1
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Xia Z, Xu L, Ma C, An Q, Bu C, Fan Y, Lu Y, Pan Y, Xie D, Liu Q, Wang S, Zou Y. Enhancing the Electrocatalytic Hydrogenation of Furfural via Anion-Induced Molecular Activation and Adsorption. J Am Chem Soc 2024; 146:24570-24579. [PMID: 39169610 DOI: 10.1021/jacs.4c07979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
The electrocatalytic hydrogenation (ECH) of furfural (FF) to furfuryl alcohol, which does not require additional hydrogen or high pressure, is a green and promising production route. In this study, we explore the effects of anions on FF ECH in two buffer electrolytes (KHCO3 and phosphate-buffered saline [PBS]). Anions influence the yield of furfuryl alcohol through molecular activation and adsorption. Molecular dynamics simulations show that bicarbonate is present in the first shell layer of the FF molecule and induces strong hydrogen bonding interactions. In contrast, hydrogen phosphate is present only in the second shell layer, resulting in weak hydrogen bonding interactions. Owing to the interfacial anions and hydrogen bonding, FF molecules exhibit strong flat adsorption on the electrode surface in the KHCO3 solution, while weak adsorption is observed in the PBS solution, as confirmed by operando synchrotron-radiation Fourier-transform infrared spectroscopy and in situ Raman spectroscopy. Density-functional theory calculations reveal that the overall anionic hydrogen bonding network promotes the activation of the carbonyl group in the FF molecule in KHCO3, whereas electrophilic activity is inhibited in PBS. Consequently, FF ECH demonstrates much faster kinetics in KHCO3, while it exhibits sluggish ECH kinetics and a severe hydrogen evolution reaction in PBS. This work introduces a new strategy to optimize the catalytic process through the modulation of the microenvironment.
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Affiliation(s)
- Zhongcheng Xia
- State Key Laboratory of Chem/Bio-Sensing and Chemometrics, Provincial Hunan Key Laboratory for Graphene Materials and Devices, College of Chemistry and Chemical Engineering, the National Supercomputer Centers in Changsha, Hunan University, Changsha 410082, P. R. China
- Greater Bay Area Institute for Innovation, Hunan University, Guangzhou 511340, P. R. China
| | - Leitao Xu
- State Key Laboratory of Chem/Bio-Sensing and Chemometrics, Provincial Hunan Key Laboratory for Graphene Materials and Devices, College of Chemistry and Chemical Engineering, the National Supercomputer Centers in Changsha, Hunan University, Changsha 410082, P. R. China
| | - Chongyang Ma
- State Key Laboratory of Chem/Bio-Sensing and Chemometrics, Provincial Hunan Key Laboratory for Graphene Materials and Devices, College of Chemistry and Chemical Engineering, the National Supercomputer Centers in Changsha, Hunan University, Changsha 410082, P. R. China
| | - Qizheng An
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, P. R. China
| | - Chenyu Bu
- State Key Laboratory of Chem/Bio-Sensing and Chemometrics, Provincial Hunan Key Laboratory for Graphene Materials and Devices, College of Chemistry and Chemical Engineering, the National Supercomputer Centers in Changsha, Hunan University, Changsha 410082, P. R. China
| | - Yun Fan
- State Key Laboratory of Chem/Bio-Sensing and Chemometrics, Provincial Hunan Key Laboratory for Graphene Materials and Devices, College of Chemistry and Chemical Engineering, the National Supercomputer Centers in Changsha, Hunan University, Changsha 410082, P. R. China
| | - Yuxuan Lu
- State Key Laboratory of Chem/Bio-Sensing and Chemometrics, Provincial Hunan Key Laboratory for Graphene Materials and Devices, College of Chemistry and Chemical Engineering, the National Supercomputer Centers in Changsha, Hunan University, Changsha 410082, P. R. China
| | - Yuping Pan
- State Key Laboratory of Chem/Bio-Sensing and Chemometrics, Provincial Hunan Key Laboratory for Graphene Materials and Devices, College of Chemistry and Chemical Engineering, the National Supercomputer Centers in Changsha, Hunan University, Changsha 410082, P. R. China
| | - Dianke Xie
- State Key Laboratory of Chem/Bio-Sensing and Chemometrics, Provincial Hunan Key Laboratory for Graphene Materials and Devices, College of Chemistry and Chemical Engineering, the National Supercomputer Centers in Changsha, Hunan University, Changsha 410082, P. R. China
| | - Qinghua Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, P. R. China
| | - Shuangyin Wang
- State Key Laboratory of Chem/Bio-Sensing and Chemometrics, Provincial Hunan Key Laboratory for Graphene Materials and Devices, College of Chemistry and Chemical Engineering, the National Supercomputer Centers in Changsha, Hunan University, Changsha 410082, P. R. China
- Greater Bay Area Institute for Innovation, Hunan University, Guangzhou 511340, P. R. China
| | - Yuqin Zou
- State Key Laboratory of Chem/Bio-Sensing and Chemometrics, Provincial Hunan Key Laboratory for Graphene Materials and Devices, College of Chemistry and Chemical Engineering, the National Supercomputer Centers in Changsha, Hunan University, Changsha 410082, P. R. China
- Greater Bay Area Institute for Innovation, Hunan University, Guangzhou 511340, P. R. China
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2
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Niklas JE, Otte KS, Studvick CM, Roy Chowdhury S, Vlaisavljevich B, Bacsa J, Kleemiss F, Popov IA, La Pierre HS. A tetrahedral neptunium(V) complex. Nat Chem 2024; 16:1490-1495. [PMID: 38710831 DOI: 10.1038/s41557-024-01529-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 04/05/2024] [Indexed: 05/08/2024]
Abstract
Neptunium is an actinide element sourced from anthropogenic production, and, unlike naturally abundant uranium, its coordination chemistry is not well developed in all accessible oxidation states. High-valent neptunium generally requires stabilization from at least one metal-ligand multiple bond, and departing from this structural motif poses a considerable challenge. Here we report a tetrahedral molecular neptunium(V) complex ([Np5+(NPC)4][B(ArF5)4], 1-Np) (NPC = [NPtBu(pyrr)2]-; tBu = C(CH3)3; pyrr = pyrrolidinyl (N(C2H4)2); B(ArF5)4 = tetrakis(2,3,4,5,6-pentafluourophenyl)borate). Single-crystal X-ray diffraction, solution-state spectroscopy and density functional theory studies of 1-Np and the product of its proton-coupled electron transfer (PCET) reaction, 2-Np, demonstrate the unique bonding that stabilizes this reactive ion and establishes the thermochemical and kinetic parameters of PCET in a condensed-phase transuranic complex. The isolation of this four-coordinate, neptunium(V) complex reveals a fundamental reaction pathway in transuranic chemistry.
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Affiliation(s)
- Julie E Niklas
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
| | - Kaitlyn S Otte
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
| | - Chad M Studvick
- Department of Chemistry, The University of Akron, Akron, OH, USA
| | | | | | - John Bacsa
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
| | - Florian Kleemiss
- Institut für Anorganische Chemie, RWTH Aachen University, Aachen, Germany
| | - Ivan A Popov
- Department of Chemistry, The University of Akron, Akron, OH, USA.
| | - Henry S La Pierre
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA.
- Nuclear and Radiological Engineering and Medical Physics Program, School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA.
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3
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Tagliavini V, Duan PC, Chatterjee S, Ferretti E, Dechert S, Demeshko S, Kang L, Peredkov S, DeBeer S, Meyer F. Cooperative Sulfur Transformations at a Dinickel Site: A Metal Bridging Sulfur Radical and Its H-Atom Abstraction Thermochemistry. J Am Chem Soc 2024; 146:23158-23170. [PMID: 39110481 PMCID: PMC11345757 DOI: 10.1021/jacs.4c05113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 06/29/2024] [Accepted: 07/01/2024] [Indexed: 08/22/2024]
Abstract
Starting from the dinickel(II) dihydride complex [ML(Ni-H)2] (1M), where L3- is a bis(tridentate) pyrazolate-bridged bis(β-diketiminato) ligand and M+ is Na+ or K+, a series of complexes [KLNi2(S2)] (2K), [MLNi2S] (3M), [LNi2(SMe)] (4), and [LNi2(SH)] (5) has been prepared. The μ-sulfido complexes 3M can be reversibly oxidized at E1/2 = -1.17 V (in THF; vs Fc+/Fc) to give [LNi2(S•)] (6) featuring a bridging S-radical. 6 has been comprehensively characterized, including by X-ray diffraction, SQUID magnetometry, EPR and XAS/XES spectroscopies, and DFT calculations. The pKa of the μ-hydrosulfido complex 5 in THF is 30.8 ± 0.4, which defines a S-H bond dissociation free energy (BDFE) of 75.1 ± 1.0 kcal mol-1. 6 reacts with H atom donors such as TEMPO-H and xanthene to give 5, while 5 reacts with 2,4,6-tri(tert-butyl)phenoxy radical in a reverse H atom transfer to generate 6. These findings provide the first full characterization of a genuine M-(μ-S•-)-M complex and provide insights into its proton-coupled electron transfer (PCET) reactivity, which is of interest in view of the prominence of M-(μ-SH/μ-S)-M units in biological systems and heterogeneous catalysis.
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Affiliation(s)
- Valeria Tagliavini
- Institute
of Inorganic Chemistry, University of Göttingen, Tammannstr. 4, D-37077 Göttingen, Germany
| | - Peng-Cheng Duan
- Institute
of Inorganic Chemistry, University of Göttingen, Tammannstr. 4, D-37077 Göttingen, Germany
| | - Sayanti Chatterjee
- Max
Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der
Ruhr, Germany
- Department
of Chemistry, Indian Institute of Technology
Roorkee, Roorkee, Uttarakhand 247667, India
| | - Eleonora Ferretti
- Institute
of Inorganic Chemistry, University of Göttingen, Tammannstr. 4, D-37077 Göttingen, Germany
| | - Sebastian Dechert
- Institute
of Inorganic Chemistry, University of Göttingen, Tammannstr. 4, D-37077 Göttingen, Germany
| | - Serhiy Demeshko
- Institute
of Inorganic Chemistry, University of Göttingen, Tammannstr. 4, D-37077 Göttingen, Germany
| | - Liqun Kang
- Max
Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der
Ruhr, Germany
| | - Sergey Peredkov
- Max
Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der
Ruhr, Germany
| | - Serena DeBeer
- Max
Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der
Ruhr, Germany
| | - Franc Meyer
- Institute
of Inorganic Chemistry, University of Göttingen, Tammannstr. 4, D-37077 Göttingen, Germany
- International
Center for Advanced Studies of Energy Conversion (ICASEC), University of Göttingen, Tammannstr. 6, D-37077 Göttingen, Germany
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4
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De Tovar J, Leblay R, Wang Y, Wojcik L, Thibon-Pourret A, Réglier M, Simaan AJ, Le Poul N, Belle C. Copper-oxygen adducts: new trends in characterization and properties towards C-H activation. Chem Sci 2024; 15:10308-10349. [PMID: 38994420 PMCID: PMC11234856 DOI: 10.1039/d4sc01762e] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Accepted: 05/11/2024] [Indexed: 07/13/2024] Open
Abstract
This review summarizes the latest discoveries in the field of C-H activation by copper monoxygenases and more particularly by their bioinspired systems. This work first describes the recent background on copper-containing enzymes along with additional interpretations about the nature of the active copper-oxygen intermediates. It then focuses on relevant examples of bioinorganic synthetic copper-oxygen intermediates according to their nuclearity (mono to polynuclear). This includes a detailed description of the spectroscopic features of these adducts as well as their reactivity towards the oxidation of recalcitrant Csp3 -H bonds. The last part is devoted to the significant expansion of heterogeneous catalytic systems based on copper-oxygen cores (i.e. within zeolite frameworks).
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Affiliation(s)
- Jonathan De Tovar
- Université Grenoble-Alpes, CNRS, Département de Chimie Moléculaire Grenoble France
| | - Rébecca Leblay
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Institut des Sciences Moléculaires de Marseille Marseille France
| | - Yongxing Wang
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Institut des Sciences Moléculaires de Marseille Marseille France
| | - Laurianne Wojcik
- Université de Brest, Laboratoire de Chimie, Electrochimie Moléculaires et Chimie Analytique Brest France
| | | | - Marius Réglier
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Institut des Sciences Moléculaires de Marseille Marseille France
| | - A Jalila Simaan
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Institut des Sciences Moléculaires de Marseille Marseille France
| | - Nicolas Le Poul
- Université de Brest, Laboratoire de Chimie, Electrochimie Moléculaires et Chimie Analytique Brest France
| | - Catherine Belle
- Université Grenoble-Alpes, CNRS, Département de Chimie Moléculaire Grenoble France
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5
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Luhach S, Lalancette RA, Prokopchuk DE. "Catch and release" of the Cp N3 ligand using cobalt: dissociation, protonation, and C-H bond thermochemistry. Dalton Trans 2024. [PMID: 38916110 DOI: 10.1039/d4dt01560f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
The coordination chemistry of an amine-rich CpN3 ligand has been explored with cobalt. We demonstrate that in the presence of NaCo(CO)4, the cationic precursor [CpN3]+ yields the complex CpN3CoI(CO)2. While 2e- oxidation generates new CoIII complexes such as [CpN3Co(NCMe)3]2+ and CpN3CoI2(CO), subsequent ligand loss is facile, generating free [CpN3]+ or the protonated dication [CpN3H]2+. We have structurally characterized both these ligand release products via single crystal X-ray diffraction and obtained thermochemical C-H bond strengths via experiment and density functional theory (DFT). Upon reversible 1e- reduction, the radical cation [CpN3H]˙+ has a weak C-H BDFE of 52 kcal mol-1 in acetonitrile. Mechanistic analysis shows that [CpN3H]˙+ undergoes radical-radical disproportionation in the absence of exogenous H-atom acceptors, which is supported by deuterium isotope labelling experiments. Structural comparison of these organic molecules shows a high degree of iminium-like electron delocalization over the C-N bonds connected to the central five-membered ring.
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Affiliation(s)
- Sanju Luhach
- Department of Chemistry, Rutgers University-Newark, 73 Warren Street, Newark, NJ 07102, USA.
| | - Roger A Lalancette
- Department of Chemistry, Rutgers University-Newark, 73 Warren Street, Newark, NJ 07102, USA.
| | - Demyan E Prokopchuk
- Department of Chemistry, Rutgers University-Newark, 73 Warren Street, Newark, NJ 07102, USA.
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6
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Ghuffar HA, Noh H. Lithium-coupled electron transfer reactions of nano-confined WO x within Zr-based metal-organic framework. Front Chem 2024; 12:1427536. [PMID: 38947957 PMCID: PMC11214277 DOI: 10.3389/fchem.2024.1427536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Accepted: 05/23/2024] [Indexed: 07/02/2024] Open
Abstract
Interfacial charge transfer reactions involving cations and electrons are fundamental to (photo/electro) catalysis, energy storage, and beyond. Lithium-coupled electron transfer (LCET) at the electrode-electrolyte interfaces of lithium-ion batteries (LIBs) is a preeminent example to highlight the importance of charge transfer in modern-day society. The thermodynamics of LCET reactions define the minimal energy for charge/discharge of LIBs, and yet, these parameters are rarely available in the literature. Here, we demonstrate the successful incorporation of tungsten oxides (WOx) within a chemically stable Zr-based metal-organic framework (MOF), MOF-808. Cyclic voltammograms (CVs) of the composite, WOx@MOF-808, in Li+-containing acetonitrile (MeCN)-based electrolytes showed an irreversible, cathodic Faradaic feature that shifted in a Nernstian fashion with respect to the Li+ concentration, i.e., ∼59 mV/log [(Li+)]. The Nernstian dependence established 1:1 stoichiometry of Li+ and e-. Using the standard redox potential of Li+/0, the apparent free energy of lithiation of WOx@MOF-808 (ΔGapp,Li) was calculated to be -36 ± 1 kcal mol-1. ΔGapp,Li is an intrinsic parameter of WOx@MOF-808, and thus by deriving the similar reaction free energies of other metal oxides, their direct comparisons can be achieved. Implications of the reported measurements will be further contrasted to proton-coupled electron transfer (PCET) reactions on metal oxides.
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Affiliation(s)
| | - Hyunho Noh
- Department of Chemistry and Biochemistry, The University of Oklahoma, Norman, OK, United States
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7
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Mondal S, Zhang W, Zhang S. Thermodynamics of Proton-Coupled Electron Transfer at Tricopper μ-Oxo/Hydroxo/Aqua Complexes. J Am Chem Soc 2024; 146:15036-15044. [PMID: 38770819 DOI: 10.1021/jacs.3c14420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Multicopper oxidases (MCOs) utilize a tricopper active site to reduce dioxygen to water through 4H+ 4e- proton-coupled electron transfer (PCET). Understanding the thermodynamics of PCET at a tricopper cluster is essential for elucidating how MCOs harness the oxidative power of O2 while mitigating oxidative damage. In this study, we determined the O-H bond dissociation free energies (BDFEs) and pKa values of a series of tricopper hydroxo and tricopper aqua complexes as synthetic models of the tricopper site in MCOs. Tricopper intermediates on the path of alternating electron and proton transfer (ET-PT-ET-PT-ET) have modest BDFE(O-H) values in the range of 53.0-57.1 kcal/mol. In contrast, those not on the path of ET-PT-ET-PT-ET display much higher (78.1 kcal/mol) or lower (44.7 kcal/mol) BDFE(O-H) values. Additionally, the pKa of bridging OH and OH2 motifs increase by 8-16 pKa units per oxidation state. The same oxidation state changes have a lesser impact on the pKa of N-H motif in the secondary coordination sphere, with an increase of ca. 5 pKa units per oxidation state. The steeper pKa increase of the tricopper center promotes proton transfer from the secondary coordination sphere. Overall, our study shed light on the PCET pathway least prone to decomposition, elucidating why tricopper centers are an optimal choice for promoting efficient oxygen reduction reaction.
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Affiliation(s)
- Saikat Mondal
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Weiyao Zhang
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Shiyu Zhang
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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8
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Wu T, Puri A, Qiu YL, Ye D, Sarma R, Wang Y, Kowalewski T, Siegler MA, Swart M, Garcia-Bosch I. Tuning the Thermochemistry and Reactivity of a Series of Cu-Based 4H +/4e - Electron-Coupled-Proton Buffers. Inorg Chem 2024; 63:9014-9025. [PMID: 38723621 PMCID: PMC11110016 DOI: 10.1021/acs.inorgchem.4c00835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/08/2024] [Accepted: 04/30/2024] [Indexed: 05/21/2024]
Abstract
Electron-coupled-proton buffers (ECPBs) store and deliver protons and electrons in a reversible fashion. We have recently reported an ECPB based on Cu and a redox-active ligand that promoted 4H+/4e- reversible transformations (J. Am. Chem. Soc. 2022, 144, 16905). Herein, we report a series of Cu-based ECPBs in which the ability of these to accept and/or donate H• equivalents can be tuned via ligand modification. The thermochemistry of the 4H+/4e- ECPB equilibrium was determined using open-circuit potential measurements. The reactivity of the ECPBs against proton-coupled electron transfer (PCET) reagents was also analyzed, and the results obtained were rationalized based on the thermochemical parameters. Experimental and computational analysis of the thermochemistry of the H+/e- transfers involved in the 4H+/4e- ECPB transformations found substantial differences between the stepwise (namely, BDFE1, BDFE2, BDFE3, and BDFE4) and average bond dissociation free energy values (BDFEavg.). Our analysis suggests that this "redox unleveling" is critical to promoting the disproportionation and ligand-exchange reactions involved in the 4H+/4e- ECPB equilibria. The difference in BDFEavg. within the series of Cu-based ECPBs was found to arise from a substantial change in the redox potential (E1/2) upon modification of the ligand scaffold, which is not fully compensated for by a change in the acidity/basicity (pKa), suggesting "thermochemical decompensation".
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Affiliation(s)
- Tong Wu
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Ankita Puri
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yi Lin Qiu
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Daniel Ye
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Rajdeep Sarma
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yiwen Wang
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Tomasz Kowalewski
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | | | - Marcel Swart
- University
of Girona, Campus Montilivi (Ciències), Plaça de Sant Domènec, 17004 Girona, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Isaac Garcia-Bosch
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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9
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Hota PK, Jose A, Panda S, Dunietz EM, Herzog AE, Wojcik L, Le Poul N, Belle C, Solomon EI, Karlin KD. Coordination Variations within Binuclear Copper Dioxygen-Derived (Hydro)Peroxo and Superoxo Species; Influences upon Thermodynamic and Electronic Properties. J Am Chem Soc 2024; 146:13066-13082. [PMID: 38688016 PMCID: PMC11161030 DOI: 10.1021/jacs.3c14422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Copper ion is a versatile and ubiquitous facilitator of redox chemical and biochemical processes. These include the binding of molecular oxygen to copper(I) complexes where it undergoes stepwise reduction-protonation. A detailed understanding of thermodynamic relationships between such reduced/protonated states is key to elucidate the fundamentals of the chemical/biochemical processes involved. The dicopper(I) complex [CuI2(BPMPO-)]1+ {BPMPOH = 2,6-bis{[(bis(2-pyridylmethyl)amino]methyl}-4-methylphenol)} undergoes cryogenic dioxygen addition; further manipulations in 2-methyltetrahydrofuran generate dicopper(II) peroxo [CuII2(BPMPO-)(O22-)]1+, hydroperoxo [CuII2(BPMPO-)(-OOH)]2+, and superoxo [CuII2(BPMPO-)(O2•-)]2+ species, characterized by UV-vis, resonance Raman and electron paramagnetic resonance (EPR) spectroscopies, and cold spray ionization mass spectrometry. An unexpected EPR spectrum for [CuII2(BPMPO-)(O2•-)]2+ is explained by the analysis of its exchange-coupled three-spin frustrated system and DFT calculations. A redox equilibrium, [CuII2(BPMPO-)(O22-)]1+ ⇄ [CuII2(BPMPO-)(O2•-)]2+, is established utilizing Me8Fc+/Cr(η6-C6H6)2, allowing for [CuII2(BPMPO-)(O2•-)]2+/[CuII2(BPMPO-)(O22-)]1+ reduction potential calculation, E°' = -0.44 ± 0.01 V vs Fc+/0, also confirmed by cryoelectrochemical measurements (E°' = -0.40 ± 0.01 V). 2,6-Lutidinium triflate addition to [CuII2(BPMPO-)(O22-)]1+ produces [CuII2(BPMPO-)(-OOH)]2+; using a phosphazene base, an acid-base equilibrium was achieved, pKa = 22.3 ± 0.7 for [CuII2(BPMPO-)(-OOH)]2+. The BDFEOO-H = 80.3 ± 1.2 kcal/mol, as calculated for [CuII2(BPMPO-)(-OOH)]2+; this is further substantiated by H atom abstraction from O-H substrates by [CuII2(BPMPO-)(O2•-)]2+ forming [CuII2(BPMPO-)(-OOH)]2+. In comparison to known analogues, the thermodynamic and spectroscopic properties of [CuII2(BPMPO-)] O2-derived adducts can be accounted for based on chelate ring size variations built into the BPMPO- framework and the resulting enhanced CuII-ion Lewis acidity.
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Affiliation(s)
- Pradip Kumar Hota
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Anex Jose
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Sanjib Panda
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Eleanor M Dunietz
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Austin E Herzog
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Laurianne Wojcik
- UMR CNRS 6521, Université de Bretagne Occidentale, 6 Avenue Le Gorgeu, CS 93837, Brest Cedex 3 29238, France
| | - Nicolas Le Poul
- UMR CNRS 6521, Université de Bretagne Occidentale, 6 Avenue Le Gorgeu, CS 93837, Brest Cedex 3 29238, France
| | - Catherine Belle
- Université Grenoble-Alpes, CNRS, DCM, UMR 5250, Grenoble 38058, France
| | - Edward I Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Kenneth D Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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10
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Proe KR, Towarnicky A, Fertig A, Lu Z, Mpourmpakis G, Matson EM. Impact of Surface Ligand Identity and Density on the Thermodynamics of H Atom Uptake at Polyoxovanadate-Alkoxide Surfaces. Inorg Chem 2024; 63:7206-7217. [PMID: 38592922 DOI: 10.1021/acs.inorgchem.3c04435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
An understanding of how molecular structure influences the thermodynamics of H atom transfer is critical to designing efficient catalysts for reductive chemistries. Herein, we report experimental and theoretical investigations summarizing structure-function relationships of polyoxovanadate-alkoxides that influence bond dissociation free energies of hydroxide ligands located at the surface of the cluster. We evaluate the thermochemical descriptors of O-H bond strength for a series of clusters, namely [V6O13-x(OH)x(TRIOLR)2]-2 (x = 2, 4, 6; R = NO2, Me) and [V6O11-x(OMe)2(OH)x(TRIOLNO2)2]-2, via computational analysis and open circuit potential measurements. Our findings reveal that modifications to the TRIOL ligand (e.g., changing from the previously reported electron withdrawing nitro-backed ligand to the electron-donating methyl variant) have limited influence on the strength of surface O-H bonds as a result of near complete thermodynamic compensation in these systems (i.e., correlated changes in redox potential and cluster basicity). In contrast, changes in surface density of alkoxide ligands via direct alkoxylation of the polyoxovanadate-alkoxide surface result in measurable increases in bond dissociation free energies of surface O-H bonds for the mixed-valent derivatives. Our findings indicate that the extent of (de)localization of electron density across the cluster core has an impact on the bond dissociation free energies of surface O-H bonds across all oxidation states of the assembly.
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Affiliation(s)
- Kathryn R Proe
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Andreas Towarnicky
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Alex Fertig
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Zhou Lu
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Giannis Mpourmpakis
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Ellen M Matson
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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11
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Nedzbala HS, Westbroek D, Margavio HRM, Yang H, Noh H, Magpantay SV, Donley CL, Kumbhar AS, Parsons GN, Mayer JM. Photoelectrochemical Proton-Coupled Electron Transfer of TiO 2 Thin Films on Silicon. J Am Chem Soc 2024; 146:10559-10572. [PMID: 38564642 DOI: 10.1021/jacs.4c00014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
TiO2 thin films are often used as protective layers on semiconductors for applications in photovoltaics, molecule-semiconductor hybrid photoelectrodes, and more. Experiments reported here show that TiO2 thin films on silicon are electrochemically and photoelectrochemically reduced in buffered acetonitrile at potentials relevant to photoelectrocatalysis of CO2 reduction, N2 reduction, and H2 evolution. On both n-type Si and irradiated p-type Si, TiO2 reduction is proton-coupled with a 1e-:1H+ stoichiometry, as demonstrated by the Nernstian dependence of the Ti4+/3+ E1/2 on the buffer pKa. Experiments were conducted with and without illumination, and a photovoltage of ∼0.6 V was observed across 20 orders of magnitude in proton activity. The 4 nm films are almost stoichiometrically reduced under mild conditions. The reduced films catalytically transfer protons and electrons to hydrogen atom acceptors, based on cyclic voltammogram, bulk electrolysis, and other mechanistic evidence. TiO2/Si thus has the potential to photoelectrochemically generate high-energy H atom carriers. Characterization of the TiO2 films after reduction reveals restructuring with the formation of islands, rendering TiO2 films as a potentially poor choice as protecting films or catalyst supports under reducing and protic conditions. Overall, this work demonstrates that atomic layer deposition TiO2 films on silicon photoelectrodes undergo both chemical and morphological changes upon application of potentials only modestly negative of RHE in these media. While the results should serve as a cautionary tale for researchers aiming to immobilize molecular monolayers on "protective" metal oxides, the robust proton-coupled electron transfer reactivity of the films introduces opportunities for the photoelectrochemical generation of reactive charge-carrying mediators.
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Affiliation(s)
- Hannah S Nedzbala
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Dalaney Westbroek
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Hannah R M Margavio
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27603, United States
| | - Hyuenwoo Yang
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27603, United States
| | - Hyunho Noh
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Samantha V Magpantay
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Carrie L Donley
- Department of Chemistry, Chapel Hill Analytical and Nanofabrication Laboratory (CHANL), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Amar S Kumbhar
- Department of Chemistry, Chapel Hill Analytical and Nanofabrication Laboratory (CHANL), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Gregory N Parsons
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27603, United States
| | - James M Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
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12
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Sonea A, Crudo NR, Warren JJ. Understanding the Interplay of the Brønsted Acidity of Catalyst Ancillary Groups and the Solution Components in Iron-porphyrin-Mediated Carbon Dioxide Reduction. J Am Chem Soc 2024; 146:3721-3731. [PMID: 38307036 DOI: 10.1021/jacs.3c10127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2024]
Abstract
The rapid and efficient conversion of carbon dioxide (CO2) to carbon monoxide (CO) is an ongoing challenge. Catalysts based on iron-porphyrin cores have emerged as excellent electrochemical mediators of the two proton + two electron reduction of CO2 to CO, and many of the design features that promote function are known. Of those design features, the incorporation of Brønsted acids in the second coordination sphere of the iron ion has a significant impact on catalyst turnover kinetics. The Brønsted acids are often in the form of hydroxyphenyl groups. Herein, we explore how the acidity of an ancillary 2-hydroxyphenyl group affects the performance of CO2 reduction electrocatalysts. A series of meso-5,10,15,20-tetraaryl porphyrins were prepared where only the functional group at the 5-meso position has an ionizable proton. A series of cyclic voltammetry (CV) experiments reveal that the complex with -OMe positioned para to the ionizable -OH shows the largest CO2 reduction rate constants in acetonitrile solvent. This is the least acidic -OH of the compounds surveyed. The turnover frequency of the -OMe derivative can be further improved with the addition of 4-trifluoromethylphenol to the solution. In contrast, the iron-porphyrin complex with -CF3 positioned opposite the ionizable -OH shows the smallest CO2 reduction rate constants, and its turnover frequency is less enhanced with the addition of phenols to the reaction solutions. The origin of this effect is rationalized based on kinetic isotope effect experiments and density functional calculations. We conclude that catalysts with weaker internal acids coupled with stronger external acid additives provide superior CO2 reduction kinetics.
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Affiliation(s)
- Ana Sonea
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Nicholas R Crudo
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
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13
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Lee TW, Chen C. Influence of Inorganic Anions on the Chemical Stability of Molybdenum Disulfide Nanosheets in the Aqueous Environment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:2490-2501. [PMID: 38284181 PMCID: PMC10851429 DOI: 10.1021/acs.est.3c08278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/30/2024]
Abstract
Chemical stability is closely associated with the transformations and bioavailabilities of engineered nanomaterials and is a key factor that governs broader and long-term application. With the growing utilization of molybdenum disulfide (MoS2) nanosheets in water treatment and purification processes, it is crucial to evaluate the stability of MoS2 nanosheets in aquatic environments. Nonetheless, the effects of anionic species on MoS2 remain largely unexplored. Herein, the stability of chemically exfoliated MoS2 nanosheets (ceMoS2) was assessed in the presence of inorganic anions. The results showed that the chemical stability of ceMoS2 was regulated by the nucleophilicities and the resultant charging effects of the anions in aquatic systems. The anions promote the dissolution of ceMoS2 by triggering a shift in the chemical potential of the ceMoS2 surface as a function of the anion nucleophilicity (i.e., charging effect). Fast charging with HCO3- and HPO42-/H2PO4- was validated by a phase transition from 1T to 2H and the emergence of MoV, and it promoted oxidative dissolution of the ceMoS2. Additionally, under sunlight, ceMoS2 dissolution was accelerated by NO3-. These findings provide insight into the ion-induced fate of ceMoS2 and the durability and risks of MoS2 nanosheets in environmental applications.
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Affiliation(s)
- Ting-Wei Lee
- Department of Environmental
Engineering, National Chung Hsing University, Taichung City 402, Taiwan
| | - Chiaying Chen
- Department of Environmental
Engineering, National Chung Hsing University, Taichung City 402, Taiwan
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14
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Cooney S, Walls MRA, Schreiber E, Brennessel WW, Matson EM. Heterometal Dopant Changes the Mechanism of Proton-Coupled Electron Transfer at the Polyoxovanadate-Alkoxide Surface. J Am Chem Soc 2024; 146:2364-2369. [PMID: 38241170 PMCID: PMC10835708 DOI: 10.1021/jacs.3c14054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/21/2024]
Abstract
The transfer of two H-atom equivalents to the titanium-doped polyoxovanadate-alkoxide, [TiV5O6(OCH3)13], results in the formation of a V(III)-OH2 site at the surface of the assembly. Incorporation of the group (IV) metal ion results in a weakening of the O-H bonds of [TiV5O5(OH2)(OCH3)13] in comparison to its homometallic congener, [V6O6(OH2)(OCH3)12], resembling more closely the thermodynamics reported for the one-electron reduced derivative, [V6O6(OH2)(OCH3)12]1-. An analysis of early time points of the reaction of [TiV5O6(OCH3)13] and 5,10-dihydrophenazine reveals the formation of an oxidized substrate, suggesting that proton-coupled electron transfer proceeds via initial electron transfer from substrate to cluster prior to proton transfer. These results demonstrate the profound influence of heterometal dopants on the mechanism of PCET with respect to the surface of the assembly.
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Affiliation(s)
- Shannon
E. Cooney
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - M. Rebecca A. Walls
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Eric Schreiber
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - William W. Brennessel
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Ellen M. Matson
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
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15
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Alvarez-Hernandez JL, Salamatian AA, Sopchak AE, Bren KL. Hydrogen evolution catalysis by a cobalt porphyrin peptide: A proposed role for porphyrin propionic acid groups. J Inorg Biochem 2023; 249:112390. [PMID: 37801884 DOI: 10.1016/j.jinorgbio.2023.112390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 09/11/2023] [Accepted: 09/26/2023] [Indexed: 10/08/2023]
Abstract
Cobalt microperoxidase-11 (CoMP11-Ac) is a cobalt porphyrin-peptide catalyst for hydrogen (H2) evolution from water. Herein, we assess electrocatalytic activity of CoMP11-Ac from pH 1.0-10.0. This catalyst remains intact and active under highly acidic conditions (pH 1.0) that are desirable for maximizing H2 evolution activity. Analysis of electrochemical data indicate that H2 evolution takes place by two pH-dependent mechanisms. At pH < 4.3, a proton transfer mechanism involving the propionic acid groups of the porphyrin is proposed, decreasing the catalytic overpotential by 280 mV.
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Affiliation(s)
| | - Alison A Salamatian
- Department of Chemistry, University of Rochester. Rochester, NY 14627-0216, United States.
| | - Andrew E Sopchak
- Department of Chemistry, University of Rochester. Rochester, NY 14627-0216, United States.
| | - Kara L Bren
- Department of Chemistry, University of Rochester. Rochester, NY 14627-0216, United States.
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16
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Zaar F, Moyses Araujo C, Emanuelsson R, Strømme M, Sjödin M. Tetraphenylporphyrin electrocatalysts for the hydrogen evolution reaction: applicability of molecular volcano plots to experimental operating conditions. Dalton Trans 2023; 52:10348-10362. [PMID: 37462421 DOI: 10.1039/d3dt01250f] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
Recent years have seen an increasing interest in molecular electrocatalysts for the hydrogen evolution reaction (HER). Efficient hydrogen evolution would play an important role in a sustainable fuel economy, and molecular systems could serve as highly specific and tunable alternatives to traditional noble metal surface catalysts. However, molecular catalysts are currently mostly used in homogeneous setups, where quantitative evaluation of catalytic activity is non-standardized and cumbersome, in particular for multistep, multielectron processes. The molecular design community would therefore be well served by a straightforward model for prediction and comparison of the efficiency of molecular catalysts. Recent developments in this area include attempts at applying the Sabatier principle and the volcano plot concept - popular tools for comparing metal surface catalysts - to molecular catalysis. In this work, we evaluate the predictive power of these tools in the context of experimental operating conditions, by applying them to a series of tetraphenylporphyrins employed as molecular electrocatalysts of the HER. We show that the binding energy of H and the redox chemistry of the porphyrins depend solely on the electron withdrawing ability of the central metal ion, and that the thermodynamics of the catalytic cycle follow a simple linear free energy relation. We also find that the catalytic efficiency of the porphyrins is almost exclusively determined by reaction kinetics and therefore cannot be explained by thermodynamics alone. We conclude that the Sabatier principle, linear free energy relations and molecular volcano plots are insufficient tools for predicting and comparing activity of molecular catalysts, and that experimentally useful information of catalytic performance can still only be obtained through detailed knowledge of the catalytic pathway for each individual system.
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Affiliation(s)
- Felicia Zaar
- Department of Materials Science and Engineering, Division of Nanotechnology and Functional Materials, Uppsala University, Box 35, SE-751 03 Uppsala, Sweden.
| | - C Moyses Araujo
- Materials Theory Division, Department of Physics and Astronomy, Ångström Laboratory, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
- Department of Engineering and Physics, Karlstad University, 651 88 Karlstad, Sweden
| | - Rikard Emanuelsson
- Department of Chemistry - BMC, Uppsala University, Box 576, SE-751 23 Uppsala, Sweden
| | - Maria Strømme
- Department of Materials Science and Engineering, Division of Nanotechnology and Functional Materials, Uppsala University, Box 35, SE-751 03 Uppsala, Sweden.
| | - Martin Sjödin
- Department of Materials Science and Engineering, Division of Nanotechnology and Functional Materials, Uppsala University, Box 35, SE-751 03 Uppsala, Sweden.
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17
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Groff BD, Cattaneo M, Coste SC, Pressley CA, Mercado BQ, Mayer JM. Independent Tuning of the p Ka or the E1/2 in a Family of Ruthenium Pyridine-Imidazole Complexes. Inorg Chem 2023; 62:10031-10038. [PMID: 37326619 PMCID: PMC10734561 DOI: 10.1021/acs.inorgchem.3c01241] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Two series of RuII(acac)2(py-imH) complexes have been prepared, one with changes to the acac ligands and the other with substitutions to the imidazole. The proton-coupled electron transfer (PCET) thermochemistry of the complexes has been studied in acetonitrile, revealing that the acac substitutions almost exclusively affect the redox potentials of the complex (|ΔE1/2| ≫ |ΔpKa|·0.059 V) while the changes to the imidazole primarily affect its acidity (|ΔpKa|·0.059 V ≫ |ΔE1/2|). This decoupling is supported by DFT calculations, which show that the acac substitutions primarily affect the Ru-centered t2g orbitals, while changes to the py-imH ligand primarily affect the ligand-centered π orbitals. More broadly, the decoupling stems from the physical separation of the electron and proton within the complex and highlights a clear design strategy to separately tune the redox and acid/base properties of H atom donor/acceptor molecules.
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Affiliation(s)
- Benjamin D Groff
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Mauricio Cattaneo
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Scott C Coste
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Chloe A Pressley
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Brandon Q Mercado
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - James M Mayer
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
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18
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VanderWeide A, Prokopchuk DE. Cyclopentadienyl ring activation in organometallic chemistry and catalysis. Nat Rev Chem 2023:10.1038/s41570-023-00501-1. [PMID: 37258685 DOI: 10.1038/s41570-023-00501-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2023] [Indexed: 06/02/2023]
Abstract
The cyclopentadienyl (Cp) ligand is a cornerstone of modern organometallic chemistry. Since the discovery of ferrocene, the Cp ligand and its various derivatives have become foundational motifs in catalysis, medicine and materials science. Although largely considered an ancillary ligand for altering the stereoelectronic properties of transition metal centres, there is mounting evidence that the core Cp ring structure also serves as a reservoir for reactive protons (H+), hydrides (H-) or radical hydrogen (H•) atoms. This Review chronicles the field of Cp ring activation, highlighting the pivotal role that Cp ligands can have in electrocatalytic H2 production, N2 reduction, hydride transfer reactions and proton-coupled electron transfer.
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19
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Mayer JM. Bonds over Electrons: Proton Coupled Electron Transfer at Solid-Solution Interfaces. J Am Chem Soc 2023; 145:7050-7064. [PMID: 36943755 PMCID: PMC10080693 DOI: 10.1021/jacs.2c10212] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
This Perspective argues that most redox reactions of materials at an interface with a protic solution involve net proton-coupled electron transfer (PCET) (or other cation-coupled ET). This view contrasts with the traditional electron-transfer-focused view of redox reactions at semiconductors, but redox processes at metal surfaces are often described as PCET. Taking a thermodynamic perspective, transfer of an electron is typically accompanied by a stoichiometric proton, much as the chemistry of lithium-ion batteries involves coupled transfers of e- and Li+. The PCET viewpoint implicates the surface-H bond dissociation free energy (BDFE) as the preeminent energetic parameter and its conceptual equivalents, the electrochemical ne-/nH+ potential versus the reversible hydrogen electrode (RHE) and the free energy of hydrogenation, ΔG°H. These parameters capture the thermochemistry of PCET at interfaces better than electronic parameters such as Fermi energies, electron chemical potentials, flat-band potentials, or band-edge energies. A unified picture of PCET at metal and semiconductor surfaces is presented. Exceptions, limitations, implications, and future directions motivated by this approach are described.
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Affiliation(s)
- James M Mayer
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
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20
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Junge J, Engesser TA, Tuczek F. N 2 Reduction versus H 2 Evolution in a Molybdenum- or Tungsten-Based Small-Molecule Model System of Nitrogenase. Chemistry 2023; 29:e202202629. [PMID: 36458957 DOI: 10.1002/chem.202202629] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 11/24/2022] [Accepted: 12/02/2022] [Indexed: 12/04/2022]
Abstract
Molybdenum dinitrogen complexes have played a major role as catalytic model systems of nitrogenase. In comparison, analogous tungsten complexes have in most cases found to be catalytically inactive. Herein, a tungsten complex was shown to be supported by a pentadentate tetrapodal (pentaPod) phosphine ligand, under conditions of N2 fixation, primarily catalyzes the hydrogen evolution reaction (HER), in contrast to its Mo analogue, which catalytically mediates the nitrogen-reduction reaction (N2 RR). DFT calculations were employed to evaluate possible mechanisms and identify the most likely pathways of N2 RR and HER activities exhibited by Mo- and W-pentaPod complexes. Two mechanisms for N2 RR by PCET are considered, starting from neutral (M(0) cycle) and cationic (M(I) cycle) dinitrogen complexes (M=Mo, W). The latter was found to be energetically more favorable. For HER three scenarios are treated; that is, through bimolecular reactions of early M-Nx Hy intermediates, pure hydride intermediates or mixed M(H)(Nx Hy ) species.
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Affiliation(s)
- Jannik Junge
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Strasse 2, 24118, Kiel, Germany
| | - Tobias A Engesser
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Strasse 2, 24118, Kiel, Germany
| | - Felix Tuczek
- Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Strasse 2, 24118, Kiel, Germany
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21
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Rennie BE, Price JS, Emslie DJH, Morris RH. Trans Ligand Determines the Stability of Paramagnetic Manganese(II) Hydrides of the Type trans-[MnH(L)(dmpe) 2] + Where L is PMe 3, C 2H 4, or CO. Inorg Chem 2023; 62:8123-8135. [PMID: 36812512 DOI: 10.1021/acs.inorgchem.2c04432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Paramagnetic metal hydride (PMH) complexes play important roles in catalytic applications and bioinorganic chemistry. 3d PMH chemistry has largely focused on Ti, Mn, Fe, and Co. Various MnII PMHs have been proposed as intermediates in catalysis, but isolated MnII PMHs are limited to dimeric high-spin MnII structures with bridging hydrides. In this paper, a series of the first low-spin monomeric MnII PMH complexes are generated by chemical oxidation of their MnI analogues. This series is of the type trans-[MnH(L)(dmpe)2]+/0 where the trans ligand L is PMe3, C2H4, or CO [dmpe is 1,2-bis(dimethylphosphino)ethane], and the thermal stability of the MnII hydride complexes was found to be strongly dependent on the identity of the trans ligand. When L is PMe3, the complex is the first example of an isolated monomeric MnII hydride complex. In contrast, when L is C2H4 or CO, the complexes are only stable at low temperatures; upon warming to room temperature, the former decomposed to afford [Mn(dmpe)3]+, accompanied by ethane and ethylene, whereas the latter eliminated H2, generating [Mn(MeCN)(CO)(dmpe)2]+ or a mixture of products including [Mn(κ1-PF6)(CO)(dmpe)2], depending on the reaction conditions. All PMHs were characterized by low-temperature electron paramagnetic resonance (EPR) spectroscopy, and stable [MnH(PMe3)(dmpe)2]+ was further characterized by UV-vis and IR spectroscopy, Superconducting Quantum Interference Device magnetometry, and single-crystal X-ray diffraction. Noteworthy spectral properties are the significant EPR superhyperfine coupling to the hydride (∼85 MHz) and an increase (+33 cm-1) in the Mn-H IR stretch upon oxidation. Density functional theory calculations were also employed to gain insights into the acidity and bond strengths of the complexes. MnII-H bond dissociation free energies are estimated to decrease in the series of complexes from 60 (L = PMe3) to 47 kcal/mol (L = CO).
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Affiliation(s)
- Benjamin E Rennie
- Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S3H6, Canada
| | - Jeffrey S Price
- Department of Chemistry, McMaster University, Hamilton, Ontario L8S4M1, Canada
| | - David J H Emslie
- Department of Chemistry, McMaster University, Hamilton, Ontario L8S4M1, Canada
| | - Robert H Morris
- Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S3H6, Canada
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22
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Schreiber E, Brennessel WW, Matson EM. Regioselectivity of concerted proton-electron transfer at the surface of a polyoxovanadate cluster. Chem Sci 2023; 14:1386-1396. [PMID: 36794190 PMCID: PMC9906639 DOI: 10.1039/d2sc05928b] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 12/19/2022] [Indexed: 01/19/2023] Open
Abstract
Proton-coupled electron transfer (PCET) is an important process in the activation and reactivity of metal oxide surfaces. In this work, we study the electronic structure of a reduced polyoxovanadate-alkoxide cluster bearing a single bridging oxide moiety. The structural and electronic implications of the incorporation of bridging oxide sites are revealed, most notably resulting in the quenching of cluster-wide electron delocalization in the most reduced state of the molecule. We correlate this attribute to a change in regioselectivity of PCET to the cluster surface (e.g. reactivity at terminal vs. bridging oxide groups). Reactivity localized at the bridging oxide site enables reversible storage of a single H-atom equivalent, changing the stoichiometry of PCET from a 2e-/2H+ process. Kinetic investigations indicate that the change in site of reactivity translates to an accelerated rate of e-/H+ transfer to the cluster surface. Our work summarizes the role which electronic occupancy and ligand density play in the uptake of e-/H+ pairs at metal oxide surfaces, providing design criteria for functional materials for energy storage and conversion processes.
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Affiliation(s)
- Eric Schreiber
- Department of Chemistry, University of Rochester Rochester NY 14611 USA
| | | | - Ellen M Matson
- Department of Chemistry, University of Rochester Rochester NY 14611 USA
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23
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Abstract
Homogeneous electrocatalysis has been well studied over the past several decades for the conversion of small molecules to useful products for green energy applications or as chemical feedstocks. However, in order for these catalyst systems to be used in industrial applications, their activity and stability must be improved. In naturally occurring enzymes, redox equivalents (electrons, often in a concerted manner with protons) are delivered to enzyme active sites by small molecules known as redox mediators (RMs). Inspired by this, co-electrocatalytic systems with homogeneous catalysts and RMs have been developed for the conversion of alcohols, nitrogen, unsaturated organic substrates, oxygen, and carbon dioxide. In these systems, the RMs have been shown to both increase the activity of the catalyst and shift selectivity to more desired products by altering catalytic cycles and/or avoiding high-energy intermediates. However, the area is currently underdeveloped and requires additional fundamental advancements in order to become a more general strategy. Here, we summarize the recent examples of homogeneous co-electrocatalysis and discuss possible future directions for the field.
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Affiliation(s)
- Amelia G Reid
- Department of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, Virginia 22904-4319, United States
| | - Charles W Machan
- Department of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, Virginia 22904-4319, United States
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Gordon JB, Albert T, Yadav S, Thomas J, Siegler MA, Moënne-Loccoz P, Goldberg DP. Oxygen versus Sulfur Coordination in Cobalt Superoxo Complexes: Spectroscopic Properties, O 2 Binding, and H-Atom Abstraction Reactivity. Inorg Chem 2023; 62:392-400. [PMID: 36538786 PMCID: PMC10194424 DOI: 10.1021/acs.inorgchem.2c03484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A five-coordinate, disiloxide-ligated cobalt(II) (S = 3/2) complex (1) was prepared as an oxygen-ligated analogue to the previously reported silanedithiolate-ligated CoII(Me3TACN)(S2SiMe2) (J. Am. Chem. Soc., 2019, 141, 3641-3653). The structural and spectroscopic properties of 1 were analyzed by single-crystal X-ray diffraction, electron paramagnetic resonance (EPR), and NMR spectroscopies. The reactivity of 1 with dioxygen was examined, and it was shown to bind O2 reversibly in a range of solvents at low temperatures. A cobalt(III)-superoxo complex, CoIII(O2·-)(Me3TACN)((OSi2Ph)2O) (2), was generated, and was analyzed by UV-vis, EPR, and resonance Raman spectroscopies. Unlike its sulfur-ligated analogue, complex 2 can thermally release O2 to regenerate 1. Vibrational assignments for selective 18O isotopic labeling of both O2 and disiloxide ligands in 2 are consistent with a 6-coordinate, Co(η1-O2·-)("end-on") complex. Complex 2 reacts with the O-H bond of 4-methoxy-2,2,6,6-tetramethylpiperidin-1-ol (4-MeO-TEMPOH) via H-atom abstraction with a rate of 0.58(2) M-1 s-1 at -105 °C, but it is unable to oxidize phenol substrates. This bracketed reactivity suggests that the O-H bond being formed in the putative CoIII(OOH) product has a relatively weak O-H bond strength (BDFE ∼66-74 kcal mol-1). These thermodynamic and kinetic parameters are similar to those seen for the sulfur-ligated Co(O2)(Me3TACN)(S2SiMe2), indicating that the differences in the electronic structure for O versus S ligation do not have a large impact on H-atom abstraction reactivity.
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Affiliation(s)
- Jesse B Gordon
- Department of Chemistry, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Therese Albert
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, United States
| | - Sudha Yadav
- Department of Chemistry, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Jithin Thomas
- Department of Chemistry, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Maxime A Siegler
- Department of Chemistry, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Pierre Moënne-Loccoz
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, United States
| | - David P Goldberg
- Department of Chemistry, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, United States
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25
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Cooney SE, Fertig AA, Buisch MR, Brennessel WW, Matson EM. Coordination-induced bond weakening of water at the surface of an oxygen-deficient polyoxovanadate cluster. Chem Sci 2022; 13:12726-12737. [PMID: 36519047 PMCID: PMC9645371 DOI: 10.1039/d2sc04843d] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 10/10/2022] [Indexed: 10/19/2023] Open
Abstract
Hydrogen-atom (H-atom) transfer at the surface of heterogeneous metal oxides has received significant attention owing to its relevance in energy conversion and storage processes. Here, we present the synthesis and characterization of an organofunctionalized polyoxovanadate cluster, (calix)V6O5(OH2)(OMe)8 (calix = 4-tert-butylcalix[4]arene). Through a series of equilibrium studies, we establish the BDFE(O-H)avg of the aquo ligand as 62.4 ± 0.2 kcal mol-1, indicating substantial bond weaking of water upon coordination to the cluster surface. Subsequent kinetic isotope effect studies and Eyring analysis indicate the mechanism by which the hydrogenation of organic substrates occurs proceeds through a concerted proton-electron transfer from the aquo ligand. Atomistic resolution of surface reactivity presents a novel route of hydrogenation reactivity from metal oxide surfaces through H-atom transfer from surface-bound water molecules.
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Affiliation(s)
- Shannon E Cooney
- Department of Chemistry, University of Rochester Rochester NY 14627 USA
| | - Alex A Fertig
- Department of Chemistry, University of Rochester Rochester NY 14627 USA
| | | | | | - Ellen M Matson
- Department of Chemistry, University of Rochester Rochester NY 14627 USA
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26
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Kim S, Kim J, Zhong H, Panetti GB, Chirik PJ. Catalytic N–H Bond Formation Promoted by a Ruthenium Hydride Complex Bearing a Redox-Active Pyrimidine-Imine Ligand. J Am Chem Soc 2022; 144:20661-20671. [DOI: 10.1021/jacs.2c07800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Sangmin Kim
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Junho Kim
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Hongyu Zhong
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Grace B. Panetti
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Paul J. Chirik
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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27
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Agarwal RG, Mayer JM. Coverage-Dependent Rate-Driving Force Relationships: Hydrogen Transfer from Cerium Oxide Nanoparticle Colloids. J Am Chem Soc 2022; 144:20699-20709. [DOI: 10.1021/jacs.2c07988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Rishi G. Agarwal
- Department of Chemistry, Yale University, New Haven, Connecticut06520-8107, United States
| | - James M. Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut06520-8107, United States
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28
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Dunn PL, Barona M, Johnson SI, Raugei S, Bullock RM. Hydrogen Atom Abstraction from an Os II(NH 3) 2 Complex Generates an Os IV(NH 2) 2 Complex: Experimental and Computational Analysis of the N-H Bond Dissociation Free Energies and Reactivity. Inorg Chem 2022; 61:15325-15334. [PMID: 36121917 DOI: 10.1021/acs.inorgchem.2c00708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Double hydrogen atom abstraction from (TMP)OsII(NH3)2 (TMP = tetramesitylporphyrin) with phenoxyl or nitroxyl radicals leads to (TMP)OsIV(NH2)2. This unusual bis(amide) complex is diamagnetic and displays an N-H resonance at 12.0 ppm in its 1H NMR spectrum. 1H-15N correlation experiments identified a 15N NMR spectroscopic resonance signal at -267 ppm. Experimental reactivity studies and density functional theory calculations support relatively weak N-H bonds of 73.3 kcal/mol for (TMP)OsII(NH3)2 and 74.2 kcal/mol for (TMP)OsIII(NH3)(NH2). Cyclic voltammetry experiments provide an estimate of the pKa of [(TMP)OsIII(NH3)2]+. In the presence of Barton's base, a current enhancement is observed at the Os(III/II) couple, consistent with an ECE event. Spectroscopic experiments confirmed (TMP)OsIV(NH2)2 as the product of bulk electrolysis. Double hydrogen atom abstraction is influenced by π donation from the amides of (TMP)OsIV(NH2)2 into the d orbitals of the Os center, favoring the formation of (TMP)OsIV(NH2)2 over N-N coupling. This π donation leads to a Jahn-Teller distortion that splits the energy levels of the dxz and dyz orbitals of Os, results in a low-spin electron configuration, and leads to minimal aminyl character on the N atoms, rendering (TMP)OsIV(NH2)2 unreactive toward amide-amide coupling.
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Affiliation(s)
- Peter L Dunn
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Melissa Barona
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Samantha I Johnson
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Simone Raugei
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - R Morris Bullock
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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29
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Cypcar AD, Kerr TA, Yang JY. Thermochemical Studies of Nickel Hydride Complexes with Cationic Ligands in Aqueous and Organic Solvents. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Andrew D. Cypcar
- Department of Chemistry, University of California, Irvine, California 92697, United States
| | - Tyler A. Kerr
- Department of Chemistry, University of California, Irvine, California 92697, United States
| | - Jenny Y. Yang
- Department of Chemistry, University of California, Irvine, California 92697, United States
- Physical Sciences Division, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
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30
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Wu T, Rajabimoghadam K, Puri A, Hebert DD, Qiu YL, Eichelberger S, Siegler MA, Swart M, Hendrich MP, Garcia-Bosch I. A 4H +/4e - Electron-Coupled-Proton Buffer Based on a Mononuclear Cu Complex. J Am Chem Soc 2022; 144:16905-16915. [PMID: 36083845 PMCID: PMC10123533 DOI: 10.1021/jacs.2c05454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this research article, we describe a 4H+/4e- electron-coupled-proton buffer (ECPB) based on Cu and a redox-active ligand. The protonated/reduced ECPB (complex 1: [Cu(8H+/14e-)]1+), consisting of CuI with 2 equiv of the ligand (catLH4: 1,1'-(4,5-dimethoxy-1,2-phenylene)bis(3-(tert-butyl)urea)), reacted with H+/e- acceptors such as O2 to generate the deprotonated/oxidized ECPB. The resulting compound, (complex 5: [Cu(4H+/10e-)]1+), was characterized by X-ray diffraction analysis, nuclear magnetic resonance (1H-NMR), and density functional theory, and it is electronically described as a cuprous bis(benzoquinonediimine) species. The stoichiometric 4H+/4e- reduction of 5 was carried out with H+/e- donors to generate 1 (CuI and 2 equiv of catLH4) and the corresponding oxidation products. The 1/5 ECPB system catalyzed the 4H+/4e- reduction of O2 to H2O and the dehydrogenation of organic substrates in a decoupled (oxidations and reductions are separated in time and space) and a coupled fashion (oxidations and reductions coincide in time and space). Mechanistic analysis revealed that upon reductive protonation of 5 and oxidative deprotonation of 1, fast disproportionation reactions regenerate complexes 5 and 1 in a stoichiometric fashion to maintain the ECPB equilibrium.
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Affiliation(s)
- Tong Wu
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | | | - Ankita Puri
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - David D Hebert
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yi Lin Qiu
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Sidney Eichelberger
- Department of Chemistry, Southern Methodist University, Dallas, Texas 75275, United States
| | - Maxime A Siegler
- Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Marcel Swart
- University of Girona, IQCC, Campus Montilivi (Cie#x300;ncies), 17003 Girona, Spain.,ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Michael P Hendrich
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Isaac Garcia-Bosch
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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31
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Fertig AA, Matson EM. Connecting Thermodynamics and Kinetics of Proton Coupled Electron Transfer at Polyoxovanadate Surfaces Using the Marcus Cross Relation. Inorg Chem 2022; 62:1958-1967. [PMID: 36049052 PMCID: PMC9906739 DOI: 10.1021/acs.inorgchem.2c02541] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Here, we evaluate the efficacy of multiple methods for elucidating the average bond dissociation free energy (BDFE) of two surface hydroxide moieties in a reduced polyoxovanadate cluster, [V6O11(OH)2(TRIOLNO2)2]-2. Through cyclic voltammetry, individual thermochemical parameters describing proton coupled electron transfer (PCET) are obtained, without the need for synthetic isolation of intermediates. Further, we demonstrate that a method involving a series of open circuit potential measurements with varying ratios of reduced to oxidized clusters is most attractive for the direct measurement of BDFE(O-H) for polyoxovanadate clusters as this approach also determines the stoichiometry of PCET. We subsequently connect the driving force of PCET to the rate constant for the transfer of hydrogen atoms to a series of organic substrates through the Marcus cross relation. We show that this method is applicable for the prediction of reaction rates for multielectron/multiproton transfer reactions, extending the findings from previous work focused on single electron/proton reactions.
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32
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Fritz M, Rupp S, Kiene CI, Kisan S, Telser J, Würtele C, Krewald V, Schneider S. Photoelectrochemical Conversion of Dinitrogen to Benzonitrile: Selectivity Control by Electrophile‐ versus Proton‐Coupled Electron Transfer. Angew Chem Int Ed Engl 2022; 61:e202205922. [PMID: 35714100 PMCID: PMC9542086 DOI: 10.1002/anie.202205922] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Indexed: 11/10/2022]
Abstract
Nitride complexes are key species in homogeneous nitrogen fixation to NH3 via stepwise proton‐coupled electron transfer (PCET). In contrast, direct generation of nitrogenous organic products from N2‐derived nitrides requires new strategies to enable efficient reductive nitride transfer in the presence of organic electrophiles. We here present a 2‐step protocol for the conversion of dinitrogen to benzonitrile. Photoelectrochemical, reductive N2 splitting produces a rhenium(V) nitride with unfavorable PCET thermochemistry towards ammonia generation. However, N‐benzoylation stabilizes subsequent reduction as a basis for selective nitrogen transfer in the presence of the organic electrophile and Brønsted acid at mild reduction potentials. This work offers a new strategy for photoelectrosynthetic nitrogen fixation beyond ammonia—to yield nitrogenous organic products.
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Affiliation(s)
- Maximilian Fritz
- Institut für Anorganische Chemie Georg August Universität Göttingen Tammannstraße 4 37077 Göttingen Germany
| | - Severine Rupp
- Theoretische Chemie Technische Universität Darmstadt Alarich-Weiss-Straße 4 64287 Darmstadt Germany
| | - Ciara I. Kiene
- Institut für Anorganische Chemie Georg August Universität Göttingen Tammannstraße 4 37077 Göttingen Germany
| | - Sesha Kisan
- Institut für Anorganische Chemie Georg August Universität Göttingen Tammannstraße 4 37077 Göttingen Germany
| | - Joshua Telser
- Department of Biological Physical and Health Sciences Roosevelt University 430 S. Michigan Avenue Chicago IL 60605 USA
| | - Christian Würtele
- Institut für Anorganische Chemie Georg August Universität Göttingen Tammannstraße 4 37077 Göttingen Germany
| | - Vera Krewald
- Theoretische Chemie Technische Universität Darmstadt Alarich-Weiss-Straße 4 64287 Darmstadt Germany
| | - Sven Schneider
- Institut für Anorganische Chemie Georg August Universität Göttingen Tammannstraße 4 37077 Göttingen Germany
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Tian YC, Jiang Y, Lin YH, Zhang P, Wang CC, Ye S, Lee WZ. Hydrogen Atom Transfer Thermodynamics of Homologous Co(III)- and Mn(III)-Superoxo Complexes: The Effect of the Metal Spin State. JACS AU 2022; 2:1899-1909. [PMID: 36032524 PMCID: PMC9400055 DOI: 10.1021/jacsau.2c00268] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 07/22/2022] [Accepted: 07/22/2022] [Indexed: 06/15/2023]
Abstract
Systematic investigations on H atom transfer (HAT) thermodynamics of metal O2 adducts is of fundamental importance for the design of transition metal catalysts for substrate oxidation and/or oxygenation directly using O2. Such work should help elucidate underlying electronic-structure features that govern the OO-H bond dissociation free energies (BDFEs) of metal-hydroperoxo species, which can be used to quantitatively appraise the HAT activity of the corresponding metal-superoxo complexes. Herein, the BDFEs of two homologous CoIII- and MnIII-hydroperoxo complexes, 3-Co and 3-Mn, were calculated to be 79.3 and 81.5 kcal/mol, respectively, employing the Bordwell relationship based on experimentally determined pK a values and redox potentials of the one-electron-oxidized forms, 4-Co and 4-Mn. To further verify these values, we tested the HAT capability of their superoxo congeners, 2-Co and 2-Mn, toward three different substrates possessing varying O-H BDFEs. Specifically, both metal-superoxo species are capable of activating the O-H bond of 4-oxo-TEMPOH with an O-H BDFE of 68.9 kcal/mol, only 2-Mn is able to abstract a H atom from 2,4-di-tert-butylphenol with an O-H BDFE of 80.9 kcal/mol, and neither of them can react with 3,5-dimethylphenol with an O-H BDFE of 85.6 kcal/mol. Further computational investigations suggested that it is the high spin state of the MnIII center in 3-Mn that renders its OO-H BDFE higher than that of 3-Co, which features a low-spin CoIII center. The present work underscores the role of the metal spin state being as crucial as the oxidation state in modulating BDFEs.
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Affiliation(s)
- Yao-Cheng Tian
- Department
of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan
| | - Yang Jiang
- State
Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Yen-Hao Lin
- Department
of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan
| | - Peng Zhang
- State
Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Chun-Chieh Wang
- Department
of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan
| | - Shengfa Ye
- State
Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Way-Zen Lee
- Department
of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan
- Department
of Medicinal and Applied Chemistry, Kaohsiung
Medical University, Kaohsiung 807, Taiwan
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Almquist CC, Removski N, Rajeshkumar T, Gelfand BS, Maron L, Piers WE. Spontaneous Ammonia Activation Through Coordination-Induced Bond Weakening in Molybdenum Complexes of a Dianionic Pentadentate Ligand Platform. Angew Chem Int Ed Engl 2022; 61:e202203576. [PMID: 35748415 DOI: 10.1002/anie.202203576] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Indexed: 11/10/2022]
Abstract
Ammonia oxidation catalyzed by molecular compounds is of current interest as a carbon-free source of dihydrogen. Activation of N-H bonds through coordination to transition metal centers is a key reaction in this process. We report the substantial activation of ammonia via reaction with low-valent molybdenum complexes of a diborate pentadentate ligand system. Spontaneous loss of dihydrogen from (B2 Pz4 Py)MoII -NH3 at room temperature to produce the dinuclear μ-nitrido compound (B2 Pz4 Py)Mo-N-Mo(B2 Pz4 Py) is observed due to substantial N-H bond weakening upon coordination to Mo. Mechanistic details are supported through the experimental observation/characterization of terminal amido, imido and nitrido complexes and density functional theory computations. The generally under-appreciated role of bridging nitrido intermediates is revealed and discussed, providing guidance for further catalyst development for this process.
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Affiliation(s)
- C Christopher Almquist
- Department of Chemistry, University of Calgary, 2500 University Dr. NW, T2N 1N4, AB, Calgary, Canada
| | - Nicole Removski
- Department of Chemistry, University of Calgary, 2500 University Dr. NW, T2N 1N4, AB, Calgary, Canada
| | - Thayalan Rajeshkumar
- LPCNO, INSA, UPS, Université de Toulouse, 135 avenue de Rangueil, 31077, Toulouse, France
| | - Benjamin S Gelfand
- Department of Chemistry, University of Calgary, 2500 University Dr. NW, T2N 1N4, AB, Calgary, Canada
| | - Laurent Maron
- LPCNO, INSA, UPS, Université de Toulouse, 135 avenue de Rangueil, 31077, Toulouse, France
| | - Warren E Piers
- Department of Chemistry, University of Calgary, 2500 University Dr. NW, T2N 1N4, AB, Calgary, Canada
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35
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Cook BJ, Barona M, Johnson SI, Raugei S, Bullock RM. Weakening the N-H Bonds of NH 3 Ligands: Triple Hydrogen-Atom Abstraction to Form a Chromium(V) Nitride. Inorg Chem 2022; 61:11165-11172. [PMID: 35829761 DOI: 10.1021/acs.inorgchem.2c01115] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Weakening and cleaving N-H bonds is crucial for improving molecular ammonia (NH3) oxidation catalysts. We report the synthesis and H-atom-abstraction reaction of bis(ammonia)chromium porphyrin complexes Cr(TPP)(NH3)2 and Cr(TMP)(NH3)2 (TPP = 5,10,15,20-tetraphenyl-meso-porphyrin and TMP = 5,10,15,20-tetramesityl-meso-porphyrin) using bulky aryloxyl radicals. The triple H-atom-abstraction reaction results in the formation of CrV(por)(≡N), with the nitride derived from NH3, as indicated by UV-vis and IR and single-crystal structural determination of Cr(TPP)(≡N). Subsequent oxidation of this chromium(V) nitrido complex results in the formation of CrIII(por), with scission of the Cr≡N bond. Computational analysis illustrates the progression from CrII to CrV and evaluates the energetics of abstracting H atoms from CrII-NH3 to generate CrV≡N. The formation and isolation of CrV(por)(≡N) illustrates the stability of these species and the need to chemically activate the nitride ligand for atom transfer or N-N coupling reactivity.
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Affiliation(s)
- Brian J Cook
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Melissa Barona
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Samantha I Johnson
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Simone Raugei
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - R Morris Bullock
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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36
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Lin L, Spasyuk DM, Lalancette RA, Prokopchuk DE. Coordination-Induced Weakening of a C(sp 3)-H Bond: Homolytic and Heterolytic Bond Strength of a CH-Ni Agostic Interaction. J Am Chem Soc 2022; 144:12632-12637. [PMID: 35786956 DOI: 10.1021/jacs.2c05667] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The scission of a C(sp3)-H bond to form a new metal-alkyl bond is a fundamental step in coordination chemistry and catalysis. However, the extent of C-H bond weakening when this moiety interacts with a transition metal is poorly understood and quantifying this phenomenon could provide insights into designing more efficient C-H functionalization catalysts. We present a nickel complex with a robust adamantyl reporter ligand that enables the measurement of C-H acidity (pKa) and bond dissociation free energy (BDFE) for a C(sp3)-H agostic interaction, showing a decrease in pKa by dozens of orders of magnitude and BDFE decrease of about 30 kcal/mol upon coordination. X-ray crystallographic data is provided for all molecules, including a distorted square planar NiIII metalloradical and "doubly agostic" NiII(κ2-CH2) complex.
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Affiliation(s)
- Lirong Lin
- Department of Chemistry, Rutgers University-Newark, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Denis M Spasyuk
- Canadian Light Source, 44 Innovation Boulevard, Saskatoon, Saskatchewan S7N2V3, Canada
| | - Roger A Lalancette
- Department of Chemistry, Rutgers University-Newark, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Demyan E Prokopchuk
- Department of Chemistry, Rutgers University-Newark, 73 Warren Street, Newark, New Jersey 07102, United States
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37
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Almquist CC, Removski N, Rajeshkumar T, Gelfand B, Piers W, Maron L. Spontaneous Ammonia Activation Through Coordination Induced Bond Weakening in Molybdenum Complexes of a Dianionic Pentadentate Ligand Platform. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202203576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
| | | | | | | | - Warren Piers
- University of Calgary Department of Chemistry 2500 University Dr. NW T2N 1N4 Calgary CANADA
| | - Laurent Maron
- University of Toulouse 3: Universite Toulouse III Paul Sabatier LPCNO FRANCE
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38
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Gradiski MV, Rennie BE, Lough AJ, Morris RH. Electronic insights into aminoquinoline-based PN HN ligands: protonation state dictates geometry while coordination environment dictates N-H acidity and bond strength. Dalton Trans 2022; 51:11241-11254. [PMID: 35731231 DOI: 10.1039/d2dt01556k] [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
A variety of transition metal complexes bearing aminoquinoline PNHH'-R ligands R = Ph (L1H), Cy (L2H) and their amido analogues are reported for rhodium(I) ([Rh(L1H)(PPh3)]+1 and Rh(L1)(PPh3) 2), cobalt(II) (Co(L2)(Cl) 3), and iron(II) ([Fe(L1H)2]2+5, Fe(L1)26, and [Fe(C5Me5)(L1H)]PF67). The acid-base and redox properties of the amido complexes 2, 6, and their protio parent complexes 1, and 5 permit the determination of the pKa and bond dissociation free energy (BDFE) of their N-H bonds while the ligand scaffold is coordinated to metal centres of square planar and octahedral geometry, respectively. From relative concentrations obtained by the use of 31P{1H} NMR spectroscopy, a pKaTHF value of 14 is calculated for rhodium complex 1, 6.4 for iron complex 5, and 24 for iron complex 7. These data, when combined with elecrochemical potentials obtained via cyclic voltammetry, allow the calculations of BDFE values for the N-H bond of 69 kcal mol-1 for 1, and of 55 kcal mol-1 for 5.
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Affiliation(s)
- Matthew V Gradiski
- Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario, M5S 3H6, Canada.
| | - Benjamin E Rennie
- Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario, M5S 3H6, Canada.
| | - Alan J Lough
- Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario, M5S 3H6, Canada.
| | - Robert H Morris
- Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario, M5S 3H6, Canada.
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39
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Fritz M, Rupp S, Kiene CI, Kisan S, Telser J, Würtele C, Krewald V, Schneider S. Photoelectrochemical Conversion of Dinitrogen to Benzonitrile: Selectivity Control by Electrophile‐ versus Proton‐Coupled Electron Transfer. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202205922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Maximilian Fritz
- University of Göttingen: Georg-August-Universitat Gottingen Institut für Anorganische Chemie GERMANY
| | - Severine Rupp
- TU Darmstadt: Technische Universitat Darmstadt Theoretische Chemie GERMANY
| | - Ciara Isabel Kiene
- University of Göttingen: Georg-August-Universitat Gottingen Institut für Anorganische Chemie GERMANY
| | - Sesha Kisan
- University of Göttingen: Georg-August-Universitat Gottingen Institut für Anorganische Chemie GERMANY
| | - Joshua Telser
- Roosevelt University Department of Biological, Physical and Health Sciences UNITED STATES
| | - Christian Würtele
- University of Göttingen: Georg-August-Universitat Gottingen Institut für Anorganische Chemie GERMANY
| | - Vera Krewald
- Darmstadt University of Technology: Technische Universitat Darmstadt Theoretische Chemie GERMANY
| | - Sven Schneider
- University of Goettingen Institute for inorganic Chemistry Tammannstr. 4 37077 Göttingen GERMANY
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40
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Wiedner ES, Appel AM, Raugei S, Shaw WJ, Bullock RM. Molecular Catalysts with Diphosphine Ligands Containing Pendant Amines. Chem Rev 2022; 122:12427-12474. [PMID: 35640056 DOI: 10.1021/acs.chemrev.1c01001] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Pendant amines play an invaluable role in chemical reactivity, especially for molecular catalysts based on earth-abundant metals. As inspired by [FeFe]-hydrogenases, which contain a pendant amine positioned for cooperative bifunctionality, synthetic catalysts have been developed to emulate this multifunctionality through incorporation of a pendant amine in the second coordination sphere. Cyclic diphosphine ligands containing two amines serve as the basis for a class of catalysts that have been extensively studied and used to demonstrate the impact of a pendant base. These 1,5-diaza-3,7-diphosphacyclooctanes, now often referred to as "P2N2" ligands, have profound effects on the reactivity of many catalysts. The resulting [Ni(PR2NR'2)2]2+ complexes are electrocatalysts for both the oxidation and production of H2. Achieving the optimal benefit of the pendant amine requires that it has suitable basicity and is properly positioned relative to the metal center. In addition to the catalytic efficacy demonstrated with [Ni(PR2NR'2)2]2+ complexes for the oxidation and production of H2, catalysts with diphosphine ligands containing pendant amines have also been demonstrated for several metals for many different reactions, both in solution and immobilized on surfaces. The impact of pendant amines in catalyst design continues to expand.
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41
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Connor GP, Delony D, Weber JE, Mercado BQ, Curley JB, Schneider S, Mayer JM, Holland PL. Facile conversion of ammonia to a nitride in a rhenium system that cleaves dinitrogen. Chem Sci 2022; 13:4010-4018. [PMID: 35440977 PMCID: PMC8985503 DOI: 10.1039/d1sc04503b] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Accepted: 02/22/2022] [Indexed: 11/21/2022] Open
Abstract
Rhenium complexes with aliphatic PNP pincer ligands have been shown to be capable of reductive N2 splitting to nitride complexes. However, the conversion of the resulting nitride to ammonia has not been observed. Here, the thermodynamics and mechanism of the hypothetical N–H bond forming steps are evaluated through the reverse reaction, conversion of ammonia to the nitride complex. Depending on the conditions, treatment of a rhenium(iii) precursor with ammonia gives either a bis(amine) complex [(PNP)Re(NH2)2Cl]+, or results in dehydrohalogenation to the rhenium(iii) amido complex, (PNP)Re(NH2)Cl. The N–H hydrogen atoms in this amido complex can be abstracted by PCET reagents which implies that they are quite weak. Calorimetric measurements show that the average bond dissociation enthalpy of the two amido N–H bonds is 57 kcal mol−1, while DFT computations indicate a substantially weaker N–H bond of the putative rhenium(iv)-imide intermediate (BDE = 38 kcal mol−1). Our analysis demonstrates that addition of the first H atom to the nitride complex is a thermochemical bottleneck for NH3 generation. Rhenium–PNP complexes split N2 to nitrides, but the nitrides do not give ammonia. Here, the thermodynamics of the hypothetical N–H bond forming steps are evaluated through the reverse reaction, showing that the first H addition is the bottleneck.![]()
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Affiliation(s)
- Gannon P Connor
- Department of Chemistry, Yale University New Haven Connecticut USA
| | - Daniel Delony
- Institute of Inorganic Chemistry, Georg-August-Universität Göttingen Göttingen Germany
| | - Jeremy E Weber
- Department of Chemistry, Yale University New Haven Connecticut USA
| | | | - Julia B Curley
- Department of Chemistry, Yale University New Haven Connecticut USA
| | - Sven Schneider
- Institute of Inorganic Chemistry, Georg-August-Universität Göttingen Göttingen Germany
| | - James M Mayer
- Department of Chemistry, Yale University New Haven Connecticut USA
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42
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Schreiber E, Fertig AA, Brennessel WW, Matson EM. Oxygen-Atom Defect Formation in Polyoxovanadate Clusters via Proton-Coupled Electron Transfer. J Am Chem Soc 2022; 144:5029-5041. [PMID: 35275632 PMCID: PMC8949770 DOI: 10.1021/jacs.1c13432] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Indexed: 11/28/2022]
Abstract
The uptake of hydrogen atoms (H-atoms) into reducible metal oxides has implications in catalysis and energy storage. However, outside of computational modeling, it is difficult to obtain insight into the physicochemical factors that govern H-atom uptake at the atomic level. Here, we describe oxygen-atom vacancy formation in a series of hexavanadate assemblies via proton-coupled electron transfer, presenting a novel pathway for the formation of defect sites at the surface of redox-active metal oxides. Kinetic investigations reveal that H-atom transfer to the metal oxide surface occurs through concerted proton-electron transfer, resulting in the formation of a transient VIII-OH2 moiety that, upon displacement of the water ligand with an acetonitrile molecule, forms the oxygen-deficient polyoxovanadate-alkoxide cluster. Oxidation state distribution of the cluster core dictates the affinity of surface oxido ligands for H-atoms, mirroring the behavior of reducible metal oxide nanocrystals. Ultimately, atomistic insights from this work provide new design criteria for predictive proton-coupled electron-transfer reactivity of terminal M═O moieties at the surface of nanoscopic metal oxides.
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Affiliation(s)
| | | | - William W. Brennessel
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Ellen M. Matson
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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43
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Walleck S, Zimmermann TP, Hachmeister H, Pilger C, Huser T, Katz S, Hildebrandt P, Stammler A, Bögge H, Bill E, Glaser T. Generation of a μ-1,2-hydroperoxo Fe IIIFe III and a μ-1,2-peroxo Fe IVFe III Complex. Nat Commun 2022; 13:1376. [PMID: 35296656 PMCID: PMC8927127 DOI: 10.1038/s41467-022-28894-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 02/17/2022] [Indexed: 12/05/2022] Open
Abstract
μ-1,2-Peroxo-diferric intermediates (P) of non-heme diiron enzymes are proposed to convert upon protonation either to high-valent active species or to activated P′ intermediates via hydroperoxo-diferric intermediates. Protonation of synthetic μ-1,2-peroxo model complexes occurred at the μ-oxo and not at the μ-1,2-peroxo bridge. Here we report a stable μ-1,2-peroxo complex {FeIII(μ-O)(μ-1,2-O2)FeIII} using a dinucleating ligand and study its reactivity. The reversible oxidation and protonation of the μ-1,2-peroxo-diferric complex provide μ-1,2-peroxo FeIVFeIII and μ-1,2-hydroperoxo-diferric species, respectively. Neither the oxidation nor the protonation induces a strong electrophilic reactivity. Hence, the observed intramolecular C-H hydroxylation of preorganized methyl groups of the parent μ-1,2-peroxo-diferric complex should occur via conversion to a more electrophilic high-valent species. The thorough characterization of these species provides structure-spectroscopy correlations allowing insights into the formation and reactivities of hydroperoxo intermediates in diiron enzymes and their conversion to activated P′ or high-valent intermediates. Iron coordination complexes can be used to gain insight on biologically relevant iron-oxygen compounds generated in iron metalloenzymes. Here, the authors characterise a μ-1,2-hydroperoxo FeIIIFeIII and a μ-1,2-peroxo FeIVFeIII, and study their reactivity in C-H activation.
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Affiliation(s)
- Stephan Walleck
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Thomas Philipp Zimmermann
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Henning Hachmeister
- Biomolekulare Photonik, Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Christian Pilger
- Biomolekulare Photonik, Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Thomas Huser
- Biomolekulare Photonik, Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Sagie Katz
- Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, D-10623, Berlin, Germany
| | - Peter Hildebrandt
- Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, D-10623, Berlin, Germany
| | - Anja Stammler
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Hartmut Bögge
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, D-45470, Mülheim an der Ruhr, Germany
| | - Thorsten Glaser
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, D-33615, Bielefeld, Germany.
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44
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Li Y, Chen JY, Miao Q, Yu X, Feng L, Liao RZ, Ye S, Tung CH, Wang W. A Parent Iron Amido Complex in Catalysis of Ammonia Oxidation. J Am Chem Soc 2022; 144:4365-4375. [PMID: 35234468 DOI: 10.1021/jacs.1c08609] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Parent amido complexes are crucial intermediates in ammonia-based transformations. We report a well-defined ferric ammine system [Cp*Fe(1,2-Ph2PC6H4NH)(NH3)]+ ([1-NH3]+), which processes electrocatalytic ammonia oxidation to N2 and H2 at a mild potential. Through establishing elementary e-/H+ conversions with the ferric ammine, a formal Fe(IV)-amido species, [1-NH2]+, together with its conjugated Lewis acid, [1-NH3]2+, was isolated and structurally characterized for the first time. Mechanism studies indicated that further oxidation of [1-NH2]+ induces the reaction of the parent amido unit with NH3. The formation of hydrazine is realized by the non-innocent nature of the phenylamido ligand that facilitates the concerted transfer of one proton and two electrons.
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Affiliation(s)
- Yongxian Li
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Jia-Yi Chen
- School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Qiyi Miao
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xin Yu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Lei Feng
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Rong-Zhen Liao
- School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Shengfa Ye
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.,Max-Planck-Institut für Kohlenforschung, D-45470 Mülheim an der Ruhr, Germany
| | - Chen-Ho Tung
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Wenguang Wang
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China.,College of Chemistry, Beijing Normal University, Beijing 100875, China
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45
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Boyd EA, Leseberg JAH, Cosner EL, Lionetti D, Henke WC, Day VW, Blakemore JD. Remote Oxidative Activation of a [Cp*Rh] Monohydride. Chemistry 2022; 28:e202104389. [PMID: 35038188 PMCID: PMC8891045 DOI: 10.1002/chem.202104389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Indexed: 11/09/2022]
Abstract
Half-sandwich rhodium monohydrides are often proposed as intermediates in catalysis, but little is known regarding the redox-induced reactivity accessible to these species. Herein, the bis(diphenylphosphino)ferrocene (dppf) ligand has been used to explore the reactivity that can be induced when a [Cp*Rh] monohydride undergoes remote (dppf-centered) oxidation by 1e- . Chemical and electrochemical studies show that one-electron redox chemistry is accessible to Cp*Rh(dppf), including a unique quasi-reversible RhII/I process at -0.96 V vs. ferrocenium/ferrocene (Fc+/0 ). This redox manifold was confirmed by isolation of an uncommon RhII species, [Cp*Rh(dppf)]+ , that was characterized by electron paramagnetic resonance (EPR) spectroscopy. Protonation of Cp*Rh(dppf) with anilinium triflate yielded an isolable and inert monohydride, [Cp*Rh(dppf)H]+ , and this species was found to undergo a quasireversible electrochemical oxidation at +0.41 V vs. Fc+/0 that corresponds to iron-centered oxidation in the dppf backbone. Thermochemical analysis predicts that this dppf-centered oxidation drives a dramatic increase in acidity of the Rh-H moiety by 23 pKa units, a reactivity pattern confirmed by in situ 1 H NMR studies. Taken together, these results show that remote oxidation can effectively induce M-H activation and suggest that ligand-centered redox activity could be an attractive feature for the design of new systems relying on hydride intermediates.
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Affiliation(s)
- Emily A. Boyd
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Julie A. Hopkins Leseberg
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Emma L. Cosner
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Davide Lionetti
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Wade C. Henke
- 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,To whom correspondence should be addressed.
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46
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Gunasekara T, Tong Y, Speelman AL, Erickson JD, Appel AM, Hall MB, Wiedner ES. Role of High-Spin Species and Pendant Amines in Electrocatalytic Alcohol Oxidation by a Nickel Phosphine Complex. ACS Catal 2022. [DOI: 10.1021/acscatal.1c05509] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Thilina Gunasekara
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Yicheng Tong
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Amy L. Speelman
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Jeremy D. Erickson
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Aaron M. Appel
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Michael B. Hall
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Eric S. Wiedner
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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47
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Skubi KL, Hooper RX, Mercado BQ, Bollmeyer MM, MacMillan SN, Lancaster KM, Holland PL. Iron Complexes of a Proton-Responsive SCS Pincer Ligand with a Sensitive Electronic Structure. Inorg Chem 2022; 61:1644-1658. [PMID: 34986307 PMCID: PMC8792349 DOI: 10.1021/acs.inorgchem.1c03499] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Sulfur/carbon/sulfur pincer ligands have an interesting combination of strong-field and weak-field donors, a coordination environment that is also present in the nitrogenase active site. Here, we explore the electronic structures of iron(II) and iron(III) complexes with such a pincer ligand, bearing a monodentate phosphine, thiolate S donor, amide N donor, ammonia, or CO. The ligand scaffold features a proton-responsive thioamide site, and the protonation state of the ligand greatly influences the reduction potential of iron in the phosphine complex. The N-H bond dissociation free energy, derived from the Bordwell equation, is 56 ± 2 kcal/mol. Electron paramagnetic resonance (EPR) spectroscopy and superconducting quantum interference device (SQUID) magnetometry measurements show that the iron(III) complexes with S and N as the fourth donors have an intermediate spin (S = 3/2) ground state with a large zero field splitting, and X-ray absorption spectra show a high Fe-S covalency. The Mössbauer spectrum changes drastically with the position of a nearby alkali metal cation in the iron(III) amido complex, and density functional theory calculations explain this phenomenon through a change between having the doubly occupied orbital as dz2 or dyz, as the former is more influenced by the nearby positive charge.
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Affiliation(s)
- Kazimer L. Skubi
- Department of Chemistry, Yale University, New Haven, Connecticut 06511
| | - Reagan X. Hooper
- Department of Chemistry, Yale University, New Haven, Connecticut 06511
| | | | - Melissa M. Bollmeyer
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853
| | - Samantha N. MacMillan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853
| | - Kyle M. Lancaster
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853
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48
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Agarwal RG, Wise CF, Warren JJ, Mayer JM. Correction to Thermochemistry of Proton-Coupled Electron Transfer Reagents and its Implications. Chem Rev 2022; 122:1482. [PMID: 34637292 PMCID: PMC10715376 DOI: 10.1021/acs.chemrev.1c00791] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rishi G Agarwal
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Catherine F Wise
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | - James M Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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49
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Electrolyte acidification from anode reactions during lithium mediated ammonia synthesis. Electrochem commun 2022. [DOI: 10.1016/j.elecom.2021.107186] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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50
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Revisiting Thin-Layer Electrochemistry in a Chip-Type Cell for the Study of Electro-organic Reactions. Anal Chem 2021; 94:1248-1255. [PMID: 34964606 DOI: 10.1021/acs.analchem.1c04467] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is important but challenging to elucidate the electrochemical reaction mechanisms of organic compounds using electroanalytical methods. Particularly, a rapid and straightforward method that provides information on reaction intermediates or other key electrochemical parameters may be useful. In this work, we exploited the advantages of classic thin-layer electrochemistry to develop a thin-layer electroanalysis microchip (TEAM). The TEAM provided better-resolved voltammetric peaks than under semi-infinite diffusion conditions owing to its small height. Importantly, rapid and accurate determination of the number of electrons transferred, n, was enabled by mechanically confining the microliter-scale volume analyte at the electrode, while securing ionic conduction using polyelectrolyte gels. The performance of the TEAM was validated using voltammetry and coulometry of standard redox couples. Utilizing the TEAM, a (spectro)electrochemical analysis of FM 1-43, an organic dye widely used in neuroscience, was successfully performed. Moreover, the TEAM was applied to study the electrochemical oxidation mechanism of pivanilides and alkyltrifluoroborate salts with different substituents and solvents. This work suggests that TEAM is a promising tool to provide invaluable mechanistic information and promote the rational design of electrosynthetic strategies.
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