Electrochemical generation of phosphine oxide

The electrochemical generation of H3PO was performed in a single electrochemical cell with a lead cathode and a sacrificial zinc anode using P4 melted in a slightly acidic water/ethanol solution (2:1 volume ratio, water acidified with HCl, 2m) at 60 C. The overall electrochemical process may be divided in two parts. In the first step, the electrochemical generation of PH3 on the lead cathode takes place as previously described, while in the second step, mild oxidation of PH3 to H3PO occurs at the anodic surface of the zinc electrode. In agreement with cyclic voltammetry experiments showing an irreversible oxidation wave, PH3 is electrochemically active in the anodic potential range +0.80–1.25 V (vs. Ag/AgNO3, 0.01m in HCN3) and can be therefore oxidized in acidic  ater/ethanol 2:1 solution to H3PO shows the overall electrochemical process resulting in the cathodic reduction of P4 to PH3 and anodic oxidation of PH3 to H3PO (E=+1.24 V vs. Ag/AgNO3, 0.01m in CHCN3).

Electrochemical generation and observation by magnetic resonance of superparamagnetic cobalt nanoparticles

Currently the development of modern chemistry occurs in several priority areas, one of which is the development and use technology based on transition metal nanoparticles. These derivatives are widely applied in modern industry. At the present time possibilities of using metal nanoparticles in creating the new catalysts for a variety of industrial processes grow extensively. So, cobalt nanosized particles occupy a special place among known metal nanoparticles as they allow to create the catalysts, magnetic recording devices, composites, carriers of biological products.

The majority of the methods of preparation of nanoparticles, especially physical methods, are energy consuming and require specialized equipment. Constraints of the methods related to difficulties in controlling the chemical composition of product, contamination of metal nanoparticles by initial reactants. Therefore, the development of research in this area requires new methods of preparation of nanoparticles. One perspective direction is an electrochemical method for the selectively generation of metal nanoparticles of a certain size with desired properties and catalytic activity.

We have found that electrochemical reduction of coordinatively unsaturated cobalt dibromide 2,2’-bipyridine (bpy) complexes results in the formation of cobalt nanoparticles (CoNPs).4 The process of the electrochemical generation of CoNPs was monitored by in situ EPR-spectroelectrochemistry where the signals of ferromagnetic resonance (FMR) have been observed for these species. According to small-angle X-ray scattering (SAXS) analysis the average diameter and average length of the formed cylindrical CoNP is varied from 9 to 10 nm and 30-32 nm, respectively, and correlates to the g-value and the broadness of the FMR signal observed by in situ EPR-spectroelectrochemistry during the electrochemical process.

The synthesis of novel N-heterocyclic α-diphenylphosphinoglycines

Synthetic amino acids are of interest in various fields of chemistry, biochemistry and pharmacy. The first experiments with a phosphanyl group were obtained by condensation of natural amino acids with secondary phosphanes and formaldehyde, usually forming bis(phosphanylmethyl) amino acids, and studied with respect to their use as ligands in rhodium-catalysed hydrogenation reactions and in complexes for radio-diagnostics. The use of primary phosphanes extended the range of N-phosphanylmethyl amino acids to various P,N-heterocyclic types. The incorporation of P-alkyl instead of Pphenyl groups led to an increase in the sensitivity of Nalkyl-α-phosphanylglycines. To obtain more stable α-phosphanyl amino acids we systematically varied the nitrogen substituents of the (diphenylphosphanyl)glycines and report here on the novel N-aryl derivatives 1, their synthesis, structure and properties, and the first examples of their transitionmetal complexes and their use in homogeneous catalysis.

A three-component one-pot reaction of diphenylphosphine, primary amine and glyoxylic acid hydrate in diethyl ether or methanol allowed an easy access to N-monosubstituted diphenylphosphinoglycines 1b-10b.

Electrochemical synthesis of organonickel sigma-complexes

The organonickel complexes are organometallic compounds containing a Ni - C σ-bond (σ-complexes). These species are very reactive and have been mainly characterized as the intermediates of catalytic processes of cross coupling and homocoupling involving organic and elementoorganic substrates such as organic halides, chlorophosphines, unsaturated hydrocarbons, etc. Thus, only a limited number of these complexes have been isolated and characterized as the free stable species. Although the organonickel complexes have been known since the 1960s, the chemistry of these species is currently at the beginning stages of development. The interest of the researchers in this class of compounds has significantly increased over the past decade, resulting in a plethora of scientific papers published on this topic. At the same time, electrochemical methods have become more and more popular in modern synthetic chemistry, due to easy access to high reactive intermediates, including organometallic species, which can be selectively generated in situ and used for subsequent synthetic processes.​

The electrochemical reduction of [NiBr2(bpy)] (bpy is 2,2'-bipyridine) complex in the presence of aryl bromide in undivided electrochemical cell supplied with a sacrificial nickel anode results in the one-pot formation of an organonickel complex [NiBr(aryl)(bpy)].

Tracking of the formation of binuclear nickel complexes of [Ni2(μ -O2PR1R2)2(bpy)4]Br2 type by ESI and MALDI mass spectrometry

The investigation of the process of binuclear nickel complexes [Ni2(μ-O2PR1R2)2(bpy)4]Br2, where R1 = H, R2 = phenyl (Ph), 2,4,6-trimethylphenyl (Mes), 2,4,6- triisopropylphenyl (Tipp) or R1R2 = - OCH2CH(Et)NHCH(Ph)-; bpy = 2,2’-bipyridine, formation and the behaviour of these species was investigated by ESI and MALDI mass spectrometry. It was found that binuclear cationic fragments [Ni2(μ-O2PR1R2)2(bpy)2Br]+ are characteristic ions displaying the formation of binuclear nickel (II) complexes in solution.

Electrochemical reactions of white phosphorus with carbonyl compounds

Current project is aimed at the investigation of in situ electrochemical reactions of white phosphorus with organic substrates, such as carbonyl compounds (aliphatic, cyclic and aromatic ketones, aliphatic and aromatic aldehydes). These reactions lead to the formation of new phosphorous intermediates which can be important for synthesis of new organometallic compounds with P-C and P-H bonds. The proposed methods are based on previously investigated phosphorus compound – phosphine oxide H 3 PO, which can be prepared directly from white phosphorus P 4 by mild anodic oxidation of electrochemically generated phosphine PH 3 as it has been shown in our previous works.

Unsymmetrical pincer complexes of transition metals

Over the past decades, the pincer ligands have attracted an increasing interest due to the unique properties of the coordination compounds they form. These monoanionic tridentate ligands are of great importance in organometallic and coordination chemistry. Their complexes with transition metals are used as homogeneous catalysts for various processes and also as functional materials with specified properties. The metal complexes formed by the pincer ligands provide an efficient alternative to the existing catalysts based on noble metals and, hence, the use of these complexes is a promising task of the modern chemical science. Therefore, nickel as the most accessible and inexpensive analog of palladium and platinum is of great practical interest.

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