A local proton source in a [Mn(bpy-R)(CO)<sub>3</sub>Br]-type redox catalyst enables CO<sub>2</sub> reduction even in the absence of Brønsted acids

Franco, Federico; Cometto, Claudio; Vallana, Federico Ferrero; Sordello, Fabrizio; Priola, Emanuele; Minero, Claudio; Nervi, Carlo; Gobetto, Roberto

doi:10.1039/c4cc05563b

Cited by 148 publications

(151 citation statements)

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“…[10] Herein, we explore the electrocatalytic CO 2 reduction properties of the new manganese complex [Mn(CO) 3 (bis-Me NHC)Br] (1), bearing the readily available bidentate methylene bis(N-methylimidazolium) ligand bis-Me NHC ( Figure 1). In agreement with FTIR-SEC data (see below) and previous studies, [4,10,11] the observed redox events involve a2e À reduction of 1 (or 2)t ogenerate afivecoordinate anion, [Mn(CO) 3 (bis-Me NHC)] À (1 À )( or [Mn-(CO) 3 (py-Me NHC)] À , 2 À ), after loss of the axial Br À (or I À ). Complex 1 was prepared from ar eaction of the bis-Me NHC with [MnBr(CO) 5 ]i nt he presence of KO t Bu and unambiguously characterized (see the Supporting Information, Figures S1-S7).…”

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confidence: 92%

A Highly Active N‐Heterocyclic Carbene Manganese(I) Complex for Selective Electrocatalytic CO₂ Reduction to CO

et al. 2018

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We report here the first purely organometallic fac-[Mn I (CO) 3 (bis-Me NHC)Br] complex with unprecedented activity for the selective electrocatalytic reduction of CO 2 to CO,e xceeding 100 turnovers with excellent faradaic yields (h CO % 95 %) in anhydrous CH 3 CN.U nder the same conditions,amaximum turnover frequency (TOF max )of2100 s À1 was measured by cyclic voltammetry,w hichc learly exceeds the values reported for other manganese-based catalysts.M oreover,t he addition of water leads to the highest TOF max value (ca. 320 000 s À1 )ever reported for amanganese-based catalyst. AMn I tetracarbonyl intermediate was detected under catalytic conditions for the first time.

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confidence: 92%

A Highly Active N‐Heterocyclic Carbene Manganese(I) Complex for Selective Electrocatalytic CO₂ Reduction to CO

et al. 2018

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“…13,50 In contrast, in the case of complex 4, DFT calculations reported here show that several pathways are possible, thus explaining the formation of the 3 products, i.e., formic acid, CO and H 2 ( Figure 5). Maria Gomez-Mingot : 0000-0002-1557-2648.…”

Section: Discussionmentioning

confidence: 83%

“…48 Ni and Mn complexes are known to produce exclusively CO except under very particular conditions which promote formate production. 49,50 In the specific case of the [Ni(cyclam)] 2+ complex, it has been shown that even after reduction, the complex is not basic enough to react with protons and thus formation of a hydride Ni-H species, the generally proposed precursor for HCOOH and H 2 evolution, is excluded. 13 This thus explains the high selectivity of the catalyst for CO production:…”

Section: Discussionmentioning

confidence: 99%

A Bioinspired Nickel(bis-dithiolene) Complex as a Homogeneous Catalyst for Carbon Dioxide Electroreduction

et al. 2018

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Inspired by the metal active sites of formate dehydrogenase and CO-dehydrogenase, a nickel complex containing a NiS 4 motif with two dithiolene ligands mimicking molybdopterin has been prepared and structurally characterized. During electroreduction, it converts to a good catalyst for the reduction of CO 2 into formate as the major product, together with minor amounts of carbon monoxide and hydrogen, with reasonable overpotential requirement, good faradaic yield, and notable stability. Catalysis operates on a mercury electrode and dramatically less on a carbon electrode, as observed in the case of [Ni(cyclam)] 2+ complexes. Density functional theory (DFT) computations indicate the key role of a Ni(III)-hydride intermediate and provide insights into the different reaction pathways leading to HCOOH, CO, and H 2 . This study opens the route toward a new, yet unexplored, class of mononuclear sulfur-coordinated Ni catalysts for CO 2 reduction.

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“…Two mechanisms have been proposed 10,[14][15][16][17][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 the dimer [Mn(CO) 3 ( -diimine)] 2 at a more negative potential than the parent complex generating the five-coordinate anion [Mn(CO) 3 ( -diimine)] to which CO 2 coordinates and is catalyti-cally reduced in the presence of a Brönsted acid (the source of H + ).…”

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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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A local proton source in a [Mn(bpy-R)(CO)₃Br]-type redox catalyst enables CO₂ reduction even in the absence of Brønsted acids

Cited by 148 publications

References 29 publications

A Highly Active N‐Heterocyclic Carbene Manganese(I) Complex for Selective Electrocatalytic CO₂ Reduction to CO

A Highly Active N‐Heterocyclic Carbene Manganese(I) Complex for Selective Electrocatalytic CO₂ Reduction to CO

A Bioinspired Nickel(bis-dithiolene) Complex as a Homogeneous Catalyst for Carbon Dioxide Electroreduction

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

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A local proton source in a [Mn(bpy-R)(CO)3Br]-type redox catalyst enables CO2 reduction even in the absence of Brønsted acids

Cited by 148 publications

References 29 publications

A Highly Active N‐Heterocyclic Carbene Manganese(I) Complex for Selective Electrocatalytic CO2 Reduction to CO

A Highly Active N‐Heterocyclic Carbene Manganese(I) Complex for Selective Electrocatalytic CO2 Reduction to CO

A Bioinspired Nickel(bis-dithiolene) Complex as a Homogeneous Catalyst for Carbon Dioxide Electroreduction

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

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A local proton source in a [Mn(bpy-R)(CO)₃Br]-type redox catalyst enables CO₂ reduction even in the absence of Brønsted acids

A Highly Active N‐Heterocyclic Carbene Manganese(I) Complex for Selective Electrocatalytic CO₂ Reduction to CO

A Highly Active N‐Heterocyclic Carbene Manganese(I) Complex for Selective Electrocatalytic CO₂ Reduction to CO

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