V. V. Khrizanforova

New Functional Cyclic Aminomethylphosphine Ligands for the Construction of Catalysts for Electrochemical Hydrogen Transformations

Eight-membered cyclic functional bisphosphines, namely 1,5-di-aryl-3,7-di(2-pyridyl)-1,5-diaza-3,7-diphosphacyclooctanes (aryl=2-pyridyl, m-tolyl, p-tolyl, diphenylmethyl, benzyl, (R)-(+)-(α-methyl)benzyl), with 2-pyridyl substituents on the phosphorus atoms have been synthesized by condensation of 2-pyridylphosphine, formaldehyde, and the corresponding primary amine. The structures of some of these bisphosphines have been investigated by X-ray crystallography. The bisphosphines readily form neutral P,P-chelate complexes [(κ(2)-P,P-L)MCl2], cationic bis-P,P-chelate complexes [(κ(2)-P,P-L)2 M](2+), or a five-coordinate complex [(κ(2)-P,P-L)2 NiBr]Br. The electrochemical behavior of two of the nickel complexes, and their catalytic activities in electrochemical hydrogen evolution and hydrogen oxidation, including the fuel-cell test, have been studied.

One-stage synthesis of FcP(O)(OC2H5)2 from ferrocene and α-hydroxyethylphosphonate

A new approach is proposed for ferrocene phosphorylation using α-hydroxylalkylphosphonate as a “masked” phosphorylating agent, by electrochemical reduction of a ferrocene and (Me)2C(OH)P(O)(OC2H5)2 mixture at −50 °C. The method makes it possible to obtain the product of diethyl ferrocenyl phosphonate with a high yield (87–89%) and 100% conversion of the initial phosphonate in one stage. It is evidenced with experiments that ferrocene reduction is carried out with preservation of the iron charge in the ferrocene fragment and with the formation of a cyclopentadienyl ligand radical anion at −3.3 V ref. Ag/AgCl (at −50 °C).

Electrochemical phosphorylation of coumarins catalyzed by transition metal complexes (Ni—Mn, Co—Mn)

A possibility of electrochemical phosphorylation of coumarins (coumarin, 6-methylcoumarin, 7-methylcoumarin) with diethyl phosphite was shown. The approach is based on the oxidation of a mixture of the aromatic compound and diethyl phosphite (1: 1) under mild conditions (room temperature, atmospheric pressure) in the presence of a bimetallic catalytic systems: MnIIbipy/NiIIbipy and MnIIbipy/CoIIbipy (bipy is the 2,2´-bipyridine). This method allows one to obtain diethyl arylphosphonates in high yields (up to 70%) and 100% conversion of the phosphite.

Oxygen reduction reaction catalyzed by nickel complexes based on thiophosphorylated calix[4]resorcinols and immobilized in the membrane electrode assembly of fuel cells

The catalytic activity of the nickel complexes of thiophosphorylated calix[4]resorcinols for oxygen reduction in a polymer electrolyte membrane fuel cell (PEMFC) has been studied. The conformation of the macrocyclic ligand determines the morphology and catalytic properties of the resulting organometallic species.

Nickel Complexes Based on Thiophosphorylated Calix[4]Resorcinols as Effective Catalysts for Hydrogen Evolution

Nickel complexes of thiophosphorylated calix[4]resorcinols showed high catalytic activity for hydrogen evolution from acidic solutions and stability in the electro-assisted catalysis at the surface of both glassy carbon and Hg-pool electrodes. The conformation of the macrocyclic ligand determines the dimensionality and shape of the catalytically active species generated on the electrode.

Electrochemical pathway to CH/PH functionalization of diphenylphosphine oxide

GRAPHICAL ABSTRACT ABSTRACT Electrochemical oxidative CH/PH functionalization reaction between diphenylphosphine oxide and diphenylacetylene has been performed. The yield of target cyclisation product was obtained with 76% yield after 4F of electricity was passed through the reaction mixture at 1.0 V (vs. Ag/AgCl).

New Biomimetic Catalysts for the Electrochemical Processes on the Basis of Redox-Active Macrocyclic Frame Structures

Abstract Efficient catalytic systems mimicking the action of metalloenzymes based on cyclic frame structures containing phosphorus, nitrogen, and sulfur coordinating atoms for hydrogen oxidation or reduction under mild conditions are proposed. GRAPHICAL ABSTRACT

Electrooxidative CH/PH functionalization as a novel way to synthesize benzo[b]phosphole oxides mediated by catalytic amounts of silver acetate

Electrochemical joint oxidation of diphenylphosphine oxide with acetylenes in the presence of silver acetate (10%) as a catalyst yields benzo[b]phosphole oxide derivatives under mild conditions at room temperature without additional oxidants or initiators and with yields up to 100%. The redox properties of the key intermediate of the catalytic cycle have been investigated by cyclic voltammetry and EPR spectroscopy. The Ph2P(O)Ag intermediate oxidizes easier (+0.05 V vs. Fc+/Fc) than all reaction precursors to form the phosphinyl radical Ph2P(O)˙, fixed as a spin-adduct by ESR. Thus, a radical mechanism type through the Ag+/Ag0 couple was developed for electrocatalytic conditions.

Selective fluorination of pyridine and its derivatives in the presence of high-oxidation-state transition metals

The oxidative fluorination of pyridine and 4-ethylpyridine under chemical and electro-chemical conditions in the presence of transition metal (high-oxidation-state nickel, cobalt, and silver) salts was studied. The chemical fluorination affords 2-fluoropyridine in all cases, while the electrochemical fluorination results in 2-fluoroor 3-fluoropyridine depending on the catalyst used.

Electrooxidative phosphorylation of coumarins by bimetallic catalytic systems Ni(II)/Mn(II) or Co(II)/Mn(II)

GRAPHICAL ABSTRACT ABSTRACT The phosphorylation of coumarins (coumarin, 6-methylcoumarin, 7-methylcoumarin) by catalytic oxidation of a mixture of coumarins and diethyl phosphite (1:1) in electrochemical mild conditions (room temperature and normal pressure) using bimetallic catalyst systems, MnCl2bpy/Ni(BF4)2bpy or MnCl2bpy/CoCl2bpy(bpy-2,2′-bipyridine) was realized.