlation between the reactivity of the chromium(III)-superoxo complexes and their redox potentials, in which the redox potentials of the chromium(III)-superoxo complexes are in the order 1 > 2 > 3. DFT calculations reproduced the reactivity order between 1 and 3 in both C-H bond activation and oxygen atom transfer reactions, and the latter reaction is described using orbital interactions. The calculations are also in agreement with the experimentally obtained redox potentials. The present results provide the first example showing that the reactivity of metal-superoxo species can be tuned by the electron-donating ability of axial ligands bound trans to the metal-superoxo moiety.
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Affiliation(s)
- Yi Re Goo
- Department of Chemistry and Nano Science, Ewha Womans University , Seoul 03760, Korea
| | - Annada C Maity
- Department of Chemistry and Nano Science, Ewha Womans University , Seoul 03760, Korea
| | - Kyung-Bin Cho
- 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
| | - Mi Sook Seo
- Department of Chemistry and Nano Science, Ewha Womans University , Seoul 03760, Korea
| | - Young Jun Park
- Department of Chemistry and Nano Science, Ewha Womans University , Seoul 03760, Korea
| | - Jaeheung Cho
- Department of Emerging Materials Science, DGIST , Daegu 42988, Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University , Seoul 03760, Korea
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16
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Feller M, Ben-Ari E, Diskin-Posner Y, Carmieli R, Weiner L, Milstein D. O2 Activation by Metal–Ligand Cooperation with IrI PNP Pincer Complexes. J Am Chem Soc 2015; 137:4634-7. [DOI: 10.1021/jacs.5b01585] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Moran Feller
- Departments
of †Organic Chemistry and ‡Chemical Research
Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eyal Ben-Ari
- Departments
of †Organic Chemistry and ‡Chemical Research
Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yael Diskin-Posner
- Departments
of †Organic Chemistry and ‡Chemical Research
Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Raanan Carmieli
- Departments
of †Organic Chemistry and ‡Chemical Research
Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Lev Weiner
- Departments
of †Organic Chemistry and ‡Chemical Research
Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - David Milstein
- Departments
of †Organic Chemistry and ‡Chemical Research
Support, Weizmann Institute of Science, Rehovot 76100, Israel
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17
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Hull EA, West AC, Pestovsky O, Kristian KE, Ellern A, Dunne JF, Carraher JM, Bakac A, Windus TL. UV-visible spectroscopy of macrocyclic alkyl, nitrosyl and halide complexes of cobalt and rhodium. Experiment and calculation. Dalton Trans 2015; 44:3811-6. [DOI: 10.1039/c4dt03143a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Visible light photolysis of Co(NH3)5CH32+ generates alkyl radicals, unlike the halide complexes Co(NH3)5X2+ which produce halogen anions, X−.
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Affiliation(s)
- Emily A. Hull
- Department of Chemistry and Ames Laboratory
- Iowa State University
- Ames
- USA
| | - Aaron C. West
- Department of Chemistry and Ames Laboratory
- Iowa State University
- Ames
- USA
| | - Oleg Pestovsky
- Department of Chemistry and Ames Laboratory
- Iowa State University
- Ames
- USA
| | | | - Arkady Ellern
- Department of Chemistry and Ames Laboratory
- Iowa State University
- Ames
- USA
| | - James F. Dunne
- Department of Chemistry and Ames Laboratory
- Iowa State University
- Ames
- USA
| | - Jack M. Carraher
- Department of Chemistry and Ames Laboratory
- Iowa State University
- Ames
- USA
| | - Andreja Bakac
- Department of Chemistry and Ames Laboratory
- Iowa State University
- Ames
- USA
| | - Theresa L. Windus
- Department of Chemistry and Ames Laboratory
- Iowa State University
- Ames
- USA
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18
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Carraher JM, Ellern A, Bakac A. Preparation and reactivity of macrocyclic rhodium(III) alkyl complexes. Inorganica Chim Acta 2014. [DOI: 10.1016/j.ica.2013.09.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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19
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Kinetics of reduction of μ-amido-μ-superoxo-bis[tetraamminecobalt(III)]4+ complex with hydroxylamine derivatives. Inorganica Chim Acta 2013. [DOI: 10.1016/j.ica.2012.09.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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20
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Teets TS, Nocera DG. Acidolyis and oxygen atom transfer reactivity of a diiridium hydroperoxo complex. Dalton Trans 2013; 42:3521-7. [DOI: 10.1039/c2dt32887a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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21
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Bakac A, Pestovsky O, Durfey BL, Kristian KE. Kinetics and thermodynamics of nitric oxide binding to transition metal complexes. Relationship to dioxygen binding. Chem Sci 2013. [DOI: 10.1039/c3sc50157d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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22
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Keith JM, Teets TS, Nocera DG. O2 Insertion into Group 9 Metal–Hydride Bonds: Evidence for Oxygen Activation through the Hydrogen-Atom-Abstraction Mechanism. Inorg Chem 2012; 51:9499-507. [DOI: 10.1021/ic301303n] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jason M. Keith
- Theoretical Division,
MS B268,
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United
States
| | - Thomas S. Teets
- Department of Chemistry,
6-335,
Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge,
Massachusetts 02139-4307, United States
| | - Daniel G. Nocera
- Department of Chemistry,
6-335,
Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge,
Massachusetts 02139-4307, United States
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23
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Cho J, Woo J, Nam W. A Chromium(III)–Superoxo Complex in Oxygen Atom Transfer Reactions as a Chemical Model of Cysteine Dioxygenase. J Am Chem Soc 2012; 134:11112-5. [DOI: 10.1021/ja304357z] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jaeheung Cho
- Department of Bioinspired
Science, Ewha Womans University, Seoul 120-750, Korea
| | - Jaeyoung Woo
- Department of Bioinspired
Science, Ewha Womans University, Seoul 120-750, Korea
| | - Wonwoo Nam
- Department of Bioinspired
Science, Ewha Womans University, Seoul 120-750, Korea
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Teets TS, Nocera DG. Oxygen Reduction Reactions of Monometallic Rhodium Hydride Complexes. Inorg Chem 2012; 51:7192-201. [DOI: 10.1021/ic300279z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Thomas S. Teets
- Department of Chemistry, 6-335, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge,
Massachusetts 02139-4307, United States
| | - Daniel G. Nocera
- Department of Chemistry, 6-335, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge,
Massachusetts 02139-4307, United States
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25
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Kristian KE, Bakac A. Reduction of nitrous acid with a macrocyclic rhodium complex that acts as a functional model of nitrite reductase. Inorg Chem 2012; 51:4877-82. [PMID: 22480334 DOI: 10.1021/ic300597n] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nitrous acid reacts with L(2)(H(2)O)Rh(2+) (L(2) = meso-hexamethylcyclam) in acidic aqueous solutions to generate a strongly absorbing intermediate Int-1 (λ(max) 400 nm, ε = 1200 M(-1) cm(-1)). The reaction follows a mixed second order rate law with k = (6.9 ± 0.3) × 10(4) M(-1) s(-1), independent of [H(+)]. The lack of acid dependence shows that Int-1 is a rhodium(II) complex of HNO(2), most reasonably assigned as L(2)(H(2)O)Rh(HNO(2))(2+). This species is analogous to the early iron and copper intermediates in the reduction of nitrite by nitrite reductases and by deoxyhemoglobin. In the presence of excess L(2)(H(2)O)Rh(2+), the lifetime of Int-1 is about 1 min. It decays to a 1:1 mixture of L(2)(H(2)O)RhNO(2+) and L(2)Rh(H(2)O)(2)(3+) with kinetics that are largely independent of the concentration of excess L(2)(H(2)O)Rh(2+) and of [H(+)] at [H(+)] < 0.03 M. At [H(+)] > 0.03 M, an acid-catalyzed pathway becomes effective, suggesting protonation and dehydration of Int-1 to generate L(2)(H(2)O)RhNO(3+) (Int-2) followed by rapid reduction of Int-2 by excess L(2)(H(2)O)Rh(2+). Int-2, which was generated and characterized independently, is an analog of the electrophilic intermediates in the mechanism of biological reduction of nitrite to (•)NO. Excess nitrite greatly reduces the lifetime of Int-1, which under such conditions decomposes on a millisecond time scale by nitrite-catalyzed disproportionation to yield L(2)(H(2)O)RhNO(2+) and L(2)Rh(III). This reaction provides additional support for the designation of Int-1 as a Rh(II) species. The complex reaction mechanism and the detection of Int-1 demonstrate the ability of inorganic complexes to perform the fundamental chemistry believed to take place in the biological reduction of HNO(2) to NO catalyzed by nitrite reductases or deoxyhemoglobin.
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Szajna-Fuller E, Bakac A. Kinetics and mechanism of the reduction of a macrocyclic Rh(III) complex by chromium(II) ions: pH-controlled selectivity to rhodium(II) vs. rhodium(III) hydride. Dalton Trans 2011; 40:10598-602. [PMID: 21796299 DOI: 10.1039/c1dt10747j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aqueous chromium(II) ions reduce a macrocyclic Rh(III) complex L(1)(H(2)O)(2)Rh(3+) (L(1) = 1,4,8,11-tetraazacyclotetradecane) to the hydride L(1)(H(2)O)RhH(2+) in two discrete, one-electron steps. The first step generates L(1)(H(2)O)Rh(2+) with kinetics that are first order in each rhodium(III) complex and Cr(H(2)O)(6)(2+), and inverse in [H(+)], k/M(-1) s(-1) = 0.065/(0.0031 + [H(+)]). Further reduction of L(1)(H(2)O)Rh(2+) to L(1)(H(2)O)RhH(2+) is kinetically independent of [H(+)], k/M(-1) s(-1) = 0.30. The difference in [H(+)] dependence allows relative rates of the two steps to be manipulated to generate either L(1)(H(2)O)Rh(2+) or L(1)(H(2)O)RhH(2+) as the final product.
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27
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Teets TS, Nocera DG. Mechanistic Studies of O2 Reduction Effected by Group 9 Bimetallic Hydride Complexes. J Am Chem Soc 2011; 133:17796-806. [DOI: 10.1021/ja2069196] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Thomas S. Teets
- Department of Chemistry, 6-335, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United States
| | - Daniel G. Nocera
- Department of Chemistry, 6-335, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, United States
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28
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Pestovsky O, Veysey SW, Bakac A. Kinetics and mechanism of hydrogen-atom abstraction from rhodium hydrides by alkyl radicals in aqueous solutions. Chemistry 2011; 17:4518-22. [PMID: 21438044 DOI: 10.1002/chem.201100094] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Indexed: 11/10/2022]
Abstract
The kinetics of the reaction of benzyl radicals with [L(1)(H(2)O)RhH{D}](2+) (L(1)=1,4,8,11-tetraazacyclotetradecane) were studied directly by laser-flash photolysis. The rate constants for the two isotopologues, k=(9.3±0.6) × 10(7) M(-1) s(-1) (H) and (6.2±0.3) × 10(7) M(-1) s(-1) (D), lead to a kinetic isotope effect k(H)/k(D)=1.5±0.1. The same value was obtained from the relative yields of PhCH(3) and PhCH(2)D in a reaction of benzyl radicals with a mixture of rhodium hydride and deuteride. Similarly, the reaction of methyl radicals with {[L(1)(H(2)O)RhH](2+) + [L(1)(H(2)O)RhD](2+)} produced a mixture of CH(4) and CH(3)D that yielded k(H)/k(D)=1.42±0.07. The observed small normal isotope effects in both reactions are consistent with reduced sensitivity to isotopic substitution in very fast hydrogen-atom abstraction reactions. These data disprove a literature report claiming much slower kinetics and an inverse kinetic isotope effect for the reaction of methyl radicals with hydrides of L(1)Rh.
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Affiliation(s)
- Oleg Pestovsky
- Ames Laboratory, Iowa State University, Ames, IA 50011, USA.
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29
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Song W, Kristian KE, Bakac A. Visible Light‐Induced Release of Nitrogen Monoxide from a Nitrosylrhodium Complex. Chemistry 2011; 17:4513-7. [DOI: 10.1002/chem.201003003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Indexed: 11/11/2022]
Affiliation(s)
- Wenjing Song
- Iowa State University, Ames, IA 50011 (USA), Fax: (+1) 515‐294‐5233
| | | | - Andreja Bakac
- Iowa State University, Ames, IA 50011 (USA), Fax: (+1) 515‐294‐5233
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30
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Konnick MM, Decharin N, Popp BV, Stahl SS. O2insertion into a palladium(ii)-hydride bond: Observation of mechanistic crossover between HX-reductive-elimination and hydrogen-atom-abstraction pathways. Chem Sci 2011. [DOI: 10.1039/c0sc00392a] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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31
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Cho J, Woo J, Eun Han J, Kubo M, Ogura T, Nam W. Chromium(v)-oxo and chromium(iii)-superoxo complexes bearing a macrocyclic TMC ligand in hydrogen atom abstraction reactions. Chem Sci 2011. [DOI: 10.1039/c1sc00386k] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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32
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Lee SY, Cheung CW, Hsu IJ, Chan KS. Mechanistic Studies of the Reaction of Ir(III) Porphyrin Hydride with 2,2,6,6-Tetramethylpiperidine-1-oxyl to an Unsupported Ir−Ir Porphyrin Dimer. Inorg Chem 2010; 49:9636-40. [DOI: 10.1021/ic1013544] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Siu Yin Lee
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People’s Republic of China
| | - Chi Wai Cheung
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People’s Republic of China
| | - I-Jui Hsu
- Department of Molecular Science and Engineering, National Taipei University of Technology, Taipei 10608, Taiwan
| | - Kin Shing Chan
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People’s Republic of China
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33
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Abstract
Coordination to transition-metal complexes changes both the thermodynamics and kinetics of oxygen reduction. Some of the intermediates (superoxo, hydroperoxo, and oxo species) are close analogues of organic oxygen-centered radicals and peroxides (ROO(*), ROOH, and RO(*)). Metal-based intermediates are typically less reactive, but more persistent, than organic radicals, which makes the two types of intermediates similarly effective in their reactions with various substrates. The self-exchange rate constant for hydrogen-atom transfer for the couples Cr(aq)OO(2+)/Cr(aq)OOH(2+) and L(1)(H(2)O)RhOO(2+)/L(1)(H(2)O)RhOOH(2+) was estimated to be 10(1+/-1) M(-1) s(-1). The use of this value in the simplified Marcus equation for the Cr(aq)O(2+)/Cr(aq)OOH(2+) cross reaction provided an upper limit k(CrO,CrOH) <or= 10((-2+/-1)) M(-1) s(-1) for Cr(aq)O(2+)/Cr(aq)OH(2+) self-exchange. Even though superoxo complexes react very slowly in bimolecular self-reactions, extremely fast cross reactions with organic counterparts, i.e., acylperoxyl radicals, have been observed. Many of the intermediates generated by the interaction of O(2) with reduced metal complexes can also be accessed by alternative routes, both thermal and photochemical.
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Affiliation(s)
- Andreja Bakac
- Ames Laboratory and Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
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34
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Cho J, Woo J, Nam W. An “End-On” Chromium(III)-Superoxo Complex: Crystallographic and Spectroscopic Characterization and Reactivity in C−H Bond Activation of Hydrocarbons. J Am Chem Soc 2010; 132:5958-9. [DOI: 10.1021/ja1015926] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jaeheung Cho
- Department of Bioinspired Science, Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Jaeyoung Woo
- Department of Bioinspired Science, Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Wonwoo Nam
- Department of Bioinspired Science, Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
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35
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Szajna-Fuller E, Bakac A. Base-Catalyzed Insertion of Dioxygen into Rhodium−Hydrogen Bonds: Kinetics and Mechanism. Inorg Chem 2009; 49:781-5. [DOI: 10.1021/ic901808t] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Andreja Bakac
- Ames Laboratory, Iowa State University, Ames, Iowa 50011
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36
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Look JL, Wick DD, Mayer JM, Goldberg KI. Autoxidation of Platinum(IV) Hydrocarbyl Hydride Complexes To Form Platinum(IV) Hydrocarbyl Hydroperoxide Complexes. Inorg Chem 2009; 48:1356-69. [DOI: 10.1021/ic801216r] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jennifer L. Look
- Department of Chemistry, Box 351700, University of Washington, Seattle, Washington 98195-1700
| | - Douglas D. Wick
- Department of Chemistry, Box 351700, University of Washington, Seattle, Washington 98195-1700
| | - James M. Mayer
- Department of Chemistry, Box 351700, University of Washington, Seattle, Washington 98195-1700
| | - Karen I. Goldberg
- Department of Chemistry, Box 351700, University of Washington, Seattle, Washington 98195-1700
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37
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Zhang X, Schlangen M, Baik MH, Dede Y, Schwarz H. DFT Studies on the Thermal Activation of Molecular Oxygen by Bare [Ni(H)(OH)]+. Helv Chim Acta 2009. [DOI: 10.1002/hlca.200800411] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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38
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Song W, Ellern A, Bakac A. Electron-Transfer Reactions of Nitrosyl and Superoxo Metal Complexes. Inorg Chem 2008; 47:8405-11. [DOI: 10.1021/ic800867j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Wenjing Song
- Chemistry Department, Iowa State University, Ames, Iowa 50011
| | - Arkady Ellern
- Chemistry Department, Iowa State University, Ames, Iowa 50011
| | - Andreja Bakac
- Chemistry Department, Iowa State University, Ames, Iowa 50011
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39
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Vasbinder MJ, Bakac A. Kinetics and mechanism of the reactions of ozone with superoxo, hydroperoxo, and hydrido complexes of rhodium(III). Inorganica Chim Acta 2008. [DOI: 10.1016/j.ica.2007.11.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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40
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Konnick MM, Stahl SS. Reaction of Molecular Oxygen with a PdII-Hydride To Produce a PdII-Hydroperoxide: Experimental Evidence for an HX-Reductive-Elimination Pathway. J Am Chem Soc 2008; 130:5753-62. [DOI: 10.1021/ja7112504] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Michael M. Konnick
- Department of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706
| | - Shannon S. Stahl
- Department of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706
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41
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Schlangen M, Schwarz H. Insertion of Molecular Oxygen in Transition-Metal Hydride Bonds, Oxygen-Bond Activation, and Unimolecular Dissociation of Metal Hydroperoxide Intermediates. Short Communication. Helv Chim Acta 2008. [DOI: 10.1002/hlca.200890043] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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42
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Furczon M, Pestovsky O, Bakac A. Kinetics of Dissociation of Molecular Oxygen from a Superoxorhodium(III) Complex and Reactivity of a Macrocyclic Rhodium(II) Ion. Inorg Chem 2007; 46:11461-6. [DOI: 10.1021/ic701686g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Oleg Pestovsky
- Ames Laboratory, Iowa State University, Ames, Iowa 50011
| | - Andreja Bakac
- Ames Laboratory, Iowa State University, Ames, Iowa 50011
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43
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Szajna-Fuller E, Bakac A. Thermodynamics of oxygen activation by macrocyclic complexes of rhodium. Inorg Chem 2007; 46:10907-12. [PMID: 17985876 DOI: 10.1021/ic7015337] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The oxidation of ABTS2- [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate)] with a superoxorhodium(III) complex, L2(H2O)RhOO2+ (L2 = meso-hexamethylcyclam) is characterized by an acid-dependent equilibrium constant, log(Ke/[H+]) = 4.91 +/- 0.10 in the pH range of 4.89-6.49. This equilibrium constant was used to calculate the reduction potential for the L2(H2O)RhOO2+/L2(H2O)RhOOH2+ couple, E0 = 0.97 V vs NHE. The pH dependence of the kinetics of the L2(H2O)RhOOH2+/I- reaction yielded the acid dissociation constant for the coordinated water in L2(H2O)RhOOH2+, pKa = 6.9. Spectrophotometric pH titrations provided pKa = 6.6 for the superoxo complex, L2(H2O)RhOO2+. The combination of the two pKa values with the reduction potential measured in acidic solutions yielded the reduction potential E0 = 0.95 V for the L2(HO)RhOO+/L2(HO)RhOOH+ couple. Thermochemical calculations yielded the bond-dissociation free energy of the L2(H2O)RhOO-H2+ bond as 315 kJ/mol at 298 K.
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44
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Popp BV, Stahl SS. Insertion of Molecular Oxygen into a Palladium−Hydride Bond: Computational Evidence for Two Nearly Isoenergetic Pathways. J Am Chem Soc 2007; 129:4410-22. [PMID: 17371024 DOI: 10.1021/ja069037v] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction of a palladiumII-hydride species with molecular oxygen to form palladiumII-hydroperoxide has been proposed as a key step in Pd-catalyzed aerobic oxidation reactions. We recently reported one of the first experimental precedents for such a step (Angew. Chem., Int. Ed. 2006, 45, 2904-2907). DFT calculations have been used to probe the mechanism for this reaction, which consists of formal insertion of O2 into the palladium-hydride bond of trans-(NHC)2Pd(H)OAc (NHC = N-heterocyclic carbene). Four different pathways were considered: (1) hydrogen atom abstraction (HAA) of the Pd-H bond by molecular oxygen, (2) reductive elimination of HX followed by oxygenation of Pd0 and protonolysis of the (eta2-peroxo)-PdII species, (3) oxygenation of palladiumII-hydride with subsequent reductive elimination of the O-H bond from an eta2-peroxo-PdIV center, and (4) formation of a cis-superoxide adduct of the palladium-hydride species followed by O-H bond formation via hydrogen atom migration. The calculations reveal that pathways 1 and 2 are preferred energetically, and both pathways exhibit very similar kinetic barriers. This result suggests that more than one pathway is possible for catalyst reoxidation in Pd-catalyzed aerobic oxidation reactions.
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Affiliation(s)
- Brian V Popp
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA.
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45
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Vasbinder MJ, Bakac A. Hydrogen-atom transfer from transition metal hydroperoxides, hydrogen peroxide, and alkyl hydroperoxides to superoxo and oxo metal complexes. Inorg Chem 2007; 46:2921-8. [PMID: 17290988 DOI: 10.1021/ic070015z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Superoxochromium(III) complexes L(H2O)CrOO2+ (L = (H2O)4 and 1,4,8,11-tetraazacyclotetradecane) oxidize hydroperoxo complexes of rhodium and cobalt in an apparent hydrogen-atom transfer process, i.e., L(H2O)CrOO2+ + L(H2O)RhOOH2+ --> L(H2O)CrOOH2+ + L(H2O)RhOO2+. All of the measured rate constants fall in a narrow range, 17-135 M-1 s-1. These values are about 2.5-3.0 times smaller in D2O, where the hydroperoxo hydrogen is replaced by deuterium, and coordinated molecules of water by D2O. The failure of the back reaction to take place in the available concentration range places the O-H bond dissociation energy in RhOO-H2+ at <or=320 kJ/mol. The rates of oxidation of L(H2O)RhOOH2+ by CraqOO2+ are comparable to those for the oxidation of the corresponding hydrides despite the great difference (>or=80 kJ/mol) in the driving force for the two types of reactions. A chromyl ion, CrIVaqO2+, oxidizes L(H2O)RhOOH2+ and the cobalt analogs to the corresponding superoxo complexes. The rate constants are approximately 102-fold larger than those for the oxidation by CraqOO2+. The oxidation of tert-BuOOH by CrIVaqO2+ has k = 160 M-1 s-1 and exhibits an isotope effect kBuOOH/kBuOOD = 12. Hydrogen atom transfer from H2O2 to CraqOO2+ is slow, k approximately 10-3 M-1 s-1.
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Affiliation(s)
- Michael J Vasbinder
- Ames Laboratory and Chemistry Department, Iowa State University, Ames, Iowa 50011, USA
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46
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Cui W, Wayland BB. Superoxo, Peroxo, and Hydroperoxo Complexes Formed from Reactions of Rhodium Porphyrins with Dioxygen: Thermodynamics and Kinetics. J Am Chem Soc 2006; 128:10350-1. [PMID: 16895384 DOI: 10.1021/ja0628755] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rhodium(II) porphyrin complexes react with dioxygen to form terminal superoxo and bridged mu-peroxo complexes. Equilibrium constants for dioxygen complex formation with rhodium(II) tetramesitylporphyrin ((TMP)Rh*) and a m-xylyl-tethered dirhodium(II) diporphyrin complex (*Rh(m-xylyl)Rh*) are reported. (TMP)Rh-H reacts with oxygen to form a transient hydroperoxy complex ((TMP)Rh-OOH), which reacts on to form the rhodium(II) complex ((TMP)Rh*) and water. Kinetic studies for reactions of (TMP)Rh-H with O2 suggest a near concerted addition of dioxygen to the (TMP)Rh-H unit. Reactivity studies for mixtures of H2/O2 and CH4/O2 with the dirhodium(II) complex (*Rh(m-xylyl)Rh*) are reported.
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Affiliation(s)
- Weihong Cui
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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47
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48
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Konnick MM, Gandhi BA, Guzei IA, Stahl SS. Reaction of Molecular Oxygen with a PdII– Hydride To Produce a PdII–Hydroperoxide: Acid Catalysis and Implications for Pd-Catalyzed Aerobic Oxidation Reactions. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200600532] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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49
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Konnick MM, Gandhi BA, Guzei IA, Stahl SS. Reaction of Molecular Oxygen with a PdII– Hydride To Produce a PdII–Hydroperoxide: Acid Catalysis and Implications for Pd-Catalyzed Aerobic Oxidation Reactions. Angew Chem Int Ed Engl 2006; 45:2904-7. [PMID: 16568486 DOI: 10.1002/anie.200600532] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Michael M Konnick
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
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50
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Abstract
In aqueous solutions, as in organic solvents, rhodium hydrides display the chemistry of one of the three limiting forms, i.e. {Rh(I)+ H+}, {Rh(II)+ H.}, and {Rh(III)+ H-}. A number of intermediates and oxidation states have been generated and explored in kinetic and mechanistic studies. Monomeric macrocyclic rhodium(II) complexes, such as L(H2O)Rh2+ (L = L1 = [14]aneN4, or L2 = meso-Me6[14]aneN4) can be generated from the hydride precursors by photochemical means or in reactions with hydrogen atom abstracting agents. These rhodium(II) complexes are oxidized rapidly with alkyl hydroperoxides to give alkylrhodium(III) complexes. Reactions of Rh(II) with organic and inorganic radicals and with molecular oxygen are fast and produce long-lived intermediates, such as alkyl, superoxo and hydroperoxo complexes, all of which display rich and complex chemistry of their own. In alkaline solutions of rhodium hydrides, the existence of Rh(I) complexes is implied by rapid hydrogen exchange between the hydride and solvent water. The acidity of the hydrides is too low, however, to allow the build-up of observable quantities of Rh(I). Deuterium kinetic isotope effects for hydride transfer to a macrocyclic Cr(v) complex are comparable to those for hydrogen atom transfer to various substrates.
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Affiliation(s)
- Andreja Bakac
- Ames Laboratory, Iowa State University, Ames, IA 50011, USA
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