Synthesis, characterization, and some electrocatalytic properties of heteromultinuclear Fe I /Ru II Clusters

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As diiron subsite models of [FeFe]-hydrogenases for catalytic proton reduction to hydrogen (H 2), a new series of the phosphine-substituted diiron ethanedithiolate complexes Fe 2 (μ-edt)(CO) 6-n L n (n = 1, 2) were prepared from the variable substitutions of all-CO precursor Fe 2 (μ-edt)(CO) 6 (A) and tertiary phosphines (L1-L4) under different reaction conditions. While the Me 3 NO-assisted substitutions of A and one equiv. ligands L1-L4 [L = Ph 2 P (CH 2 NHBu t), Ph 2 P(CH 2 CH 2 NH 2), Ph 2 P(NHBu t), and Ph 2 P(C 6 H 4 Me-p)] produced the monosubstituted complexes Fe 2 (μ-edt)(CO) 5 L (1-4) in good yields, the refluxing xylene solution of A and two equiv. ligand L1 prepared complex Fe 2 (μ-edt)(CO) 5 {κ 1-Ph 2 P(CH 2 NHBu t)} (1) in low yield. Meanwhile, the UV-irradiated toluene solution of A and two equiv. ligand L3 resulted in the rare formation of the disubstituted complex Fe 2 (μ-edt) (CO) 4 {κ 1 , κ 1-(Ph 2 PNHBu t) 2 } (5) in low yield, whereas the Me 3 NO-assisted substitution of A and two equiv. ligand L4 afforded the disubstituted complex Fe 2 (μ-edt)(CO) 4 {κ 1 , κ 1-(Ph 2 PC 6 H 4 Me-p) 2 } (6) in good yield. All the model complexes 1-6 have been characterized by elemental analysis, FT-IR, NMR spectroscopy, and particularly for 1, 3, 5 by X-ray crystallography. Further, the protonations of complexes 1-4 are studied and compared with excess acetic acid (HOAc) and trifluoroacetic acid (TFA) by using FT-IR and NMR techniques. Additionally, the electrochemical and electrocatalytic properties of model complexes 1-6 are investigated and compared by cyclic voltammetry (CV), suggesting that they are electrocatalytically active for proton reduction to H 2 in the presence of HOAc.

Amine‐containing tertiary phosphine‐substituted diiron ethanedithioate (edt) complexes Fe₂(μ‐edt)(CO)_6‐nL_n (n= 1, 2): Synthesis, protonation, and electrochemical properties

Lǐ

Lü

et al. 2020

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Diiron ethane‐1,2‐dithiolate complexes with 1,2,3‐thiadiazole moiety: Synthesis, X‐ray crystal structures, electrochemistry and fungicidal activity

Yang

Liu

et al. 2020

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Four diiron ethane‐1,2‐dithiolate complexes containing 1,2,3‐thiadiazole moiety have been synthesized and characterized. Esterification of the starting complex [Fe2(CO)6{μ‐SCH2CH(CH2OH)S}] (1) with 4‐methyl‐1,2,3‐thiadiazole‐5‐carboxylic acid in the presence of 4‐dimethylaminopyridine and N,N′‐dicyclohexylcarbodiimide yielded the corresponding ester [Fe2(CO)6{μ‐SCH2CHCH2O2C(4‐C2N2SCH3)S}] (2) in good yield. Further treatment of complex 2 with a phosphine ligand triphenylphosphine, tris(2‐methoxyphenyl)phosphine, or tri(p‐tolyl)phosphine and the decarbonylation reagent Me3NO·2H2O resulted in the formation of phosphine‐substituted analogues [Fe2(CO)5L{μ‐SCH2CHCH2O2C(4‐C2N2SCH3)S}] [L = PPh3, 3; P(2‐C6H4OCH3)3, 4; P(4‐C6H4CH3)3, 5] in 60 − 80% yields. The new complexes 2–5 were characterized by elemental analysis, IR and NMR spectroscopy and further confirmed by X‐ray diffraction analysis. The electrochemical properties were studied by cyclic voltammetry, showing that these complexes can catalyse the reduction of protons to H2 in the presence of HOAc. In addition, the fungicidal activity studies revealed that the hydroxy group possibly play a significant role in the biological activity.

Heterocyclic pyrazole‐containing diiron dithiolato analogues: Synthesis, characterization, electrochemistry, and fungicidal activity

Liu

2022

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In this article, a series of diiron dithiolato analogues with a pyrazole moiety has been obtained as models for [FeFe]‐hydrogenases active site. The starting material [Fe2(CO)6{μ‐SCH2CH(CH2OH)S}] (1) reacted with N‐methyl‐5‐trifluoromethyl‐pyrazole‐4‐carboxylic acid promoted by 4‐dimethylaminopyridine and N,N′‐dicyclohexylcarbodiimide to give the target ester [Fe2(CO)6{μ‐SCH2CHCH2O2C(CF3C3N2CH3)S}] (2) in very good yield. Complex 2 further reacted with various phosphine ligands and Me3NO·2H2O to yield analogues [Fe2(CO)5L{μ‐SCH2CHCH2O2C(CF3C3N2CH3)S}] {L = PPh3, 3; P(4‐C6H4CH3)3, 4; P(2‐C6H4OCH3)3, 5; P(3‐C6H4Cl)3, 6; Ph2P(C6H11), 7} in 72%–84% yields. The new products 2–7 were structurally identified by nuclear magnetic resonance (NMR), infrared (IR), elemental analysis, and particularly for 2–6 by X‐ray crystallography. The electrochemical studies have shown that these complexes can electrocatalyze the reduction of protons to H2 with added HOAc. In addition, the fungicidal activities of these complexes have been investigated.