Proton reduction by a bimetallic zinc selenolate electrocatalyst

Upadhyay, Aditya; Saurav, K. V.; Varghese, Evelin; Hodage, Ananda S.; Paul, Amit; Awasthi, Mahendra Kumar; Singh, Sanjay Kumar; Kumar, Sangit

doi:10.1039/d1ra08614f

Cited by 4 publications

(5 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Redox-active ligands are of special interest in HER because the ligand can act as an electron reservoir and facilitate two-electron activity with earth-abundant, cost-efficient, first-row transition metals in molecular catalysts. − For several years, we and others have evaluated Zn, , Cu, − Ni, − Pd, and Co , complexes with redox-active bis-thiosemicarbazone (BTSC) ligands (Figure ) as electrocatalysts for the HER. The highly modular nature of BTSCs allows tuning of ligand electronics and basicity.…”

Section: Introductionmentioning

confidence: 99%

Ligand-Centered Hydrogen Evolution with Ni(II) and Pd(II)DMTH

et al. 2022

View full text Add to dashboard Cite

In this study, we report a pair of electrocatalysts for the hydrogen evolution reaction (HER) based on the noninnocent ligand diacetyl-2-(4-methyl-3-thiosemicarbazone)-3-(2-pyridinehydrazone) (H 2 DMTH, H 2 L 1 ). The neutral complexes NiL 1 and PdL 1 were synthesized and characterized by spectroscopic and electrochemical methods. The complexes contain a non-coordinating, basic hydrazino nitrogen that is protonated during the HER. The pK a of this nitrogen was determined by spectrophotometric titration in acetonitrile to be 12.71 for NiL 1 and 13.03 for PdL 1 . Cyclic voltammograms of both NiL 1 and PdL 1 in acetonitrile exhibit diffusion-controlled, reversible ligand-centered events at −1.83 and −1.79 V (vs ferrocenium/ferrocene) for NiL 1 and PdL 1 , respectively. A quasireversible, ligand-centered event is observed at −2.43 and −2.34 V for NiL 1 and PdL 1 , respectively. The HER activity in acetonitrile was evaluated using a series of neutral and cationic acids for each catalyst. Kinetic isotope effect (KIE) studies suggest that the precatalytic event observed is associated with a proton-coupled electron transfer step. The highest turnover frequency values observed were 6150 s −1 at an overpotential of 0.74 V for NiL 1 and 8280 s −1 at an overpotential of 0.44 V for PdL 1 . Density functional theory (DFT) computations suggest both complexes follow a ligand-centered HER mechanism where the metals remain in the +2 oxidation state.

show abstract

Section: Introductionmentioning

confidence: 99%

Ligand-Centered Hydrogen Evolution with Ni(II) and Pd(II)DMTH

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Other redox-inactive metal complexes of NILs have also since been reported to exhibit HER and carbon dioxide reduction reaction (CO 2 RR). CO 2 RR behavior has been reported in work by Brudvig, 82 Grapperhaus, 83 Kumar, 84 and their co-workers. Reports of catalytic HT from (DHP – )–Al complexes are also known, but those may proceed via Al–hydride or Al–(DHP – ) intermediates.…”

Section: Reaction Chemistry and Applications Of Nil (Group 13) Complexesmentioning

confidence: 71%

“…In one report a structural analog to NAD + , [(pz 2 P)CH 3 ]OTf, was synthesized by alkylating pz 2 P at the central pyridyl N. Cyclic Voltammetry (CV) of [(pz 2 P)CH 3 )]OTf displayed irreversible reduction events that have a potential E p that is ∼900 mV more anodic relative to ligand-based reduction events of pz 2 P-type complexes of divalent metals. 81 Experiments probing the origin of the irreversibility of the reduction event suggest the formation of DHP − species: (pz 2 82 Grapperhaus, 83 Kumar, 84 and their coworkers. Reports of catalytic HT from (DHP − )−Al complexes are also known, but those may proceed via Al−hydride or Al− (DHP − ) intermediates.…”

Section: Ligand Proton-coupled Electron Transfer (Pcet): Hydride Tran...mentioning

confidence: 99%

Expanding the Scope of Aluminum Chemistry with Noninnocent Ligands

Parsons,

Berben

2024

Acc. Chem. Res.

View full text Add to dashboard Cite

Conspectus Aluminum is the most abundant metal in the earth’s crust at 8%, and it is also widely available domestically in many countries worldwide, which ensures a stable supply chain. To further the applications of aluminum (Al), such as in catalysis and electronic and energy storage materials, there has been significant interest in the synthesis and characterization of new Al coordination compounds that can support electron transfer (ET) and proton transfer (PT) chemistry. This has been achieved using redox and chemically noninnocent ligands (NILs) combined with the highly stable M(III) oxidation state of Al and in some cases the heavier group 13 ions, Ga and In. When ligands participate in redox chemistry or facilitate the breaking or making of new bonds, they are often termed redox or chemically noninnocent, respectively. Al(III) in particular supports rich ligand-based redox chemistry because it is so redox inert and will support the ligand across many charge and protonation states without entering into the reaction chemistry. To a lesser extent, we have reported on the heavier group 13 elements Ga and In, and this chemistry will also be included in this Account, where available. This Account is arranged into two technical sections, which are (1) Structures of Al–NIL complexes and (2) Reactivity of Al–NIL complexes. Highlights of the research work include reversible redox chemistry that has been enabled by ligand design to shut down radical coupling pathways and to prevent loss of H2 from unsaturated ligand sites. These reversible redox properties have in turn enabled the characterization of Class III electron delocalization through Al when two NIL are bound to the Al(III) in different charge states. Characterization of the metalloaromatic character of square planar Al and Ga complexes has been achieved, and characterization of the delocalized electronic structures has provided a model within which to understand and predict the ET and PT chemistry of the NIL group 13 compounds. The capacity of Al–NIL complexes to perform ET and PT has been employed in reactions that use ET or PT reactivity only or in reactions where coupled ET/PT affords hydride transfer chemistry. As an example, ligand-based PT reactions initiate metal–ligand cooperative bond activation pathways for catalysis: this includes acceptorless dehydrogenation of formic acid and anilines and transfer hydrogenation chemistry. In a complementary approach, ligand based ET/PT chemistry has been used in the study of dihydropyridinate (DHP–) chemistry where it was shown that N-coordination of group 13 ions lowers kinetic barriers to DHP– formation. Taken together, the discussion presented herein illustrates that the NIL chemistry of Al(III), and also of Ga(III) and In(III) holds promise for further developments in catalysis and energy storage.

show abstract

“…An appreciable number of mononuclear, – homo- ,,– and hetero- ,, binuclear, cubane-type tetranuclear – and other homo- and heteromultinuclear ,,– complexes as well as polymers – of first-row transition metals bearing selenolate/selenide have been reported in the literature. On the other hand, there is no report for first-row transition metal-mediated hydrolytic C–Se bond cleavage of selenolates.…”

Section: Resultsmentioning

confidence: 99%

Hydrolysis and Transfer Reactivity of the Coordinated Thiolate, Thiocarboxylate, and Selenolate in Binuclear Zinc(II) Complexes

2023

View full text Add to dashboard Cite

A new binuclear Zn(II) complex, [Zn2(PhBIMP)(DMF)2]3+ (1) (where PhBIMP1 is the anion of 2,6-bis[bis[(N-1-methyl-4,5-diphenylimidazoylmethyl)amino]methyl]-4-methylphenol), has been shown for the first time to mediate the hydrolytic C–S bond cleavage of a series of aliphatic and aromatic thiolates to yield the corresponding alcohols/phenols along with the formation of a hydrosulfide-bridged complex, [Zn2(PhBIMP)(μ-SH)(DMF)]2+ (2), which has been thoroughly characterized in comparison with the corresponding chloride complex, [Zn2(PhBIMP)(Cl)(DMF)]2+ (3), as a control. The binuclear Zn(II)-thiolate complexes [Zn2(PhBIMP)(μ-SR)]2+ (R = Ph, 4a; 3-Br-C6H4, 4b) have also been synthesized by avoiding the C–S bond cleavage reaction. Based on the experimental results for the effects of H2O and Et3N on 1, 4a, and 4b, the complex [Zn2(PhBIMP)(μ-SR)(OH)]1+ has been proposed to be the active intermediate that precedes the C–S bond cleavage of thiolates. The complex [Zn2(PhBIMP)(μ-SCOPh)(DMF)]2+ (5) also demonstrates the hydrolysis of the coordinated thiobenzoate to produce [Zn2(PhBIMP)(μ-O2CPh)(MeCN)]2+ (6). However, unlike 4a and 5, the benzeneselenolate-bridged complex, [Zn2(PhBIMP)(μ-SePh)]2+ (7), does not generate the species, [Zn2(PhBIMP)(μ-SePh)(OH)]1+, in solution, and in line with that, the coordinated benzeneselenolate in 7 does not undergo hydrolysis to generate hydroselenide and phenol. Finally, a comparative study for the transfer reactivity of the bridging –SH, –SPh, –SC(O)Ph, and –SePh ligands in 2, 4a, 5, and 7, respectively, toward selected organic substrates has been performed to reveal the distinct differences in the reactivity of these bridging ligands.

show abstract

Proton reduction by a bimetallic zinc selenolate electrocatalyst

Abstract: We report the synthesis and structural characterization of a bimetallic zinc selenolate complex consisting of a redox silent zinc metal ion and a trifunctional ligand that electrocatalyzes the reduction of protons into hydrogen gas.

Cited by 4 publications

References 48 publications

Ligand-Centered Hydrogen Evolution with Ni(II) and Pd(II)DMTH

Ligand-Centered Hydrogen Evolution with Ni(II) and Pd(II)DMTH

Expanding the Scope of Aluminum Chemistry with Noninnocent Ligands

Hydrolysis and Transfer Reactivity of the Coordinated Thiolate, Thiocarboxylate, and Selenolate in Binuclear Zinc(II) Complexes

Contact Info

Product

Resources

About