Electrochemical Synthesis and Properties of Organonickel σ-Complexes

Abstract

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.

Synthesis of Nickel(II) Complexes of Novel Naphthalimide Based Heterodipodal Schiff Base Ligands, Structure, Characterization and Application for Degradation of Pesticides

“…It can be used for the synthesis of organic compounds in both laboratory and industrial scale. In electrosynthesis, the clean energy source such as electrons is used as redox reagent instead of harmful chemicals . The electrons can easily be added and remove from the system without any complication.…”

Direct Electrochemical Synthesis of an Unusual Complex Salt: Almost Structural Identity - Different Charge

“…The direct electrochemical synthesis of metal complexes has been introduced to coordination and organometallic chemistry by Kumar and Tuck . Many main group metals,, transition metals,, or even lanthanides or actinides are usable as anode material in the electrochemical synthesis although they are used in most cases just in combination with a platinum cathode because of its noble character . But even noble metal complexes or alloy nanostructures are possible as anode material with lower yields but with unique properties .…”

The use of sacrificial anodes for the electrochemical synthesis of metallic complexes

“…D. G. Tuck and coworkers [1,2] developed this method, not only for coordination complexes but also for organometallic compounds. Several reviews reporting the possibilities of this synthetic procedure have been previously published [3][4][5][6][7][8][9][10][11][12][13].…”

“…1b) [14] or even with thermostats… More sophisticated electrochemical cells were also used; that is the case of electrochemical flow cells [13,15] which were used, in example, for the electrochemical synthesis of organometallic nickel complexes, with a continuous reagent loading (Fig. 1c).…”

“…1c). [14] and [13,15] syntheses are pure; when a highly pure metal is not available, it can be deposited on a platinum sheet by an electrolytic procedure in order to be used as an anode for the preparation of the metallic complexes.…”