Reduction-induced CO dissociation by a [Mn(bpy)(CO)4][SbF6] complex and its relevance in electrocatalytic CO2reduction

Kuo, Hsin‐Ya; Tignor, Steven E.; Lee, Tia S.; Ni, Danrui; Park, James Eujin; Scholes, Gregory D.; Bocarsly, Andrew Bruce

doi:10.1039/c9dt04150h

Cited by 16 publications

(19 citation statements)

References 36 publications

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“…52 Recently, Andrew and co-workers directly synthesized a tetracarbonyl Mn complex [Mn(bpy)(CO) 4 ][SbF 6 ] with CO bands at 2130, 2046, 2024, and 1984 cm −1 , and this complex is an efficient electrocatalyst for the reduction of CO 2 in the presence of water. 53 In our case, when a THF solution of complex 1 was stirred for 36 h under 10 atm of CO, we observed new CO stretching bands at 2086, 1995, and 1969 cm −1 (denoted with stars in Figure S20) and this species is assigned to the tetracarbonyl manganese complex [Mn(bis-Mes NHC)(CO) 4 ] + ([2-CO] + ). The CO bands at 2085, 1993, and 1969 cm −1 in the stopped-flow experiment are consistent with the CO stretching bands of this tetracarbonyl complex.…”

Section: ■ Experimental Sectionsupporting

confidence: 63%

“…In addition, Cowan and co-workers also observed a tetracarbonyl Mn complex [Mn(bpy)(CO) 4 ] + during CO 2 reduction in situ at the electrode surface by vibrational sum-frequency generation spectroscopy . Recently, Andrew and co-workers directly synthesized a tetracarbonyl Mn complex [Mn(bpy)(CO) 4 ][SbF 6 ] with CO bands at 2130, 2046, 2024, and 1984 cm –1 , and this complex is an efficient electrocatalyst for the reduction of CO 2 in the presence of water . In our case, when a THF solution of complex 1 was stirred for 36 h under 10 atm of CO, we observed new CO stretching bands at 2086, 1995, and 1969 cm –1 (denoted with stars in Figure S20) and this species is assigned to the tetracarbonyl manganese complex [Mn(bis- Mes NHC)(CO) 4 ] + ( [2-CO] + ).…”

Section: Resultsmentioning

confidence: 99%

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Highly Active Manganese-Based CO₂ Reduction Catalysts with Bulky NHC Ligands: A Mechanistic Study

et al. 2020

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Because of the strong σ-donor and weak π-acceptor of the N-heterocyclic carbene (NHC), Mn-NHC complexes were found to be active for the reduction of CO 2 to CO with high activity. However, some NHC-based manganese complexes showed low catalytic activity and required very negative potentials. We report herein that complex fac-[Mn I (bis-Mes NHC)(CO) 3 Br] [1; bis-Mes NHC = 3,3-bis(2,4,6-trimethylphenyl)-(1,1′-diimidazolin-2,2′-diylidene)methane] could catalyze the electrochemical reduction of CO 2 to CO with high activity (TOF max = 3180 ± 6 s −1 ) at a less negative potential. Due to the introduction of the bulky Mes groups, a one-electron-reduced intermediate {[Mn 0 (bis-Mes NHC)(CO) 3 ] 0 (2 • )} was isolated as a packed "dimer" and crystallographically characterized. Stopped-flow Fourier-transform infrared spectroscopy was used to prove the direct reaction between doubly reduced intermediate fac-[Mn(bis-Mes NHC)(CO) 3 ] − and CO 2 ; the tetracarbonyl Mn complex [Mn + (bis-Mes NHC)(CO) 4 ] + ([2-CO] + ) was captured, and its further reduction proposed as the rate-limiting step.

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Section: ■ Experimental Sectionsupporting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Highly Active Manganese-Based CO₂ Reduction Catalysts with Bulky NHC Ligands: A Mechanistic Study

et al. 2020

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“…This species is reported to be the active catalyst that coordinates to CO 2 to initiate the catalytic cycle. 10 , 71 Upon application of a positive potential, the IR absorption bands of the starting complex did not completely reform, consistent with the quasi-reversibility of the reduction processes observed in the CV data. In CO 2 -saturated solution, the same spectral changes were observed during the two-electron reduction process.…”

Section: Resultssupporting

confidence: 73%

Photocatalytic Reduction of CO₂ to CO in Aqueous Solution under Red-Light Irradiation by a Zn-Porphyrin-Sensitized Mn(I) Catalyst

et al. 2022

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This work demonstrates photocatalytic CO 2 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′-{Et 2 O 3 PCH 2 } 2 -2,2′-bipyridyl)(CO) 3 ] ( 1 ), has been fully characterized, including single-crystal X-ray crystallography, and shown to reduce CO 2 to CO following photosensitization by tetra( N -methyl-4-pyridyl)porphyrin Zn(II) tetrachloride [Zn(TMPyP)]Cl 4 ( 2 ) under 625 nm irradiation. This is the first example of 2 employed as a photosensitizer for CO 2 reduction. The incorporation of −P(O)(OEt) 2 groups, decoupled from the core of the catalyst by a −CH 2 – 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 1 H and 13 C{ 1 H} 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.

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“…The most prominent [Mn(bpy)(CO) 3 ] + type complexes (Table 2, entries 1a–i) are known to dimerize to [Mn(bpy)(CO) 3 ] 2 after an initial one‐electron reduction concomitant with halide dissociation (if applicable). Further reduction leads to the formation of the active species [Mn(bpy)(CO) 3 ] − as investigated by Kuo et al [86] . In a report by Bourrez et al., the corresponding reduction waves occur at −1.56 V and −1.80 V vs. Ag/Ag + electrode [79] .…”

Section: Transition Metal Complexes As Catalysts In Electrochemical Co2 Reductionmentioning

confidence: 84%

Transition Metal Complexes as Catalysts for the Electroconversion of CO₂: An Organometallic Perspective

2021

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The electrocatalytic transformation of carbon dioxide has been a topic of interest in the field of CO2 utilization for a long time. Recently, the area has seen increasing dynamics as an alternative strategy to catalytic hydrogenation for CO2 reduction. While many studies focus on the direct electron transfer to the CO2 molecule at the electrode material, molecular transition metal complexes in solution offer the possibility to act as catalysts for the electron transfer. C1 compounds such as carbon monoxide, formate, and methanol are often targeted as the main products, but more elaborate transformations are also possible within the coordination sphere of the metal center. This perspective article will cover selected examples to illustrate and categorize the currently favored mechanisms for the electrochemically induced transformation of CO2 promoted by homogeneous transition metal complexes. The insights will be corroborated with the concepts and elementary steps of organometallic catalysis to derive potential strategies to broaden the molecular diversity of possible products.

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Reduction-induced CO dissociation by a [Mn(bpy)(CO)₄][SbF₆] complex and its relevance in electrocatalytic CO₂reduction

Abstract: [Mn(bpy)(CO)4] is isolated, characterized, and demonstrated to be an on-cycle catalytic intermediate in the [MnX(bpy)(CO)3]-catalyzed electroreduction of CO2 to CO.

Cited by 16 publications

References 36 publications

Highly Active Manganese-Based CO₂ Reduction Catalysts with Bulky NHC Ligands: A Mechanistic Study

Highly Active Manganese-Based CO₂ Reduction Catalysts with Bulky NHC Ligands: A Mechanistic Study

Photocatalytic Reduction of CO₂ to CO in Aqueous Solution under Red-Light Irradiation by a Zn-Porphyrin-Sensitized Mn(I) Catalyst

Transition Metal Complexes as Catalysts for the Electroconversion of CO₂: An Organometallic Perspective

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Reduction-induced CO dissociation by a [Mn(bpy)(CO)4][SbF6] complex and its relevance in electrocatalytic CO2reduction

Abstract: [Mn(bpy)(CO)4] is isolated, characterized, and demonstrated to be an on-cycle catalytic intermediate in the [MnX(bpy)(CO)3]-catalyzed electroreduction of CO2 to CO.

Cited by 16 publications

References 36 publications

Highly Active Manganese-Based CO2 Reduction Catalysts with Bulky NHC Ligands: A Mechanistic Study

Highly Active Manganese-Based CO2 Reduction Catalysts with Bulky NHC Ligands: A Mechanistic Study

Photocatalytic Reduction of CO2 to CO in Aqueous Solution under Red-Light Irradiation by a Zn-Porphyrin-Sensitized Mn(I) Catalyst

Transition Metal Complexes as Catalysts for the Electroconversion of CO2: An Organometallic Perspective

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Reduction-induced CO dissociation by a [Mn(bpy)(CO)₄][SbF₆] complex and its relevance in electrocatalytic CO₂reduction

Highly Active Manganese-Based CO₂ Reduction Catalysts with Bulky NHC Ligands: A Mechanistic Study

Highly Active Manganese-Based CO₂ Reduction Catalysts with Bulky NHC Ligands: A Mechanistic Study

Photocatalytic Reduction of CO₂ to CO in Aqueous Solution under Red-Light Irradiation by a Zn-Porphyrin-Sensitized Mn(I) Catalyst

Transition Metal Complexes as Catalysts for the Electroconversion of CO₂: An Organometallic Perspective