[Fe(C5Ar5)(CO)2Br] complexes as hydrogenase mimics for the catalytic hydrogen evolution reaction

Hemming, Ellen B.; Chan, Bun; Turner, Peter; Corcilius, Leo; Price, Jason R.; Gardiner, MG; Masters, Anthony F.; Maschmeyer, Thomas

doi:10.1016/j.apcatb.2017.04.053

Cited by 32 publications

(33 citation statements)

References 33 publications

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“…The bonds B-F with the coordinated fluorine atoms were slightly longer than the corresponding bonds with uncoordinated ones (1.49(2) Å vs. 1.39(2) Å). The Fe-F bond lengths were within the typical range of few known BF 4 -ligated iron (II) complexes (1.96-2.26 Å), which contained only terminally η 1 -coordinated tetrafluoroborate anions [32][33][34][35][36][37][38][39]. The most of known complexes-containing bidentate κ 2 -bound tetrafluoroborate ligands were silver (I) complexes with weakly coordinated BF 4 anions, where the Ag-F distances were relatively long (2.79-3.01 Å) [40][41][42][43].…”

Section: Resultsmentioning

confidence: 69%

Synthesis and Structure of Iron (II) Complexes of Functionalized 1,5-Diaza-3,7-Diphosphacyclooctanes

et al. 2020

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In order to synthesize new iron (II) complexes of 1,5-diaza-3,7-diphosphacyclooctanes with a wider variety of the substituents on ligands heteroatoms (including functionalized ones, namely, pyridyl groups) and co-ligands, it was found that these ligands with relatively small phenyl, benzyl, and pyridin-2-yl substituents on phosphorus atoms in acetonitrile formed bis-P,P-chelate cis-complexes [L2Fe(CH3CN)2]2+ (BF4)2−, whereas P-mesityl-substituted ligand formed only monoligand P,P-complex [LFe(CH3CN)4]2+ (BF4)2−. 3,7-dibenzyl-1,5-di(1′-(R)-phenylethyl)-1,5-diaza-3,7-diphosphacyclooctane reacted with hexahydrate of iron (II) tetrafluoroborate in acetone to give an unusual bis-ligand cationic complex of the composition [L2Fe(BF4)]+ BF4−, where two fluorine atoms of the tetrafluoroborate unit occupied two pseudo-equatorial positions at roughly octahedral iron ion, according to X-ray diffraction data. 1,5-diaza-3,7-diphosphacyclooctanes replaced tetrahydrofurane and one of the carbonyl ligands of cyclopentadienyldicarbonyl(tetrahydrofuran)iron (II) tetrafluoroborate to form heteroligand complexes [CpFeL(CO)]+BF4−. The structural studies in the solid phase and in solutions showed that diazadiphosphacyclooctane ligands of all complexes adopted chair-boat conformations so that their nitrogen atoms were in close proximity to the central iron ion. The redox properties of the obtained complexes were performed by the cyclic voltammetry method.

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Section: Resultsmentioning

confidence: 69%

Synthesis and Structure of Iron (II) Complexes of Functionalized 1,5-Diaza-3,7-Diphosphacyclooctanes

et al. 2020

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“…On the basis of the above information, complexes 2a , 3a , and 4a all display a linear relationship between [TFA] and the i cat / i p ratio as the TFA concentration is changed from 2 to 10 mM (Figure ), indicating that they all do not decompose in this range. Moreover, at this linear level, the k obs (TOF) value of 2a , 3a , and 4a can be calculated by using the following equation: k obs = 1.94ν( i cat / i p ) 2 . It is therefore seen from Table that the i cat / i p values of 2a , 3a , and 4a are found to be 6.20, 5.88, and 7.28 at the highest concentration of TFA (10 mM); correspondingly, the k obs (TOF) value of 4a is calculated to be 10 s −1 , which is slightly larger than those of 2a and 3a ( ca.…”

Section: Resultsmentioning

confidence: 95%

“…In the meanwhile, the turnover frequencies (TOF) for H 2 production catalyzed by 2a , 3a , and 4a are estimated through the kinetic rate constant ( k obs ) of hydrogen evolution reaction with them as electrocatalysts, which are determined by plotting the concentration of added acid ([TFA]) against the ratio of catalytic current ( i cat ) versus reduction current ( i pc ) . On the basis of the above information, complexes 2a , 3a , and 4a all display a linear relationship between [TFA] and the i cat / i p ratio as the TFA concentration is changed from 2 to 10 mM (Figure ), indicating that they all do not decompose in this range.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, structures, and electrocatalytic properties of phosphine‐monodentate, −chelate, and ‐bridge diiron 2,2‐dimethylpropanedithiolate complexes related to [FeFe]‐hydrogenases

Zhao

Lǐ

et al. 2020

Applied Organom Chemis

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To further extend diiron subsite models of [FeFe]‐hydrogenases, the various substitutions of all‐carbonyl diiron complex Fe2(μ‐Me2pdt)(CO)6 (A, Me2pdt = (SCH2)2CMe2) with monophosphines or small bite‐angle diphosphines are studied as follows. Firstly, the monodentate complexes Fe2(μ‐Me2pdt)(CO)5{κ1‐P(C6H4R‐p)3} [R = Me (1a) and Cl (1b)] and Fe2(μ‐Me2pdt)(CO)5{κ1‐Ph2PX'} [X' = NHPh (2a) and CH2PPh2 (2b)] are readily afforded through the Me3NO‐assisted reactions of A with monophosphines P(C6H4R‐p)3 (R = Me, Cl) and diphosphines (Ph2P)2X (X = NPh, CH2 (dppm)) in MeCN at room temperature, respectively. Secondly, the chelate complexes Fe2(μ‐Me2pdt)(CO)4(κ2‐(Ph2P)2X) [X = NPh (3a) and NBun (3b)] can be efficiently prepared by the UV‐irradiated reactions of A with small bite‐angle diphosphines (Ph2P)2X (X = NPh, NBun) in toluene. Thirdly, the bridge complexes Fe2(μ‐Me2pdt)(CO)4(μ‐(Ph2P)2X) [X = NPh (4a) and CH2 (4b)] are well obtained from the refluxing solutions of A and diphosphines (Ph2P)2X (X = NPh, CH2) in xylene. Rarely, the diphosphine‐bridge complex 4b may be produced in low yield via the UV‐irradiated solutions of A and the dppm ligand in toluene emitting at 365 nm. Eight new complexes obtained above have been well characterized by using element analysis, FT‐IR, NMR (1H, 31P) spectroscopies, and particularly for 1a, 1b, 2a, 3b, 4a, 4b by X‐ray crystallography. Meanwhile, the electrochemical and electrocatalytic properties of three representative complexes 2a, 3a, and 4a with pendant N‐phenyl groups are investigated and compared by using cyclic voltammetry (CV) in the absence and presence of trifluoroacetic acid (TFA) as a proton source, indicating that they are all found to be active for electrocatalytic proton reduction to hydrogen (H2).

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“…Most importantly, the turnover frequency (TOF) for 2–4 as the active electrocatalysts are estimated through the kinetics (rate constant, k obs ) of hydrogen evolution reaction catalyzed by them, which are determined by plotting the concentration of added acid ([TFA]) against the ratio of catalytic current ( i cat ) versus reduction current ( i p ) for 2–4 as shown in Figure . Complexes 2–4 all displayed a linear relationship between the acid concentration ([TFA]) and the i cat / i p ratio when the concentration of TFA is from 2 to 10 mM (Figure ), suggesting that they do not decompose in this range.…”

Section: Resultsmentioning

confidence: 99%

Reactions of Fe₂(μ‐odt)(CO)₆ (odt = 1, 3‐oxadithiolate) with small bite‐angle diphosphines to afford the monodentate, chelate, and bridge diiron complexes: Selective substitution, structures, protonation, and electrocatalytic proton reduction

Yang

Lǐ

et al. 2019

Applied Organom Chemis

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Selective substitutions of Fe2(μ‐odt)(CO)6 (odt = 1,3‐oxadithiolate, A) and small bite‐angle diphosphines (Ph2P)2X [X = CH2 (dppm) or N (CH2CHMe2) (dppa)] have been well investigated in this study. With Me3NO·2H2O in MeCN at room temperature, the reaction of A and dppm produced the monodentate complex [Fe2(μ‐odt)(CO)5(κ1‐dppm)] (1), whereas the similar reaction with dppa afforded the chelate complex [Fe2(μ‐odt)(CO)4(κ2‐dppa)] (2). Using UV irradiation in toluene emitting at 365 nm, the treatment of A and dppm rarely resulted in the formation of the bridge complex [Fe2(μ‐odt)(CO)4(μ‐dppm)] (3), whereas the similar treatment with dppa formed the chelate complex 2. Under thermolysis condition, refluxing solution of A with dppm or dppa gave the bridge complex 3 and [Fe2(μ‐odt)(CO)4(μ‐dppa)] (4), respectively, in which the former was formed in toluene (110 °C) but the latter was produced in xylene (138 °C). All the new complexes 1–4 obtained above were characterized by element analysis, FT‐IR, NMR (1H, 31P) spectroscopies, and particularly for 1–3 by X‐ray crystallography. Furthermore, the in situ protonations of 2 with a weak acid HOAc (acetic acid) and a strong acid TFA (trifluoroacetic acid) are explored by means of FT‐IR and NMR (1H, 31P) spectra. In addition, the electrochemical behaviors of 2–4 are studied and compared through cyclic voltammetry (CV) in the absence and presence of a strong acid (TFA) as a proton source, indicating that they all are active for electrocatalytic proton reduction to hydrogen (H2).

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[Fe(C5Ar5)(CO)2Br] complexes as hydrogenase mimics for the catalytic hydrogen evolution reaction

Cited by 32 publications

References 33 publications

Synthesis and Structure of Iron (II) Complexes of Functionalized 1,5-Diaza-3,7-Diphosphacyclooctanes

Synthesis and Structure of Iron (II) Complexes of Functionalized 1,5-Diaza-3,7-Diphosphacyclooctanes

Synthesis, structures, and electrocatalytic properties of phosphine‐monodentate, −chelate, and ‐bridge diiron 2,2‐dimethylpropanedithiolate complexes related to [FeFe]‐hydrogenases

Reactions of Fe₂(μ‐odt)(CO)₆ (odt = 1, 3‐oxadithiolate) with small bite‐angle diphosphines to afford the monodentate, chelate, and bridge diiron complexes: Selective substitution, structures, protonation, and electrocatalytic proton reduction

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[Fe(C5Ar5)(CO)2Br] complexes as hydrogenase mimics for the catalytic hydrogen evolution reaction

Cited by 32 publications

References 33 publications

Synthesis and Structure of Iron (II) Complexes of Functionalized 1,5-Diaza-3,7-Diphosphacyclooctanes

Synthesis and Structure of Iron (II) Complexes of Functionalized 1,5-Diaza-3,7-Diphosphacyclooctanes

Synthesis, structures, and electrocatalytic properties of phosphine‐monodentate, −chelate, and ‐bridge diiron 2,2‐dimethylpropanedithiolate complexes related to [FeFe]‐hydrogenases

Reactions of Fe2(μ‐odt)(CO)6 (odt = 1, 3‐oxadithiolate) with small bite‐angle diphosphines to afford the monodentate, chelate, and bridge diiron complexes: Selective substitution, structures, protonation, and electrocatalytic proton reduction

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Reactions of Fe₂(μ‐odt)(CO)₆ (odt = 1, 3‐oxadithiolate) with small bite‐angle diphosphines to afford the monodentate, chelate, and bridge diiron complexes: Selective substitution, structures, protonation, and electrocatalytic proton reduction