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Saha S, Doughty T, Banerjee D, Patel SK, Mallick D, Iyer ESS, Roy S, Mitra R. Electrocatalytic reduction of CO 2 to CO by a series of organometallic Re(I)-tpy complexes. Dalton Trans 2023; 52:15394-15411. [PMID: 37203345 DOI: 10.1039/d3dt00441d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A series of organometallic Re(I)(L)(CO)3Br complexes with 4'-substituted terpyridine ligands (L) has been synthesised as electrocatalysts for CO2 reduction. The complexes' spectroscopic characterisation and computationally optimised geometry demonstrate a facial geometry around Re(I) with three cis COs and the terpyridine ligand coordinating in a bidentate mode. The effect of substitution on the 4'-position of terpyridine (Re1-5) on CO2 electroreduction was investigated and compared with a known Lehn-type catalyst, Re(I)(bpy)(CO)3Br (Re7). All complexes catalyse CO evolution in homogeneous organic media at moderate overpotentials (0.75-0.95 V) with faradaic yields of 62-98%. The electrochemical catalytic activity was further evaluated in the presence of three Brønsted acids to demonstrate the influence of the pKa of the proton sources. The TDDFT and ultrafast transient absorption spectroscopy (TAS) studies showed combined charge transfer bands of ILCT and MLCT. Amongst the series, the Re-complex containing a ferrocenyl-substituted terpyridine ligand (Re5) shows an additional intra-ligand charge transfer band and was probed using UV-Vis spectroelectrochemistry.
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Affiliation(s)
- Shriya Saha
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Farmagudi, Goa 403401, India.
| | - Thomas Doughty
- School of Chemistry, University of Lincoln, Green Lane, Lincoln, Lincolnshire, LN6 7DL, UK.
| | - Dibyendu Banerjee
- Department of Chemistry, Presidency University, Kolkata 700073, India.
| | - Sunil K Patel
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Farmagudi, Goa 403401, India.
| | - Dibyendu Mallick
- Department of Chemistry, Presidency University, Kolkata 700073, India.
| | - E Siva Subramaniam Iyer
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Farmagudi, Goa 403401, India.
| | - Souvik Roy
- School of Chemistry, University of Lincoln, Green Lane, Lincoln, Lincolnshire, LN6 7DL, UK.
| | - Raja Mitra
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Farmagudi, Goa 403401, India.
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2
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Loke WLJ, Guo W, Sohail M, Bengali AA, Fan WY. Manganese Tricarbonyl Diimine Bromide Complexes as Electrocatalysts for Proton Reduction. Inorg Chem 2022; 61:20699-20708. [DOI: 10.1021/acs.inorgchem.2c03675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Wen Liang James Loke
- Department of Chemistry, National University of Singapore, 3 Science Drive 3,117543, Singapore
| | - Wenzhuo Guo
- Department of Chemistry, National University of Singapore, 3 Science Drive 3,117543, Singapore
| | - Muhammad Sohail
- Department of Chemistry, Texas A&M University at Qatar, Doha23874, Qatar
| | - Ashfaq A. Bengali
- Department of Chemistry, Texas A&M University at Qatar, Doha23874, Qatar
| | - Wai Yip Fan
- Department of Chemistry, National University of Singapore, 3 Science Drive 3,117543, Singapore
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3
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Capulín Flores L, Paul LA, Siewert I, Havenith R, Zúñiga-Villarreal N, Otten E. Neutral Formazan Ligands Bound to the fac-(CO) 3Re(I) Fragment: Structural, Spectroscopic, and Computational Studies. Inorg Chem 2022; 61:13532-13542. [PMID: 35969867 PMCID: PMC9438031 DOI: 10.1021/acs.inorgchem.2c02168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Metal complexes with ligands that coordinate via the nitrogen atom of azo (N═N) or imino (C═N) groups are of interest due to their π-acceptor properties and redox-active nature, which leads to interesting (opto)electronic properties and reactivity. Here, we describe the synthesis and characterization of rhenium(I) tricarbonyl complexes with neutral N,N-bidentate formazans, which possess both N═N and C═N fragments within the ligand backbone (Ar1-NH-N═C(R3)-N═N-Ar5). The compounds were synthesized by reacting equimolar amounts of [ReBr(CO)5] and the corresponding neutral formazan. X-ray crystallographic and spectroscopic (IR, NMR) characterization confirmed the generation of formazan-type species with the structure fac-[ReBr(CO)3(κ2-N2,N4(Ar1-N1H-N2═C(R3)-N3═N4-Ar5))]. The formazan ligand coordinates the metal center in the 'open' form, generating a five-membered chelate ring with a pendant NH arm. The electronic absorption and emission properties of these complexes are governed by the presence of low-lying π*-orbitals on the ligand as shown by DFT calculations. The high orbital mixing between the metal and ligand results in photophysical properties that contrast to those observed in fac-[ReBr(CO)3(L,L)] species with α-diimine ligands.
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Affiliation(s)
- Liliana Capulín Flores
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.,Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Circuito Exterior, 04510 México, D.F., México
| | - Lucas A Paul
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Inke Siewert
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Remco Havenith
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Noé Zúñiga-Villarreal
- Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Circuito Exterior, 04510 México, D.F., México
| | - Edwin Otten
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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4
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Shipp J, Parker S, Spall S, Peralta-Arriaga SL, Robertson CC, Chekulaev D, Portius P, Turega S, Buckley A, Rothman R, Weinstein JA. Photocatalytic Reduction of CO 2 to CO in Aqueous Solution under Red-Light Irradiation by a Zn-Porphyrin-Sensitized Mn(I) Catalyst. Inorg Chem 2022; 61:13281-13292. [PMID: 35960651 PMCID: PMC9446891 DOI: 10.1021/acs.inorgchem.2c00091] [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] [Indexed: 11/28/2022]
Abstract
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This work demonstrates photocatalytic CO2 reduction
by a noble-metal-free photosensitizer-catalyst system in aqueous solution
under red-light irradiation. A water-soluble Mn(I) tricarbonyl diimine
complex, [MnBr(4,4′-{Et2O3PCH2}2-2,2′-bipyridyl)(CO)3] (1), has been fully characterized, including single-crystal X-ray crystallography,
and shown to reduce CO2 to CO following photosensitization
by tetra(N-methyl-4-pyridyl)porphyrin Zn(II) tetrachloride
[Zn(TMPyP)]Cl4 (2) under 625 nm irradiation.
This is the first example of 2 employed as a photosensitizer
for CO2 reduction. The incorporation of −P(O)(OEt)2 groups, decoupled from the core of the catalyst by a −CH2– spacer, afforded water solubility without compromising
the electronic properties of the catalyst. The photostability of the
active Mn(I) catalyst over prolonged periods of irradiation with red
light was confirmed by 1H and 13C{1H} NMR spectroscopy. This first report on Mn(I) species as a homogeneous
photocatalyst, working in water and under red light, illustrates further
future prospects of intrinsically photounstable Mn(I) complexes as
solar-driven catalysts in an aqueous environment. A Mn(I) bipyridyl tricarbonyl complex,
where the diimine
ligand is functionalized with water-solubilizing phosphonate ester
groups, has been prepared and is shown to catalytically convert CO2 to CO in aqueous solution following photosensitization from
a water-soluble Zn(II) porphyrin under red-light irradiation.
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Affiliation(s)
- James Shipp
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Simon Parker
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Steven Spall
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | | | - Craig C Robertson
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Dimitri Chekulaev
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Peter Portius
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Simon Turega
- Department of Chemistry, Sheffield Hallam University, Sheffield S1 1WB, U.K
| | - Alastair Buckley
- Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, U.K
| | - Rachael Rothman
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, U.K
| | - Julia A Weinstein
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
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5
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Fujita E, Grills DC, Manbeck GF, Polyansky DE. Understanding the Role of Inter- and Intramolecular Promoters in Electro- and Photochemical CO 2 Reduction Using Mn, Re, and Ru Catalysts. Acc Chem Res 2022; 55:616-628. [PMID: 35133133 DOI: 10.1021/acs.accounts.1c00616] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Recycling of carbon dioxide to fuels and chemicals is a promising strategy for renewable energy storage. Carbon dioxide conversion can be achieved by (i) artificial photosynthesis using photoinduced electrons; (ii) electrolysis using electricity produced by photovoltaics; and (iii) thermal CO2 hydrogenation using renewable H2. The focus of our group's research is on molecular catalysts, in particular coordination complexes of transition metals (e.g., Mn, Re, and Ru), which offer versatile platforms for mechanistic studies of photo- and electrochemical CO2 reduction. The interactions of catalytic intermediates with Lewis or Brønsted acids, hydrogen-bonding moieties, solvents, cations, etc., that function as promoters or cofactors have become increasingly important for efficient catalysis. These interactions may have dramatic effects on selectivity and rates by stabilizing intermediates or lowering transition state barriers, but they are difficult to elucidate and challenging to predict. We have been carrying out experimental and theoretical studies of CO2 reduction using molecular catalysts toward addressing mechanisms of efficient CO2 reduction systems with emphasis on those containing intramolecular (or pendent) and intermolecular (solution phase) additives. This Account describes the identification of reaction intermediates produced during CO2 reduction in the presence of triethanolamine or ionic liquids, the benefits of hydrogen-bonding interactions among intermediates or cofactors, and the complications of pendent phenolic donors/phenoxide bases under electrochemical conditions.Triethanolamine (TEOA) is a common sacrificial electron donor for photosensitizer excited state reductive quenching and has a long history of use in photocatalytic CO2 reduction. It also functions as a Brønsted base in conjunction with more potent sacrificial electron donors, such as 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH). Deprotonation of the BIH•+ cation radical promotes irreversible photoinduced electron transfer by preventing charge recombination. Despite its wide use, most research to date has not considered the broader reactions of TEOA, including its direct interaction with CO2 or its influence on catalytic intermediates. We found that in acetonitrile, TEOA captures CO2 in the form of a zwitterionic adduct without any metal catalyst. In the presence of ruthenium carbonyl catalysts bearing α-diimine ligands, it participates in metal hydride formation, accelerates hydride transfer to CO2 to form the bound formate intermediate, and assists in the dissociation of formate anion from the catalyst ( J. Am. Chem. Soc. 2020, 142, 2413-2428).Hydrogen bonding and acid/base promoters are understood to interact with key catalytic intermediates, such as the metallocarboxylate or metallocarboxylic acid during CO2 reduction. The former is a high energy species, and hydrogen-bonding or Lewis acid-stabilization are beneficial. We have found that imidazolium-based ionic liquid cations can stabilize the doubly reduced form of the [ReCl(bpy)(CO)3] (bpy = 2,2'-bipyridine) electrocatalyst through both hydrogen-bonding and π-π interactions, resulting in CO2 reduction occurring at a more positive potential with a higher catalytic current ( J. Phys. Chem. Lett. 2014, 5, 2033-2038). Hydrogen bonding interactions between Lewis basic methoxy groups in the second coordination sphere of a Mn-based catalyst and the OH group of the Mn-COOH intermediate in the presence of a Brønsted acid were also found to promote C-(OH) bond cleavage, enabling access to a low-energy protonation-first pathway for CO2 reduction ( J. Am. Chem. Soc. 2017, 139, 2604-2618).The kinetics of forming the metallocarboxylic acid can be enhanced by internal acids, and its proton-induced C-OH bond cleavage to the metallocarbonyl and H2O is often the rate-limiting step. Therefore, proton movement organized by pendent hydrogen-bonding networks may also accelerate this step. In contrast, during electrolysis, OH groups in the second coordination sphere are deprotonated to the oxyanions, which deter catalytic CO2 reduction by directly binding CO2 to form the carbonate or by making an M-O bond in competition with CO2 binding ( Inorg. Chem. 2016, 55, 4582-4594). Our results emphasize that detailed mechanistic research is critical in discovering the design principles for improved catalysts.
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Affiliation(s)
- Etsuko Fujita
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - David C. Grills
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Gerald F. Manbeck
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Dmitry E. Polyansky
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
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6
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Rotundo L, Grills DC, Gobetto R, Priola E, Nervi C, Polyansky DE, Fujita E. Photochemical CO
2
Reduction Using Rhenium(I) Tricarbonyl Complexes with Bipyridyl‐Type Ligands with and without Second Coordination Sphere Effects. CHEMPHOTOCHEM 2021. [DOI: 10.1002/cptc.202000307] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Laura Rotundo
- Chemistry Department University of Torino Via P. Giuria 7 10125 Torino Italy
- CIRCC Via Celso Ulpiani 27, 70126 Bari Italy
| | - David C. Grills
- Chemistry Division Brookhaven National Laboratory Upton NY 11973–5000 USA
| | - Roberto Gobetto
- Chemistry Department University of Torino Via P. Giuria 7 10125 Torino Italy
- CIRCC Via Celso Ulpiani 27, 70126 Bari Italy
| | - Emanuele Priola
- Chemistry Department University of Torino Via P. Giuria 7 10125 Torino Italy
- CIRCC Via Celso Ulpiani 27, 70126 Bari Italy
| | - Carlo Nervi
- Chemistry Department University of Torino Via P. Giuria 7 10125 Torino Italy
- CIRCC Via Celso Ulpiani 27, 70126 Bari Italy
| | | | - Etsuko Fujita
- Chemistry Division Brookhaven National Laboratory Upton NY 11973–5000 USA
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