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Lee D, Molani F, Choe MS, Lee HS, Wee KR, Hwang S, Kim CH, Cho AE, Son HJ. Photocatalytic Conversion of CO 2 to Formate/CO by an (η 6- para-Cymene)Ru(II) Half-Metallocene Catalyst: Influence of Additives and TiO 2 Immobilization on the Catalytic Mechanism and Product Selectivity. Inorg Chem 2024; 63:11506-11522. [PMID: 38856726 DOI: 10.1021/acs.inorgchem.3c03879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
The catalytic efficacy of the monobipyridyl (η6-para-Cymene)Ru(II) half-metallocene, [(p-Cym)Ru(bpy)Cl]+ was evaluated in both mixed homogeneous (dye + catalyst) and heterogeneous hybrid systems (dye/TiO2/Catalyst) for photochemical CO2 reduction. A series of homogeneous photolysis experiments revealed that the (p-Cym)Ru(II) catalyst engages in two competitive routes for CO2 reduction (CO2 to formate conversion via RuII-hydride vs CO2 to CO conversion through a RuII-COOH intermediate). The conversion activity and product selectivity were notably impacted by the pKa value and the concentration of the proton source added. When a more acidic TEOA additive was introduced, the half-metallocene Ru(II) catalyst leaned toward producing formate through the RuII-H mechanism, with a formate selectivity of 86%. On the other hand, in homogeneous catalysis with TFE additive, the CO2-to-formate conversion through RuII-H was less effective, yielding a more efficient CO2-to-CO conversion with a selectivity of >80% (TONformate of 140 and TONCO of 626 over 48 h). The preference between the two pathways was elucidated through an electrochemical mechanistic study, monitoring the fate of the metal-hydride intermediate. Compared to the homogeneous system, the TiO2-heterogenized (p-Cym)Ru(II) catalyst demonstrated enhanced and enduring performance, attaining TONs of 1000 for CO2-to-CO and 665 for CO2-to-formate.
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Affiliation(s)
- Daehan Lee
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Republic of Korea
| | - Farzad Molani
- Department of Bioinformatics, Korea University, Sejong 30019, Republic of Korea
| | - Min Su Choe
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Republic of Korea
| | - Hyun Seok Lee
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Republic of Korea
| | - Kyung-Ryang Wee
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Republic of Korea
| | - Seongpil Hwang
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Republic of Korea
| | - Chul Hoon Kim
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Republic of Korea
| | - Art E Cho
- Department of Bioinformatics, Korea University, Sejong 30019, Republic of Korea
| | - Ho-Jin Son
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Republic of Korea
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2
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Chang ET, Green DB, Brereton KR. Microwave-assisted synthesis of pentamethylcyclopentadienyl iridium dihalide dimers. Polyhedron 2022. [DOI: 10.1016/j.poly.2022.116089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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3
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Henke WC, Stiel JP, Day VW, Blakemore JD. Evidence for Charge Delocalization in Diazafluorene Ligands Supporting Low-Valent [Cp*Rh] Complexes. Chemistry 2022; 28:e202103970. [PMID: 35006643 PMCID: PMC8857064 DOI: 10.1002/chem.202103970] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Indexed: 12/14/2022]
Abstract
Ligands based upon the 4,5-diazafluorene core are an important class of emerging ligands in organometallic chemistry, but the structure and electronic properties of these ligands have received less attention than they deserve. Here, we show that 9,9'-dimethyl-4,5-diazafluorene (Me2 daf) can stabilize low-valent complexes through charge delocalization into its conjugated π-system. Using a new platform of [Cp*Rh] complexes with three accessible formal oxidation states (+III, +II, and +I), we show that the methylation in Me2 daf is protective, blocking Brønsted acid-base chemistry commonly encountered with other daf-based ligands. Electronic absorption spectroscopy and single-crystal X-ray diffraction analysis of a family of eleven new compounds, including the unusual Cp*Rh(Me2 daf), reveal features consistent with charge delocalization driven by π-backbonding into the LUMO of Me2 daf, reminiscent of behavior displayed by the workhorse 2,2'-bipyridyl ligand. Taken together with spectrochemical data demonstrating clean conversion between oxidation states, our findings show that 9,9'-dialkylated daf-type ligands are promising building blocks for applications in reductive chemistry and catalysis.
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Affiliation(s)
- Wade C. Henke
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Jonah P. Stiel
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Victor W. Day
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - James D. Blakemore
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
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4
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Lee D, Choi S, Choe MS, Kim SY, Park K, Kim CH, Son HJ, Kang SO. Photochemical CO 2-to-Formate/CO Conversion Catalyzed by Half-Metallocene Ir(III) Catalyst and Its Mechanistic Investigation. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Daehan Lee
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Korea
| | - Sunghan Choi
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Korea
| | - Min Su Choe
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Korea
| | - So-Yoen Kim
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Korea
| | - Kyutai Park
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Korea
| | - Chul Hoon Kim
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Korea
| | - Ho-Jin Son
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Korea
| | - Sang Ook Kang
- Department of Advanced Materials Chemistry, Korea University, Sejong 30019, Korea
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5
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Schreier MR, Pfund B, Guo X, Wenger OS. Photo-triggered hydrogen atom transfer from an iridium hydride complex to unactivated olefins. Chem Sci 2020; 11:8582-8594. [PMID: 34123118 PMCID: PMC8163408 DOI: 10.1039/d0sc01820a] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 07/27/2020] [Indexed: 12/18/2022] Open
Abstract
Many photoactive metal complexes can act as electron donors or acceptors upon photoexcitation, but hydrogen atom transfer (HAT) reactivity is rare. We discovered that a typical representative of a widely used class of iridium hydride complexes acts as an H-atom donor to unactivated olefins upon irradiation at 470 nm in the presence of tertiary alkyl amines as sacrificial electron and proton sources. The catalytic hydrogenation of simple olefins served as a test ground to establish this new photo-reactivity of iridium hydrides. Substrates that are very difficult to activate by photoinduced electron transfer were readily hydrogenated, and structure-reactivity relationships established with 12 different olefins are in line with typical HAT reactivity, reflecting the relative stabilities of radical intermediates formed by HAT. Radical clock, H/D isotope labeling, and transient absorption experiments provide further mechanistic insight and corroborate the interpretation of the overall reactivity in terms of photo-triggered hydrogen atom transfer (photo-HAT). The catalytically active species is identified as an Ir(ii) hydride with an IrII-H bond dissociation free energy around 44 kcal mol-1, which is formed after reductive 3MLCT excited-state quenching of the corresponding Ir(iii) hydride, i.e. the actual HAT step occurs on the ground-state potential energy surface. The photo-HAT reactivity presented here represents a conceptually novel approach to photocatalysis with metal complexes, which is fundamentally different from the many prior studies relying on photoinduced electron transfer.
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Affiliation(s)
- Mirjam R Schreier
- Department of Chemistry, University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
| | - Björn Pfund
- Department of Chemistry, University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
| | - Xingwei Guo
- Department of Chemistry, University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
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6
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Stratakes BM, Miller AJM. H 2 Evolution at an Electrochemical “Underpotential” with an Iridium-Based Molecular Photoelectrocatalyst. ACS Catal 2020. [DOI: 10.1021/acscatal.0c02265] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Bethany M. Stratakes
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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7
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Barrett SM, Stratakes BM, Chambers MB, Kurtz DA, Pitman CL, Dempsey JL, Miller AJM. Mechanistic basis for tuning iridium hydride photochemistry from H 2 evolution to hydride transfer hydrodechlorination. Chem Sci 2020; 11:6442-6449. [PMID: 34094109 PMCID: PMC8152724 DOI: 10.1039/d0sc00422g] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 03/05/2020] [Indexed: 01/01/2023] Open
Abstract
The photochemistry of metal hydride complexes is dominated by H2 evolution, limiting access to reductive transformations based on photochemical hydride transfer. In this article, the innate H2 evolution photochemistry of the iridium hydride complexes [Cp*Ir(bpy-OMe)H]+ (1, bpy-OMe = 4,4'-dimethoxy-2,2'-bipyridine) and [Cp*Ir(bpy)H]+ (2, bpy = 2,2'-bipyridine) is diverted towards photochemical hydrodechlorination. Net hydride transfer from 1 and 2 to dichloromethane produces chloromethane with high selectivity and exceptional photochemical quantum yield (Φ ≤ 1.3). Thermodynamic and kinetic mechanistic studies are consistent with a non-radical-chain reaction sequence initiated by "self-quenching" electron transfer between excited state and ground state hydride complexes, followed by proton-coupled electron transfer (PCET) hydrodechlorination that outcompetes H-H coupling. This unique photochemical mechanism provides a new hope for the development of light-driven hydride transfer reactions.
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Affiliation(s)
- Seth M Barrett
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
- Department of Chemistry, Muskingum University New Concord OH 43762-1118 USA
| | - Bethany M Stratakes
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
| | - Matthew B Chambers
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
- Department of Chemistry, Louisiana State University Baton Rouge LA 70803-1804 USA
| | - Daniel A Kurtz
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
| | - Catherine L Pitman
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
| | - Alexander J M Miller
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
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8
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Brereton KR, Jadrich CN, Stratakes BM, Miller AJM. Thermodynamic Hydricity across Solvents: Subtle Electronic Effects and Striking Ligation Effects in Iridium Hydrides. Organometallics 2019. [DOI: 10.1021/acs.organomet.9b00278] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Kelsey R. Brereton
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Caleb N. Jadrich
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Bethany M. Stratakes
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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9
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Moore WNG, Henke WC, Lionetti D, Day VW, Blakemore JD. Single-Electron Redox Chemistry on the [Cp*Rh] Platform Enabled by a Nitrated Bipyridyl Ligand. Molecules 2018; 23:E2857. [PMID: 30400193 PMCID: PMC6278249 DOI: 10.3390/molecules23112857] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 10/23/2018] [Accepted: 11/01/2018] [Indexed: 11/16/2022] Open
Abstract
[Cp*Rh] complexes (Cp* = pentamethylcyclopentadienyl) are attracting renewed interest in coordination chemistry and catalysis, but these useful compounds often undergo net two-electron redox cycling that precludes observation of individual one-electron reduction events. Here, we show that a [Cp*Rh] complex bearing the 4,4'-dinitro-2,2'-bipyridyl ligand (dnbpy) (3) can access a distinctive manifold of five oxidation states in organic electrolytes, contrasting with prior work that found no accessible reductions in aqueous electrolyte. These states are readily generated from a newly isolated and fully characterized rhodium(III) precursor complex 3, formulated as [Cp*Rh(dnbpy)Cl]PF₆. Single-crystal X-ray diffraction (XRD) data, previously unavailable for the dnbpy ligand bound to the [Cp*Rh] platform, confirm the presence of both [η⁵-Cp*] and [κ²-dnbpy]. Four individual one-electron reductions of 3 are observed, contrasting sharply with the single two-electron reductions of other [Cp*Rh] complexes. Chemical preparation and the study of the singly reduced species with electronic absorption and electron paramagnetic resonance spectroscopies indicate that the first reduction is predominantly centered on the dnbpy ligand. Comparative cyclic voltammetry studies with [NBu₄][PF₆] and [NBu₄][Cl] as supporting electrolytes indicate that the chloride ligand can be lost from 3 by ligand exchange upon reduction. Spectroelectrochemical studies with ultraviolet (UV)-visible detection reveal isosbestic behavior, confirming the clean interconversion of the reduced forms of 3 inferred from the voltammetry with [NBu₄][PF₆] as supporting electrolyte. Electrochemical reduction in the presence of triethylammonium results in an irreversible response, but does not give rise to catalytic H₂ evolution, contrasting with the reactivity patterns observed in [Cp*Rh] complexes bearing bipyridyl ligands with less electron-withdrawing substituents.
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Affiliation(s)
- William N G Moore
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.
| | - Wade C Henke
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.
| | - Davide Lionetti
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.
| | - Victor W Day
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.
| | - James D Blakemore
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.
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10
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Kobayashi K, Koizumi TA, Ghosh D, Kajiwara T, Kitagawa S, Tanaka K. Electrochemical behavior of a Rh(pentamethylcyclopentadienyl) complex bearing an NAD +/NADH-functionalized ligand. Dalton Trans 2018. [PMID: 29537007 DOI: 10.1039/c7dt04594h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A RhCp* (Cp* = pentamethylcyclopentadienyl) complex bearing an NAD+/NADH-functionalized ligand, [RhCp*(pbn)Cl]Cl ([1]Cl, pbn = (2-(2-pyridyl)benzo[b]-1,5-naphthyridine)), was synthesized. The cyclic voltammogram of [1]Cl in CH3CN shows two reversible redox waves at E1/2 = -0.58 and -1.53 V (vs. the saturated calomel electrode (SCE)), which correspond to the RhIII/RhI and pbn/pbn˙- redox couples, respectively. The addition of acetic acid to the solution afforded the proton-coupled two-electron reduction of [1]Cl at -0.62 V, from which [RhCp*(pbnHH)Cl]+ was selectively generated, probably via a hydride transfer from a RhIII-hydride intermediate to the pbn ligand. Complex [1]Cl is stable under acidic conditions, whereas a methyl proton of the Cp* moiety dissociates under basic conditions. The resulting anionic methylene group attacks the para carbon of the free pyridine of pbn, accompanied by protonation of the nitrogen atom of the ligand. As a result, treatment of [1]Cl with a base produces selectively the cyclic complex [1CH]Cl, which bears a reduced pbn framework (pbnCH). [1CH]Cl forms 1 : 1 adducts with PhCOO-via hydrogen bonding. A similar adduct, formed by a Ru-pbnHH scaffold and RCOO- (R = CH3, C6H5), has been reported to react with CO2 to produce HCOO- under concomitant regeneration of Ru-pbn. The adduct of [1CH]Cl with PhCOO-, however, lacks such hydride-donor ability, due to a steric barrier in the molecular structure of [1CH]Cl, which hampers the hydride transfer.
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Affiliation(s)
- Katsuaki Kobayashi
- Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan.
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11
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Castillo CE, Stoll T, Sandroni M, Gueret R, Fortage J, Kayanuma M, Daniel C, Odobel F, Deronzier A, Collomb MN. Electrochemical Generation and Spectroscopic Characterization of the Key Rhodium(III) Hydride Intermediates of Rhodium Poly(bipyridyl) H2-Evolving Catalysts. Inorg Chem 2018; 57:11225-11239. [PMID: 30129361 DOI: 10.1021/acs.inorgchem.8b01811] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
| | - Thibaut Stoll
- Univ. Grenoble Alpes, CNRS, DCM, F-38000 Grenoble, France
| | - Martina Sandroni
- Univ. Grenoble Alpes, CNRS, DCM, F-38000 Grenoble, France
- Univ. Grenoble Alpes, CEA, CNRS, INAC-SyMMES 38000 Grenoble, France
| | - Robin Gueret
- Univ. Grenoble Alpes, CNRS, DCM, F-38000 Grenoble, France
| | - Jérôme Fortage
- Univ. Grenoble Alpes, CNRS, DCM, F-38000 Grenoble, France
| | - Megumi Kayanuma
- Laboratoire de Chimie Quantique, Institut de Chimie Strasbourg, UMR 7177 CNRS/UdS, 1-4 Rue Blaise pascal, 67037 Strasbourg, France
| | - Chantal Daniel
- Laboratoire de Chimie Quantique, Institut de Chimie Strasbourg, UMR 7177 CNRS/UdS, 1-4 Rue Blaise pascal, 67037 Strasbourg, France
| | - Fabrice Odobel
- CEISAM, Université de Nantes, CNRS, 2 rue de la Houssinière, 44322 Nantes Cedex 3, France
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12
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Henke WC, Lionetti D, Moore WNG, Hopkins JA, Day VW, Blakemore JD. Ligand Substituents Govern the Efficiency and Mechanistic Path of Hydrogen Production with [Cp*Rh] Catalysts. CHEMSUSCHEM 2017; 10:4589-4598. [PMID: 29024563 DOI: 10.1002/cssc.201701416] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 09/01/2017] [Indexed: 06/07/2023]
Abstract
We demonstrate that [Cp*Rh] complexes bearing substituted 2,2'-bipyridyl ligands are effective hydrogen evolution catalysts (Cp*=η5 -pentamethylcyclopentadienyl). Disubstitution (at the 4 and 4' positions) of the bipyridyl ligand (namely -tBu, -H, and -CF3 ) modulates the catalytic overpotential, in part due to involvement of the reduced ligand character in formally rhodium(I) intermediates. These reduced species are synthesized and isolated here; protonation results in formation of complexes bearing the unusual η4 -pentamethylcyclopentadiene ligand, and the properties of these protonated intermediates further govern the catalytic performance. Electrochemical studies suggest that multiple mechanistic pathways are accessible, and that the operative pathway depends on the applied potential and solution conditions. Taken together, these results suggest synergy in metal-ligand cooperation that modulates the mechanisms of fuel-forming catalysis with organometallic compounds bearing multiple non-innocent ligands.
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Affiliation(s)
- Wade C Henke
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA
| | - Davide Lionetti
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA
| | - William N G Moore
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA
| | - Julie A Hopkins
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA
| | - Victor W Day
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA
| | - James D Blakemore
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA
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Lionetti D, Day VW, Blakemore JD. Synthesis and Electrochemical Properties of Half-Sandwich Rhodium and Iridium Methyl Complexes. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00136] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Davide Lionetti
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
| | - Victor W. Day
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
| | - James D. Blakemore
- Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
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14
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Brereton KR, Pitman CL, Cundari TR, Miller AJM. Solvent-Dependent Thermochemistry of an Iridium/Ruthenium H2 Evolution Catalyst. Inorg Chem 2016; 55:12042-12051. [DOI: 10.1021/acs.inorgchem.6b02223] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Kelsey R. Brereton
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Catherine L. Pitman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Thomas R. Cundari
- Department
of Chemistry and CASCaM, University of North Texas, Denton, Texas 76203, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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15
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Chambers MB, Kurtz DA, Pitman CL, Brennaman MK, Miller AJM. Efficient Photochemical Dihydrogen Generation Initiated by a Bimetallic Self-Quenching Mechanism. J Am Chem Soc 2016; 138:13509-13512. [DOI: 10.1021/jacs.6b08701] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew B. Chambers
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Daniel A. Kurtz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Catherine L. Pitman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - M. Kyle Brennaman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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16
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Abstract
Efficient generation of hydrogen from renewable resources requires development of catalysts that avoid deep wells and high barriers. Information about the energy landscape for H2 production can be obtained by chemical characterization of catalytic intermediates, but few have been observed to date. We have isolated and characterized a key intermediate in 2e(-) + 2H(+) → H2 catalysis. This intermediate, obtained by treatment of Cp*Rh(bpy) (Cp*, η(5)-pentamethylcyclopentadienyl; bpy, κ(2)-2,2'-bipyridyl) with acid, is not a hydride species but rather, bears [η(4)-Cp*H] as a ligand. Delivery of a second proton to this species leads to evolution of H2 and reformation of η(5)-Cp* bound to rhodium(III). With suitable choices of acids and bases, the Cp*Rh(bpy) complex catalyzes facile and reversible interconversion of H(+) and H2.
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17
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Abstract
Transition metal hydride complexes are usually amphoteric, not only acting as hydride donors, but also as Brønsted-Lowry acids. A simple additive ligand acidity constant equation (LAC for short) allows the estimation of the acid dissociation constant Ka(LAC) of diamagnetic transition metal hydride and dihydrogen complexes. It is remarkably successful in systematizing diverse reports of over 450 reactions of acids with metal complexes and bases with metal hydrides and dihydrogen complexes, including catalytic cycles where these reactions are proposed or observed. There are links between pKa(LAC) and pKa(THF), pKa(DCM), pKa(MeCN) for neutral and cationic acids. For the groups from chromium to nickel, tables are provided that order the acidity of metal hydride and dihydrogen complexes from most acidic (pKa(LAC) -18) to least acidic (pKa(LAC) 50). Figures are constructed showing metal acids above the solvent pKa scales and organic acids below to summarize a large amount of information. Acid-base features are analyzed for catalysts from chromium to gold for ionic hydrogenations, bifunctional catalysts for hydrogen oxidation and evolution electrocatalysis, H/D exchange, olefin hydrogenation and isomerization, hydrogenation of ketones, aldehydes, imines, and carbon dioxide, hydrogenases and their model complexes, and palladium catalysts with hydride intermediates.
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Affiliation(s)
- Robert H Morris
- Department of Chemistry, University of Toronto , 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada
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18
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Gupta A, Blakemore JD, Brunschwig BS, Gray HB. Immobilization and electrochemical properties of ruthenium and iridium complexes on carbon electrodes. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:094002. [PMID: 26871865 DOI: 10.1088/0953-8984/28/9/094002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report the synthesis and surface immobilization of two new pyrene-appended molecular metal complexes: a ruthenium tris(bipyridyl) complex (1) and a bipyridyl complex of [Cp*Ir] (2) (Cp* = pentamethylcyclopentadienyl). X-ray photoelectron spectroscopy confirmed successful immobilization on high surface area carbon electrodes, with the expected elemental ratios for the desired compounds. Electrochemical data collected in acetonitrile solution revealed a reversible reduction of 1 near -1.4 V, and reduction of 2 near -0.75 V. The noncovalent immobilization, driven by association of the appended pyrene groups with the surface, was sufficiently stable to enable studies of the molecular electrochemistry. Electroactive surface coverage of 1 was diminished by only 27% over three hours soaking in electrolyte solution as measured by cyclic voltammetry. The electrochemical response of 2 resembled its soluble analogues, and suggested that ligand exchange occurred on the surface. Together, the results demonstrate that noncovalent immobilization routes are suitable for obtaining fundamental understanding of immobilized metal complexes and their reductive electrochemical properties.
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Affiliation(s)
- Ayush Gupta
- Beckman Institute and Division of Chemistry and Chemical Engineering, California Institute of Technology, Mail Code 139-74, Pasadena, CA 91125, USA
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19
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Pitman C, Brereton KR, Miller AJM. Aqueous Hydricity of Late Metal Catalysts as a Continuum Tuned by Ligands and the Medium. J Am Chem Soc 2016; 138:2252-60. [PMID: 26777267 PMCID: PMC4768292 DOI: 10.1021/jacs.5b12363] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Indexed: 12/21/2022]
Abstract
Aqueous hydride transfer is a fundamental step in emerging alternative energy transformations such as H2 evolution and CO2 reduction. "Hydricity," the hydride donor ability of a species, is a key metric for understanding transition metal hydride reactivity, but comprehensive studies of aqueous hydricity are scarce. An extensive and self-consistent aqueous hydricity scale is constructed for a family of Ru and Ir hydrides that are key intermediates in aqueous catalysis. A reference hydricity is determined using redox potentiometry and spectrophotometric titration for a particularly water-soluble species. Then, relative hydricity values for a range of species are measured using hydride transfer equilibria, taking advantage of expedient new synthetic procedures for Ru and Ir hydrides. This large collection of hydricity values provides the most comprehensive picture so far of how ligands impact hydricity in water. Strikingly, we also find that hydricity can be viewed as a continuum in water: the free energy of hydride transfer changes with pH, buffer composition, and salts present in solution.
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Affiliation(s)
- Catherine
L. Pitman
- Department of Chemistry, University of
North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Kelsey R. Brereton
- Department of Chemistry, University of
North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of
North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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20
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Barrett SM, Slattery SA, Miller AJM. Photochemical Formic Acid Dehydrogenation by Iridium Complexes: Understanding Mechanism and Overcoming Deactivation. ACS Catal 2015. [DOI: 10.1021/acscatal.5b01995] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Seth M. Barrett
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Samuel A. Slattery
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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21
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Sypaseuth FD, Matlachowski C, Weber M, Schwalbe M, Tzschucke CC. Electrocatalytic carbon dioxide reduction by using cationic pentamethylcyclopentadienyl-iridium complexes with unsymmetrically substituted bipyridine ligands. Chemistry 2015; 21:6564-71. [PMID: 25756194 DOI: 10.1002/chem.201404367] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 01/25/2015] [Indexed: 11/05/2022]
Abstract
Eight [Ir(bpy)Cp*Cl](+) -type complexes (bpy= bipyridine, Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) containing differently substituted bipyridine ligands were synthesized and characterized. Cyclic voltammetry (CV) of the complexes in Ar-saturated acetonitrile solutions showed that the redox behavior of the complexes could be fine tuned by the electronic properties of the substituted bipyridine ligands. Further CV in CO2 -saturated MeCN/H2 O (9:1, v/v) solutions showed catalytic currents for CO2 reduction. In controlled potential electrolysis experiments (MeCN/MeOH (1:1, v/v), Eapp =-1.80 V vs Ag/AgCl), all of the complexes showed moderate activity in the electrocatalytic reduction of CO2 with good stability over at least 15 hours. This electrocatalytic process was selective toward formic acid, with only traces of dihydrogen or carbon monoxide and occasionally formaldehyde as byproducts. However, the turnover frequencies and current efficiencies were quite low. No direct correlation between the redox potentials of the complexes and their catalytic activity was observed.
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Affiliation(s)
- Fanni D Sypaseuth
- Institut für Chemie und Biochemie, Organische Chemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin (Germany)
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22
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McSkimming A, Chan B, Bhadbhade MM, Ball GE, Colbran SB. Bio-Inspired Transition Metal-Organic Hydride Conjugates for Catalysis of Transfer Hydrogenation: Experiment and Theory. Chemistry 2014; 21:2821-34. [DOI: 10.1002/chem.201405129] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Indexed: 11/07/2022]
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23
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Barrett SM, Pitman CL, Walden AG, Miller AJM. Photoswitchable Hydride Transfer from Iridium to 1-Methylnicotinamide Rationalized by Thermochemical Cycles. J Am Chem Soc 2014; 136:14718-21. [DOI: 10.1021/ja508762g] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Seth M. Barrett
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Catherine L. Pitman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Andrew G. Walden
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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24
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Nakai H, Jeong K, Matsumoto T, Ogo S. Catalytic C–F Bond Hydrogenolysis of Fluoroaromatics by [(η5-C5Me5)RhI(2,2′-bipyridine)]. Organometallics 2014. [DOI: 10.1021/om500647h] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Hidetaka Nakai
- Department
of Chemistry and Biochemistry, Graduate
School of Engineering, and ‡International Institute for Carbon-Neutral
Energy Research (WPI-I2CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Kihun Jeong
- Department
of Chemistry and Biochemistry, Graduate
School of Engineering, and ‡International Institute for Carbon-Neutral
Energy Research (WPI-I2CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Takahiro Matsumoto
- Department
of Chemistry and Biochemistry, Graduate
School of Engineering, and ‡International Institute for Carbon-Neutral
Energy Research (WPI-I2CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Seiji Ogo
- Department
of Chemistry and Biochemistry, Graduate
School of Engineering, and ‡International Institute for Carbon-Neutral
Energy Research (WPI-I2CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
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25
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Pitman CL, Miller AJM. Molecular Photoelectrocatalysts for Visible Light-Driven Hydrogen Evolution from Neutral Water. ACS Catal 2014. [DOI: 10.1021/cs500441f] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Catherine L. Pitman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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26
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Lattimer JRC, Blakemore JD, Sattler W, Gul S, Chatterjee R, Yachandra VK, Yano J, Brunschwig BS, Lewis NS, Gray HB. Assembly, characterization, and electrochemical properties of immobilized metal bipyridyl complexes on silicon(111) surfaces. Dalton Trans 2014; 43:15004-12. [DOI: 10.1039/c4dt01149j] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Morris RH. Estimating the Acidity of Transition Metal Hydride and Dihydrogen Complexes by Adding Ligand Acidity Constants. J Am Chem Soc 2014; 136:1948-59. [DOI: 10.1021/ja410718r] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Robert H. Morris
- Department of Chemistry, University of Toronto, 80 Saint
George Street, Toronto, Ontario M5S 3H6, Canada
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28
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Chevalley A, Cherrier MV, Fontecilla-Camps JC, Ghasemi M, Salmain M. Artificial metalloenzymes derived from bovine β-lactoglobulin for the asymmetric transfer hydrogenation of an aryl ketone – synthesis, characterization and catalytic activity. Dalton Trans 2014; 43:5482-9. [DOI: 10.1039/c3dt53253d] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protein hybrids resulting from the supramolecular anchoring to bovine β-lactoglobulin of fatty acid-derived Rh(iii) diimine complexes catalysed the asymmetric transfer hydrogenation of trifluoroacetophenone with up to 32% ee.
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Affiliation(s)
- Alice Chevalley
- Chimie ParisTech (Ecole Nationale Supérieure de Chimie de Paris)
- Laboratoire Charles Friedel
- 75231 Paris cedex 05, France
- CNRS
- UMR 7223
| | - Mickael V. Cherrier
- Metalloproteins Unit
- Institut de Biologie Structurale Jean-Pierre Ebel
- UMR 5075
- CEA
- CNRS
| | | | - Mahsa Ghasemi
- Chimie ParisTech (Ecole Nationale Supérieure de Chimie de Paris)
- Laboratoire Charles Friedel
- 75231 Paris cedex 05, France
- CNRS
- UMR 7223
| | - Michèle Salmain
- Chimie ParisTech (Ecole Nationale Supérieure de Chimie de Paris)
- Laboratoire Charles Friedel
- 75231 Paris cedex 05, France
- CNRS
- UMR 7223
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29
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McSkimming A, Bhadbhade MM, Colbran SB. Bio-Inspired Catalytic Imine Reduction by Rhodium Complexes with Tethered Hantzsch Pyridinium Groups: Evidence for Direct Hydride Transfer from Dihydropyridine to Metal-Activated Substrate. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201210086] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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30
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McSkimming A, Bhadbhade MM, Colbran SB. Bio-Inspired Catalytic Imine Reduction by Rhodium Complexes with Tethered Hantzsch Pyridinium Groups: Evidence for Direct Hydride Transfer from Dihydropyridine to Metal-Activated Substrate. Angew Chem Int Ed Engl 2013; 52:3411-6. [DOI: 10.1002/anie.201210086] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Indexed: 11/06/2022]
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31
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Yao SA, Ruther RE, Zhang L, Franking RA, Hamers RJ, Berry JF. Covalent Attachment of Catalyst Molecules to Conductive Diamond: CO2 Reduction Using “Smart” Electrodes. J Am Chem Soc 2012; 134:15632-5. [DOI: 10.1021/ja304783j] [Citation(s) in RCA: 166] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Shu A. Yao
- Department
of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison,
Wisconsin 53706, United States
| | - Rose E. Ruther
- Department
of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison,
Wisconsin 53706, United States
| | - Linghong Zhang
- Department
of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison,
Wisconsin 53706, United States
| | - Ryan A. Franking
- Department
of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison,
Wisconsin 53706, United States
| | - Robert J. Hamers
- Department
of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison,
Wisconsin 53706, United States
| | - John F. Berry
- Department
of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison,
Wisconsin 53706, United States
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32
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Penner A, Braun T. Rhodium and Iridium Complexes with α‐Diketimine Ligands: Oxidative Addition of H
2
and O
2. Eur J Inorg Chem 2011. [DOI: 10.1002/ejic.201100135] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Anna Penner
- Humboldt‐Universität zu Berlin, Department of Chemistry, Brook‐Taylor‐Str. 2, 12489 Berlin, Germany, Fax: +49‐30‐2093‐6939
| | - Thomas Braun
- Humboldt‐Universität zu Berlin, Department of Chemistry, Brook‐Taylor‐Str. 2, 12489 Berlin, Germany, Fax: +49‐30‐2093‐6939
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33
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The 1,4-diazabutadiene/1,2-enediamido non-innocent ligand system in the formation of iridaheteroaromatic compounds: Spectroelectrochemistry and electronic structure. J Organomet Chem 2010. [DOI: 10.1016/j.jorganchem.2009.11.042] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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34
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Beyer B, Ulbricht C, Winter A, Hager MD, Hoogenboom R, Herzer N, Baumann SO, Kickelbick G, Görls H, Schubert US. Unexpected metal-mediated oxidation of hydroxymethyl groups to coordinated carboxylate groups by bis-cyclometalated iridium(iii) centers. NEW J CHEM 2010. [DOI: 10.1039/b9nj00785g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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35
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Fukuzumi S, Kobayashi T, Suenobu T. Efficient catalytic decomposition of formic acid for the selective generation of H2 and H/D exchange with a water-soluble rhodium complex in aqueous solution. CHEMSUSCHEM 2008; 1:827-834. [PMID: 18846597 DOI: 10.1002/cssc.200800147] [Citation(s) in RCA: 152] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Formic acid (HCOOH) decomposes efficiently to afford H2 and CO2 selectively in the presence of a catalytic amount of a water-soluble rhodium aqua complex, [Rh(III)(Cp*)(bpy)(H2O)]2+ (Cp*=pentamethylcyclopentadienyl, bpy=2,2'-bipyridine) in aqueous solution at 298 K. No CO was produced in this catalytic decomposition of HCOOH. The decomposition rate reached a maximum value at pH 3.8. No deterioration of the catalyst was observed during the catalytic decomposition of HCOOH, and the catalytic activity remained the same for the repeated addition of HCOOH. The rhodium-hydride complex was detected as the catalytic active species that undergoes efficient H/D exchange with water. When the catalytic decomposition of HCOOH was performed in D2O, D2 was produced selectively. Such an efficient H/D exchange and the observation of a deuterium kinetic isotope effect in the catalytic decomposition of DCOOH in H2O provide valuable mechanistic insight into this efficient and selective decomposition process.
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Affiliation(s)
- Shunichi Fukuzumi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST (Japan) Science and Technology Agency (JST), 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
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36
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Canivet J, Süss-Fink G, Štěpnička P. Water-Soluble Phenanthroline Complexes of Rhodium, Iridium and Ruthenium for the Regeneration of NADH in the Enzymatic Reduction of Ketones. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200700505] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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37
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Govindaswamy P, Canivet J, Therrien B, Süss-Fink G, Štěpnička P, Ludvík J. Mono and dinuclear rhodium, iridium and ruthenium complexes containing chelating 2,2′-bipyrimidine ligands: Synthesis, molecular structure, electrochemistry and catalytic properties. J Organomet Chem 2007. [DOI: 10.1016/j.jorganchem.2007.04.048] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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38
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Ogo S, Kabe R, Hayashi H, Harada R, Fukuzumi S. Mechanistic investigation of CO2 hydrogenation by Ru(ii) and Ir(iii) aqua complexes under acidic conditions: two catalytic systems differing in the nature of the rate determining step. Dalton Trans 2006:4657-63. [PMID: 17028673 DOI: 10.1039/b607993h] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ruthenium aqua complexes [(eta(6)-C(6)Me(6))Ru(II)(L)(OH(2))](2+) {L = bpy (1) and 4,4'-OMe-bpy (2), bpy = 2,2'-bipyridine, 4,4'-OMe-bpy = 4,4'-dimethoxy-2,2'-bipyridine} and iridium aqua complexes [Cp*Ir(III)(L)(OH(2))](2+) {Cp* = eta(5)-C(5)Me(5), L = bpy (5) and 4,4'-OMe-bpy (6)} act as catalysts for hydrogenation of CO(2) into HCOOH at pH 3.0 in H(2)O. The active hydride catalysts cannot be observed in the hydrogenation of CO(2) with the ruthenium complexes, whereas the active hydride catalysts, [Cp*Ir(III)(L)(H)](+) {L = bpy (7) and 4,4'-OMe-bpy (8)}, have successfully been isolated after the hydrogenation of CO(2) with the iridium complexes. The key to the success of the isolation of the active hydride catalysts is the change in the rate-determining step in the catalytic hydrogenation of CO(2) from the formation of the active hydride catalysts, [(eta(6)-C(6)Me(6))Ru(II)(L)(H)](+), to the reactions of [Cp*Ir(III)(L)(H)](+) with CO(2), as indicated by the kinetic studies.
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Affiliation(s)
- Seiji Ogo
- Center for Future Chemistry, Kyushu University, Nishi-ku, Fukuoka, 819-0395, Japan.
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39
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Gabrielsson A, van Leeuwen P, Kaim W. Acidic iridium hydrides: Implications for aerobic and Oppenauer oxidation of alcohols. Chem Commun (Camb) 2006:4926-7. [PMID: 17136249 DOI: 10.1039/b610857a] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
[Cp*Ir(H)(bpym)]+ and [Cp*Ir(H)(bpy)]+ are the first examples of iridium based catalysts for the aerobic oxidation of alcohols; the catalytic cycle proceeds via acidic hydrides. Deprotonation of the hydride leads to a highly oxygen sensitive Ir I species that regenerate the Ir III complexes upon oxidation with dioxygen.
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Affiliation(s)
- Anders Gabrielsson
- Institute für Anorganische Chemie, Universität Stuttgart, 70569, Stuttgart, Germany.
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40
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Baumann F, Kaim W, Denninger G, Kümmerer HJ, Fiedler J. Widely Separated Reduction Processes of abpy-Coupled Areneosmium(II) Reaction Centers (abpy = 2,2‘-Azobispyridine): Stabilization of the Radical Intermediate and of the Os0OsII State. Organometallics 2005. [DOI: 10.1021/om049085t] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | | | | | - Jan Fiedler
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, CZ-18223 Prague, Czech Republic
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41
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Berger S, Scheiring T, Fiedler J, Kaim W. Kopplung metallorganischer Reaktionszentren durch den nichtplanaren Br�ckenliganden 2, 3-Bis(2-pyridyl)pyrazin. Z Anorg Allg Chem 2004. [DOI: 10.1002/zaac.200400133] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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42
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Kaim W, Scheiring T, Weber M, Fiedler J. Die konjugative Verbr�ckung metallorganischer Reaktionszentren in Heterozweikernkomplexen [(OC)3ClRe(?-L)MCl(C5Me5)]+, M = Rh oder Ir - Spektroskopische Konsequenzen reduktiver Aktivierung. Z Anorg Allg Chem 2004. [DOI: 10.1002/zaac.200400174] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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43
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Frantz S, Weber M, Scheiring T, Fiedler J, Duboc C, Kaim W. Mechanism and product characterization from the electroreduction of heterodinuclear complexes [(C5Me5)ClM(μ-L)Re(CO)3X](PF6), M=Rh or Ir, L=2,2′-azobispyridine or 2,2′-azobis(5-chloropyrimidine), X=halide. Inorganica Chim Acta 2004. [DOI: 10.1016/j.ica.2004.02.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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44
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Berger S, Fiedler J, Reinhardt R, Kaim W. Metal vs Ligand Reduction in Complexes of Dipyrido[3,2-a:2‘,3‘-c]phenazine and Related Ligands with [(C5Me5)ClM]+(M = Rh or Ir): Evidence for Potential Rather Than Orbital Control in the Reductive Cleavage of the Metal−Chloride Bond. Inorg Chem 2004; 43:1530-8. [PMID: 14966991 DOI: 10.1021/ic0351388] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Complexes between the chlorometal(III) cations [(C5Me5)ClM]+, M = Rh or Ir, and the 1,10-phenanthroline-derived alpha-diimine (N--N) ligands dipyrido[3,2-a:2',3'-c]phenazine (dppz), 1,4,7,10-tetraazaphenanthrene (tap), or 1,10-phenanthroline-5,6-dione (pdo) were investigated by cyclic voltammetry, EPR, and UV-vis-NIR spectroelectrochemistry with respect to either ligand-based or metal-centered (and then chloride-dissociative) reduction. Two low-lying unoccupied molecular orbitals (MOs) are present in each of these three N wedge N ligands; however, their different energies and interface properties are responsible for different results. Metal-centered chloride-releasing reduction was observed for complexes of the DNA-intercalation ligands dppz and tap to yield compounds [(N--N)(C5Me5)M] in a two-electron step. The separation of alpha-diimine centered optical orbitals and phenazine-based redox orbitals is apparent from the EPR and UV-vis-NIR spectroelectrochemistry of [(dppz)(C5Me5)M](0/*-/2-). In contrast, the pdo complexes undergo a reversible one-electron reduction to yield o-semiquinone radical complexes [(pdo)(C5Me5)ClM]* before releasing the chloride after the second electron uptake. The fact that the dppz complexes undergo a Cl(-)-dissociative two-electron reduction despite the presence of a lowest lying pi* MO (b1(phz)) with very little overlap to the metal suggests that an unoccupied metal/chloride-based orbital is lower in energy. This assertion is confirmed both by the half-wave reduction potentials of the ligands (tap, -1.95 V; dppz, -1.60 V; pdo, -0.85 V) and by the typical reduction peak potentials of the complexes [(L)(C5Me5)ClM](PF6) (tap, -1.1 V; dppz, -1.3 V; pdo, -0.6 V; all values against Fc(+/0)).
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Affiliation(s)
- Sascha Berger
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany
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45
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Sieger M, Kaim W, Stufkens DJ, Snoeck TL, Stoll H, Zalis S. Reduced and excited states of the intermediates (α-diimine)(C5R5)Rh in hydride transfer catalysis schemes: EPR and resonance Raman spectroscopy, and comparative DFT calculations of Co, Rh and Ir analogues. Dalton Trans 2004:3815-21. [PMID: 15540123 DOI: 10.1039/b411892h] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The electronic structures of the highly air-sensitive intermediates (N[caret]N) (C(5)Me(5))Rh, (N[caret]N = 2,2'-bipyridine (bpy), 2,2'-bipyrimidine (bpym), 2,2'-bipyrazine (bpz) and 3,3'-bipyridazine (bpdz)) of hydride transfer catalysis schemes were studied through resonance Raman (rR) spectroscopy and through EPR of the reduced forms [(N[caret]N) (C(5)Me(5))Rh](.-). The rR results are compatible with a predominant MLCT character of the lowest excited states [ (N[caret]N) (C(5)Me(5))Rh]*, and the EPR spectra of the reduced states reveal the presence of anion radical ligands, (N[caret]N) (.-), coordinated by unusually electron rich rhodium(i) centres. The experimental results, including the assignments of electronic transitions, are supported by DFT calculations for the model compounds [(N[caret]N)(C(5)H(5))Rh](o)/(.-), (N[caret]N) = bpy or bpym. The calculations confirm a significant but not complete mixing of metal and ligand orbitals in the lowest unoccupied MO which still retains about 3/4 pi* (N[caret]N) character. DFT calculations on (bpy)(C(5)H(5))M and [(bpy)(C(5)H(5))ClM](+), M = Co, Rh, Ir, agree with the experimental results such as the differences between the homologues, especially the different LUMO characters of the precursor cations in the case of Co-->d(M)) and Rh or Ir (-->pi*(bpy)).
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Affiliation(s)
- Monika Sieger
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany.
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46
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Zális S, Sieger M, Greulich S, Stoll H, Kaim W. Replacement of 2,2'-bipyridine by 1,4-diazabutadiene acceptor ligands: why the bathochromic shift for [(N empty set N)IrCl(C5Me5)]+ complexes but the hypsochromic shift for (N empty set N)Ir(C5Me5)? Inorg Chem 2003; 42:5185-91. [PMID: 12924889 DOI: 10.1021/ic034464k] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Replacement of 2,2'-bipyridine (bpy) by substituted 1,4-diazabutadiene (R-DAB) alpha-diimine ligands N empty set N leads to a substantial hypsochromic shift of about 0.8 eV for the long-wavelength absorption band in compounds (N empty set N)Ir(C(5)Me(5)) but to a bathochromic absorption shift of about 0.4 eV for the complex ions [(N empty set N)IrCl(C(5)Me(5))](+). DFT calculations on model complexes based on experimental (R-DAB compounds) and geometry-optimized structures (bpy systems) reveal that the low-energy transitions of the cationic chloro complexes are largely of ligand-to-ligand charge-transfer character L'LCT (L = alpha-diimine, L' = Cl) whereas the neutral compounds exhibit pi --> pi transitions between the considerably mixed metal d(pi) and alpha-diimine pi orbitals. The much more pronounced metal-ligand orbital interaction for the R-DAB complexes causes the qualitatively different shifts on replacing the stronger basic bpy by the better pi-acceptors R-DAB. Only the LUMO of the neutral compounds is destabilized on replacement of bpy by R-DAB whereas the LUMO of [(N empty set N)IrCl(C(5)R'(5))](+) and both HOMOs are stabilized through this change.
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Affiliation(s)
- Stanislav Zális
- J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, CZ-18223 Prague, Czech Republic.
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47
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Kaim W, Reinhardt R, Greulich S, Fiedler J. Resolving the Two-Electron Process for the Couple [(C5Me5)M(N∧N)Cl]+/[(C5Me5)M(N∧N)] (M = Rh, Ir) into Two One-Electron Steps Using the 2,2‘-Azobis(pyridine) N∧N Ligand, Fast Scan Cyclovoltammetry, and Spectroelectrochemistry: Detection of Radicals instead of MII Intermediates. Organometallics 2003. [DOI: 10.1021/om020860j] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Wolfgang Kaim
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany
| | - Ralf Reinhardt
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany
| | - Stefan Greulich
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany
| | - Jan Fiedler
- J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, CZ-18223 Prague, Czech Republic
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Frantz S, Reinhardt R, Greulich S, Wanner M, Fiedler J, Duboc-Toia C, Kaim W. Multistep redox sequences of azopyridyl (L) bridged reaction centres in stable radical complex ions {(μ-L)[MCl(η5-C5Me5)]2}˙+, M = Rh or Ir: spectroelectrochemistry and high-frequency EPR spectroscopy. Dalton Trans 2003. [DOI: 10.1039/b305311c] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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49
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Wik BJ, Rømming C, Tilset M. Reversible heterolytic CH cleavage by intramolecular CH activation at diazabutadiene ligands at iridium. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1381-1169(02)00197-8] [Citation(s) in RCA: 21] [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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50
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Greulich S, Klein A, Knödler A, Kaim W. Qualitatively Different Reactivities of Hydride Reagents toward [(α-diimine)(η5-C5Me5)ClIr]+ Cations: Substitution, Electron Transfer (Reduction), or Stepwise Hydrogenation. Organometallics 2002. [DOI: 10.1021/om010529k] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Stefan Greulich
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany
| | - Axel Klein
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany
| | - Axel Knödler
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany
| | - Wolfgang Kaim
- Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany
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