Synthesis and structural characterization of the mono- and diphosphine-containing diiron propanedithiolate complexes related to [FeFe]-hydrogenases. Biomimetic H2 evolution catalyzed by (μ-PDT)Fe2(CO)4[(Ph2P)2N(n-Pr)]

Song, Li‐Cheng; Li, Changgong; Ge, Jin; Yang, Zhi Yong; Wang, Hu‐Ting; Zhang, Juan; Hu, Qing‐Mei

doi:10.1016/j.jinorgbio.2008.04.003

Cited by 68 publications

(19 citation statements)

References 37 publications

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“…We further determined the overpotentials of 2 and 4 in MeCN according to the Artero relationship (note that the overpotential is equal to the difference between the potentiala th alf-maximum of the catalytic current and the theoreticalh alf-waver eduction potential (E 1/2 T )o ft he acid). [69][70][71] Because the value of E 1/2 T of HOAc in MeCN is À1.39 V [69,70] and the half-wavep otentials of 2 and 4 determined for HOAc with ac oncentration of 50 mm were À2.09 and À2.07 V, respectively,t he overpotentials fort he H 2 production catalyzed by 2 and 4 in MeCN should be 700 and 680 mV,r espectively (see Figur- On the basis of above-mentioned observations and the previously reported similar cases, [38,56,58,64] we might proposea n electrochemical/chemical/chemical/electrochemical (ECCE) mechanism for H 2 production catalyzed by 2 and 4 in the presence of HOAc. Scheme 5s hows the ECCE mechanism of the representative complex 4.C omplex 4 is first reduced at À2.09 Vt og ive monoanion 4 À À and then it is protonated by HOAc to form the FeÀHspecies 4H (Scheme 5).…”

Section: Electrocatalytic Hydrogen Production Catalyzed By Model Compsupporting

confidence: 58%

“…The IR spectra of 1 and 2 displayed four and two strong absorption bands in the ranges ñ = 2004-1908 and 2016-1942 cm À1 ,r espectively,f or the carbonylg roups.T hese bands are considerably shiftedt oward al ower energy relative to those bands that correspond to the parentc omplex A (the IR spectrum of which was determined under comparable conditions: ñ CO = 2071 (s), 2031 (vs), 1986 (vs), 1937 (sh) cm À1 )d ue to substitution of their two CO ligands by the stronger electron-donating PNPl igands. [56] In addition, relative to the four n CO bands of 1,t hose bands for 2 are slightly shiftedt owardh igher energy.T his outcomei sc onsistent with the fact that the PNP ligand of 2 contains an electron-withdrawing quaternary ammonium group. The 31 P{ 1 H} NMR spectrum of 2 showed as inglet at d = 100.5 ppm for its two chemically equivalent phosphorus atoms, which is slightly downfield shiftedr elative to the corresponding singlet (d = 98.6 ppm) displayed by 1.A pparently,t his resulti sd ue to the electron-withdrawing effect of the positively-charged quaternary ammonium group in 2.…”

Section: Resultsmentioning

confidence: 96%

“…The two iron atoms of 1 and 2 adopt ad istorted square-pyramidal geometry.A lthough the Fe1ÀFe2 bond lengths in 1 and 2 are 2.6010 (7) and 2.6213 (6) ,t he P1-N1-P2 bond angles in 1 and 2 are 97.51 (10) and 99.14 (12)8,r espectively.I tf ollows that the aforementioned geometric parameters for 1 and 2 are very close to those parameters for the previously reported PNPligand-bridged PDT-type of diiron complex. [23,56] Synthesis and molecular structures of the PNP-ligandbridged precursor complex 3and the quaternary-ammonium-group-containingP NP-ligand-bridged model complex 4…”

Section: Resultsmentioning

confidence: 99%

“…These findings reflect the different coordination modes of the PNP ligandsp resent in the chelated complexes 1/2 and their isomers 3/4.I na ddition, it is worth pointingo ut that such differences in the aforementioned geometric parameters between the chelated and bridgedc omplexes are consistent with the parameters of the previously reported PNP-ligand-containing PDT-type of diiron complex. [23,56] Thermal isomerizationo fc helated complexes 1and 2i nto bridged complexes 3and 4…”

Section: Resultsmentioning

confidence: 99%

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Hydrophilic Quaternary Ammonium‐Group‐Containing [FeFe]‐Hydrogenase Models: Synthesis, Structures, and Electrocatalytic Hydrogen Production

Song

Wang

Xing

et al. 2016

Chemistry A European J

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The first quaternary ammonium-group-containing [FeFe]-hydrogenase models [(μ-PDT)Fe (CO) {κ -(Ph P) N(CH ) NMe BzBr}] (2; PDT=propanedithiolate) and [(μ-PDT)Fe (CO) {μ-(Ph P) N(CH ) NMe BzBr}] (4) have been prepared by the quaternization of their precursors [(μ-PDT)Fe (CO) {κ -(Ph P) N(CH ) NMe }] (1) and [(μ-PDT)Fe (CO) {μ-(Ph P) N(CH ) NMe }] (3) with benzyl bromide in high yields. Although new complexes 1-4 have been fully characterized by spectroscopic and X-ray crystallographic studies, the chelated complexes 1 and 2 converted into their bridged isomers 3 and 4 at higher temperatures, thus demonstrating that these bridged isomers are thermodynamically favorable. An electrochemical study on hydrophilic models 2 and 4 in MeCN and MeCN/H O as solvents indicates that the reduction potentials are shifted to less-negative potentials as the water content increases. This outcome implies that both 2 and 4 are more easily reduced in the mixed MeCN/H O solvent than in MeCN. In addition, hydrophilic models 2 and 4 act as electrocatalysts and achieve higher i /i values and turnover numbers (TONs) in MeCN/H O as a solvent than in MeCN for the production of hydrogen from the weak acid HOAc.

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Section: Electrocatalytic Hydrogen Production Catalyzed By Model Compsupporting

confidence: 58%

Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Hydrophilic Quaternary Ammonium‐Group‐Containing [FeFe]‐Hydrogenase Models: Synthesis, Structures, and Electrocatalytic Hydrogen Production

Song

Wang

Xing

et al. 2016

Chemistry A European J

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“…[38] Although synthetic chemists, who aim to reproduce [FeFe]-hydrogenase reactivity in small organometallic complexes, have been trying to overcome such problems by replacing cyanides with less basic ligands showing similar electron-donating properties (e.g., phosphines, references [8,39]), the present results illustrate the ability of nature to select a hydrogen-bonding network for the Fe d -bound cyanide ligand such that strong electrostatic interactions between the latter and the protein matrix are preserved, while at the same time the CN À group Brønsted-Lowry basicity is lowered. Analogous considerations also hold true for the Fe p -bound cyanide group.…”

mentioning

confidence: 99%

Isocyanide in Biochemistry? A Theoretical Investigation of the Electronic Effects and Energetics of Cyanide Ligand Protonation in [FeFe]‐Hydrogenases

Greco

Bruschi

Fantucci

et al. 2011

Chemistry A European J

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The presence of Fe-bound cyanide ligands in the active site of the proton-reducing enzymes [FeFe]-hydrogenases has led to the hypothesis that such Brønsted-Lowry bases could be protonated during the catalytic cycle, thus implying that hydrogen isocyanide (HNC) might have a relevant role in such crucial microbial metabolic paths. We present a hybrid quantum mechanical/molecular mechanical (QM/MM) study of the energetics of CN(-) protonation in the enzyme, and of the effects that cyanide protonation can have on [FeFe]-hydrogenase active sites. A detailed analysis of the electronic properties of the models and of the energy profile associated with H(2) evolution clearly shows that such protonation is dysfunctional for the catalytic process. However, the inclusion of the protein matrix surrounding the active site in our QM/MM models allowed us to demonstrate that the amino acid environment was finely selected through evolution, specifically to lower the Brønsted-Lowry basicity of the cyanide ligands. In fact, the conserved hydrogen-bonding network formed by these ligands and the neighboring amino acid residues is able to impede CN(-) protonation, as shown by the fact that the isocyanide forms of [FeFe]-hydrogenases do not correspond to stationary points on the enzyme QM/MM potential-energy surface.

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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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Synthesis and structural characterization of the mono- and diphosphine-containing diiron propanedithiolate complexes related to [FeFe]-hydrogenases. Biomimetic H2 evolution catalyzed by (μ-PDT)Fe2(CO)4[(Ph2P)2N(n-Pr)]

Cited by 68 publications

References 37 publications

Hydrophilic Quaternary Ammonium‐Group‐Containing [FeFe]‐Hydrogenase Models: Synthesis, Structures, and Electrocatalytic Hydrogen Production

Hydrophilic Quaternary Ammonium‐Group‐Containing [FeFe]‐Hydrogenase Models: Synthesis, Structures, and Electrocatalytic Hydrogen Production

Isocyanide in Biochemistry? A Theoretical Investigation of the Electronic Effects and Energetics of Cyanide Ligand Protonation in [FeFe]‐Hydrogenases

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

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