Electrochemical generation and observation by magnetic resonance of superparamagnetic cobalt nanoparticles

© 2017 Elsevier Ltd The electrochemical reduction of cobalt dibromide 2,2′-bipyridine (bpy) complexes (Co/bpy molar ratio 1:1) results in the formation of cobalt nanoparticles (CoNP) formed by the disproportionation reaction of the electrochemically generated cobalt(I) mononuclear complexes. The process of the electrochemical generation of CoNP was monitored by in situ EPR-spectroelectrochemistry where the signals of the ferromagnetic resonance (FMR) have been observed for these species. According to small-angle X-ray scattering (SAXS) analysis the average diameter and the 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 electrochemical process

農産物の最適貿易政策―最大値原理の応用による動学的最適化の視点から―

A reaction of bis(triphenylphosphine)palladium dibromide with white phosphorus in the presence of NaBPh4 selectively gives phosphorous acid H3PO3. The mechanism of the formation involves coordination of a white phosphorus molecule, ligand exchange, and hydrolysis of the coordinated P4 molecule in the coordination sphere of palladium. © 2010 Springer Science+Business Media, Inc

Electrochemical synthesis and properties of organonickel σ-complexes

© 2014 American Chemical Society. 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. This review summarizes the elaborated electrochemical approaches for the preparation of organonickel complexes, including a discussion of the important role of the electrochemical cell construction and the influence of the electrode material nature on the electrochemical process. In order to give more insight into the importance of organonickel complexes in synthetic chemistry and introduce the reader to this problem of organometallic chemistry, focused on the development of new synthetic protocols for preparation of stable organonickel complexes, an overview of the most important catalytic processes proceeding with participation of these highly reactive intermediates and the main types of organonickel complexes are presented. However, in this review organonickel complexes will be limited by examples in which the organic fragment is singly bonded to the nickel center, because these species are responsible for the catalytic reactions

The influence of the sacrificial anode nature on the mechanism of electrochemical arylation and alkylation of white phosphorus

The material of the sacrificial anode has a substantial effect on the nature and yield of the target products of electrochemical phosphorylation of organic halides by white phosphorus in the presence of the nickel complexes with 2,2′-bipyridine. The use of the zinc anode results in the products with tricoordinated phosphorus, viz., triorganylphosphines, the reaction on the aluminum anode affords triorganylphosphine oxides, and the presence of Mg 2+ ions in the reaction mixture provides the transformation of white phosphorus into cyclic phosphines (PhP)5

Reactions of activated organonickel σ-complexes with elemental (white) phosphorus

The reactivity of organonickel σ-complexes of the type [NiBr(Ar)(bpy)] (Ar is 2,4,6-tri-methylphenyl (Mes) or 2,4,6-triisopropylphenyl (Tipp); bpy is 2,2′-bipyridine) toward elemental (white) phosphorus was studied. For the reaction to occur, the complexes must be activated by removal of the bromide anion from the coordination sphere of nickel. This can be achieved either in the presence of halogen scavengers or by electrochemical reduction. The arylphosphinic acids ArP(O)(OH)H formed by hydrolysis of organic nickel phosphides are the major reaction products of the overall process. © 2013 Springer Science+Business Media New York

The reactivity of 2,2′-bipyridine complexes in the electrochemical reduction of organohalides

Nickel(0) complexes coordinatively unsaturated with 2,2′-bipyridine (bpy) are more reactive in the oxidative addition to organic halides than the saturated analogs, σ-Organonickel complexes formed as intermediates of catalytic cycles were prepared in high yields using nickel complexes coordinatively unsaturated with bpy and aromatic halides containing a methyl group in the ortho-position of the ring

表紙

© 2017 IUPAC & De Gruyter. The new efficient and environmentally safe methods for preparation of various classes of organic and organoelement compounds, including organonickel sigma-complexes and organophosphorus compounds bearing P-C bonds have been created using the electrochemical methods. The synthetic application of the elaborated techniques towards the process of formation of new carbon-carbon, carbon-metal and carbon-phosphorus bonds are discussed. The mechanisms of the proposed processes and the nature of the formed in the overall electrochemical process intermediates are disclosed. The elaborated methods operated in the principals of "green chemistry" can be considered as an efficient alternative to some classical methods for preparation of active catalysts, biologically active molecules and new polynuclear complexes displaying practically useful properties

Effect of a sacrificial anode material on the electrochemical generation of phosphane oxide (H3PO)

The highest yields of phosphane oxide in the title process were obtained in electrochemical cells supplied with aluminium (49%), tin (36%) or zinc (67%) anodes

Synthesis and properties of zwitterionic phosphonioglycolates

Reaction of diphenylphosphane with glyoxylic acid hydrate in diethyl ether furnished diphenylphosphanylglycolic acid 1 and in a 1:2 molar ratio almost quantitatively the zwitterionic phosphonioglycolic acid glycolate 2. Tertiary phosphanes with aryl or alkyl groups (phenyl, m/p-tolyl, p-anisyl, n-butyl, tert-butyl) react similarly to triorganylphosphonioglycolates 3a-h, which like 2 precipitate from the etheral solutions of the reactants. Tri-n- butylphosphonioglycolate (3e) forms an ionic liquid and tri-tert- butylphosphonioglycolate (3f) a viscous product whereas the other phosphonioglycolates are solids. Yields and stabilities of 3a-e increase with the P-basicity of the starting phosphane whereas bulky groups like tert-butyl cause destabilization. Compound 2 is the most stable phosphonioglycolate with only minor amounts of 1 in the solvolysis equilibrium in D2O. The triaryl and tributylphosphonioglycolates 3a-f decompose in protic solvents with recovery of tertiary phosphanes. On heating at 100 C the compounds decompose to the corresponding phosphine oxides, minor amounts of glycolic acid and unidentified products. © 2013 Elsevier Ltd. All rights reserved

Electrochemical reactions of white phosphorus

The main electrochemical transformations of elemental (white) phosphorus were considered. Special attention was given to the recently developed processes of preparation of organophosphorus compounds (OPCs) with phosphorus-carbon bonds. The electrochemical approaches to the synthesis of OPCs from white phosphorus using organonickel and organozinc reagents are described. The importance of using the electrochemical methods for the generation of highly reactive phosphorus intermediates was shown for phosphine oxide H3PO obtained for the first time. This provides significant prospects for the electrochemical approaches that could be applied for the development of technologies of the chlorine-free synthesis of OPCs from white phosphorus. © 2012 Springer Science+Business Media New York