One- and two-electron pathways in the electrocatalytic reduction of CO<sub>2</sub>by fac-Re(bpy)(CO)<sub>3</sub>Cl (bpy = 2,2′-bipyridine)

Sullivan, B. Patrick; Bolinger, C. Mark; Conrad, David W.; Vining, William J.; Meyer, Thomas J.

doi:10.1039/c39850001414

Cited by 378 publications

(331 citation statements)

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“…The air-stable green complex was subsequently isolated and characterized as the rhenium (0) dimer [cfuc-Re (bpy) (CO),}J (10). A recent study carried out in CH,CN with Bu,NPF, as supporting electrolyte agrees with this formulation [64]. Reaction of this complex with HCl gave H, and [Re(bpy) (CO)3Cl] (1; starting complex).…”

supporting

confidence: 74%

Photochemical and Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide Mediated by (2,2′‐Bipyridine)tricarbonylchlororhenium(I) and Related Complexes as Homogeneous Catalysts

Hawecker¹,

Lehn²,

Ziessel³

1986

Helvetica Chimica Acta

657

441

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Wac-Re(bpy) (CO),Cl] (bpy = 2,2'-bipyridine) is an efficient homogeneous catalyst for the selective and sustained photochemical or electrochemical reduction of CO, to CO. A quantum yield of 14% and a faradic efficiency of 98 % were measured in the presence of excess C1-ions.The photochemical process took place under visible-light irradiation and consumed a tertiary amine as electron donor. A formato-rhenium complex was isolated in the absence ofexcess CI-ions. Substitution by CI-ion generated free formate, but no CO was detected. Luminescence measurements showed that the tertiary amine quenches the metal-to-ligand charge-transfer excited state of the rhenium complex via a reductive mechanism, with a rate constant of 3.4 x lo7M-'S-'. The 19e-complex [Re(bpy) (CO),X]-produced either photochemically or electrochemically appears to be the active precursor in the CO-generation process. Detailed spectroscopic studies on I3C-enriched carbonyl-rhenium and formato-rhenium complexes derived from I3C-enriched C 0 2 were performed in order to confirm the origin of the products and to study the exchange of the ligands. A mechanism for the present C 0 2 photoreduction process is presented; it involves separate pathways for CO and formate generation, in which the [Re(bpy) (CO),X] complex plays the role of boih rhephotoactivr and fhe catalytic center.

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supporting

confidence: 74%

Photochemical and Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide Mediated by (2,2′‐Bipyridine)tricarbonylchlororhenium(I) and Related Complexes as Homogeneous Catalysts

Hawecker¹,

Lehn²,

Ziessel³

1986

Helvetica Chimica Acta

657

441

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“…The high overpotential creates a situation where catalysis can occur without an added proton source. Previous reports have suggested that the oxygen from CO 2 is transferred to an unknown oxide acceptor (19). The oxide acceptor can be a proton that can be extracted from acetonitrile (20) or even from the supporting electrolyte via Hoffman degradation (21).…”

Section: Uv-vis Stopped-flow Spectroscopy: Probing the Selectivity Ofmentioning

confidence: 99%

Kinetic and structural studies, origins of selectivity, and interfacial charge transfer in the artificial photosynthesis of CO

Smieja

Benson

Kumar

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

197

235

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The effective design of an artificial photosynthetic system entails the optimization of several important interactions. Herein we report stopped-flow UV-visible (UV-vis) spectroscopy, X-ray crystallographic, density functional theory (DFT), and electrochemical kinetic studies of the Reðbipy-tBuÞðCOÞ 3 ðLÞ catalyst for the reduction of CO 2 to CO. A remarkable selectivity for CO 2 over H þ was observed by stopped-flow UV-vis spectroscopy of ½Reðbipy-tBuÞðCOÞ 3 −1 . The reaction with CO 2 is about 25 times faster than the reaction with water or methanol at the same concentrations. X-ray crystallography and DFT studies of the doubly reduced anionic species suggest that the highest occupied molecular orbital (HOMO) has mixed metal-ligand character rather than being purely doubly occupied d z 2 , which is believed to determine selectivity by favoring CO 2 (σ þ π) over H þ (σ only) binding. Electrocatalytic studies performed with the addition of Brönsted acids reveal a primary H∕D kinetic isotope effect, indicating that transfer of protons to Re-CO 2 is involved in the rate limiting step. Lastly, the effects of electrode surface modification on interfacial electron transfer between a semiconductor and catalyst were investigated and found to affect the observed current densities for catalysis more than threefold, indicating that the properties of the electrode surface need to be addressed when developing a homogeneous artificial photosynthetic system. carbon dioxide reduction | electrochemistry | kinetics | electrocatalyst T he development of artificial photosynthetic systems is of immediate concern in view of the world's dependence on fossil fuels and the increasing emissions of CO 2 . Rapid industrial growth in developing nations will significantly increase the global energy demand in coming years, and although known reserves of fuels such as natural gas and coal are sufficient for the near future, they are becoming increasingly costly to obtain. As the use of fossil fuels is fundamentally unsustainable and generates greenhouse gases and other pollutants, the development of environmentally benign energy sources is important. Solar energy is an abundant alternative but suffers from being a diffuse energy source, and its availability varies by location and time of day. If we can capture solar energy and use CO 2 as a C 1 feedstock for liquid fuels, we can envision converting our global energy economy into a nearly carbon-neutral system (1).Photosynthesis is one of the great triumphs of nature and is the cornerstone for advanced life on the planet. Mankind has yet to master nature's ability to store sunlight as chemical energy by splitting CO 2 and H 2 O to form C─C, C─H, and O─O bonds. The energy-dense liquid fuels formed by this process would have the advantage of conforming to the existing infrastructure. Photosynthesis can be divided into two parts: water splitting and reduction of carbon dioxide. Water oxidation has been reviewed extensively by others (2-4).Our laboratory is currently exploring the development of C...

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“…Atmosphere IR spectroscopy 20,53,54 is an ideal tool to monitor the cathodic processes in the studied complexes, due to presence of the carbonyl ligands as strong IR reporters. Table 1 lists the key experimental and calculated vibrational frequencies for the starting complexes and several relevant intermediate and dimer species.…”

Section: Ir and Uv-vis Spectroelectrochemistry Under Inertmentioning

confidence: 99%

“…The anionic pathway is broadly similar to the two-electron pathway observed for Re complexes. 20,21 In contrast, the uncommon second pathway identified using pulsed EPR studies 19 involves coordination of CO 2 to the dimer [Mn(CO) 3 (2,2 -bpy)] 2 in the presence of a Brönsted acid in a concerted oxidative addition step. This process is shown to generate a low-spin Mn II -COOH complex, from which CO is subsequently released.…”

mentioning

confidence: 99%

Manganese Tricarbonyl Complexes with Asymmetric 2-Iminopyridine Ligands: Toward Decoupling Steric and Electronic Factors in Electrocatalytic CO₂ Reduction

et al. 2016

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Manganese tricarbonyl bromide complexes incorporating IP (2-[(phenylimino)]pyridine) derivatives, [MnBr(CO) 3 (IP)], are demonstrated as a new group of catalysts for CO 2 reduction, which represent the first example of utilization of phenylimino pyridine ligands on manganese centers for this purpose. The key feature is the asymmetric structure of the redox non-innocent ligand that permits independent tuning of its steric and electronic properties. The -diimine ligands and five new Mn(I) compounds have been synthesized, isolated in high yields and fully characterized, including X-ray crystallography. Their electrochemical and electrocatalytic behavior was investigated using cyclic voltammetry and UV-vis /IR spectroelectrochemistry within an OTTLE cell. Mechanistic investigations under an inert atmosphere have revealed differences in the nature of the reduction products as a function of steric bulk of the ligand. The direct ECE (electrochemical-chemical-electrochemical) formation of a five-coordinate anion [Mn(CO) 3 (IP)] -, a product of 2-electron reduction of the parent complex, is observed in case of the bulky The interest in solar fuels in terms of both photocatalytic and electrocatalytic CO 2 reduction 1 , in the latter case utilizing sustainable electricity, has been increasing markedly in the new millennium. The recent demonstration of the electrocatalytic activity of manganese 2 analogues of the archetypal Re(I) catalysts 3,4,5,6 for CO 2 reduction has given a new impetus to research into noble-metal-free catalytic systems. [MnBr(CO) 3 ( -diimine)] complexes have been shown to outperform rhenium-based analogues with regard to CO 2 reduction under certain conditions. 7 Most notably, the presence of a Brönsted acid 7-10 appears to be a prerequisite for catalysis with a range of tricarbonyl Mndiimine complexes. Mechanistic studies 5,10 of the active 2,2 -bipyridine-based (Rbpy) manganese catalysts have shown that one-electron reduction of the parent complex [MnBr(CO) 3 (R-bpy)] precursor results in the formation of the Mn Mn dimer [Mn(CO) 3 (Rbpy)] 2 . 8,9 Notably, neither the primary reduction product [MnBr(CO) 3 (R-bpy )] nor the five-coordinate radical intermediates [Mn(CO) 3 (R-bpy)] have been detected by either UV-vis or IR spectroscopy. 2,7 Nanosecond time-resolved infrared (TRIR) studies reveal that no detectable solvent adduct is formed before the dimerization of Mn species on this timescale; instead, the five-coordinate species is observed, which rapidly dimerises. 10 For some of the Re analogues, a one-electron reduced complex, [ReCl(CO) 3 (R-bpy )] was observed by IR spectroscopy and identified by the ca. 15-20 cm -1 decrease in the (CO) energy, 11,12,13 as was the five-coordinate radical [Re(CO) 3 ( t Bubpy)] by an additional 15-20 cm -1 shift .Two mechanisms have been proposed 10,14-18 for the ultimate reduction of [Mn(CO) 3 ( -diimine)] 2 in the presence of CO 2 , which can be referred to as the anionic, and the oxidative addition 19 pathways. The anionic pathway involves reduction of ...

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One- and two-electron pathways in the electrocatalytic reduction of CO₂by fac-Re(bpy)(CO)₃Cl (bpy = 2,2′-bipyridine)

Cited by 378 publications

References 1 publication

Photochemical and Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide Mediated by (2,2′‐Bipyridine)tricarbonylchlororhenium(I) and Related Complexes as Homogeneous Catalysts

Photochemical and Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide Mediated by (2,2′‐Bipyridine)tricarbonylchlororhenium(I) and Related Complexes as Homogeneous Catalysts

Kinetic and structural studies, origins of selectivity, and interfacial charge transfer in the artificial photosynthesis of CO

Manganese Tricarbonyl Complexes with Asymmetric 2-Iminopyridine Ligands: Toward Decoupling Steric and Electronic Factors in Electrocatalytic CO₂ Reduction

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One- and two-electron pathways in the electrocatalytic reduction of CO2by fac-Re(bpy)(CO)3Cl (bpy = 2,2′-bipyridine)

Cited by 378 publications

References 1 publication

Photochemical and Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide Mediated by (2,2′‐Bipyridine)tricarbonylchlororhenium(I) and Related Complexes as Homogeneous Catalysts

Photochemical and Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide Mediated by (2,2′‐Bipyridine)tricarbonylchlororhenium(I) and Related Complexes as Homogeneous Catalysts

Kinetic and structural studies, origins of selectivity, and interfacial charge transfer in the artificial photosynthesis of CO

Manganese Tricarbonyl Complexes with Asymmetric 2-Iminopyridine Ligands: Toward Decoupling Steric and Electronic Factors in Electrocatalytic CO2 Reduction

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One- and two-electron pathways in the electrocatalytic reduction of CO₂by fac-Re(bpy)(CO)₃Cl (bpy = 2,2′-bipyridine)

Manganese Tricarbonyl Complexes with Asymmetric 2-Iminopyridine Ligands: Toward Decoupling Steric and Electronic Factors in Electrocatalytic CO₂ Reduction