Reactions of organometallic complexes with halogenes SE2 mechanism

REACTIONS OF ORGANOMETALLIC COMPLEXES WITH HALOGENES (Se2 MECHANISM) 

Many organometallic complexes react strongly with chlorine and bromine. Their standard reduction potentials are as follows  

Substitutions of the Sgl type are encountered in reactions of organometal-lic compounds in which carbon-metal bond (C-M) is clearly ionic in character. 

Bimolecular electrophilic substitutions (Se2) are very frequent. They proceed with retention or with inversion of configuration at the alkyl group. Examples are Sg2 reactions (2.2.2) and (2.2.3)  

The transition state for reaction (2.2.3) is similar to that in reactions of the Sf 2 type steric factors are similar as well. The transition state has the structure  

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