Electrochemical synthesis of organometallic compounds

Electrochemical reactions serve as efficient and convenient methods for the synthesis of organoelemental compounds. There are four major methods for the formation of element (metal)-carbon bonds. The first method utilizes the anodic oxidation of organometallic compounds using reactive metal anodes. In the second method, the organic compounds are reduced using reactive metal cathodes. The third method involves the cathodic reduction of organic compounds in the presence of metal halides. The fourth one utilizes both the cathodic and the anodic processes. 

Metal nanoparticles can be prepared in a myriad of ways, e.g., by pulse radiolysis [110], vapor synthesis techniques [111], thermal decomposition of organometallic compounds [112], sonochemical techniques [113,114], electrochemical reduction [115,116], and various chemical reduction techniques. Some of the most frequently used reducing agents include alcohols [117,118], citrate [119,120], H2 [121], borohydrides [122], and, more recently, superhydride [123]. The chosen experimental conditions determine the size, size distribution, shape, and stability of the particles. Because naked metal particles tend to aggregate readily in solution, stabilizing the nanoparticles is the key factor for a successful synthesis. Sometimes the solvent can act as a stabilizer, but usually polymers and surfac-... 

Scheme 10 Electrochemical synthesis of aUcyl substituted nitroaromatic compounds by the reaction of nitrobenzenes with organometallic reagents...

Tuck, D.G. (1979) Direct electrochemical synthesis of inorganic and organometallic compounds . Pure and Appl. Chem., 51, 2005-2018. 

Tuck, D. G., Direct Electrochemical Synthesis of Inorganic and Organometallic Compounds, Pure AppL Chem. 51 [1979] 2005/18. 

Conversely, other processes are totally original. This is especially encountered when the electrochemical act is associated with a transition metal complex catalysis. These methods have the advantage of affording the organozinc compound synthesis under simple and mild conditions that are compatible with the presence of reactive functional groups on the substrate. Importantly, these procedures are reproducible and can be run by any chemist. Besides, the preparation from a few millimoles to tens of millimoles of the organometallic compound is easy at the laboratory scale. 

The above conventional synthetic methods are based on the use of metal salts or carbonyls as complex-formers. At the same time, as far back as at the end of the nineteenth century [504], the possibility of use of compact elemental metals for obtaining complex compounds was shown. This circumstance served as a basis for development of the electrochemical [10,24,201,202,206,505-507], gas-phase [201,202,508-512], and liquid-phase [201,202,513] syntheses of metal complexes using zero-valent metals. All these syntheses are united as direct synthesis of metal complexes [201,202,513]. Much literature is devoted to this area, generalized in a series of reviews [505-507,510-513] and monographs [10,201,202,206,508]. In this respect, only principal aspects of the direct synthesis and the most recent achievements of its application for obtaining various types of coordination and organometallic compounds will be discussed in this section. 

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