Cleavage of metal-carbon bonds

Of-carbon atom, both retention and inversion have been evoked to account for the cleavage of metal-carbon bonds by halogens20,35,70,74. ... 

The anionic complex M2 [IrCl6] (M = Na and K) are commercially available and have been used as outer-sphere single-electron oxidants in mechanistic studies of the cleavage of metal-carbon bonds [218]. The isostructural oxidant [PtCle] is also known, especially its ability to oxidize saturated hydrocarbon by electrophilic C-H activation (inner-sphere two-electron oxidant) [219]. 

FR Hartley and S Patai, The Chemistry of the Metal Carbon Bond, John Wiley and Sons, New York Vol 1, The Structure, Preparation, Thermochemistry and Characterization of Organometallic Compounds, 1983 Vol 2, The Nature and Cleavage of Metal-Carbon Bonds,... 

Barker, P. J., Winter, J. N., Homolytic Cleavage of Metal-Carbon Bonds, Chem. Met.-Carbon Bond 2 [1985] 151/218. 

Cleavage of Platinum-Carbon o-Bonds.—Electrophilic cleavage of metal-carbon bonds may take place either by a direct attack on the bond or by an oxidative addition of the central metal followed by reductive elimination, cf. a recent review. Romeo and co-workers have studied reaction (8), which is first order... 

Once absorbed, metal ions and compounds enter the blood, mostly bound to blood cells and/or plasma proteins, which can be very specific (transferrins, ceruloplasmin). By the bloodstream metals are usually distributed throughout the body. Metallothioneins play an important role in distribution, function, detoxification, and maybe also toxicity of heavy metals [8]. There is a blood-brain barrier which can only be crossed by lipid-soluble molecules. Liver and kidney have a high capacity to bind metals. Bones and other mineralized tissues such as teeth can serve as storage organs for metals such as Ba, Be, Tl, Pb, Sr, La, Y. A number of metals have been shown to cross the placenta and to enter the fetal blood circulation. Biotransformation includes changes in the oxidation state, methylation processes, and cleavage of metal-carbon bonds. Gastrointestinal... 

Photochemical cleavage of metal-carbon bonds constitutes a brief part of a recent review on the photochemistry of metal carbonyls. Reviews of metal-alkyl and -aryl complexes have also appeared, one of which is concerned solely with metals in Groups IV— VII. The other deals with the formation, stability, and decomposition pathways of transition metal-carbon a-bonds, subjects of much interest in recent years. Consequently the recent isolation of the first stable methylene complex [Ta(Me)(CHa)(jj-C6H6)2] and its unequivocal characterization by a single-crystal JlT-ray diffraction study is of great interest in view of the probability that related derivatives are involved in the recently reported (see Vol, 4, p. 293) examples of a-hydride elimination in metal alkyls. 

Reversible elimination of hydrogen from a carbon which is in a jS-position relative to the transition metal has become a widely established mechanism for the cleavage of metal-carbon bonds. Until recently, however, it had been assumed that a-hydrogen elimination (Scheme 1) was not a likely process. This situation has now... 

Finally, some electrophiles can behave as monoelectronic oxidants towards 18-electron metal-alkyl complexes, which leads to decomposition of these complexes by heterolytic cleavage of metal-carbon bond in the resulting 17-electron species ... 

Sufficient evidence exists to suggest that the instability of transition-metal-carbon cr-bonds is not a consequence of a weak metal-carbon bond but is caused by the possibility of decomposition by pathways having low activation energy. Pathways readily available for the cleavage of metal-carbon bonds include... 

---