Electrochemical synthesis and properties of organonickel σ-complexes

Yakhvarov, D.G., Khusnuriyalova, A.F., Sinyashin, O.G.


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.


Organometallics, Volume 33, Issue 18, 2014, Pages 4574-4589

Electrode reactions of elemental (white) phosphorus and phosphane PH 3

Yakhvarov, D.G. , Gorbachuk, E.V., Sinyashin, O.G.


Electrochemical methods have become important from the viewpoint of the development and creation of new ecologically safe and resource-saving chemical processes. The use of electrons as a "universal" and "inexhaustible" reagent for chemical reactions is the main advantage of electrochemical tools. Although electrochemical processes have been already successfully applied in the preparation of different classes of practically important chemical compounds, a very limited number of industrially applicable electrochemical processes that involve elemental (white) phosphorus is currently known, except for some examples of the electrochemical production of phosphane PH3. These are mainly associated with the investigation of bulk reactions of the electrochemically activated P4molecule and phosphorus intermediates derived therefrom; very limited attention has been paid to the electrode surface reactions as a key stage of the electrochemical process. In this Microreview we describe the electrode reactions of elemental (white) phosphorus and phosphane that accompany the electrochemical process of the preparation of some phosphorus compounds starting directly from P 4. The important role of the nature of the electrode material, the reactivity of the formed phosphorus intermediates and the surface processes are discussed. Moreover, recently, we succeeded in discovering a new, previously unstable phosphorus compound, phosphane oxide H3PO, which can be easily produced using an electrochemical method by mild anodic oxidation of phosphane PH3 electrochemically formed from P4. In this respect, some attention has been paid to the electrochemically induced processes of PH3 oxidation that result in the selective formation of phosphane oxide, which is of high interest from the viewpoint of the investigation of its properties and reactivity. Electrochemical processes involving elemental (white) phosphorus (P4) and phosphane (PH3) have been investigated and described. The importance of surface processes and the role of the electrode material in the electrochemical reactions have been elucidated. The electrochemical oxidation of PH3 and the generation of unstable H3PO using sacrificial metal anodes are discussed.


European Journal of Inorganic Chemistry, Issue 27, September 2013, Pages 4709-4726

Experimental evidence of phosphine oxide generation in solution and trapping by ruthenium complexes

Dmitry Yakhvarov, Maria Caporali, Luca Gonsalvi, Shamil Latypov, Vincenzo Mirabello, Ildar Rizvanov, Oleg Sinyashin, Piero Stoppioni, and Maurizio Peruzzini


Phosphine oxide (H3PO), the first defined compound of phosphorus in the oxidation state -1, was obtained in solution by electrochemical methods starting from white phosphorus (see picture). H3PO was characterized by NMR solution spectroscopy as a free molecule and isolated as a ligand in ruthenium(II) complexes following tautomerization to phosphinous acid, H2P(OH).


Angewandte Chemie - International Edition, Volume 50, Issue 23, 27 May 2011, Pages 5370-5373

New dinuclear nickel(II) complexes: Synthesis, structure, electrochemical, and magnetic properties

Yakhvarov, D., Trofimova, E., Sinyashin, O., Kataeva, O., Budnikova, Y., Lönnecke, P., Hey-Hawkins, E., Petr, A., Krupskaya, Y., Kataev, V., Klingeler, R., Büchner, B.


The reaction of [NiBr2(bpy)2] (bpy = 2,2′-bipyridine) with organic phosphinic acids ArP(O)(OH)H [Ar = Ph, 2,4,6-trimethylphenyl (Mes), 9-anthryl (Ant)] leads to the formation of binuclear nickel(II) complexes with bridging ArP(H)O2 - ligands. Crystal structures of the binuclear complexes [Ni2(μ- O2P(H)Ar)2(bpy)4]Br2 (Ar = Ph, Mes, Ant) have been determined. In each structure, the metal ions have distorted octahedral coordination and are doubly bridged by two arylphosphinato ligands. Magnetic susceptibility measurements have shown that these complexes display strong antiferromagnetic coupling between the two nickel atoms at low temperatures, apparently similar to binuclear nickel(II) complexes with bridging carboxylato ligands. Cyclic voltammetry and in situ EPR spectroelectrochemistry show that these complexes can be electrochemically reduced and oxidized with the formation of Ni(I),Ni(0)/Ni(III) derivatives.


Inorganic Chemistry, Volume 50, Issue 10, 16 May 2011, Pages 4553-4558

A snapshot of P4 tetrahedron opening: Rh- and Ir-mediated activation of white phosphorus

Yakhvarov, D., Barbaro, P., Gonsalvi, L., Carpio, S.M., Midollini, S., Orlandini, A., Peruzzini, M., Sinyashin, O., Zanobini, F.


White phosphorus reacts with [M(dppm)2]OTf (M = Rh, Ir; dppm = PPh2CH 2PPh2) to give [M(dppm)-(Ph2PCH 2PPh2PPPP)]OTf whereby a tri-hapto "P 5" ligand is assembled through P-P bond formation between one dppm PPh2 group and an activated P4 molecule (see scheme; P green, M red, C white, phenyl groups omitted). A bimetallic reaction pathway leading to the final product is proposed, as based on in situ 31P NMR studies.


Angewandte Chemie - International Edition, Volume 45, Issue 25, 19 June 2006, Pages 4182-4185

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