Alkyls electrophilic cleavag

Furthermore, gallium compounds can serve as model systems for aluminum congeners. Cationic gallium alkyls are of interest in synthesis and catalytic applications involving polar substituents because of the relative stability of the Ga—R bond toward hydrolysis and electrophilic cleavage compared to the otherwise superior Al-R species [11]. 

Metal alkyl reagents react with the acidic OH groups of silica, probably by the electrophilic cleavage of the metal-carbon bond. For example, the electrophilic cleavage of the metal-carbon bond occurs when organometallic reagents react with the electrophilic OH groups of the silica surface (Scheme... 

Figure 4.24 Electrophilic cleavage of alkyl ligands FeLg = Fe(CO)2Cp...

There are a number of modes by which carbon-metal bonds can be cleaved. Conceptually, they can be represented by the microscopic reverse of each of the processes in Equations 2-5 which lead to the alkylation of the metal center. Thus, the reverse of Equation 2 is represented by the well-known electrophilic cleavage of organometals.(5)... 

The electrophilic cleavage of an alkyl-tin bond can be assisted by a suitably positioned intramolecular ligating group. Thus in 5-3, the ease of the cleavage of the methyl-tin bond is ascribed to nucleophilic assistance by the sulphoxide group.38... 

The rate expression (Equation 12.15) for electrophilic cleavage of the metal-carbon bond in CpFe(CO)jR (Equation 12.12) is consistent with a mechanism in which the equilibrium in Equation 12.14 precedes removal of the alkyl ligand from the iron. The rate of the reaction increases with ionic strength and solvent polarity, and these data are consistent with an ionic intermediate. The second-order dependence of the rate on HgX shows that the coordinated electrophile E in the intermediate is likely to be HgX with an HgX " counterion. ... 

Decomposition of the diethyl acetal of formylmethylcobalamin occurs via a multistage reaction the initial step of which has a second-order rate constant of 2.6 X 10 1 mol s. These kinetic results are used to explain conflicting reports concerning the synthesis and nature of formylmethylcobalamin. A second communication has appeared with the same objective, but the studies are not as extensive as those in ref. 25. Electrophilic cleavage of cobalt-alkyl reactions between Hg + and complexes [Co(Me)(L)(H20)] (L = macrocyclic chelate) in which the rate-determining step is considered to be reaction of Hg + with the neutral cobalt complex according to the equation... 

Studies of the stereochemistry of Co—alkyl bond cleavage by electrophiles Brg and Hg + in complexes [Co(R)(dmg)2(py)] [R = cw-2-methoxycyclohexyl (i), cis- and fm 5 -4-t-butylcyclohexyl (ii) and (iii), or /m -2-hydroxycyclohexyl (iv)] are the subject of another report in this area. The bonds to (i), (ii), and (iii) are all cleaved by both electrophiles with exclusive inversion of stereochemistry at carbon. These reactions can be considered to proceed via an Se2 mechanism which usually involves retention at carbon, particularly with Hg + as the electrophile. However, steric effects are considered to be responsible for inversion reactions when large macrocyclic... 

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