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

The heterostructured Ag nanoparticles decorated Fe3O4 Glutathione (Fe3O4‐Glu‐Ag) nanoparticles (NPs) were synthesized by sonicating glutathione (Glu) with magnetite and further surface immobilization of silver NPs on it. The ensuing magnetic nano catalyst is well characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), powder X‐ray diffraction (PXRD), thermogravimetric analysis (TGA). The prepared Fe3O4‐Glu‐Ag nanoparticles have proved to be an efficient and recyclable nanocatalyst with low catalyst loading for the reduction of nitroarenes and heteronitroarenes to respective amines in the presence of NaBH4 using water as a green solvent which could be easily separated at the end of a reaction using an external magnet and can be recycled up to 5 runs without any significant loss in catalytic activity. Gram scale study for the reduction of 4‐NP has also being carried out successfully and it has been observed that this method can serve as an efficient protocol for reduction of nitroarenes on industrial level.

Fe₃O₄ – Glutathione stabilized Ag nanoparticles: A new magnetically separable robust and facile catalyst for aqueous phase reduction of nitroarenes

Kumari

Jain

2019

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

Self Cite

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).

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

Self Cite

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.